Secondary Metabolites of Medicinal Plants. Bharat Singh

flowers and green fruits of Cassia spectabilis (Viegas Júnior et al. 2004). Besides alkaloids, the other compounds like β-sitosterol, the flavonoids luteolin and 3-methoxyluteolin, the triterpene betulinic acid and trans-cinnamic acid were also separated first time from this plant species (Pereira et al. 2016; Viegas Júnior et al. 2013; Pivatto et al. 2014). The isolated alkaloids demonstrated antimalarial activity (Pivatto et al. 2014). The kaempferol-3-O-α-L-rhamnopyranosyl-(1 → 2)-β-D-glucoside, 4,5-dihydroxyanthraquinone-2-carboxylic acid, chrysophanol, and kaempferol 3-O-α-L-rhamnoside have been isolated from ethyl acetate fraction of flowers and leaves of Cassia nodosa (Zhao et al. 2016). The isolated anthraquinones exhibited antioxidant activity (El-Sherbeni et al. 2014). Similarly, the other types of compounds such as triterpenoid glycoside, 3-O-{β-D-glucuronopyranosyl-(1→4)-[β-D-galactopyranosyl-(1→2)]-{β-D-xylopyranosyl-(1→3)–β-D-glucopyranosyl}-2,16α-dihydroxy-4, emodin, aloe emodin, and 20-hydroxy methyl olean-12-ene-28-oic acid were characterized from fraction of seeds of Cassia angustifolia (Ayo 2010). The isolated compounds showed antifungal activity against Colletotrichum dematium (Khan and Srivastava 2009; Sundaramoorthy et al. 2016). Anthraquinones, viz obtusifolin, racemochrysone, sengulone, cassiamin A, cassiamin B, 1,8-dihydroxy-6-methoxy-3-methylanthraquinone, 1,8-dihydroxy-6-methoxy-2-methylanthraquinone, emodic acid, 1,2-dihydro-1,3,8-trihydroxy-2-methylanthraquinone, citreorosein, 4,4′-bis(1,3-dihydroxy-6,8-dimethoxy-2-methylanthraquinone), 1,3-dihydroxy-6,8-dimethoxyanthraquinone, 1,3,5,8-tetrahydroxy-2-methylanthraquinone, 1,3,5,8-tetrahydroxy-6-methoxy-2-methylanthraquinone, floribundone 2, 4-4′-bis(1,3,8-trihydroxy-6-methyl-2-methyl)anthraquinone, floribundone 1, 3-formyl-1-hydroxy-8-methoxyanthraquinone, 5-hydroxy emodin, fistulic acid, and rubiadin, were isolated from several species of the Cassia genus (Dave and Ledwani 2012). The GC–MS analysis of the extract revealed the presence of 4-hydroxyanthraquinone-2-carboxylic acid; heptadecanoic acid, 14-methyl-, and methyl ester; bis(2-ethylhexyl) phthalate; and β-cholest-3-ene and β-sitosterol acetate compounds in Cassia nigricans (Ayo et al. 2009).

      The epicatechin, (−)-(2S)-6-methoxy-[2″,3″:7,8]-furanoflavanone, kaempferol 3-O-sulfate-7-O-c-arabinopyranoside, vidalenolone, (2S)-7,8-bis-3′,4′-(2,2-dimethyl-chromano)-5-hydroxyflavanone, 3,7-dihydroxy-4′,8-dimethoxyflavone, and 14-hydroxyartonin E were isolated and identified from C. angustifolia (Laghari et al. 2011). The kaempferol, proanthocyanidin (Narayanan and Seshadri 1972), (−)-epiafzelechin 3-O-β-D-glucopyranoside, (−)-epiafzelechin, and (−)-epicatechin were isolated from the leaves of C. fistula (Morimoto et al. 1988). The epiafzelechin and epicatechin along with catechin, procyanidin B-2, rhamnetin 3-O-gentiobioside, and epiafzelechin were characterized and identified from pods and roots of C. fistula (Kashiwgada et al. 1996; Vaishnav and Gupta 1996).

      Cassia roxburghii is a large tree with pinnately compound leaves and twigs covered with a dense carpet of soft hair (Girhepunje et al. 2009; Mohammed et al. 2013). The members of Cassia species are rich sources of polyphenols, anthraquinone derivatives, and flavonoids (Mupangwa et al. 2000; Moriyama et al. 2003). These compounds have anti-inflammatory (Chidume et al. 2001), antioxidant (Yen et al. 1998), hypoglycemic (Jalalpure et al. 2004), larvicidal (Yang et al. 2003; Rajni et al. 2014), antimutagenic, and anticancer activities (Yadav et al. 2010). The anthraquinone derivatives are used for the treatment of wounds (Bhakta et al. 1998); skin diseases such as ringworm, scabies, and eczema; gastrointestinal disorders (Abo et al. 1999; Jacob et al. 2002), and jaundice (Pieme et al. 2006). The emodin 1-O-β-D-glucopyranosyl-(1→2)-glucopyranoside and aloemodin 8-O-β-D-glucopyranosyl-(1→6)-glucopyranoside along with aloemodin 8-O-β-D-glucopyranoside, emodin, aloemodin, and quercetin-3-O-α-L-rhamnopyranoside were isolated from the leaves of C. roxburghii and showed strong antioxidant and antiviral activities (El-Toumy et al. 2012; Mohammed et al. 2013).

      Cassia occidentalis is an annual or perennial plant that is used in several traditional medicines to cure various diseases. This plant species grows all over the India as well as hotter parts of Burma and Sri Lanka (Kapoor 2000). It is also grown as an ornamental plant (Shankar and Ved 2003). Decoction of C. occidentalis roots with black pepper is useful in treatment of filaria (Arvind and Shamshun 2007). The decoction of C. occidentalis, Glycosmis pentaphylla, and Vitex negundo is used for bathing a newborn baby to make the baby immune to skin diseases in the regions of Malyagiri hills (Yadav et al. 2010). As per the reports of Bhavaprakasa, the plant species is used in constipation, and the leaves, roots, and seeds are useful as purgative (Warrier and Nambiar 1993) and antiplasmodial (Iwalewa et al. 1990, 1997). The seed powder is used to cure fever, while two tablespoons of leaf juice mixed with honey cures cough. For intestinal gas, half a cup of leaf decoction is taken twice daily and leaf paste is applied to cure skin diseases (Manikandaselvi et al. 2016).

Cassia alata is an erect tropical annual herb with compounded leaves and distributed in America, India, Fiji, Indonesia, Malaysia, Brazil, and Africa (Hugnette et al. 2005; Kumar 1984). Plants have the great potential used in traditional medicine in pharmacopoeia drugs (Sharanaiah et al. 2013). Plants produce a wide range of bioactive molecules, making rich sources of different types of medicines. Plant parts synthesize some phytochemicals in themselves that metabolize their physiological activities, and these compounds are used to cure disease (Morton and Malone 1972). C. alata is one of the most important species of the genus Cassia, which is rich in anthraquinones and polyphenols (Palanichamy and Nagarajan 1990; Yagi et al. 1998). Traditionally this plant is effective in treating skin infections in man and animals (Igoli et al. 2005; Damodaran and Venkataraman 1994). The fresh leaves of C. alata used in the treatment of skin diseases such as ringworm, eczema, pruritis, itching, scabies, ulcers, and other related diseases (Reezal et al. 2002). The seed is used as anthelmintic, the roots are used against uterus disorder, and the crushed leaves are used for skin infections (Herman et al. 1978; Bahorun et al. 2005; Aboul-Enein et al. 2014). C. alata is a source of chrysoeriol, kaempferol, quercetin, 5,7,4′-trihydroflavanone, chrobisiamone A, kaempferol-3-O-β-D-glucopyranoside, kaempferol-3-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside, 17-hydrotetratriacontane, n-dotriacontanol, n-triacontanol, palmitic acid cetyl ester, stearic acid, palmitic acid, and 1,3,5-trihydroxy-7-methylanthracene-9,10-dione (Oshimi et al. 2008; Liu et al. 2009; Mitra et al. 2016). C. alata leaf is also credited for the treatment of hemorrhoids, constipation, inguinal hernia, intestinal parasitosis, blennorrhagia, syphilis, and diabetes (Abo et al. 1998; Adjanahoun et al. 1991). The flowers and leaves are used for the treatment of ringworms and eczema. The other uses of C. alata are as an anthelmintic, antibacterial, laxative, and diuretic and for treatment of snake bites and uterine disorders (Kirtikar and Basu 1975b). Besides the leaf, extract of this species has shown several pharmacological properties such as antimicrobial, antifungal (Khan et al. 2001), antiseptic (Esimone et al. 2008), anti-inflammatory, analgesic (Palanichamy and Nagarajan 1990), and antihyperglycemic activities (Palanichamy et al. 1988).