ERICACEAE

Ericaceae usually consist of shrubs, often low and creeping, or sometimes small trees. Widely distributed on acid soils mainly in temperate areas of the world.

Arctostaphylos uva-ursi, Vaccinium myrtillus and Gaultheria procumbens are medicinal herbs belonging to this family.

Arctostaphylos uva-ursi

Bearberry, uva-ursi

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Family Ericaceae

Description

A prostrate, evergreen shrub with semi-trailing, pale brown, smooth, woody stems and numerous branches with small, (about 2 cm long), obovate or oblong entire leaves, leathery, glossy dark green above, paler and veined beneath. Flowers grow in compact, drooping terminal racemes of 4–6 and are white with a red tip, waxy and urn-shaped. They bloom between November and December. The ovary and fruit are free, the sepals being at the base of the berry, not crowning it. Fruit is a thickskinned, glossy, bright red berry with 5 or fewer seeds, ripening in autumn.

Odour—slightly aromatic; taste—astringent and bitter.

Habitat and cultivation

Bearberry is native to the whole Arctic and temperate zone of the Northern Hemisphere south to the Mediterranean and California. Grows in dry, heathy, mountainous places on moors and banks. Grown from seed, cuttings or layers in cooler, open places. Drought and frost resistant.

Parts used

The green leaves harvested in early autumn.

Active constituents

1) Hydroquinone derivatives including arbutin (6–9%)1 and methylarbutin, also free hydroquinone. The arbutin level varies with geographical location and time of year, being highest in autumn.1

2) Polyphenols (tannins)—(10–15%) mainly gallotannins, also catechin and corilagin.2 A tannin level of 6–7% is generally quoted (BPC), although the range can be anywhere between 10%–20%, this higher level may reflect total polyphenols rather than just tannins. However a study of commercial bearberry teas found a tannin content of between 17% and 22%3

3) Phenolic acids including mainly gallic acid and also p-coumaric and syringic acids4

4) Flavonoids, mainly quercetin and myricetin glycosides

5) Iridoids including monotropein5

Also a phenolic glucoside (piceoside)6 and triterpenes including ursolic acid. Ericolin is not widely cited as a constituent of this herb in modern literature.

The total phenolic content is around 30%.7

Nutritional constituents

Vitamins: C and A

Minerals: Calcium, iron, magnesium and potassium

Actions

1) Urinary antiseptic

2) Astringent

Scientific information

The herb has a long history of medicinal use mainly as an astringent and haemostatic, but modern uses date back only to the 18th Century. Arctostaphylos has been an official preparation in a number of pharmacopoeias8 and it is approved by German Commission E for the treatment of inflammatory conditions of the lower urinary tract and for catarrh of the bladder and renal pelvis.

Although bearberry had been considered a diuretic pharmacological studies do not bear this out. Instead it is a urinary antiseptic in which arbutin is likely to contribute significantly.9 The herb also has a very high tannin content and is therefore an effective astringent.

The leaves have been used by the Carrier people from northcentral British Columbia as a poultice on wounds and for high blood pressure, menstrual cramps and as a mood enhancer in menopause.10

Antimicrobial

In vitro—Arctostaphylos is a very good bacteriostatic agent against a number of Helicobacter pylori strains, an action ascribed to the tannins.11 The herb and/or arbutin also show growth inhibition of a number of infective organisms including Streptococcus, Enterobacter, Klebsiella and Shigella spp., Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhimurium, Proteus mirabilis, Escherichia coli, Ureaplasma urealyticum and Mycoplasma hominis.12–15 Corilagin is antibacterial and increases the effectiveness of β-lactam antibiotics, e.g. oxacillin (a penicillin), against MRSA.2

Ex vivo—Urine from volunteers who had consumed arbutin or whole Arctostaphylos extract showed an impressive range of antibacterial activity when tested at an alkaline pH.15

Antiviral activity against HSV-2, influenza virus A2 and vaccinia virus by aqueous extracts has also been reported.15

In vivo—A preparation containing Arctostaphylos and Taraxacum officinale (root and herb) was taken over the course of a month and found to be very effective in preventing the development of cystitis in the following 12-month period in a group of women who had had recurrent bladder infections.16

The antibacterial effects of the herb are due largely to the conversion in the kidney tubule of arbutin to hydroquinone and hydroquinone esters (see Pharmacokinetics).

Anti-oxidant

In vitro—Arctostaphylos is a very strong anti-oxidant, an action likely due to the phenol fraction.7 (The total phenolic content of this herb is comparable with that of green tea.7)

Hydroquinone is also an anti-oxidant, inhibiting lipid peroxidation, and may have an inhibitory effect on protein glycation.17

Other

In vitro—The herb, and arbutin in particular, strongly inhibit the enzyme tyrosinase18–20 which is responsible for melanin production and this may represent a treatment option in conditions where melanin production is undesirable e.g. to lighten dark blemishes.15

Medicinal uses

Gastro-intestinal tract

The astringency of the tannins is effective in the digestive tract:

Urinary tract

Externally

Pharmacy

Three times daily  
Infusion –   1.5–2.5 g
Tincture 1:5 (25%) –   2–4 ml (suggested guidelines)
Fluid Extract (25%) –   1.5–2.5 ml

According to Weiss arbutin is difficult to extract from the tough leaf and therefore is best prepared as a decoction. It should be boiled, covered and steeped for half an hour, however this process would increase the tannins extracted too (see below).

Arbutin is slightly better and more quickly absorbed from aqueous extracts of Arctostaphylos than from coated tablets.21

CONTRAINDICATIONS—Pregnancy (BHC and German Commission E).

Pharmacokinetics

The enzyme responsible for converting arbutin to hydroquinone is not found in mammalian tissues and hydroquinone produced in any quantity is therefore presumed to be the result of gut flora or infecting microbes.22 Hydroquinone absorbed from the gut is converted in the liver to hydroquinone esters for renal excretion, being released again in its free form in the kidneys, particularly if urine is alkaline. It has also been shown that E. coli organisms absorb arbutin metabolites and convert them to hydroquinone within their own cells without the requirement of an alkaline pH.23 Hydroquinone and its esters’ antibacterial activity is maximal 3–4 hours after dosing.15 Although bearberry itself is only weakly bactericidal, its action in inhibiting E. coli strains from adhering to host cells walls is strong and this would add to any direct antimicrobial effect.24 In vivo oral dosing with an infusion resulted in over 50% of arbutin being excreted within 4 hours, mainly as hydroquinone glucuronide and hydroquinone sulphate,25 and 75% being excreted within 24 hours. Free hydroquinone is excreted in insignificant quantities.26

Precautions and/or safety

The high tannin content of this herb can lead to gastric irritation and large doses may cause nausea and vomiting. Tannin levels may be reduced by preparing a cold infusion and/or gastric irritation may be counteracted by first giving a demulcent.

A case of bull's-eye maculopathy has been reported after the herb was used for 3 years, the speculated cause being the herb's inhibition of tyrosinase.27

It is recommended in the BHC that this herb should only be used short term—maximum 7 days. However the Commission E monograph (1984) does not note this restriction but advises that long term use should not be undertaken without consulting a practitioner.

Hydroquinone has no reported carcinogenic effects in humans but can produce gene mutations in high enough concentrations. Arbutin and Arctostaphylos itself appear to be devoid of genotoxicity even at relatively high doses.22 The hydroquinone content of bearberry generated by human metabolism is low and the herb is considered safe when used as recommended.

Historical uses

Bladder and kidney disease; tonic to urinary tract; with tobacco as a smoking mix.

Gaultheria procumbens

Wintergreen, checkerberry

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Family Ericaceae

Description

Dwarf evergreen shrub, 10–15 cm, with thin creeping rootstock from which grow erect hairy stems Family Ericaceae topped with a few leaves. Leaves 2–4 cm long, pointed elliptic, stiff, leathery with toothed margins; glossy dark green above and paler beneath. Flowers white, 7.5 mm long, solitary, drooping, growing on paired stalks from base of leaf axils. Blooms mid to late summer. Fruit scarlet 7 mm berries.

Habitat and cultivation

Native to North America from Newfoundland to Georgia and also to most of Europe and the north of Britain growing in open woods, thickets, rocky moors and mountainous regions. It grows on poor sandy soils. Cultivated in similar conditions elsewhere. Drought and frost resistant.

Parts used

Leaves and stems.

Active constituents

1) Phenolic compounds including gaultherin and salicylic, p-hydroxy benzoic, gentisic, vanillic and caffeic acids28

2) Volatile oil (up to 1%) containing mostly (98%) methyl salicylate (min. 85 μg/g)29 produced through hydrolysis (either by enzyme action or steam distillation) of gaultherin, which consists of the disaccharide primeverose bound to methyl salicylate. Gaultheria is the richest plant source of total and free salicylic acid, the level being especially high in the cultivated herb.28

Actions

1) Anti-inflammatory

2) Antirheumatic

3) Diuretic

4) Mild analgesic

Scientific information

By 1843 wintergreen was a recognised source of salicylates, these were being used commercially in both the pharmaceutical and food industries (methyl salicylate formed the base of many synthetic flavours). Through excessive harvesting Gaultheria in the wild became seriously depleted. Betula lenta, a North American variety of birch was the main natural alternative source of methyl salicylate but it was and still is also chemically synthesised. Methyl salicylate is usually sold as wintergreen oil8 however it is possible to distinguish between the naturally derived and synthetic chemical.30

The pharmacology of the whole extract is not well studied or much used in modern phytotherapy, and it is the isolated oil, widely sold as wintergreen oil, that is well known. The synthetic version of salicylic acid—acetyl salicylate or aspirin—is by contrast one of the best studied pharmaceuticals. The natural salicylates whilst sharing some of the pharmacological effects of their synthetic counterparts do not have their range of activity. Indeed due to the irritant potential of salicylic acid and aspirin, alternative chemical derivatives have been sought to use as anti-inflammatory medications and gaultherin has been tested in this context as the presence of the disaccharide renders the salicylate non-irritant.29

In vitro—Gaultheria has antifungal activity against some species including Microsporum gypseum and Trichophyton mentagrophytes.31

However it is mainly as an external application of the essential oil that Gaultheria is used today.

Medicinal uses

Musculoskeletal

The herb is used internally in the treatment of:

Externally

As a liniment the essential oil (mainly) is used for:

Pharmacy

Three times daily  
Infusion of dried herb –   0.5–1 g
Fluid Extract (25%) –   0.5–1 ml

It is easily absorbed from the skin but may cause reactions.

Precautions and/or safety

The essential oil must not be taken internally.

Salicylate poisoning can occur with very large doses of herb or ingestion of the essential oil32 leading within 2 hours to symptoms including nausea, vomiting, pulmonary oedema, convulsions and tinnitus. One teaspoon of wintergreen oil has been calculated as equivalent to about 21 adult aspirin tablets.33 6 ml of oil may be a lethal dose for a child and 30 ml for an adult. A case of an infant being poisoned by accidentally swallowing the oil and developing laryngeal oedema34 has been reported.

Although topical applications of salicylate-containing herbs rarely cause problems, there are cases of patients with skin diseases who, having been exposed to extensive amounts of these preparations, developed signs of toxicity.35 This is an uncommon event.36

The FDA estimates the incidence of sensitivity to salicylates could be as high as 5% of the population37 and in susceptible individuals this may precipitate asthma,38 eczema,39 urticaria,40 gastrointestinal problems,41 headaches, recurrent mouth ulcers, irritability and at worst anaphylaxis.8

Some sources warn that salicylates in plants could have antiplatelet activity, there are no reported cases to date42 (see Salix).

Historical uses

Emmenagogue; chronic mucus discharges; galactagogue. Externally as an insect repellent.

Vaccinium myrtillus

Bilberry, blueberry

Description

A shrubby perennial with creeping rootstock 0.6 × 1 m. Stems green, erect, wiry, branched. Leaves oval, 1–2 cm long, leathery with conspicuous veins and finely serrate margins, bright green. Flowers reddish pink or red and white, solitary and bell-shaped, blooming in spring. Fruit blue-black, sweet-tasting, globular berries.

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Family Ericaceae

Leaf odour and taste faintly bitter and astringent. Fruit odour—faintly spicy; taste—slightly bitter and pungent.

Habitat and cultivation

Native to woods and forest meadows of Northern Britain, Europe and North America, bilberries prefer a moist, acid soil and semi-shade. They are propagated by cuttings and division in autumn and are frost resistant but drought tender. V. corymbosum is grown as a commercial fruit and is also known as blueberry. It is not the medicinal blueberry.

Parts used

The ripe fruit harvested in the autumn. Historically the leaves have also been used.

Active constituents

1) Flavonoids including at least 15 different anthocyanins comprising 0.1–0.25% of the whole extract.43–50 Also (–)-epicatechin, (+)- catechin, procyanidins (mainly trimers)51 and the flavonols quercetin52,56 and myricetin.53 The flavonoid level is generally higher in sun-exposed leaves and fruit.54 During maturation of the fruit anthocyanin levels rise and procyanidin and quercetin levels fall55

2) Phenolics—the total phenolic content of most berries is high but Vaccinium berries is amongst the highest73

a) phenolic acids—derivatives of hydroxycinnamic acid including predominantly ferulic but also p-coumaric, caffeic and chlorogenic acids56

b) polyphenols including trans-resveratrol,57,58 the content of which varies with geographical location and is reduced by cooking58

3) Alkaloid of the quinolizidine type including myrtine and epimyrtine59

4) Volatile oil including methyl salicylate, farnesol, vanillin, myristicin and citronellol60

5) Tannins in fruit and leaves61

6) Iridoid glucosides—monotropein62

Also contains fruit acids and sugars, pectin, hydroxy-fatty acids,63 arbutin and proteins.64 Carotenoids and sterols have been isolated from the fruit.65

N.B. Potter's states that V. myrtillus does not in fact contain arbutin or any other hydroquinone derivatives that occur in other species of the genus. Very low levels of hydroquinones have been reported more recently in the leaf.66

Nutritional constituents

Vitamins: C and E

Minerals: Phosphorus, iron, zinc, magnesium, potassium, sulphur, selenium and smaller amounts of boron, calcium, copper, manganese, sodium and silica67,68

Actions

1) Astringent

2) Urinary antiseptic

3) Anti-oxidant

4) Collagen stabiliser

5) Nutritive

Scientific information

Vaccinium has been in use as a medicine for over 1000 years, has been an official medicine in a number of European countries8 and is approved by German Commission E for the treatment of acute non-specific diarrhoea and for local use in mild mucosal inflammation of throat and mouth.

Much of the recent work on the pharmacology of this herb has centred round the in vitro effects of the anthocyanins or anthocyanosides and their aglycones, called anthocyanidins. The anthocyanins appear to be more physiologically active although their intestinal absorption was at one time in doubt. Studies now indicate they are absorbed and excreted in this glycosidic form.69,70 One of the main reasons for the interest in these phytochemicals is that they are very water-soluble and occur in high enough levels in plants to have the potential of reaching effective levels in vivo.

Anti-oxidant

In vitro—Vaccinium, its anthocyanins71 and also the catechin and procyanidin fractions are all strong anti-oxidants.43,51,72–74 The anti-oxidant strength of the herb is directly correlated with its total phenolic content.56 Vaccinium is a potent preventative of low density lipoprotein oxidation and if this action extends to in vivo the herb may offer protection against atherogenesis.75

In vivo—Serum anti-oxidant potential increased with the consumption of the herb70 and the serum levels of quercetin was found to be higher in people who consumed bilberries (and other berries) than those on a normal diet.76

Anticancer

In vitro—Vaccinium, individual anthocyanins and anthocyanidins inhibit a number of different cancer cell lines.74,77–79 In addition the herb and/or its constituents are:-

In vivo—Epidemiological studies suggest eating berries like Vaccinium may be protective against cancer development.82

Vision

The effects of bilberry on vision were established in more recent times. It was said that night vision of pilots in World War II was improved through eating bilberry jam and this prompted research into a possible connection. Studies were conducted in the 1970's and seemed to mostly corroborate both in vivo83–87 and in vitro88,89 benefits to visual function.

In vitro—Recent studies found that Vaccinium as well as a number of the anthocyanins and resveratrol protect retinal pigment90 and retinal cell membranes91 from damage due to oxidation. Oxidation damage is implicated in age-related vision deterioration, retinal disorders and macular degeneration.

In vivo—A survey of clinical trials purporting to test the benefits of Vaccinium anthocyanins for night vision produced mixed results.92 Possible flaws in methodology are cited as accounting for some of the lack of consistency, in particular, many studies used subjects who were not suffering from impaired night vision to begin with and therefore there was no measurable benefit from using the herb.93

Clinical trials into other benefits on visual function showed that the anthocyanins were protective in a number of disorders including diabetic retinopathy, retinitis pigmentosa, macular degeneration, anticoagulant-induced haemorrhagic retinopathy,94 cataracts95 and glaucoma.96 The anthocyanins also normalise connective tissue production in diabetic retinopathy, a process that is disordered by the disease, and can lead to loss of vision.97

Antimicrobial

In vitro—Vaccinium's phenolic component has antibacterial activity against strains of Gram-negative organisms including Salmonella, Staphylococcus, Bacillus and Helicobacter (including H. pylori98). Some of this activity seems related to disruption of the bacterial cell wall but there is also direct immobilisation of pathogens.99 The leaf extract also has antibacterial activity.100

Whole extracts were antiviral to tick-borne encephalitis virus.101

Other

In vitro—The herb has low to moderate anti-inflammatory activity102,103 but the anthocyanidin, cyanidin, has very strong activity.104

Ex vivo—Blood from healthy individuals who had consumed bilberries strongly inhibited platelet aggregation.105

In vivo—Much early work into the benefits of Vaccinium's anthocyanins for strengthening and protecting blood vessels is no longer easily accessible nor have they been subjected to recent clinical studies. The herb had been tested in the treatment of a variety of circulatory disorders, including venous and vascular permeability problems, apparently with positive results.106–110

Most studies on the herb's effect on inflammation and connective tissue support was carried out using animals and may suggest mechanisms of action as well as applications for clinical use. These showed the herb promoted synthesis and stabilisation of collagen and enhanced cross-linkages of fibres. It also inhibited the release of enzymes that lyse collagen and decreased release of inflammatory prostaglandins, leukotrienes and histamine.

Cyanidin is protective against aspirin-induced ulceration.74,111

Medicinal uses

Cardiovascular system

Due to the beneficial effects in strengthening blood vessels, the herb may be used to treat:

Gastro-intestinal tract

The fruit acids and pectin act as soluble fibre and make the herb a bulk laxative but it is also astringent:

Weiss claims a “marked anti-emetic” effect.

Urinary tract

Vaccinium was traditionally used for the treatment of problems in this system. The anthocyanosides are excreted via kidneys. The herb's astringency, antimicrobial and diuretic8 activities suggests it may be useful in conditions like:

Nervous system

It is possible that by reducing permeability of the blood/brain barrier, Vaccinium may be useful in psychotic conditions like schizophrenia.60

Reproductive tract

Grieve lists Vaccinium as anti-galactogogue, an action not mentioned elsewhere.

Musculoskeletal

It may help improve excretion of uric acid. As an agent that strengthens connective tissue and prevents inflammatory damage the herb is used in the treatment of:

Externally

With the high tannin content it may be used externally to treat:

Pharmacy

Three times daily  
Decoction dried herb –   2–4 g
Fluid Extract (25%) –   2–4 ml

Scientific investigations used extracts standardised to contain 25% anthocyanins.

Pharmacokinetics

The anthocyandins reached maximum levels in urine 3–4 hours after ingestion.74

Precautions and/or safety

It has been recommended by some surgeons that Vaccinium supplements be discontinued 2 weeks prior to surgery due to potential antiplatelet effects.112

The leaves have been reported to be toxic in animals due to the presence of hydroquinones. It is possible that the inconsistent levels of this constituent have arisen from contamination of the leaves with other species of this genus.66 The anthocyanidins are non-toxic.60,74

Interactions

Due to its antiplatelet activity bilberry could interact with antithrombotics but there are no reports of interactions to-date.113

In vitro—Vaccinium inhibited organic anion-transporting polypeptide-B found in intestinal epithelial cells and this may affect the absorption of drugs which use this mechanism if the two are consumed concomitantly.114

Historical uses

Scurvy; agues; vomiting; old coughs; menorrhagia; haemoptysis; ulcer in the lung; discharges or bleeding generally whether internal or external; dropsy; gravel. Leaf extracts for diabetes mellitus type 2.