Читать книгу Secondary Metabolites of Medicinal Plants - Bharat Singh - Страница 40

Arnebia benthamii (Wall. ex G. Don) Johnston (Fam. – Boraginaceae) is a Himalayan medicinal plant found in Western Himalaya. It is an erect, herbaceous, and perennial habitat, used in the formulation of gaozaban, antibacterial, antifungal, anti-inflammatory, and wound-healing drug (Manjkhola and Dhar 2002). The root contains shikonin, possesses several medicinal properties, and is available in the market with a trade name Ratan Jot (Kirtikar and Basu 1984). The species also possesses stimulant, tonic, diuretic, and expectorant properties. The flowering shoots are used in the treatment of tongue, throat, fever, and cardiac disorders. Arnebin-1 and arnebin-3 isolated from this species possess anticancer activity (Harborne and Baxter 1996).

The Arnebia species is a perennial grass, found in India, Persia, Sudan, Arabia, China, Egypt, Nubia, and Pakistan. Some common species are A. benthamii, A. euchroma, A. guttata, A. nobilis, and A. hispidissima (Anonymous 1985). Roots are recommended for the treatment of ulcers, boils, cuts, heart ailments, headache, and fever. The aqueous extract of flowering shoot is known as remedy for tongue and throat troubles and cardiac complaints, while the whole plant is used as a stimulant, tonic, diuretic, and expectorant. Likewise, the roots of A. euchroma are used in bruises and skin eruptions (Chopra et al. 1956; Kirtikar and Basu 1967; Anonymous 1976). A. hispidissima also possesses anti-inflammatory (Singh and Singh 2003; Singh et al. 2004), antimicrobial (Bhakuni et al. 1969; Shukla et al. 1969; Jain et al. 1999), antitumor (Sankawa et al. 1977; Katti et al. 1979), antiviral (Kashiwada et al. 1995), and inhibition of platelet aggregation activities (Yao et al. 1991).

Most of the naphthaquinones are found in higher plants, distributed among more than 20 families located in leaves, flowers, wood, root bark, and fruits (Thompson 1971). Alkannin, an isomer of shikonin, isolated originally from Alkanna tinctoria (Brockmann 1935) and A. hispidissima (Jain et al. 1999). The petroleum ether extract of roots later yielded a pigment as glittering red solid identified as shikonin (Jain and Mathur 1965). Shikonin has been isolated from A. euchroma (Romanova et al. 1968; Fu et al. 1984). The shikonin content in dried roots of A. euchroma was reported to be 2.47% (Zhang et al. 1989). Hexane fraction of A. nobilis roots yielded the four crystalline naphthaquinones, viz arnebin-1, arnebin-2, arnebin-3, arnebin-4 (Shukla et al. 1969), arnebin-5, arnebin-6, and arnebin-7 (Shukla et al. 1971, 1973). A. euchroma and A. guttata produce acetyl shikonin (Lin et al. 1980; Lu et al. 1983), alkannin-β, β-dimethyl acrylate, β-hydroxyisovalerate (Lin 1981; Khan et al. 1983), β-deoxyshikonin, β-dimethyl acryl shikonin, acetyl shikonin, teracryl shikonin, and β-hydroxyisovaleryl shikonin (Zhu et al. 1984). Arnebia decumbens was found to contain 5,8-dihydroxy-2,1,4-methylpentyl-13-enyl-1,4-naphthaquinones, shikonin isovalerate, and 3,6-dihydroxy-2-isovaleryl-1,2,4-benzoquinones (Afzal and Al-Oriquat 1986a,b; Salim et al. 1996). Teracryl alkannin was found to be present in roots of Arnebia densiflora (Kirimer et al. 1995). Cycloarnebin-7, tiglic acid, and others were isolated from A. hispidissima (Singh and Singh 2003; Singh et al. 2004). Arnebinol and arnebinone were isolated from the roots of A. euchroma and A. hispidissima (Eisai Co. Ltd 1983; Yao et al. 1983a,b). The A. hispidissima and A. nobilis roots' ethanolic extract provided β-sitosterol (Nigam and Mitra 1964), lupeol, betulin, and β-amyrin acetate (Sharma et al. 1972). Two triterpenic acids identified as tormentic acid and 2-α-hydroxyursolic acid have been isolated from A. euchroma (Yang et al. 1992). Several flavonoids were separated from fresh flowers of A. hispidissima (Hamdard et al. 1988). A. hispidissima gave echimidine, monocrotaline (Gamila et al. 1987), O⁹-angeloyl retronecine, and minor amounts of O⁷-angeloyl retronecine were isolated from A. euchroma (Roeder and Rengel-Meyer 1993; Srivastava et al. 1999). The presence of 7- and 9-tigloyl retronecine, supinine, heliotrine, lycopsamine, and europine was confirmed by gas-liquid chromatography (GLC) and gas chromatography–mass spectrometry (GC–MS) in A. decumbens (El-Dahmy et al. 1995).