Читать книгу Secondary Metabolites of Medicinal Plants - Bharat Singh - Страница 58

Camptotheca acuminata Decne (Fam. – Nyssaceae) is a deciduous tree endemic to China, and its bark and fruits have been used in folk medicine to treat cancer (Hisang et al. 1985; Tu et al. 2000; Lansiaux et al. 2001; Sun et al. 2001; Yang et al. 2002; Xu et al. 2003; Chen et al. 2004, 2013; Wang et al. 2004; He et al. 2006; Wu et al. 2007; Ye et al. 2007; Lan et al. 2010; Chen and Wang 2011; Song and Hu 2012; Lin et al. 2013, 2014), virus (Li et al. 2002b), and bacterial diseases (Li et al. 2018). The plant species showed the presence of camptothecin, ethyl caffeate, ursolic acid, betulinic acid, and inositol (Wu et al. 1985). Several tannins were isolated from C. acuminata, viz, camptothins A and B, cornusiin A, gemin D, tellimagrandin I, tellimagrandin II, 1,2,6-tri-o-galloyl-β-D-glucose, 1,2,3,6-tetra-o-galloyl-β-D-glucose, and pedunculagin. The identification of these compounds was confirmed by spectral data (Wu et al. 1980; Hatano et al. 1988). The camptothecin is normally accumulated in glandular trichomes of leaves and stems, and the concentration varies from species to species or season to season. Younger leaves, which are more photosynthetic, produce higher yield of camptothecin (Li et al. 2002a). Similarly, the accumulation of camptothecin was higher in mature fruits than in younger fruits. The camptothecin synthesis was observed in all organs as well as all the developmental stages of C. acuminata (Valletta et al. 2007). The methanolic extract of leaves and seeds demonstrated the presence of camptothecin as well as two its derivatives, hydroxycamptothecin and methoxycamptothecin (Zhang et al. 2007). The Camptotheca species have been evaluated for various categories of secondary metabolites including alkaloids, ellagic acids, flavonoids, sterols, terpenes, tannins, polyphenols and fatty acids, iridoid, lignan, polyols, amide, and sacchardide (Li and Wang 2014).

The camptothecin (a pyrroloquinoline alkaloid), identified from C. acuminata, has anticancer property. The pyrroloquinoline alkaloid is characterized by a pentacyclic ring with pyrrolo[3,4-β]-quinoline moiety (rings A, B, and C), conjugated pyridone moiety (ring D), and a chiral center within a six-membered hydroxy lactone (ring E). The pentacyclic ring of pyrroloquinoline alkaloid plays an important role in the inhibition of DNA topoisomerase I. Later on this plant species is considered as an important source of camptothecinoids, and its various parts (root, stem, leaves, fruits, and flower buds) are used for separation of camptothecinoids. Due to inhibition of DNA topoisomerase I activity, the camptothecinoids have showed the anticancer property. The several camptothecinoids (10-hydroxy-20-deoxycamptothecin, 10-methoxy-20-O-acetylcamptothecin, 20-D-glucopyranosyl 18-hydroxycamptothecin, 10-methoxycamptothecin, 18-hydroxycamptothecin, 20-O-acetylcamptothecin, 20-deoxycamptothecin) have been isolated from root bark and leaves of C. acuminata. The isolated compounds possessed a strong cytotoxicity against P388 leukemia cell (Lin et al. 1989; Zhang et al. 2004; Chen et al. 2017). Similarly, 11-hydroxycamptothecin, 11-methoxycamptothecin, 10-methoxycamptothecin, 20-deoxycamptothecin, and 18-hydroxycamptothecin were characterized from the fruits of C. acuminata (Hsu et al. 1977; Lin et al. 1978, 1979a,b, 1982). From the stem bark of C. acuminata, 20-hexanoylcamptothecin, 20-hexanoyl-10-methoxycamptothecin, and 20-deoxycamptothecin were also isolated (Lin et al. 1979b). 20-Formylbenz, indolizino[1,2-β]quinoline-11(13H)-one, 22-hydroxyacuminatine, and 19-hydroxymappicine are three minor quinoline alkaloids isolated from the roots and fruits of C. acuminata (Wani and Wall 1969; Lin and Cordell 1989; Lin et al. 1989; Carte et al. 1990; Yin and Hu 2005). 10-methoxy-20-O-acetylcamptothecin, 20-O-β-glucopyranosyl 18-hydroxycamptothecin, 20-formylbenz indolizino[1,2-β]quino-line-11(13H)-one, and 3,4-methylenedioxy-3′-O-methyl-5′-hydroxyellagic acid were isolated and characterized from C. acuminata (Zhang et al. 2004; Lu et al. 2007; Li et al. 2018).

From the fruits of C. acuminata, five alkaloids including angustoline, 19-O-methylangustoline, camptacumotine, camptacumanine, and naucleficine were isolated (Lin et al. 1988a,b). Similarly, several indole alkaloid glycosides (strictosamide, pumiloside, vincosamide, strictosidinic acid) were characterized from stem bark, roots, and fruits of C. acuminata (Yin and Hu 2005). The three simple alkaloids (dihydroisoquinamine, venoterpine, and 1,2-dihydro-2-oxoquinoline-4-carboxylic acid) were also isolated and characterized from the fruits and roots of C. acuminata (Lin et al. 1988b). The several flavonol glycosides (hyperoside, isoquercitrin, trifolin, astragalin, quercetin, and kaempferol) were isolated, and their identities were confirmed by analysis of spectral data (Tien et al. 1977). The camptothin A, camptothin B, cornusiin A, gemin D, tellimagrandin II, tellimagrandin I, 1,2,6-tri-O-galloyl-β-D-glucose, 1,2,3,6-tetra-O-galloyl-β-D-glucose, pedunculagin, camptothecoside, camptothecin 11-O-β-D-glucopyranoside, (5R)-camptothecin 5-O-β-D-glucopyranoside, strictosidinic acid 6′-O-β-D-glucopyranoside, vincosamide 11-O-β-D-glucopyranoside, and vincosamide 11,6′-di-O-β-D-glucopyranoside were isolated from the leaves and fruits of C. acuminata (Hatano et al. 1988; Wang et al. 2015).

Several ellagic acids and syringic acid were isolated from the fruits of C. acuminata including 3,4′-O-dimethylellagic acid, 3,3′,4-O-trimethylellagic acid, 3′-O-methyl-3,4-O,O-methylideneellagic acid, 3,4-O,O-methylideneellagic acid, 3′,4′-O-dimethyl-3,4-O,O-methylideneellagio acid, 5′-methoxy-3′,4′-O-dimethyl-3,4-O,O-methylidene ellagic acid, 3,3′,4,4′-O-tetramethyl-5′-methoxyellagic acid, and 5′-hydroxy-3′,4′-O-dimethyl-3,4-O,O-methylideneellagic acid (Lin et al. 1979a). Similarly, the other compounds such as 11-hydrogyoamptothecin, 10-methozycamptothecin, (+)-abscisic acid, syringaresinol and β-sitosterol, and 18-hydroxycamptothecin were characterized (Lin et al. 1982, 1988a,b). Sequential fractionation of this plant species has afforded hydroxycamptothecin, 22-hydroxyacuminatine, 19-hydroxymappicine, camptothecin, 10-methoxycamptothecin, and methoxycamptothecin from C. acuminata (Wani and Wall 1969; Buta and Novak 1978; Lin and Cordell 1989), and 3α-hydroxyoblongolide C, 8-acetylobolngolide P, and 1‴-hydroxyoblongolide X from the fruits of C. acuminata (Li et al. 2017).

A total of six minor indole alkaloids (camptacumotine, 19-O-methylangustoline, camptacumanine, naucleficine, angustoline, and dihydroisoquinamine) and glycosides (10-O-(1-β-D-glycosyl), camptothecin, syringaresinol-4,4′-O-bis-β-D-glucoside, hyperoside, and pumiloside) were isolated from the seeds of C. acuminata, and their identities were confirmed by analysis of spectral data (Lin et al. 1988a; Lin and Cordell 1990). Besides these phytochemicals, vincoside lactam and strictosidinic acid were also separated from the C. acuminata (Guo and Yuan 2016).