18 : Stress Management and Herbal Adaptogens

SHALINI SAGGU^1* AND RATAN KUMAR¹

Abstract

Prolonged and chronic stress lead to decreased performance and stress induced disorders. ‘Adaptogens’ are non-pharmacological natural herbal and mineral substances used for managing stress. Various single and composite herbal preparations are known and have been scientifically evaluated for their anti-stress, adaptogenic and performance enhancing activity. The studies have indicated that herbal adaptogens help in increasing the stress tolerance in adverse climatic conditions such as high altitude and cold.

Key words: Adaptogens, Anti-stress, Health food supplements

1.    Department of Biochemical Pharmacology, Defence Institute of Physiology and Allied Sciences (DIPAS), Lucknow Road, Timarpur, Delhi 110 054, India. Present address: Department of Pharmaceutical Sciences, College of Pharmacy, Medical University of South Carolina, Charleston, SC, 29425, USA.

* Corresponding author : E-mail: shalinisaggu05@gmail.com

Introduction

Exposure to adverse climatic conditions in organisms may cause stress. Stressors related to physical, chemical, immunological, biological and emotional factors do play a role in causing the stress. People staying and working in adverse climatic conditions such as cold, heat and high altitude also suffer from stress-induced disorders including decreased performance. But not all the individuals suffer from stress-induced maladies. Only some persons who are unable to acclimatize successfully suffer from such diseases. This indicates that genetic factors do play an important role in acclimatization during exposure to adverse climatic conditions. Some of the studies have shown that there is association of various gene polymorphisms and up or down regulation of genes with stress-induced diseases in animals and humans during exposure to adverse climatic conditions (Dolt et al., 2007; Grill et al., 2003; Kumar et al., 2003, 2004; Pasha et al., 2001, 2002; Rupert & Hochachka, 2001; Saxena et al., 2005).

During stressful conditions there is a metabolic shift from anaerobic to aerobic metabolism to meet the energy requirements. This results in generation of more free radicals which are also a factor in causing diseases. In mammals, the organs that have shown to be the most vulnerable to the accumulation of oxidative damage are brain, heart and skeletal muscle (Sies, 1991), resulting in various disorders and decreased performance. However the people, who can acclimatize successfully, demonstrate better anti-oxidants level (Kumar et al., 2000). Hence, differential expression of genes, proteins and biomolecules is an important area to be studied to better understand stress mechanism.

The work setting beyond a certain threshold limit in alien environments results into decreased physical and mental performance. This is on account of stress induced increased demands posed on body resources including energy, resulting into physiological adjustments affecting the health and performance. With change in life style and day-to-day increase in stress producing factors beyond the threshold limits, a large number of populations suffer from stress-induced diseases. Stress is a non-specific response of the body to any demand imposed on it. The stress comprises a set of reactions in the organism to help its body to overcome the effect of changing conditions. Such reactions mobilize energy and gear up the body to withstand ‘demands’ for successful survival (Cannon & De La-Paz, 1911; Selye, 1950). Normally such stress induced changes are compensatory, self limiting and adaptive. However, in higher animals when stress events of any nature (physical, chemical, biological and emotional) over ride certain ‘threshold’ limits, the changes become rather irreversible. It leads to altered homeostasis and exhaustion, manifesting itself in the pathological form of stress induced diseases and maladjustment (Avtsyn, 1974). Stress could be a simple one such as low environment temperature or a complex one such as in Combat and Psychosocial stress. A complex stressful situation occurs at high altitude.

High altitude stress

The term ‘high altitude’ has no precise definition. High altitude is taken an elevation of 3000 m or more, because it is this height that the majority of subjects ascending high mountains develop unequivocal signs and symptoms associated with the ascent. The high altitude environment consists of various stressors viz. hypoxia, cold, humidity, solar radiation, ultraviolet radiation and ionizing radiation. The major stress stimuli are hypoxia and cold. The percentage of O₂ in the atmosphere is the same at high altitude as it is at sea level. Indeed this percentage of 20.93% remains constant in the atmosphere up to an altitude of 110000 m but the partial pressure of O₂ (PO₂) is progressively reduced with increasing altitude. Shortage of O₂ is most important feature of physical environment at high altitude for living organisms and physiological adjustments to a chronic deprivation of O₂. In common medical and physiological parlance, shortage of O₂ is termed ‘hypoxia’ (Heath & Williams, 1980).

Another environment hazard to life in mountains is cold. Temperature falls with increasing altitude by about 1 ^oC for every 150 m and this is independent of latitude. High mountain regions usually have a low temperature and low relative humidity, a combination of which can prove very unpleasant to man. The sojourners who are unable to acclimatize successfully in such a stressful environment suffer from high altitude induced diseases such as acute mountain sickness, high altitude pulmonary edema, high altitude cerebral edema, retinal hemorrhages, chronic mountain sickness, systemic hypertension, frost bite etc (Heath & Williams, 1980). However, not everyone visiting high altitude suffers from high induced diseases suggesting that the genetic factors also play important role in high altitude acclimatization (Pasha et al., 2001, 2002; Kumar et al., 2003, 2004). The effect of environmental stress due to low oxygen pressure and low temperatures is a subject of interest not only to the armed forces but also to those staying at high altitudes for long and short periods.

Techniques available for managing stress

The management of unusual psycho-physiological stress therefore has acquired enormous significance in day-to-day life. Such ‘adaptive management’ does not endeavor to eliminate stress but raise the threshold beyond which stress would start injuring and disturbing the life and living processes. The reduced endurance of man both physical and mental during a long and strenuous task results primarily due to decreased availability of energy to the system.

The available techniques for increasing endurance performance (Srivastava & Sen Gupta, 1987) can be classified as following:

1.   Physical training for endurance work: The most widely utilized method of increasing physical endurance effort, tolerance and resistance to a wide variety of stressors is exposure to gradual increasing load of such a stressor. The organism over a prolonged period acquires a better capacity to overcome the insults and develops tolerance or resistance to face an increasing load of strenuous work.

2.   Yogic and meditation practices: It has been claimed that yogic practices can lead to remarkable resistance and tolerance to cold and hypoxic conditions (Anand et al., 1961; Selvamurthy et al., 1988). But most of the times such remarkable achievements have been demonstrated by few individuals only, who have attained a particular status in the art of yogic practices.

3.   Supplementation of food components or ‘Neutraceuticals’: Nutraceuticalsencompass a large group of preventive and curative health careingredients that have been predominantly derived from naturalsubstances especially those with a well-established use as food products.The blend of these pharmaceutical and nutritional characteristics resultedin the name “nutraceuticals”. Nutraceuticals differ from dietarysupplements in two ways, 1) Nutraceuticals must not only supplementthe diet but should also aid in the prevention and treatment of diseaseand disorder 2) Nutraceuticals are represented for use as a conventionalfood or as the sole item of meal or diet.

During exposure to various stressful situations viz. heat, cold, hypoxia and combat, one major limiting factor for decreased physical and mental endurance is known to be the depletion of body energy reserves. Additional quantities of macro and micronutrients are required to cater for the caloric needs of working man in alien hostile environments such as of high altitude (Askew, 1995; Kumar et al., 1993; Srivastava & Kumar, 1992)) and maintain his endurance capability. Some other dietary substances have also been studied for their efficacy during stressful situations. Choline supplementation, in the form of lecithin, increased stress tolerance of animals (Kumar et al., 2002). The requirement of some of the conditionally essential amino acids such as glutamine and arginine is increased during stressful conditions. Supplementation of arginine, precursor of nitric oxide a potent vasodilator, has been shown to help in adaptation during exposure to hypoxia; cold and restraint stress (Gupta et al., 2005a).

4.   Intervention by adaptogens: The use of tonic remedies to restore balanceand health of people is an ancient idea. The word and concept of an“adaptogen” is a relatively new way of describing a type of remedycommonly found in traditional Chinese (Qi tonic), African (Manyasi),Tibetan, and Ayurvedic (Rasayana) medicine. The actual word adaptogenwas first used by a Soviet scientist, Dr. Nikolai Lazarev, who undergrants from the military was researching substances which produced a“state of nonspecific resistance (Panossian et al., 1999). The idea was tofind ways to enhance the productivity and performance of soldiers,athletes, and workers without using dangerous stimulants. Much of theearly research into adaptogens was done by Dr. Brekhman who, in thelate 1950’s, studied Panax ginseng. Looking for a less expensive andmore available substitute, he changed his focus to a native Russian shrub,Eleutherococcus senticosis. His first monograph of this now popular herb(Siberian Ginseng, Eleuthero) was published in 1960. Brekhman andDardymov (1969) defined the general pharmacological properties ofadaptogenic substances:

a.   The substance is relatively non-toxic to the recipient.

b.   An adaptogen has “non-specific” activity and acts by increasing resistanceof the organism to a broad spectrum of adverse biological, chemical, andphysical factors.

c.   These substances tend to help regulate or normalize organ and systemfunction within the organism.

Several theories have been suggested to explain the effects of adaptogenic substances. One theory proposed argues that adaptogens function primarily due to their antioxidant and free radical scavenging effects. While the theory is partially accurate, it is inadequate to explain the full effects of these preparations. More recent research postulates that adaptogens work primarily by affecting the hypothalamic-pituitary-adrenal (HPA) axis and the Sympatho-adrenal System (SAS). Thus, adaptogens modulate our response to stress (physical, environmental, or emotional) and help regulate the interconnected endocrine, immune, and nervous systems. This re-regulation of a disordered or highly stressed system is achieved by metabolic regulators such as cytokines, catecholamine, glucocorticoids, cortisol, serotonin, nitric oxide (NO), cholecystokinin, corticotrophin-releasing factor (CRF), and sex hormones. This broad array of biochemical activators helps explain why adaptogens also have anti-inflammatory, antioxidant, anxiolytic, antidepressant and nervine effects as well.

Adaptogens are biologically active substances, which improve physical and mental performance even in adverse circumstances and in difficult environmental conditions. They increase tolerance to change in environmental conditions and resistance to noxious stimuli as exposure to cold, heat, pain and infectious organisms. Such health food supplements have been claimed to arrest ageing processes and age induced deterioration in physical and mental performance. Such interventions for increasing endurance performance are largely concerned with increasing energy supply and influencing biosynthesis of proteins and nucleic acids. Generally, natural products of herbal nature called ‘Adaptogens’ have been found to possess such activity without leading to addiction and any side effects. Such substances have wide range of therapeutic activity having minimal alterations in body functions; manifest action under conditions of challenge to the system and their actions are non-specific.

There are various herbal plant products known to have ‘adaptogenic’ properties and used in several countries. Some of the plants are:

Panax ginseng (Ginseng root)

It is a potent adaptogen possessing antioxidant, anti-inflammatory, anti-asthmatic, cardio tonic, CNS stimulant (mild) and immunomodulatory properties (Brekhman & Dardymov, 1969). Traditionally it is used in Chinese medicine for anti-aging and other diseases viz. impotence, fatigue, low back pain, depression, exhaustion, insomnia, diabetes, immune deficiency etc. (Suh et al., 2002). Revital, a preparation containing Panax ginseng, mineral and vitamin, at a dose of 11 mg/kg body weight, was found to increase resistance in animals to cold, hypoxia, and restraint stress induced hypothermia and faster post-stress recovery from hypothermia (Kumar et al., 1996).

Eleutherococcus senticosus (Siberian ginseng root)

It is an adaptogen possessing cholesterol lowering, antioxidant, anti-inflammatory (mild), immuno modulator and nervine activity. Eleutherococcus has less tonic effect than the true Ginsengs (Panax ginseng). It is neutral energetically and so is appropriate for daily use. It is indicated for the people, who are overstressed, undernourished, and doesn’t get enough sleep or exercise (Brekhman & Dardymov, 1969). In these situations of HPA axis depletion without overt pathology is precisely where Eleutherococcus is useful. Taken regularly it enhances immune function, reduces cortisol levels and inflammatory response, and it promotes improved cognitive and physical performance. In human studies Eleutherococcus has been successfully used to treat bone marrow suppression caused by chemotherapy or radiation, angina, hypercholesterolemia, and neurasthenia with headache, insomnia, and poor appetite (Brekhman & Dardymov, 1969; Fulder, 1980).

Withania somnifera (Ashwagandha root)

It is an adaptogen with anti-inflammatory, antioxidant, antispasmodic, astringent, immune properties. It is one of the Rasayana (rejuvenative) herbs of Ayurveda and traditionally has been used for anxiety, bad dreams, insomnia, and nervous exhaustion. It acts as an antispasmodic and anti-inflammatory. It is an immuno modulator and useful for hyper- and hypo-immune conditions. It enhances male fertility (sperm count and sperm motility) and, due to its iron content, it benefits iron-deficient anemia. Ashwagandha also stimulates thyroid function. Studies in mice showed significant increases of serum T₃ (18%) and T₄ (111%) after 20 days of use (Panda & Kar, 1998).

Cordyceps sinensis (Cordyceps fungus)

It is a fungus growing at caterpillar. The caterpillar fungus (winter insect, summer plant) is one of the more unusual adaptogens (Sharma, 2004). While the parasitized larvae are still available, most Cordyceps is now grown on soybeans. It is used in traditional Chinese medicine for kidney dysfunctions. It improves libido and sperm count, relieves fatigue, anemia, chronic coughs, and bone marrow suppression due to radiation therapy. Cordyceps also has anti-tumor activity; it enhances circulation and cardiac output, as well as lung capacity (Sharma, 2004).

Ocimum sanctum (Holy Basil herb)

It is a potent adaptogen with antibacterial, antidepressant, antioxidant, antiviral, carminative and expectorant activity. Tulsi, or Holy Basil, has a long tradition of use in Ayurvedic, Siddha, and the Unani-Tibb systems of medicine. It is considered a Rasayana or rejuvenative medicine and is traditionally used to improve memory, to treat coughs, colds, indigestion, asthma and fatigue. In addition, in animal studies, it increases endurance, inhibits ulcer formation, and protects against gamma radiation. In a human trial, Tulsi showed benefits in NIDDM, reducing fasting and postprandial blood glucose (Rege et al., 1999).

Rhodiola rosea, R. crenulata (Rhodiola root)

Rhodiola a high altitude growing plant is widely distributed throughout Europe and Asia. The plant belongs to the family Crassulaceae, sub family sedoideae, and genus Rhodiola. The plant roots contain a range of biologically active substance including phenylpropanoids (rosavins, rosin); phenylethanolderivatives (salidroside, tyrosol) organic acids, flavonoids, tannins and phenolic glycosides (Khannum et al., 2005). The plant species Rhodiola rosea has been scientifically studied for its biological activities and reported to possess oxygen scavenging (Ohsugi et al., 1999), adaptogenic (Spasov, 2000), anti-fatigue (Darbinyan, 2000), neuroprotective (Mook-Jung et al., 2002) and hepatoprotective (Nan et al., 2003) bio-activities.

Hippophae rhamnoides L. (Seabuckthorn)

Hippophae rhamnoides L., commonly known as seabuckthorn (Family: Elaeagnaceae) growing in North-West Himalayas at high altitude, 7000– 15,000 feet, is a dwarf to tall (3–15 feet), branched, and thorny nitrogen fixing deciduous shrub, native to Europe and Asia (Rousi, 1971). All parts of the plant are considered to be good source of a large number of bioactive substances and reported to possess immunomodulatory, anti-oxidant, antibacterial and wound healing activity (Geetha et al., 2002; Gupta et al., 2005; Negi et al., 2005). The medicinal effects of seabuckthorn have been suggested to be due to the presence of high anti-oxidant contents (Beveridge et al., 1999; Eccleston et al., 2002).

Emblica officinalis (Amla fruit)

The adaptogenic properties include antioxidant, anticholesteremic, anti-inflammatory, astringent, radio-protective, thyroxin inhibitor, diuretic, hepatoprotective, and nutritive. Amla, or Amalaki, is a Rasayana or rejuvenative remedy used in Ayurvedic medicine. Rege et al. (1999) concluded that Amla was not only a useful antioxidant and anti-inflammatory, but had adaptogenic activity as well. The extract was shown to protect against biological, physical, and chemical stressors.

Bryonia alba (Bryonia root)

Usually thought of as a highly toxic plant, Bryonia root has been found to be both an adaptogen and non-toxic if gathered in the spring or autumn. The summer gathered roots have a very different chemistry and are, as commonly thought, quite toxic. It is used to prevent radiation-induced cell damage, side effects from chemotherapy, and it improves physical endurance and work capacity (Panossian et al., 1997).

Asparagus racemosus (Shatavari)

This Indian species of plant is used as a Rasayana remedy in Ayurveda. It has long been used as a tonic remedy, especially for women, promoting fertility and reducing menopausal symptoms. It is also used for dry coughs, to heal or prevent gastric ulcers, as a nutritive tonic, and as a soothing diuretic. Recent research indicates Shatavari enhances immune function, increases corticosteroid production, and promotes cell regeneration (Rege et al., 1999).

Besides above mentioned some of the plants the Indian traditional medicines, specially, Ayurveda has been using food supplements, dietary elements, herbs and minerals for increasing physical endurance and mental performance since ages. These substances, Rasayanas and Vajikaran have been described to possess properties of Adaptogens (Nadkarni, 1954). A number of Indian herbs such as Withania somnifera, Asparagus racemosus and Ocimum sanctum have been reported to possess anti-stress and endurance promoting activity (Singh et al., 1982; Sharma et al., 1985; Bhargava et al., 1981). However the experimental evidence of efficacy in favour of such products, called adaptogens was meagre. To fulfil this lacuna several studies in the field of adaptogens were carried out. To start studies on adaptogens, one needed an experimental model representing general stress situation, as stress has many facets some common and other specific to one type of stress, and at least one vital function, which could deteriorate non-specifically under stress could be maintained as a result of treatment with adaptogens.

A passive cold (5 ^oC) – hypoxiz (428 mmHg)- restraint (C-H-R) animal model to test adaptogenic substances

An experimental model for general stress was developed. The experimental animal was white rat. Stress consisted of restraining rat in overnight fasting state in a restrainers (creating emotional anxiety stress) and exposing it to 428 mm Hg atmospheric pressure in a decompression chamber and cooled to 5 ^oC. The physiological vital function monitored to measure endurance was, the maintenance of core body temperature. This vital function represented the thermogenic efficiency in cold, hypoxia and restraint (C-H-R) environment and indicated the functioning of central nervous system, cardiovascular efficiency and integrity of metabolic system of skeletal muscles. The rectal temperature of the rat starts falling in the restrained state under cold and hypoxia. The rate and time to attain a rectal temperature of 23 ^oC was determined. The rat at this stage was taken out of cold-hypoxia chamber and was allowed to recover at 32 ^oC + 1 ^oC in the restrained state. Again the rate and time to recover the rectal temperature to 37 ^oC was determined. The nature and shape of the curve during fall of rectal temperature to 23 ^oC and to recovery to 37 ^oC along with the time were important indices, which were related to endurance running, swimming time in cold water (23 ^oC) and the nature of the thermogenic processes. This experimental model was capable of evaluating quantitatively the endurance promoting property of an adaptogen (Ramachandran et al., 1990).

Studies on herbal adaptogens using C-H-R animal model

Using C-H-R model, several herbal preparations and some Indian composite herbal preparations containing minerals, vitamins and plant extracts were evaluated for their adaptogenic activity (Grover et al., 1995; Kumar et al., 1996, 1999, 2000; Srivastava & Co-workers, 1994). Some of them were potent adaptogen with activity which keep on increasing on repeated intake over several days and weeks (cumulative action) whereas others, though acclaimed, do not increase adaptogenic action on repeated intake. In some cases delay in fall of rectal temperature increased but recovery time remained unaffected. Whereas, in some the time to cool down 23 ^oC was unaffected but the recovery time to 37 ^oC was shortened suggesting that the thermogenesis in cold and hypoxia was modified in animals by different plant preparations through different process/ processes.

Studies with cold-hypoxia and restrained model suggested that adaptogens might be of help in combating and arresting the high altitude induced deterioration in physical and mental performance of people sojourning in such adverse environment. The possibility of improving the performance of people at high altitude by means of health food supplements (Adaptogens) has never been attempted. This generated interest in exploring the possibility whether the adaptogens could be of any use in ameliorating the problems at high altitudes.

A Composite Indian Herbal Preparation I (CIHP I) containing ingredients derived from 7 different plants and Asphalt, described in Ayurveda to increase the physical performance, was developed. The composition of CIHP I is given in Table 1.

Table 1. Composition of CIHP I

CIHP I was tested for its adaptogenic activity using C-H-R animal model. In rats after 12 weeks administration of an oral dose of 7.5 mg/kg/ day, CIHP I was found to possess significant adaptogenic activity. It helped in improving resistance to C-H-R induced hypothermia and enhanced post stress recovery to regain Trec 37 ^oC. CIHP I was also evaluated under condition of combat stress of anti-insurgency nature in Border Security Force (B.S.F) personnel. In B.S.F. volunteers CIHP I intake was found to restrict combat stress induced deterioration in physical and mental performance (Srivastava & Co-workers, 1996).

Another Composite Indian Herbal Preparation II (CIHP II), combination of several plant ingredients and minerals was commercially available (Himalaya Drug Co. India). It was a combination of large number of herbal and mineral ingredients claimed in Ayurveda to enhance physical and mental performance. CIHP II was tested for its adaptogenic action using C-H-R animal model. CIHP II had a strong adaptogenic action in single, multiple and prolonged dose schedule. It had a cumulative adaptogenic property. In animals CIHP II intake appeared to induce a state of nonspecific increased resistance (SNIR) during stress. Composition of CIHP II is given in Table 2.

The experiments were also conducted on the effect of CIHP II intake in rats exposed to a simulated altitude of 25,000 feet for 6 hours a day for six days. It was shown that Composite Indian Herbal Preparation II (CIHP II) administration stimulated oxygen delivery system to the tissues which in turn possibly maintained the integrity of muscular cell membrane permeability, adversely affected in rats exposed to similar altitude but without CIHP II administration (Grover et al., 1995). The acclimatization to hypoxia of extreme altitude was facilitated by the administration of CIHP II during exposure.

Table 2. Composition of CIHP II (460 mg Tablet)

Chyavanprash concentrate	100.0 mg	Shilajit (Purified)	20.0 mg
Exts. Capparis spinosa	13.8 mg	Terminalia chebula	15.0 mg
Cichorium intybus	13.8 mg	Mucuna pruriens	10.0 mg
Solanum nigrum	6.4 mg	Myristica fragrans	10.0 mg
Cassia occidentalis	3.2 mg	Piper longum	10.0 mg
Terminalia arjuna	6.4 mg	Mace	10.0 mg
Achillea millefolium	3.2 mg	Eugenia caryophyllate	05.0 mg
Tamarix gallica	3.2 mg	Elettaria cardamomum	05.0 mg
Mandur bhasma	5.0 mg	Carum copticum	05.0 mg
Saffron	5.0 mg	Curcuma longa	05.0 mg
Amber	2.0 mg	Exts. Berberis aristata	10.0 mg
Makardhwaj	10.0 mg	Adhatoda vasica	10.0 mg
Asparagus adscendens	10.0 mg	Eclipta alba	10.0 mg
Caesalpinia digyna	10.0 mg	Celastrus paniculatus	05.0 mg
Asparagus racemosus	20.0 mg	Argyreia speciosa	10.0 mg
Withania somnifera	30.0 mg	Abhrak bhasma	10.0 mg
Glycyrrhiza glabra	20.0 mg	Loh bhasma	05.0 mg
Centella asiatica	20.0 mg	Jasad bhasma	05.0 mg
Processed in Phyllanthus emblica, Terminalia chebula, Eclipta alba, Asparagus racemosus, >Allium cepa, Allium sativum , Phyllanthus niruri, Boerhaavia diffusa , Tinospora cordifolia, Berberis aristata, Raphanus sativus, Tribulus terrestris

The mechanism of action for increasing tolerance to stress by CIHP I and II was investigated. It has been found that both the CIHPs increased oxygen delivery system by increasing red cell 2,3 Diphosphoglyceric acid levels during hypobaric hypoxic exposure, improved cellular membrane permeability and improved maintenance of blood glucose and muscle glycogen levels. CIHPs also regulated mobilization of lipids from adipose tissue and their utilization for thermogenesis in preference to carbohydrates (Grover et al., 1995, Kumar et al., 1999, 2000).

The above studies have indicated that Ayurvedic herbal preparations/ Rasayana with adaptogenic activity increase the high altitude and cold tolerance and relieve the debilitating effect of stress in work performance of sojourners.

Studies plants growing at high altitude for adaptogenic activity using C-H-R animal model

Evaluation of plants growing at high altitude

A number of plants growing at high altitude area were screened for their hypoxia and cold resistance. A plant preparation similar to common gram was found to possess strong adaptogenic activity (Divekar et al., 1996). This suggested that the plant growing in adverse climatic conditions acquire sustain in stressful conditions. Two plants Hippophae rhamnoides and Rhodiola imbricata, growing at high altitude, were evaluated for their anti-stress and adaptogenic properties. These plants have been reported to possess various bioactive properties.

Rhodiola imbricata (Rhodiola)

Rhodiola a high altitude growing plant is widely distributed throughout Europe and Asia. The plant belongs to the family Crassulaceae, sub family sedoideae, and genus Rhodiola. There are about 200 species of the plant and its roots contain a range of biologically active substance including phenylpropanoids (rosavins, rosin); phenylethanolderivatives (salidroside, tyrosol) organic acids, flavonoids, tannins and phenolic glycosides (Khannum et al., 2005). The extracts of the Rhodiola roots have also been scientifically studied and reported to possess oxygen scavenging (Ohsugi et al., 1999), adaptogenic (Spasov, 2000; Rege et al., 1999), anti-hypoxic (Kurmukov, 1986), anti-fatigue (Darbinyan, 2000), anti-cancer (Udintsev et al., 1991), neuroprotective (Mook-Jung et al., 2002) and hepatoprotective (Nan et al., 2003) bio-activities. Extracts of the R. rosea root were found to contain powerful adaptogens (Kelly, 2001). Research revealed that it protected animals and humans from mental and physical stress, toxins, and cold (Saratikov et al., 1987; Krylov, 1969).

Rhodiola imbricata Edgew, a high altitude plant, grows on rocky slopes of western Himalaya at an altitude of 4000-5000 m. The root of R. imbricata was found to possess radioprotective (Arora et al., 2005; Goel et al., 2006), wound healing (Gupta et al., 2007) and immunomodulatory (Mishra et al., 2006) activities. Also, the extract of Rhodiola imbricata root was found to be free from heavy metal toxicity (Saggu et al., 2006). Only study reported the cytoprotective and antioxidant activity of alcoholic and aqueous extracts of Rhodiola imbricata root (Kanupriya et al., 2005) in U937 human macrophage cell line. The cytoprotective and anti-oxidant activities are important characteristics of a substance to be classified as an adaptogen.

To examine the dose dependent adaptogenic activity aqueous extract of Rhodiola imbricata root was orally administered in rats at different doses, 30 min prior to cold (5^oC)–hypoxia (428 mm Hg)–restraint (C–H–R) exposure. The maximal effective adaptogenic dose of the extract was 100 mg/kg body weight (Gupta et al., 2008). The acute and sub-acute toxicity of the extract was also studied in rats. Subacute toxicity studies included administration of single oral dose of 1 g/kg and 2 g/ kg of extract once daily for 14 days and maximal effective single oral dose of 100 mg/kg once daily for 30 days. At the end of each treatment period the biochemical parameters related to liver function, kidney function, lipids (triglycerides, cholesterol) and hematological parameters were estimated in serum and blood. Biochemical and hematological analysis showed no significant changes in any of the parameters examined in treated group’s animal, in comparison to control animals. No significant change was observed in organ weight/body weight ratios, of any organ studied in comparison to control rats. The oral LD₅₀ of the extract was observed to be >10 g/kg, indicating an adequate margin of safety. No histopathological changes were observed in the vital organs studied of the treated animals. These results suggested that aqueous extract of R. imbricata root possess potent adaptogenic activity with no acute and sub-acute toxicity (Gupta et al., 2008).

The antioxidant potential of Rhodiola imbricata root extract was also investigated in male rats treated with 100mg/kg body weight. oral dose in single and multiple doses, 30 min prior to C-H-R exposure. Single and five doses extract treatment restricted the stress induced increase in liver and muscle MDA levels. Single dose extract treatment further improved liver and muscle superoxide dismutase (SOD) both on attaining Trec 23 °C and Trec 37 °C and liver CAT on attaining Trec 23 °C; increased reduced glutathione (GSH) and glutathione-S-transferase (GST) activity in liver during recovery. Five doses extract administration further improved the liver and muscle GSH levels during exposure and recovery and increased liver CAT during recovery process. Results suggested that supplementation with rhodiola extract helps to reduce oxidative stress in liver and muscle of rats during C-H-R exposure and post-stress recovery.

Hippophae rhamnoides (Seabuckthorn)

Hippophae rhamnoides L., commonly known as seabuckthorn (Family: Elaeagnaceae) growing in North-West Himalayas at high altitude, 7000– 15,000 feet, is a dwarf to tall (3–15 feet), branched, and thorny nitrogen fixing deciduous shrub, native to Europe and Asia (Rousi, 1971). All parts of the plant are considered to be good source of a large number of bioactive substances. The chemical and phytochemical composition of seabuckthorn has been reviewed and found to vary with the origin, climate and method of extraction (Beveridge et al., 1999; Zeb, 2004). The ripe fruit has been reported to be a source of exceptionally high contents of vitamins (A, C, E and K), carotenoids, flavonoids, and organic acids. Extracts of whole fruit, fruit pulp, pulp oil, and seed oil has been reported to possess immunomodulatory, anti-oxidant, and anti-bacterial activity (Geetha et al., 2002; Negi et al., 2005) and reported to be useful in treating various diseases such as gastric ulcers (Suleyman et al., 2001; Xing et al., 2002), skin disorders (Yang et al., 2000), coronary heart disease (Eccleston et al., 2002), radiation induced oxidative damage (Goel et al., 2005), wound healing (Gupta et al., 2005) and thrombosis and platelet aggregation (Cheng et al., 2003). The medicinal effects of seabuckthorn have been suggested to be due to the presence of high antioxidant contents (Beveridge et al., 1999; Eccleston et al., 2002). Seabuckthorn leaves are rich in flavonoids, tannins, and triterpenes (Kallio et al., 2002). But only few studies are available on the pharmacological effects of seabuckthorn leaf, as compared to fruits and seed. Seabuckthorn leaves ethyl alcohol (70%) extract was reported to possess antioxidant and immunomodulatory (Geetha et al., 2003) and anti-inflammatory activity (Ganju et al., 2005). In a single available study, oral administration of single dose (100 mg/ kg body weight) extract of

However, a detailed dose dependent study of seabuckthorn leaf for its anti-stress adaptogenic activity was lacking. A study was undertaken to evaluate dose dependent adaptogenic activity of seabuckthorn dried leaves aqueous extract in rats using a passive cold (5 ^oC)– hypoxia (428 mmHg)–restraint (C– H–R) animal model (Ramachandran et al., 1990). Further, for safety studies on seabuckthorn leaf aqueous extract administration acute and sub-acute toxicity, if any and effect on biochemical and hematological parameters in the serum and blood of animals were determined (Saggu et al., 2007). The maximal effective adaptogenic dose of the extract in rats was found to be 100 mg/kg body weight. In acute toxicity study LD₅₀ of the extract was observed to be > 10 g/kg when given orally. These results indicated that seabuckthorn leaf aqueous extract had potent adaptogenic activity with no toxicity even after sub-acute (30 days) maximal effective dose administration (Saggu et al., 2007). The evaluated extract was also found to be free of any heavy metal toxicity (Saggu et al., 2006). The mechanism of adaptogenic activity of seabuckthorn leaf extract was also evaluated and found to be due to its anti-oxidative activity and helping in maintaining blood glucose levels, better utilization of FFA and improved cell membrane permeability (Saggu & Kumar, 2008). The single and five doses extract treatment restricted the decrease or better maintained tissue glycogen and enzyme activities, viz. HK, phosphofructokinase (PFK), CS and G-6-PD, in blood, liver and muscle, during C–H–R exposure (Trec 23 ^oC) and recovery of Trec 37 ^oC. The results suggested that seabuckthorn extract treatment caused a trend for shifting anaerobic metabolism to aerobic during C–H–R exposure and post stress recovery (Saggu & Kumar, 2007a). The supplementation with seabuckthorn extract also helped in reducing oxidative stress in liver and muscle of rats during C-H-R exposure and post-stress recovery Saggu and Kumar (2007b). However the supplementation with seabuckthorn extract was not found to have any memory enhancing effect in the animals (Saggu & Kumar, 2008a).

Thus, the studies on the management of stress by the administration of adaptogens brought about the following valuable contributions:

1.   Development of a standard model for the evaluation of comprehensive antistress and endurance promoting properties of an adaptogen.

2.   The psycho-physiological performance, physical performance and sensitive indices of oxygen availability to the tissues were improved by the intake of adaptogens. As the adaptogens intake provided protection from stress therefore, they should be given as health food supplements to the people working in adverse climatic conditions.

3.   The above studies on adaptogenic herbal preparations of Indian origin viz. Rasayana of Ayurveda established them as preparations of real value.

References

Anand, B.K., Chinna, G.S. and Singh, B. 1961. Studies on Sri Ram Chandra Yogi during his stay in air tight box. Ind. J. Med. Res. 49: 82-89.

Arora, R., Chawla, R., Sagar, R., Prasad, J., Sing, S., Kumar, R., Sharma, A., Singh, S., and Sharma, R.K. 2005. Evaluation of radioproective activities of Rhodiola imbricata Edgew- A high altitude plant. Mol. Cellular Biochem. 273: 209-223.

Askew, E.W. 1995. Environmental and physical stress and nutrient requirement. Am. J. Clin. Nutr. 61(Suppl): 631S-637S. Avytsyn, A.V. 1974.

Adaptation and disadaptation from the standpoint of pathology. Clinical Med. 5: 3-15.

Beveridge, T., Li, T.S.C., Oomah, B.D. and Smith, A. 1999. Sea Buckthorn products: manufacture and composition. J. Agri. Food. Chem. 47: 3480-3488.

Bhargava, K.P. and Singh, N. 1981. Anti-stress activity of Ocimum sanctum Linn. Ind. J. Med. Res. 73: 433-451.

Brekhman, I.I. and Dardymov, I.V. 1969. New substances of plant origin which increase non-specific resistance. Annu. Rev. Pharmacol. 9: 419-430.

Cannon, W.B. and De La-Paz, D. 1911. Emotional stimulation of adrenal secretion. Am. J. Physiol. 27: 64 -70.

Cheng, J., Kondo, K., Suzuki, Y., Ikeda, Y., Meng, X. and Umemura, K. 2003. Inhibitory effects of total flavones of Hippophae rhamnoides L. on thrombosis in mouse femoral artery and in vitro platelet aggregation. Life Sci. 72: 2263-2271.

Darbinyan, V., Kteyan, A., Panossian, A., Gabrielian, E., Wikman, G. and Wagner, H. 2000.   Rhodiola rosea in stress induced fatigue-a double blind cross-over study of a standardizatized extract SHR-5 with a repeated low-dose regimen on the mental performance of healhy physicians during night duty. Phytomedicine 7: 365-371.

Divekar, H.M., Shyam, R., Gupta, A.K., Pahwa, M.L., Grover, S.K., Kumar, R. and Srivastava, K.K. 1996. Screening of adaptogenic activity of some Laddakhi plants, Report no. 1/96 DIPAS, Delhi. Dolt, K.S., Karar, J., Mishra, M.K., Salim, J., Kumar, R., Grover, S.K. and Pasha, M.A.Q. 2007.   Transcriptional downregulation of sterol metabolism genes in murine liver exposed to acute hypobaric hypoxia. Biochem. Biophys. Res. Comm. 354: 148-153.

Eccleston, C., Baoru, Y., Tahvonen, R., Kallio, H., Rimbach, G.H. and Minihane, A.M. 2002.   Effects of an antioxidant-rich juice (Sea Buckthorn) on risk factors for coronary heart disease in humans. J. Nut. Biochem. 13: 346-354.

Fulder, S. 1980. The Root of Being. Published by Hutchinson & Co. Ltd. London. Ganju, L., Padwad, Y., Singh, R., Karan, D., Chanda, S., Chopra, M.K., Bhatnagar, P., Kashyap, R. and Sawhney, R.C. 2005. Anti-inflammatory activity of Sea Buckthorn (Hippophae rhamnoides) leaves. Int. Immunopharmacol. 5: 1675-1684.

Geetha, S., Sai, R.M., Singh, V., Ilavazhagan, G. and Sawhney, R.C. 2002. Anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides) - An in vitro study. J Ethnopharmacol 79 : 373-378.

Geetha, S., Sai, R.M., Mongia, S.S., Singh, V. , Ilavazhagan, G. and Sawhney, R.C. 2003. Evaluation of antioxidant activity of leaf extract of Sea Buckthorn (Hippophae rhamnoides L.) on chromium (VI) induced oxidative stress in albino rats. J. Ethnopharmacol. 87: 247-251.

Geetha, S. 2004. Antioxidant, Immunomodulatory and Adaptogenic Potential of Sea Buckthorn (Hipphophae rhamnoides L.) – In vitro and in vivo Studies. Ph.D. Thesis Submitted to Delhi University, Delhi, p. 111.

Goel, H.C., Gupta, D., Gupta, S., Garg, A.P. and Bala, M. 2005. Protection of mitochondrial system of Hippophae rhamnoides L. against radiation induced oxidative damage in mice. J. Pharm. Pharmacol. 57: 135-143.

Goel, H.C., Bala, M., Prasad, J., Singh, S., Agarwala, P.K. and Sawhney, R.C. 2006. Radioprotection by Rhodiola imbricata in mice against whole-body lethal irradiation. J. Med. Food Summer 9(2): 154-160.

Grill, A., De Lutiis, M.A., Patruno, A., Speranza, L., Gizzi, F. , Taccardi, A.A., Napoli, P. , De Caterina, R., Conti, P. and Felaco, M. 2003. Inducible Nitric Oxide Synthase and Heme Oxygenase-1 in Rat Heart: Direct Effect of Chronic Exposure to Hypoxia. Annal. Clin. Lab. Sci. 33: 208-215.

Grover, S.K., Divekar, H.M., Kumar, R., Pahwa, M.L., Bhardwaj, S.K., Gupta, A.K. and Srivastava, K.K. 1995. Experimental evaluation of Composite Indian Herbal preparation II (CIHP II) as an adaptogen and its mechanism of action. Int. J. Pharmacognosy 33: 148-154.

Grover, S.K., Kumar, R., Divekar, H.M., Bhardwaj, S.K. and Gupta, A.K. 2004. Large-scale field trials of Composite Indian Herbal Preparations I & II for introduction in the army. DIPAS Report No. 2.

Gupta, A., Kumar, R., Pal, K., Banerjee, P.K. and Sawhney, R.C. 2005. A preclinical study of the effect of Sea Buckthorn (Hippophae rhamnoides L.) leaf extract on cutaneous wound healing in albino rats. Int. J. Low. Extrem. Wounds 4(2): 88-92.

Gupta, A., Kumar, R., Upadhayay, N.K., Pal, K., Kumar, R. and Sawhney, R.C. 2007. Effects of Rhodiola imbricata on dermal wound healing. Planta Med. 73(8): 774-777.

Gupta, V., Gupta, A., Saggu, S., Divekar, H.M., Grover, S.K. and Kumar, R. 2005a. Antistress and adaptogenic activity of L-arginine supplementation, eCAM 2: 93-97.

Gupta, V., Saggu, S., Tulsawani, R.K., Sawhney, R.C. and Kumar, R. 2008. A dose dependent adaptogenic and safety evaluation of Rhodiola imbricata Edgew, a high altitude rhizome. Food and Chem. Toxicol (in press). Heath, D. and Williams, R.D. 1980. Life at High Altitude, Published by Arnold- Heinemann Publishers (India) Pvt. Ltd., New Delhi. Kallio, H., Yang, B. and Peippo, P. 2002. Effects of different origins and harvesting time on vitamin C, tocopherols and tocotrienols in Sea Buckthorn (Hippophae rhamnoides L.) berries. J. Agric. Food Chem 50: 6136-6142.

Kanupriya, Prasad, D., Sairam, M., Kumar, R., Sawhney, R.C., Sharma, S.K., Ilavazhagan, G., Kumar, D. and Banerjee, P.K. 2005. Cytoprotective and antioxidant activity of Rhodiola imbricata against tert-butyl hydroperoxide injury in U-937 human macrophages. Mol. Cell. Biochem. 275(1-2): 1-6.

Kelly, G.S. 2001. Rhodiola rosea: A possible plant adaptogen. Altern. Med. Rev. 6: 293-298.

Khanum, F., Bawa, A.S. and Singh, B. 2005. Rhodiola rosea: A Versatile Adaptogen, Comprehensive Reviews in Food Science and Food 4: 55-58.

Krylov, G.V. 1969. Herbs for Life. Novosibirsk: Academic Press, p. 264.

Kumar, R., Chattopadhyay, D.P. and Shyam, R. 1993. Effect of intraperitoneal administration of carbohydrates on simulated altitude tolerance in rats. Ind. J. Clin. Biochem. 8: 20-25.

Kumar, R., Divekar, H.M., Gupta, A.K., Shyam, R. and Srivastava, K.K. 1996. Enhanced thermogenesis in rats by Panax ginseng, multivitamins and minerals. Int. J. Biometerol. 39: 187-219.

Kumar, R., Divekar, H.M., Gupta, V. and Srivastava, K.K. 2002. Anti-stress and adaptogenic activity of lecithin supplementation. J. Altern. Complement. Med. 8: 487-492.

Kumar, R., Grover, S.K., Shyam, R., Divekar, H.M., Gupta, A.K. and Srivastava, K.K. 1999.

Enhanced thermogenesis in rats by a Composite Indian Herbal Preparation-I and its mechanism of action. J. Altern. Complement. Med. 5: 245-251.

Kumar, R., Pasha, M.A.Q., Khan, A.P., Gupta, V., Grover, S.K., Norboo, T., Srivastava, K.K., Selvamurthy, W. and Brahamchari, S.K. 2003. Association of high altitude systemic hypertension with the deletion allele of the angiotensin converting enzyme (ACE) gene. Int. J. Biometeorol. 48: 10-14.

Kumar, R., Pasha, M.A.Q., Khan, A.P. and Gupta, V. 2004. Renin angiotensin aldosterone system and ACE I/D gene polymorphism in high altitude pulmonary edema. Aviat Space Environ. Med. 75: 981-983.

Kumar, R., Shyam, R., Divekar, H.M., Pahwa, M.L. and Srivastava, K.K. 2000. Mechanism of increased tolerance to hypothermia after Composite Indian Herbal Preparation II administration. J. Altern. Complement. Med. 6: 509-517.

Kumar, R. and Srivastava, K.K. 2000. Anti-oxidant level during combat stress: Effect of a Composite Indian Herbal Preparation- I. J. Res. Ayurveda & Siddha 21(3-4): 158-163.

Kurmukov, A.G., Aizikov, M.I. and Rakhitove, S.S. 1986. Pharmacology of the plant polyphenol epigalokhin. Farmakol Toksikol 49(2): 45-48.

Mishra, K.P., Padwad, Y.S., Jain, M., Karan, D., Ganju, L. and Sawhney, R.C. 2006. Aqueous extract of Rhodiola imbricata rhizome stimulates pro-inflammatory mediators via phosphorylated IkB and transcription factor nuclear factor-kB, Immunopharmacol. Immunotoxicol 28(2): 201-212.

Mook-Jung, I., Kim, H., Fan, W., Tezuka, Y., Kadota, S., Nishizo, H. and Jung, M.W. 2002.

Neuroproective effects of constituents of the original crude drugs, Rhodiola imbricate, R. sachalinensis and Tokaku-joki-to, against-amyloid toxicity, oxidative stress and apoptosis. Biol. Pharm. Bull 25: 1101-1104.

Nadkarni, A.K. 1954. Indian Material Medica. 3^rd edition. Pub. Popular Book. Deport, Bombay. Nan, J.X., Jiang, Y.Z., Park, E.J., Ko, G., Kim, Y.C. and Sohn, D.H. 2003. Protective effect of Rhodiola sacchalinensis extract on carbon tetrachloride-induced liver injury in rats. J. Ethnopharmacol 84: 143-148.

Negi, P.S., Chauhan, A.S., Sadia, G.A., Rohinishree, Y.S. and Ramteke, R.S. 2005. Antioxidant and antibacterial activities of various Sea Buckthorn (Hippophae rhamnoides L.) seed extracts. Food Chem. 92: 119-124.

Ohsugi, M., Fan, Wenzhe., Hase, K., Xiong, Q., Tezuka, Y., Komatsu, K., Namba, T., Saitoh, T., Taziwa, K. and Kadota, S. 1999. Active-oxygen scavenging activity of traditional nourishing tonic herbal medicines and active constituents of Rhodiola sacra. J. Ethanophrmacol. 67: 111-119.

Panda, S. and Kar, A. 1998. Changes in thyroid hormone concentrations after administration of Ashwagandha root extract to adult male mice. J. Pharm. Pharmacol. 50: 1065-1068.

Panossian, A., Gabrielian, E. and Wagner, H. 1997. Plant Adaptogens II, Bryonia as an Adaptogen. Phytomedicine 4(1): 85-99.

Panossian, A., Wikman, G. and Wagner, H. 1999. Plant Adaptogens III, Earlier and more recent aspects and concepts on their mode of action. Phytomedicine 6(4): 287-299.

Pasha, M.A.Q., Khan, A.P., Kumar, R., Grover, S.K., Ram, R.B., Norboo, T., Srivastava, K.K., Selvamurthy, W. and Brahmachari, S.K. 2001 Angiotensin converting enzyme insertion allele in relation to high altitude adaptation. Ann. Hum. Genet. 65: 531-536.

Pasha, M.A.Q., Khan, A.P., Kumar, R., Ram, R.B., Grover, S.K., Srivastava, K.K., Selvamurthy, W. and Brahmachari, S.K. 2002. Variations in angiotensin converting enzyme gene insertion/deletion polymorphism in Indian populations of different ethnic origins. J. Biosci. 27: 67-70.

Ramachandran, U., Divekar, H.M., Grover, S.K. and Srivastava, K.K. 1990. New experimental model for evaluation of adaptogenic products. J. Ethanopharmacol. 29: 275-281.

Rousi, A. 1971. The genus Hippophae L., a taxonomic study. Annals. Bot. 8: 177-227.

Rege, N.N., Thatte, U.M. and Dahanukar, S.A. 1999. Adaptogenic properties of six rasayana herbs used in Ayurvedic medicine. Phytotherapy Res. 13(4): 275-291.

Rupert, J.L. and Hochachka, P.W. 2001. Genetic approaches to understanding human adaptation to altitude in Andes. J. Expt. Biol. 204: 3151-3160.

Saggu, S., Divekar, H.M., Gupta, V., Sawhney, R.C., Banerjee, P.K. and Kumar, R., 2007. Adaptogenic and safety evaluation of Sea Buckthorn (Hippophae rhamnoides) leaf extract: A dose dependent study. Food and Chem. Toxicol 45: 609-617.

Saggu, S., Gupta, V., Sawhney, R.C. and Kumar, R. 2006. Analysis of heavy metal in herbal extracts of high altitude growing plants Hippophae rhamnoides and Rhodiola imbricata. Toxicol. Int. 13: 111-117.

Saggu, S. and Kumar, R. 2007a. Possible mechanism of adaptogenic activity of Sea Buckthorn (Hippophae rhamnoides) during exposure to cold, hypoxia and restraint (C–H–R) stress induced hypothermia and post stress recovery in rats. Food and Chem. Toxicol 45: 2426-2433.

Saggu, S. and Kumar, R. 2007b. Modulatory effect of Sea Buckthorn leaf extract on oxidative stress parameters in rats during exposure to cold, hypoxia and restraint (C-H-R) stress and post stress recovery. J. Pharm. Pharmacol. 59: 1739-1745.

Saggu, S. and Kumar, R. 2008. Effect of Sea Buckthorn leaf extracts on circulating energy fuels, lipid peroxidation and antioxidant parameters in rats during exposure to cold, hypoxia and restraint (C-H-R) stress and post stress recovery. Phytomedicine (in press). Saggu, S. and Kumar, R. 2008a. Effect of Sea Buckthorn (Hippophae rhamnoides) leaf aqueous and ethanol extracts on Avoidance learning during stressful endurance performance of rats: A dose dependent study. Phytotherapy Res. (in press). Saratikov, A.S. and Krasnov, E.A. 1987. Rhodiola rosea is a valuable medicinal plant (Golden Root). Tomsk, Russia: Tomsk State University. Saxena, S., Kumar, R., Madan, T., Gupta, V., Murlidhar, K. and Sharma, P.U. 2005. Association of polymorphisms in pulmonary surfactant protein A1 and A2 genes with high altitude pulmonary edema. Chest 128: 1611-1619.

Selvamurthy, W., Ray, U.S., Hegde, K.S. and Sharma, R.P. 1988. Physiological responses to cold (10 ^oC) in men after six months practice of yoga exercise. Int. J. Biometeorol. 32: 188-193.

Selye, H. 1950. Pub Mc Graw Hill Book. Co. New York. Sharma, S. 2004.

Trade of Cordyceps sinensis from high altitudes of the Indian Himalaya: Conservation and Biotechnological properties. Current Science 86(12): 1614-1619.

Sharma, S., Dehanukar, S. and Karandikar, S.M. 1985. Effect of long term administration of the roots of Ashwagandha (Withania somnifera) and Shatavari (Asparagus racemosus) in rats. Ind. Drugs 23: 133-139.

Sies, H. 1991. Oxidative stress: From basic research to clinical application. Am. J. Med. 91: 31S-38S. Singh, N., Nath, R., Lata, A., Singh, S.P., Kohli, R.P. and Bhargava, K.P. 1982. Withania somnifera (Ashwagandha) A rejuvenating herbal drug which enhances survival during stress (an adaptogen). Int. J. Crude Drug Res. 20: 29-35.

Spasov, A.A., Wikman, G.K., Mandrikov, V.B., Mironova, I.A. and Neumoin, V.V. 2000. A doubleblind, placebo-controlled pilot study of the stimulating and adaptogenic effect of Rhodiola rosea SHR-5 extract on the fatigue of student caused by stress during an examination period with a repeated low-dose regimen. Phytomedicine 7: 85-89.

Srivastava, K.K. and Co-workers. 1992. Man in extreme altitude, Studies on high terrestrial altitudes, Adaption to 15000-20000 feet in man. DIPAS Project Report No. RD-P1-85/ DIP-168.

Srivastava, K.K. and Co-workers. 1994. Stay in high mountains and Panax ginseng. Published by: Defence Institute of Physiology and Allied Sciences, Delhi. Srivastava, K.K. and Co-workers. 1995. Management of Environment Stress with Composite Indian Herbal Preparation. Published by: Himalaya Drug Co Makali Banglore. Srivastava, K.K. and Co-workers. 1996. Studies on combat Stress, Physiological, Biochemical and Physiological correlates. DIPAS Report No 11/96.

Srivastava, K.K. and Kumar, R. 1992. Human nutrition in cold and high terrestrial altitudes. Int. J. Biometeorol. 36: 10-13.

Srivastava, K.K. and Sen Gupta, J. 1987. Studies to improve human physical working capacity. Probe 26: 107-111.

Suh, S.O. and Kroh, M. et al., 2002. Effects of red ginseng upon postoperative immunity and survival in patients with stage III Gastric Cancer. Am. J. Chin. Med. 30(4): 483-494.

Suleyman, H., Demirezer, L.O., Buyukokuroglu, M.E., Akcay, M.F., Gepdiremen, A., Banoglu, Z.N. and Gocer, F. 2001. Antiulcerogenic effect of Hippophae rhamnoides L. Phytother. Res. 15: 625-627.

Udintsev, S.N. and Schakhov, V.P. 1991. Decrease of cyclophosphamide haematotoxicity by Rhodiola rosea root extract in mice with Ehrlich and Lewis transplantable tumors. Eur. J. Cancer. 27(9): 1182.

Xing, J., Yang, B., Dong, Y., Wang, B., Wang, J. and Kallio, H.P. 2002. Effects of Sea Buckthorn (Hippophae rhamnoides L.) seed and pulp oils on experimental models of gastric ulcer in rats. Fitoterapia 73: 644- 650.

Yang, B., Kalimo, K.O., Tahvonen, R.I., Mattila, L.M., Katajisto, J.K. and Kallio, H.P. 2000.   Effect of dietary supplementation with Sea Buckthorn (Hippophae rhamnoides) seed and pulp oils on the fatty acid composition of skin glycerophospholipids of patients with atopic dermatitis. J. Nutr. Biochem. 11: 338-340.

Zeb, A. 2004. Chemical and nutritional constituents of Sea buckthorn juice. Pak. J. Nutr. 3: 99-106.