Читать книгу Secondary Metabolites of Medicinal Plants - Bharat Singh - Страница 36

The plant Aloe vera (Fam. – Liliaceae) is used in Ayurvedic, homoeopathic, and allopathic systems of medicine and not only in tribal community but also by most of the people for food and medicine (Grindlay and Reynolds 1986; Mothana and Linclequist 2005). The plant leaves contain numerous vitamins, minerals, enzymes, amino acids, natural sugars, and other bioactive compounds with emollient, purgative, antimicrobial, anti-inflammatory, anticancer, antioxidant, aphrodisiac, anthelmintic, antifungal, antiseptic, and cosmetic values for health care (Lawrence et al. 2009; Kumar et al. 2017a; Jain et al. 2011; Kametani et al. 2007; Botes et al. 2008; Joshi 1997; Tudose et al. 2009). The Aloe plant species possessed strong antimalarial activity (Oumer et al. 2014; Deressa et al. 2010; Bbosa et al. 2013; van Zyl and Viljoen 2002; Ndhlala et al. 2009). This plant has potential to cure sunburns, burns and minor cuts, and even skin cancer. Its external use in cosmetics primarily includes as skin healer and prevents injury of epithelial tissues, cures acne, and gives a youthful glow to skin; it also acts as an extremely powerful laxative (West and Zhu 2003) and has potential chronic toxicity (Matsuda et al. 2008).

Several phytochemicals aloesin, 2′-O-feruloylaloesin, aloeresin A, barbaloin, isobarbaloin, aloenin, aloe emodin, 8-C-glucosyl-7-O-methyl-(S)-aloesol, isoaloeresin D, and aloeresin E (which are phenolic constituents of aloe) were isolated from Aloe barbadensis, Aloe arborescens, A. vera var. chinensis, Aloe marlothii, and Aloe striata (Okamura et al. 1996a,b). The grasslike and scandent aloes accumulate flavonoids in co-occurrence with the anthrone isomers aloin A and aloin B from Aloe boylei (Choi and Chung 2003; Surjushe et al. 2008; Lindsey et al. 2002). Phytochemical investigation of the ethyl acetate extract of the roots of Aloe megalacantha and Aloe turkanensis showed the presence of several compounds, viz 1,8-dimethoxynepodinol, aloesaponarin III, 10-O-methylchrysalodin, methyl-26-O-feruloyl-oxyhexacosanate and chrysalodin, 10-(chrysophanol-7′-yl)-10-hydroxychrysophanol-9-anthrone, 7-hydroxy-4-methoxy-5-methylcoumarin, chrysophanol, helminthosporin, aloe emodin, aloesaponarin II, aloesaponarin I, aloesaponol I, and asphodelin (Abdissa et al. 2017; Muthii et al. 2015).

The leaf exudate of A. marlothii and Aloe rupestris showed the presence of 7-omethylaloeresin A and 5-hydroxyaloin A (Bisrat et al. 2000). Similarly, the 5-hydroxyaloin A and microstigmin A were identified from the leaf exudate of Aloe microstigma (Dagne et al. 1997). The 10-hydroxyaloin B 6′-O-acetate has been identified from the leaf exudate of Aloe claviflora (Dagne et al. 1998a). Methanolic extracts of the aloes contain several types of anthraquinones (aloesin, aloeresin A, aloeresin C, aloeresin D, aloeresin F, isoaloeresin, aloeresin E, isoaloeresin D, rabaichromone, neoaloesin A), anthrones (isorabaichromone, 2-acetonyl-7-hydroxy-8-(2-furanonyl)-7-hydroxy-5-methylchromone, 7-hydroxy-2,5-dimethylchromone 2-(carboxyethenyl)-5,7-dihydroxychromone, aloesol, aloesone, deacetyl aloesin, furoloesone, isoaloesin, 2-acetonyl-7-hydroxy-8-(3-hydroxyacetonyl)-5-methylchromone, 2-acetonyl-8-(2-furoylmethyl)-7-hydroxy-5-methylchromone, chromones (Kuo et al. 2002; Waller et al. 1978; Hutter et al. 1996; Saoo et al. 1996), and flavones (2-acetonyl-8-(2′,6′-di-O-O-coumaroyl)-glucopyranosyl-7-hydroxy-5-methylchromone, 2-acetonyl-8-(2′,caffeoyl)-glucopyranosyl-7-hydroxy-5-methylchromone, 2-acetonyl-8-(2′,cinnamoyl)-glucopyranosyl-7-hydroxy-5-methylchromone, 6′-O-coumaroylaloesin, 2′-O-tigloylaloaesin, 2′-O-feruloylaloaesin, 2′-p-O-methylcoumaroylaloesin, 7″-deoxyaloersin D, 4′-O-glucosyl-isoaloeresin DI, and 4′-O-glucosyl-isoaloeresin DII C-glycosides) were isolated from A. vera (Gomes et al. 2009; Maurya and Devasagayam 2010; Reynolds 2004; Hamman 2008; Joseph and Raj 2010; Lawrence et al. 2009; Lobine et al. 2017). The aloesin, 7-O-methylaloesin, 6-phenyl-2-pyrone-O,O-diglucoside, and aloenin B were isolated from A. rupestris (Speranza et al. 1986a,b).

The exudates of aloes (A. barbadensis, Aloe ferox, Aloe harlans, and Aloe hildebrandtii) contain several important compounds, viz protocatechuic acid, 3-furanmethanol, dihydrocoumarone, methyl-p-coumarate, pluridone, isoeleutherol, isoeleutherol-5-O-glucoside, 5-OH-3-methylnaphto(2,3-c)-furan-4(1H)-one, 3-methylnaphto(2,3-c)-furan-4(9H)-one, 3-methylnaphto(2,3-c)furan-4,9-dione, feroxidin, feroxidin A, plicataloside, feroxidin B, 7-O-methylaloesin, 7-O-methylaloesinol, 7-O-methylaloeresin A, 8[C-B-D-(2-O-(E)-cinnamoyl]glucopyranolsyl]-2-[(R)-2-hydroxypropyl]-7-methoxy-5-methylchromone, 8-C-glucosyl-noreudenin, 8-C-glucosyl-(2′-O-cinnamoyl)-7-O-methylaloediol, 8-C-glycosyl-7-O-methyl aloediol, 8-C-glycosyl-S-aloesol, and 8-C-glycosyl-7-O-methyl-S-aloesol (Levin et al. 1988; van Wyk and Smith 2008; van Wyk et al. 1995a,b; Veitch et al. 1994; Dagne et al. 2000; Ombito et al. 2015). The γ-coniceine and coniine were identified from Aloe gillilandii and Aloe viguieri (Dring et al. 1984); dihydroisorhamnetin, aloeresin D, aloeresin A (2′-O-p-coumaroylaloesin), aloesol, aloesin, aloesone, 2′-O-tigloylaloesin, isoeleutherol, 10-hydroxyaloin B, N-methyltyramine, O,N-dimethyltyramine, 5-hydroxyaloin A, chrysophanol anthrone, aloe emodin, aloin A/B, aloinoside A/B, naringenin, apigenin, isovitexin, and aloe emodin anthrone from Aloe spp. (Holdsworth 1972; Sigler and Rauwald 1994; Rauwald and Lohse 1992; Rauwald et al. 1989; Manitto et al. 1990; Reynolds 1985; Rauwald and Beil 1993; Nash et al. 1992; Speranza et al. 1986a; Makino et al. 1974; Conner et al. 1990a,b; Hay and Haynes 1956; Horhammer et al. 1964; Dagne et al. 1994, 1996, 1997; Viljoen et al. 1998; Haynes et al. 1970); aloe-emodin-11-O-rhamnoside, rabaichromone, and aloe-emodin-10-C-rhamnoside from Aloe rabaiensis (Conner et al. 1989); 6′-O-coumaroylaloesin from Aloe castanea (van Heerden et al. 2000); neoaloesin A, isorabaichromone, isoaloesin, isoaloeresin D, deacetylaloesin, aloeresin E, 8-C-glucosyl-noreugenin 8-C-glucosyl-(8)-aloesol, 8-C-glucosyl-7-O-methyl-(8)-aloesol, 8-C-glucosyl-7-O-methylaloediol, 8-C-glucosyl-(2′-O-cinnamoyl)-7-O-methyl-aloediol A, 8-C-glucosyl-(2′-O-cinnamoyl)-7-O-methyl-aloediol B, 4′-O-glucosyl-isoaloeresin DI, and 4′-O-glucosyl-isoaloeresin DII from A. vera (van Heerden et al. 1996; Okamura et al. 1996a,b, 1997, 1998; Park et al. 1996); dihydroisocoumarin glucoside from A. hildebrandtii (Veitch et al. 1994); 7-O-methylaloesin from A. rupestris (Bisrat et al. 2000); 7-O-methylaloesinol from Aloe capensis (Park et al. 1997); nataloin A/B, aloenin (Aloecarbonoside), aloenin aglycone, and aloenin-2″-p-O-coumaroyl ester from Aloe nyeriensis (Suga et al. 1974; Conner et al. 1987); and chrysophanol-8-methyl ether, protocatechuic acid, and aloechrysone have been identified from Aloe berhana (Dagne and Alemu 1991; Dagne et al. 1991, 1992). Nataloin and 7-hydroxyaloin have been isolated from latex of Aloe pulcherrima and demonstrated antimalarial activity in a dose-independent manner (Teka et al. 2014, 2016; Bbosa et al. 2013); asphodelin, bianthracene II–IV, aloesaponol IV-8-O-glucoside, aloesaponol III-8-O-glucoside, aloesaponol I-6-O-glucoside, aloesaponol II-6-O-glucoside, aloesaponol I, aloesaponarin I, aloesaponol II–IV, laccaic acid D methyl ester, isoeleutherol-5-O-glucoside, isoxanthorin, helminthosporin, desoxyerythrolaccin, aloesaponarin II, and chrysophanol from Aloe saponaria (Yagi et al. 1974, 1977a,b, 1978, 1983; Snider and Zhang 1993), 2′-p-O-methylcoumaroylaloesin, and 1,5-dihydroxy-3-hydroxymethylanthraquinone from Aloe excelsa (Mebe 1987); 7-hydroxyaloin-6′-O-monoacetate A/B, 7-hydroxyaloe-emodin, 7-hydroxyaloin-4′,6′-O-diacetate A/B from Aloe succotrina (Sigler and Rauwald 1994; Rauwald and Diemer 1986); nataloe-emodin and nataloe-emodin-2-O-glucoside from A. nyeriensis (Conner et al. 1987); nataloe-emodin-8-methyl ether from Aloe speciosa (Thomson 1987); campesterol, cholesterol, lupeol, bisbenzopyran, 8-[C-β-D-[2-O-(E)-cinnamoyl]glucopyranosyl]-2-[(R)-2-hydroxypropyl]-7-methoxy-5-methylchromone, 6′-O-p-coumaroyl-7-hydroxylaloin A/B, 7-hydroxyaloin A/B, 6′-O-cinnamoyl-8-O-methyl-7-hydroxylaloin A/B, 8-O-methyl-7-hydroxylaloin A/B, aloesaponol IV-4-O-glucoside, aloe barbendol, aloesaponol IV, 7″-deoxyaloeresin D, O-demethyl,4-O-glucoside and aloesaponol IV- O-demethyl, 4-O-glucoside from A. barbadensis (Rauwald 1990; Yagi et al. 1998; Saleem et al. 1997a,b; Rauwald and Voetig 1982; Haynes et al. 1960; Hutter et al. 1996; Saleem et al. 1997a,b); prechrysophanol from Aloe graminicola (Yenesew et al. 1993); eigonicardine (elgonica-dimers A and B) from Aloe elgonica (Conner et al. 1990b); 7-O-methylaloeresin A and 5-hydroxyaloin A 6′-O-acetate from A. marlothii (Bisrat et al. 2000); microstigmin A from A. microstigma (Dagne et al. 1997); 10-hydroxyaloin B 6′-O-acetate from A. claviflora (Dagne et al. 1998a,b); littoraloside, littoraloin, and deacetyllittoraloin from Aloe littoralis (Dagne et al. 1996, 1998b; Viljoen et al. 1996); (E)-2-acetonyl-8-(2′-O-cinnamoyl)-β-D-glucopyranosyl-7-methoxy-5-methylchromone, (E)-2-acetonyl-8-(2′-O-caffeoyl)-β-D-glucopyranosyl-7-methoxy-5-methylchromone, and 6′-O-cinnamoyl-5-hydroxyaloin A from Aloe broomii (Holzapfel et al. 1997); microdontin A/B from Aloe microdonta (Farah et al. 1992); homonataloin A/B from Aloe jacksonii (Conner et al. 1990a; Haynes et al. 1960); homonataloside B from Aloe lutescens (van Heerden et al. 2000; Viljoen et al. 2002); 2-(carboxyethenyl)-5,7-dihydroxychromone from Aloe cremnophila (Conner et al. 1990a); aloenin B, isoaloeresin A, aloeresin C, 2-acetonyl-7-hydroxy-8-(3-hydroxyacetonyl)-5-methylchromone, 2-acetonyl-8-(2-furoylmethyl)-7-hydroxy-5-methylchromone, CA-14 [benzo(f)chroman-3-one (process product)], feralolide, 7-hydroxy-2,5-dimethylchromone, CA-12 (1,1-diphenylethane derivative), and feroxin A and B from Cape and Kenya aloe (Speranza et al. 1985, 1986b, 1988, 1990, 1993a,b, 1994, 1996, 1997); β-sitosterol,4″,6″-ethylidene-aloenin, aloenin acetal, 3-furanmethanol, 2′-O-feruloylaloesin, and dihydrocoumarone (2,3-dihydrobenzofuran) from A. arborescens (Woo et al. 1994; Makino et al. 1974; Yamamoto et al. 1991); plicataloside from Aloe plicatilis (Wessels et al. 1996); pluridone from Aloe pluridens (Confalone et al. 1983); aloeresin E and aloeresin F from Aloe peglerae (van Heerden et al. 1996); (E)-2-acetonyl-8-(2′,6′-di-O,O-coumaroyl)-β-D-glucopyranosyl-7-hydroxy-5-methylchromone from A. speciosa (Holzapfel et al. 1997); (E)-2-acetonyl-8-(2′-O-feruloyl)-β-D-glucopyranosyl-7-methoxy-5-methylchromone from Aloe africana (Holzapfel et al. 1997); methyl-p-coumarate, feroxidin, 5-OH-3-methylnaphto[2,3-c]furan-4(1H)-one, 5-OH-3-methylnaphto[2,3-c]furan-4(9H)-one, and 5-OH-3-methylnaphto[2,3-c]furan-4,9-dione from A. ferox (Speranza et al. 1990; Koyama et al. 1994).

The stem extract of A. saponaria, A. sabaea, A. barbadensis, and A. vera exhibited the presence of aloesaponol I, aloesaponol II, aloin, aloesaponarin I, aloesaponarin II, cycloartanol, 24-methylene-cycloartanol, ziganein, ziganein-5-methyl ether, lophenol, 24-methyl-lophenol, 24-ethyl-lophenol, and cosmosiin; the compounds were identified by their spectral data (Rubina et al. 2009; Yagi et al. 1974; Blitzke et al. 2000; Abd-Alla et al. 2008, 2012; Kumar et al. 2017b). The leaf extract of A. berhana, Aloe rivae, A. megalacantha, A. barbadensis, and South African Aloe species A. pulcherrima resulted in the characterization of chrysophanol, acemannan, aloin, aloe emodin, aloechrysone, protocatechuic acid, barbaloin, aloin A, aloinoside, natoloin, and 7-hydroxy barbaloin (Choche et al. 2014; Boudreau and Beland 2006; Dagne and Alemu 1991; Amoo et al. 2014) and aloeresin E and aloeresin F from A. peglerae (van Heerden et al. 1996).

The γ-coniceine, coniine, N-methyltyramine, and O,N-dimethyltyramine alkaloids were isolated and identified from leaf extract of A. gillilandii, Aloe ballyi, Aloe ruspoliana, Aloe ibitiensis, Aloe deltoideodonta, and A. viguieri (Dring et al. 1984). Root extract of Aloe species was used for isolation of chrysophanol and asphodelin. The other compounds are derived through 1-methyl-8-hydroxyanthraquinone pathway, viz aloesaponarin I and aloesaponarin II. The reported results show that isoeleutherol is a useful chemotaxonomic compound that helps in characterization of Saponarieae series (van Wyk et al. 1995a). A. saponaria was investigated for isolation of phenolic compounds and revealed the presence of aloesaponol III, aloesaponol IV, chrysophanol, helminthosporin, and isoxanthorin. The identity of aloesaponol III and aloesaponol IV were confirmed to be 1-oxo-4,8,9-trihydroxy-6-methyl-1,2,3,4-tetrahydroanthracene and 1-oxo-4,8,9-trihydroxy-2-methoxy-6-methyl-1,2,3,4-tetrahydroanthracene by spectral analysis (Yagi et al. 1977a,b). The exudate of A. nyeriensis var. kedongensis leaves afforded six compounds, viz 4-methoxy-6-(2′,4′-dihydroxy-6′-methylphenyl)-pyran-2-one, its 2′-O-β-D-glucopyranoside, and the 2″-O-p-coumaroyl ester of aloenin, l,2,8-trihydroxy-6-methylanthraquinone, its 2-O-β-D-glucopyranosyl ester, and the corresponding 10-C-β-D-glucopyranoside nataloin (Conner et al. 1987). The 6-hydroxy-3,5-dimethoxy-2-methyl-1,4-naphthoquinone, ancistroquinone C, 5,8-dihydroxy-3-methoxy-2-methyl-1,4-naphthoquinone, malvone A, droserone, droserone-5-methyl ether, and hydroxydroserone have been isolated from Aloe dawei (Abdissa et al. 2014).

The A. elgonica leaf exudate was examined for anthraquinones, and several other phytochemicals were found such as aloe emodin, aloenin, aloeresin, aloeresin B, emodin-10-C-β-glucopyranoside linked through C-10 to C-7 of the anthraquinone aloe emodin (Conner et al. 1990a,b). Similarly, four bianthraquinoid pigments (A, B, C, and D) were characterized from rhizome of A. saponaria. Besides bianthraquinoid pigments, the (+)-asphodelin; 1,1′,8,8′,10-pentahydroxy-3,3′-dimethyl-10,7′-bianthracene-9,9′,10′-trione; 1,1′,8,8′-tetrahydroxy-3,3′-dimethyl-4,7′-bianthracene (10′H, 10′H)-9,9′,10-trione; and 1,1′,8,8′,10-pentahydroxy-3,3′-dimethyl-10,7′-bianthracene (10′H, 10′H)-9,9′-dione structures were also established by analyzing the spectral data (Crosswhite and Crosswhite 1984; Reynolds and Dweck 1999; Rajasekaran et al. 2005; Loots et al. 2007; Yagi et al. 1978, 1983; Speranza et al. 1993). The geographical conditions affect the production of aloeresin A, aloesin, and aloin and distributed as major compounds in A. ferox leaf exudate. Along with major compounds, aloinoside A and aloinoside B found in western parts of the Cape and aloeresin C and 5-hydroxyaloin A aloin found in all the areas of Cape (van Wyk et al. 1995b). The levels of Barbaloin were determined in Aloe species in the Kew. The maximum concentration of barbaloin was found in exudates of young leaves but the concentration decreased in older leaves (Groom and Reynolds 1987). The littoraloside was isolated from A. littoralis leaf exudate along with littoraloin, deacetyllittoraloin, and 10-hydroxyaloin B, and their structures were confirmed by spectral analysis (Dagne et al. 1998b). The prechrysophanol, chrysophanol, helminthosporin, (R)-aloesaponol I, (R)-aloesaponol II, aloesaponarin I, aloesaponarin II, and laccaic acid D methyl ester were isolated from A. graminicola (Yenesew et al. 1993; Lakshmi and Rajlakshmi 2011).