Lepidium sativum (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Lepidium sativum L.

Protologue: Sp. pl. 2: 644 (1753).

Family: Cruciferae

Chromosome number: 2n= (16,) 24, (36)

• Garden cress, pepper cress, cress (En).
• Cresson alénois (Fr)
• Indonesia: alim.

L. sativum is grown worldwide as a spicy salad herb. Its origin is not known, but is possibly Ethiopia or Iran.

In Java and China, the seedlings of L. sativum are mixed into medicinal preparations of unknown use. In India, the seed oil, like mustard oil, is applied for hiccough and intestinal problems. The pounded seeds are poulticed on the skin, and have a vesicant and soothing action on bruises and sprains. The seeds are also considered galactagogue, emmenagogue, laxative, tonic, diuretic and aphrodisiac. The mucilage of the germinating seeds allays the irritation of the intestines in dysentery and diarrhoea. The aerial parts are used in the treatment of asthma, cough and bleeding piles. Leaves are mildly stimulant and diuretic, and useful in scorbutic diseases and liver complaints. The roots are used in secondary syphilis.

In Ethiopia, a paste of the seeds with water is used on chapped lips, and also against sunburn and other skin problems. The paste is taken internally with honey for amoebic dysentery, and given to animals with stomach problems. The seeds are chewed for sore throat, cough, asthma and headache, but in large quantities also to induce abortion. It is also applied externally as an insect repellent.

In Europe, the herb is used for cough and for vitamin C deficiency, as well as for constipation, as a diuretic and for poor immunity.

The seedlings or young leaves, which taste like radish, are widely eaten in salads, soups and omelets. The whole seed pods can be used, fresh or dried, as a seasoning with a peppery flavour. The seed oil is used for soap making.

In the temperate zone, L. sativum is extensively used as a test organism in plant physiological studies, as an indicator organism to examine toxicity levels of environmental pollutants, and in experimental studies assessing diverse pathogens.

Seed of L. sativum is widely traded.

The stem and leaves of L. sativum contain glucosinolates, the main component being glucotropaeolin (benzylglucosinolate), yielding benzyl cyanide when the plant is bruised, or benzyl cyanide, benzylthiocyanate, benzylisothiocyanate and benzylamine when the plant is extracted with water. Upon steam distillation the herb yields about 0.1% of a colourless essential oil,with a characteristic pungent odour, containing variable amounts of benzyl isothiocyanate and benzyl cyanide. The seeds yield 25% of a yellowish-brown, semi-drying oil with a peculiar, disagreeable odour. The oil is rich in oleic-, linoleic- and uric acid, and also contains the dimeric imidazole alkaloids lepidine B, C, D, E and F, as well as the imidazole alkaloid lepidine and two monomeric imidazole alkaloids, semilepidinoside A and B. The seed oil has anti-oxidant properties.

Seeds were fed in a toxicity study to Wistar albino rats, and were found to be non-toxic at 2% (w/w), toxic but not fatal at 10% (w/w) and lethal at 50% (w/w) of the diet for 6 weeks, causing depression in growth rate and entero-hepato-nephrotoxicity.

The seed-coat of germinating seeds contains much mucilage, which has an allelopathic substance, lepidimoide, also found in the exudate of germinated seeds of many other species, e.g. sunflower, rice, and lettuce. Lepidimoide promoted the hypocotyl growth of etiolated Amaranthus caudatus L. at concentrations higher than 3 μM and inhibited the root growth at concentrations higher than 100 μM. The growth-promoting activity in hypocotyls was 20 or 30 times as much as that of gibberellic acid. The mucilage also contains cellulose (18%), and after hydrolysis it produces arabinose, rhamnose, galactose and galacturonic acid.

The effects of the germinating seeds on the in vitro rate of potato starch hydrolysis were studied to determine the potential for slowing down the hydrolysis of starch to glucose in diabetic persons. The seeds showed a high reduction in starch hydrolysis (42%) and were tested in vivo on 11 non-insulin dependent diabetes mellitus (NIDDM) persons as well as 14 normal healthy persons. It was observed that for both controls and diabetics, the seeds significantly lowered the glycaemic response to a test meal as compared with their response to the meal alone. Furthermore, diabetics showed a higher reduction than the healthy subjects. In the long-term (21 days) treatment of diabetics with 15 g seeds/day, 9 out of 11 subjects showed a reduction in the levels of blood glucose from 10.2 to 8.3 mM at the end of study period. The ethanol extract of the seeds showed significant anti-inflammatory effects against carrageenan-induced rat paw oedema, at a dose of 500 mg/kg.

The seed oil has a pronounced oestrogenic activity. Tests on immature rats receiving 3-4 drops of the oil with their diet showed significantly better development and higher weight of their ovaries than control animals.

The antibacterial action of L. sativum has been demonstrated in several tests. The extract of the fresh leaves showed strong antibacterial action against Bacillus subtilis and Micrococcus pyogenes var. aureus, but was less effective against Escherichia coli. The antibacterial action depends largely on the age of the plants used. An antiviral effect against the encephalitis virus Columbia SH was demonstrated in a test on mice.

Seeds of L. sativum did not show significant in vitro antimalarial activity, however, at the highest concentration used (50 μg/ml), as measured by the inhibition of [³H]hypoxanthine uptake into Plasmodium falciparum (strain FCA-2/Ethiopia).

An in vitro study was conducted to investigate the nematicidal effect of some glucosinolates and the products of their myrosinase-mediated enzymatic hydrolysis on second-stage juveniles of the sugar beet cyst nematode Heterodera schachtii. The glucosinolates tested were purified from the seeds of L. sativum and some other Cruciferae, which are hosts of the nematode. The glucosinolates tested in their original form showed no nematocidal effect, whereas the products of the enzymatic hydrolysis at pH 7.0 (essentially the isothiocyanates) of e.g. glucotropeolin, demonstrated a mortality rate that varied as a function of both the concentration of product and the exposure time.

Furthermore, an extract of L. sativum was tested for antimutagenic effects on pesticides in the Salmonella typhimurium strains TA98 and TA100 with and without the metabolic activation of S9. The extract decreased the mutagenic effects of Captan, Folpet, DDVP, Azinphosmethyl, Bioresmethrin and Trifluralin, and also the antimutagenic effects of glutathione, cysteine and ascorbic acid.

In addition, the antireproductive potential of the leaves was tested with aqueous or 90% ethanol extracts in rats orally dosed for 10 days after insemination, with special reference to effects on foetal development, and showed significant teratologic effect. The continental Asian L. capitatum Hook.f. & Thomson showed similar effects in rats.

• An erect, polymorphic, annual herb, 30-70 cm tall, taproot slender, stems usually much branched, glabrous or with scattered minute hairs.
• Leaves alternate, membranaceous, ovate-oblong in outline, up to 12 cm × 9 cm, imparipinnati- or bipinnatipartite, with 2-4 pairs of lateral lobes, lobes linear, lanceolate or oblanceolate, up to 3 cm long, uppermost leaves sometimes simple, serrate, glabrous or sparsely pubescent; petiole up to 4 cm long in basal leaves; stipules absent.
• Inflorescence a terminal or axillary raceme, 1-3 cm long, accrescent to 25 cm when fruiting.
• Flowers bisexual, rather conspicuous, whitish to violet, pedicel 3-6 mm long in fruit, ascending; sepals 4, elliptical, 1-1.5 mm long, green, margins membranaceous; petals 4, spathulate to slightly clawed, 1.5-3 mm long, apex rounded; stamens 6, unequal in length, nectaries 6, alternating with filaments; ovary superior, flattened dorso-ventrally, apex emarginate, lateral margins wing-like, style up to 0.5 mm long, stigma capitate, finely pappilate.
• Fruit an ovoid, flattened silique, 4.5-6.5 mm × 3-4 mm, pale green to yellowish, apical wings prominent, apex emarginate, dehiscing by 2 valves, leaving the replum with thin, white septum; 1 seed per locule.
• Seed subovoid, flattened, 2-3 mm × 1.5 mm, wingless, reddish-brown.
• Seedling with epigeal germination; cotyledons trifoliolate, lobes spathulate, lateral lobes smaller.

L. sativum completes its life cycle in 3-4 months.

Lepidium consists of about 140 species with a cosmopolitan distribution, but mainly in the temperate regions.

Some Lepidium species other than L. sativum are also biologically active, the most interesting being the South American L. meyenii Walp. The effect of oral administration of a purified lipidic extract from L. meyenii (MacaPure M-01 and M-02) on the sexual behaviour of mice and rats was evaluated by the number of complete matings in normal mice, and on the latent period of erection (LPE) in rats with erectile dysfunction. Oral administration of M-01 and M-02 enhanced the sexual function of the mice and rats, as evidenced by an increase in the number of complete intromissions and the number of sperm-positive females in normal mice, and a decrease in the LPE in male rats with erectile dysfunction.

L. sativum is mainly known from cultivation but escaped, ruderal types occur as well, especially in the temperate regions, more rarely in tropical regions. L. sativum prefers full sun or partial shade.

L. sativum is propagated by seed. For sprout production, the seeds are sown thickly in rows, covered lightly with soil or not, and a few days after germination the seedlings are ready for harvesting. Plants can also be thinned if larger plants are preferred. For seed production, a few plants are left till the seeds are fully mature. The plants are then pulled up, dried and threshed so that the seeds fall out.

Germination rate in the first and second year after harvesting was >90%, and decreased slightly after 5-6 years, but remained above 50% for 10 years.

Significant amounts of lepidine were detected in mature and juvenile explants from both in vivo and in vitro grown L. sativum plants. The yield, however, was variable depending upon the source and type of explant used. Mature in vivo plants at vegetative stage exhibited highest yield, after 8 weeks in shoot apex callus on Murashige & Skoog medium supplemented with naphthalene acetic acid at 2 mg/day and benzylaminopurine (benzyladenine) at 5 mg/day. Addition of 900 μM Zn²⁺ or 100 μM Cu²⁺ further enhanced the yield of lepidine.

L. sativum thrives on any rich, light, moisture-retentive soils, but grows best on moist loams. It can be grown at all elevations throughout the year, but grows best in the cool season in tropical regions. In warm climates the flavour becomes quite peppery.

L. sativum has few diseases and pests. Some fungal and viral infections are recorded, as well as susceptibility to nematodes.

In Europe, medicinally used plant parts of L. sativum are harvested during or just after the flowering season. For culinary use, the leaves should be harvested before flowering, and for sprout production plants are harvested a few days after germination.

Most plant parts of L. sativum are normally used fresh. The seeds can be stored for future use.

L. sativum is widely grown throughout South-East Asia. Breeding is done for culinary purposes only.

Glucosinolates and their derivatives after breakdown in general are known to display several interesting pharmacological activities, which merit further research. L. sativum is therefore of interest as a source of these compounds. Also, the mucilage from the seeds shows an interesting effect on the rate of potato starch hydrolysis, which might be of use in the treatment of non-insulin dependent diabetes.

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