English: Chiretta

Hindi: Kirat, chirayita

Sanskrit: Kirata-tikta, bhunimba

Chirata is an ancient Ayurvedic drug, sometimes known as 'Nepali Neem' because it is common in the forests of Nepal. The name is sometimes used for other gentian-like plants sold in Indian bazaars. It was introduced into Europe in 1839 and is still widely used there.

Habitat

It is found in the temperate Himalayas from Kashmir to Bhutan up to a height of 1200-1500 m.

Botanical description

An erect or prostrate herb, much branched, with lanceolate leaves (Plate 57). The flowers are greenish-yellow with a purplish tinge, in large panicles. The fruits are egg-shaped capsules containing a large number of seeds.

Parts used

Whole plant.

Traditional and modern use

The drug is used to stimulate the appetite and relieve acidity, biliousness and nausea and is highly valued as a tonic in debility and convalescence and for liver disorders. It is also an alterative, laxative, vermifuge and sedative and has been used in asthma, cough, bronchitis and malaria.

Ethnoveterinary usage

The whole plant is used to treat fever in ruminants.

Major chemical constituents
Iridoids

Amarogenin, amarogentin, amaroswerin, chiratin, chiratanin, chiratogenin, decussatJn, enicoflavine, gentianine, gentiocrucin, gentiopicrin, isobellidifolin, swertiamarin, sweroside, swerchirin, swertianin and swertinin.

Xanthones

1,3,7,8- Tetrahydroxyxanthone,
1 ,8-dihydroxy-3, 7 -dimethoxyxanthone, 1-hydroxy-3,5,8-trimethoxyxanthone and mangiferin.

Triterpenes

The plant yields ß-amyrin and lupeo!.

Medicinal and pharmacological activities

Hepatoprotective activity: The methanol extract has been evaluated for antihepatotoxic activity using paracetamol and galactosamine models. It was found to be active at a dose of 100 mg/kg and on fractionating the activity was found to reside mainly in the chloroform fraction which was most active at a dose level of 25 mg/kg. These two hepatotoxins induce hepatotoxicity by different mechanisms, suggesting a broad and non-specific protection of the liver for Swertia chirata. The liver-protecting activity was also ascertained in carbon tetrachlorideinduced liver damage in albino rats over 16 days. Simultaneous administration of S. chirata at a dose of 50 mg/kg produced an improvement in both biochemical and histopathological parameters and again the chloroform extract was the most active.

Leishmanicidal activity: Amarogentin, isolated from the methanolic extract of S. chirata, exhibited potent inhibitory action against type I DNA topoisomerase from Leishmania donovani. The mechanism of action is thought to be by preventing binary complex formation. The activity of amarogentin, in the form of liposomes and niosomes, was also examined in a hamster model of experimental leishmaniasis. The liposomal, and particularly the niosomal, forms were found to be more effective than the free amarogentin. Blood pathology, histological staining of tissues and specific enzyme levels related to normal liver function revealed no toxicity.

Antiulcer activity: An ethanolic extract of S. chirata markedly reduced the intensity of gastric ulcers induced by indomethacin and necrotising agents in rats. Ethanol-induced gastric wall mucus depletion and restoration of the non-protein sulfhydryl (NP-SH) content in the glandular stomachs was also achieved by pretreating the rats with the extract. It also showed anticholinergic activity by inhibiting acetylcholine-induced contraction of guinea pig ileum.

CNS depressant activity: An ethanolic extract (excluding mangiferin) of S. chirata reversed mangiferin-induced CNS stimulation effects in albino mice and rats. Swertiamarin and mangiferin, both present in the same plant, antagonised each other in vivo.

Hypoglycaemic activity: Significant blood sugar lowering effects of the 95% ethanolic extract were observed in fed, fasted and glucose-loaded albino rats. The hypoglycaemic activity of tolbutamide was increased in healthy albino rats by giving S. chirata extract orally.

>Antiinflammatory activity: The ethanolic extract of S. chirata exhibited significant antiinflammatory activity when tested in acute, subacute and chronic models of inflammation.

Antimicrobial activity: Antimicrobial activity has been demonstrated by S. chirata.

Safety profile

The drug normally produced no problems at recommended doses. The maximum tolerated dose of the 50% ethanolic extract of the whole plant was 1000 mg/kg IP in adult rats.