BORAGINACEAE

The Boraginaceae are a family of annual, biennial or perennial herbs comprising about 2000 species mostly from the Mediterranean and Western Asia.

Medicinal plants in the Boraginaceae include the genera Borago, Lithospermum, Pulmonaria and Symphytum.

Borago officinalis

Borage

Description

A sturdy annual beginning as a basal rosette and growing to about 1 × 1 m in flower. Stems and leaves hispid. Basal leaves 30 × 20 cm, petiolate, oval-oblong, dark-green, wrinkled, acuminate; base usually rounded. Stem leaves alternate, smaller, becoming sessile. Flowers: calyx 10 mm long, becoming longer at fruiting. Corolla about 2.5 cm in diameter with 5 usually bright blue petals (though white and pink flowered forms are known), arranged like a star around the erect, black cone of stamens. Fruit 4 nutlets sheltered in the calyx. Flowers from spring to autumn.

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Family Boraginaceae

Habitat and cultivation

Native to the Mediterranean, Borago self-sows freely in any sunny situation and garden soil. Seedlings may be transplanted when small. It is a good bee plant. It is drought and frost resistant.

Parts used

The herb harvested just prior to or at the start of flowering.

Active constituents

1) Saponins

2) Mucilage1

3) Tannins

4) Pyrrolizidine alkaloids (PAs) including lycopsamine and intermedine, with smaller amounts of amabiline and supinine. These alkaloids occur in very low concentration, the content being estimated to be of the order of 2–10 ppm (parts per million) or 0.0002% to 0.001% in commercially analysed samples2

5) Lipids containing fatty acids, the major one being stearidonic acid (max. 9%)3 and γ-linoleinc acid (max. 2%).4 The composition of unsaturated fatty acids is in fact similar to that found in the seed. Their levels have been reported as 4.4% in leaves and 14.6% in stems compared to 25.3% in seeds.5 The seeds contain oil with omega 3 and 6 essential fatty acids (being particularly rich in γ-linolenic acid)9 but these are generally in lower levels than found in evening primrose.

Also choline, the polyphenol—rosmarinic acid (around 1.5%),6 a small amount of dhurrin7 (a derivative of the cyanogenic glucoside, prunassin) and trace amounts of essential oil. The fresh herb has a very high water content around 94% on average.8

Nutritional constituents

Minerals: Potassium, iron8 and calcium

Actions

1) Diuretic

2) Demulcent

3) Emollient

It is also reportedly expectorant, anti-inflammatory, an adrenal tonic and a galactagogue.

Scientific information

Little pharmacological data is available for the herb although some of the constituents have been subject to scientific study.

In vitro—The leaves have very good anti-oxidant activity mainly, but not only, attributed to rosmarinic acid.9

In vivo—An epidemiological study has found that in areas where Borago leaves and stems are boiled and eaten regularly as a vegetable, the incidence of gastric cancer is much lower.5 Therefore there is possibly some protective benefit from its consumption.

There is also a body of clinical and experimental data highlighting the benefits of the particular fatty acids in Borago e.g. in the treatment of rheumatoid arthritis10 and atopic eczema.11 The amount of γ-linolenic acid in the herb, after boiling, was around 0.06%.5

It was valued traditionally for treating many ailments.

Medicinal uses

Cardiovascular system

Respiratory tract

Urinary tract

Reproductive tract

Musculoskeletal

Skin

Externally

Pharmacy

Three times daily  
Infusion of dried herb –   2–4 g
Fluid Extract –   2–4 ml

Precautions and/or safety

Because of the presence of unsaturated PAs and their possible hepatotoxicity, Borago is deemed unsafe by some sources. These alkaloids, with the exception of supinine, have shown genotoxicity and carcinogenicity using a standard model.12 However as stated the alkaloids are present in very low concentration. To date no adverse reactions of any sort have been reported in spite of its long history of human consumption. Apart from in Australia, its use is unrestricted.

Historical uses

The historical use is largely as indicated above. In addition it was used by Culpeper to expel venoms and poisons; to raise the spirits in melancholia (adrenal action?); to treat jaundice; with Fumaria in the treatment of the itch, ringworm, tetters, sores and scabs. The flowers were also employed in convalescence, depression (“passions of the heart”), as a wash for sore eyes. Culpeper does stipulate that the green herb must be used, not the dried. This may account for the diminished use of this herb in modern practice. Borage flowers form part of La tisane de Cinque Fleurs together with flowers of Calendula officinalis, Cytisus scoparius, Lavandula officinalis and Viola tricolour.

Symphytum spp. [Symphytum officinale, S. asperum and S. x uplandicum]

Comfrey, Russian comfrey

Originally the herb officially consisted of the leaves and/or root of Symphytum officinale but in commercial practice at the present time the three species are all used interchangeably.

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Family Boraginaceae

Description

S. officinale is a perennial herb which dies back in winter. Stems grow a metre high in flower. Roots, brittle and easily broken, black skinned but white inside, growing very thick with age and forming large clumps. Basal leaves very large and long stalked with an ovate or ovate-lanceolate lamina. Densely hispid above and below but not scabrid. Cauline leaves smaller, the uppermost sessile with the base continued down the stem to form a narrow wing extending to the node below. Cymes densely bristly, calyx 5–8 cm long and lobed nearly to the base. Corolla broadly cylindric, lower part of the tube whitish, expanded upper part and lobes pale pink, occasionally creamy white, often becoming purplish with age and when dried. Nutlets 3–6 cm long, but rarely formed. Flowers from spring to autumn.

Habitat and cultivation

Native of Europe and Asia. Propagated by root division, grows almost anywhere but prefers a sunny situation and moist, rich, well-drained soil. Once established it is difficult to eradicate. Dormant from mid-winter to early spring. Drought and frost tender.

Parts used

The leaves and roots are used. The leaves are gathered at the start of or just prior to flowering. The roots are gathered in autumn or spring.

Active constituents

1) Allantoin (around 1.3% in leaves and 0.8% in roots13 although up to 4.7% has been reported in the latter14)

2) Mucilage (up to 29%) polysaccharides of fructose and glucose15 and gum (root)

3) Pyrrolizidine alkaloids (PAs) (0.02–0.18% in dried leaves and 0.25–0.29% in roots16) including symphytine, symlandine (these are stereoisomers), cynaglossine, lycopsamine,17 echinatine and N-oxides of some of the above.18 The total and individual level of alkaloids seems to be quite variable.18,19 Echimidine has been reported in the roots of S. officinale20

4) Tannins (4–6%)

5) Phytosterols—including β-sitosterol and stigmasterol13

6) Phenolics including chlorogenic, rosmarinic, lithospermic and caffeic acids21,22

Also contains asparagine, resin and triterpenoid saponins (root).23–25

Nutritional constituents

Vitamins: A, B12 and C

Minerals: Calcium, potassium, phosphorus, iron, magnesium, selenium, sulphur, copper and zinc Comfrey also contains some protein and eighteen amino acids including lysine.

Actions

1) Vulnerary

2) Demulcent

3) Astringent

4) Anti-inflammatory

Scientific information

The use of comfrey as a medicine dates back thousands of years, both radix and folia were used as tissue healers and soothing agents. The root was listed in the British Pharmacopoeia as a medicine to treat wounds and ulcers (both internal and external) the healing action having been attributed to the uric acid metabolite, allantoin.26 Allantoin is a well established dermatological agent which has been synthesised for use in pharmaceutical preparations to “stimulate tissue formation and hasten wound healing”.26 Comfrey is approved by German Commission E for treatment by external application only of bruises, sprains and joint distortions.

Much of the more recent research into the herb has concentrated on the safety issues surrounding the PAs whilst clinical trials have assessed the benefits associated with the external use of the herb.

In vitro—The whole extract is anti-inflammatory, partly due to a strong inhibition of PAF, to which rosmarinic acid and allantoin contribute.21,27

The extract and alkaloid fraction also have immunomodulatory activity.28,29

In vivo—External preparations of the herb have been effective in the treatment of ankle injuries/sprains (equal to and possibly superior to diclofenac)30–33 and in promoting the healing of bruises and pain in muscles and joints.33

Also in chronic and sub-acute conditions the external use of the herb was able to34:

Herbal combinations which included Symphytum improved the healing of gum damage due to chronic inflammation and/or dental surgery with no adverse side-effects.36,37

Medicinal uses

Gastro-intestinal tract

Used for inflamed and damaged tissue in this tract:

Externally

An ideal healing agent for all skin and musculoskeletal injuries applied externally over the site of deeper, damaged tissues and around injured skin:

As an adjunct in the treatment of:

Pharmacy

Three times daily  
Infusion of dried herb –   2–8 g
Tincture 1:5 –   2–5 ml (suggested guidelines)
Fluid Extract (25%) –   2–8 ml (suggested guidelines)
Ointment or cream –   10–15% w/w of root or leaves

For open wounds the herb is best applied as a compress or poultice. Although allantoin has poor water solubility26 it is apparently extracted into cold water macerates27 and is well absorbed through the skin.

Precautions and/or safety

The external preparations used in the above clinical trials were all very well tolerated.

Since the discovery that livestock that had eaten ragwort which contains PAs developed liver disease scientists have been interested in the potential human health effects of ingestion of these alkaloids. Plants other than comfrey are known to contain them—they are also found in members of the Asteraceae and Fabaceae families—but comfrey has been of particular interest because it has been used extensively both as a medicine and a food.

The scientific evidence against comfrey is largely based on animal experiments which showed a connection between liver abnormalities and the consumption of very large quantities of the herb. PAs have been well researched in the last few decades and it is now known that they are metabolised in the liver, being converted to pyrroles which increases their reactivity and therefore their potential to cause damage.38 As the liver becomes damaged the alkaloids can go on to damage other tissues e.g. the lungs. Again using animal studies it seems that PAs may persist in the body, being rereleased so that they can cause damage long after their initial ingestion.39

As far as the PAs in comfrey are concerned their total content varies with:

a) plant part—levels are ten times higher in root than in leaves

b) state of maturation—smaller leaves have higher levels than more mature ones40

c) species—content and type of alkaloid may be different19

The particular PAs in comfrey are not the toxic ones associated with reported PA poisoning19 and the toxicity of Symphytum in humans needs to be assessed carefully. Firstly the whole herb is likely to behave differently from isolated alkaloids, sulphurcontaining amino acids, which occur in quantity in comfrey, for example reduce their toxicity.19,41 Secondly there is some uncertainty about the presence of the hepatotoxic PAs echimidine and lasiocarpine in S. officinale19,42 and if one or both are present their levels are likely to be very low. The main comfrey PAs are based on retronecine which has low hepatotoxicity and indeed lycopsamine and intermedine have not shown toxicity even at high dose in animal models.43 Thirdly the hepatotoxicity of Symphytum spp. has been based on a rat model and conversion of quantities of herb that would need to be ingested by humans to reach equivalent levels would be very difficult to achieve.19 (The lowest dose of PAs from comfrey that could cause toxicity according to the World Health Organisation (1989) has been estimated at a very conservative 0.015 mg/kg this equates to 1 mg a day for a 70 kg person or 5 g of dried leaf or 25 ml of 1:5 extract.)

The potential effects of PAs is further complicated by the fact that different animal models have quite different susceptibilities to their toxicity—which animal model is likely to adequately represent human reactions?19

Liver function tests on long term comfrey users were normal even though some users had consumed up to 25 g per day of leaf for up to 30 years.19

To-date a very small number of human cases have been reported in the medical literature implicating comfrey as a causative factor in hepatic veno-occlusive disease44 and these appeared in the decade around 1980, nothing has been reported recently. In the cases that have been reported and analysed the link between liver abnormalities and comfrey was not clearly established.19 A variety of over-the-counter products of leaf and root were shown to contain measurable and variable quantities of hepatotoxic PAs which reflects a need for caution in using these preparations45. In countries where the internal use of comfrey is still allowed there is a voluntary restriction on using the root, leaf extracts only are now recommended.

The percutaneous absorption of PAs in toxic form appears to be negligible, again based on animal data.17

PAs have also been associated with carcinogenicity and mutagenicity although they have not been associated with human cancers to-date.39 In vitro the isolated alkaloids of S. officinale were mutagenic to human lymphocytes at very high concentration only.46

Historical uses

Lung and urinary tract problems especially where associated with bleeding. Quinsy; whooping cough and consumption. Joint diseases; wounds and cuts; broken bones and “ruptures”. Diarrhoea; dysentery and other “intestinal troubles” including ulcers of stomach and liver. Also used for “defective circulation” and anaemia. Externally to ease the pain of gout. Haemorrhoids; suppurating boils and abscesses; gangrenous ulcers. Historically the root was more highly prized than the leaves.