Lignan glycosides and flavonoids from Saraca asoca with antioxidant activity

Abstract

Five lignan glycosides, lyoniside, nudiposide, 5-methoxy-9-b-xylopyranosyl-(À)-isolariciresinol, icariside E 3 , and schizandriside, and three flavonoids, (À)-epicatechin, epiafzelechin-(4b?8)-epicatechin and procyanidin B 2 , together with b-sitosterol glucoside, were isolated from a methyl alcohol (MeOH) extract of Saraca asoca dried bark. Their structures were determined by 1D and 2D nuclear magnetic resonance (NMR) and mass spectroscopic analysis. Antioxidant activities were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay.Keywords Saraca asoca Á Caesalpiniaceae Á Lignan glycoside Á Flavonoid Á Antioxidant activity Saraca asoca (Roxb.) De Wilde or S. indica Linn. (Family: Caesalpiniaceae; local names: Ashok, Anganapriya, etc.) is a medicinal plant of Bangladesh whose bark is astringent and used in menorrhagia, bleeding haemorrhoids and haemorrhagic dysentery [1]. The isolation of tannins [2], flavonoids [3], proanthocyanidins [4] and leucoanthocyanidins [5] were previously reported from the bark. In our assay method, a methyl alcohol (MeOH) extract of the dried bark showed potent antioxidant activity determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay [6]. Following this activity, we isolated eight compounds (1-8) from this plant (Fig. 1). This paper describes isolation and identification of isolated compounds together with their antioxidative potential. The bark of S. asoca was collected from Satkhira, Bangladesh, in August 2005. A voucher specimen has been deposited in The dried bark of S. asoca was ground into a coarse powder (195 g), which was extracted with 1.3 L MeOH to get the extract (14.7 g). Based on the medicinal uses, the extract was tested for antioxidant activity using DPPH radical-scavenging assay that showed a potent effect with an IC 50 value of 25 lg/ml. The extract was then suspended in 440 ml 10% aqueous MeOH and partitioned successively with n-hexane, ethyl acetate (EtOAc) and n-butanol (n-BuOH) that afforded four extracts (n-hexane extract: 217 mg; EtOAc extract: 3.11 g; n-BuOH extract: 8.74 g; water extract: 2.87 g). Among them, EtOAc and n-BuOH extracts showed clear DPPH positive spots on thin-layer chromatography (TLC). These two extracts were then subjected to further separations by repeated-column chromatography. From the n-BuOH extract (4.0 g), compounds 1 (20 mg), 2 (16 mg), 3 (4 mg) and 4 (8 mg) were isolated. Compounds 1 (5 mg), 3 (2 mg), 5 (5 mg), 6 (20 mg), 7 (36 mg) and 8 (17 mg), together with b-sitosterol glucoside (12 mg) [7], were isolated from the EtOAc extract (3.0 g). Compounds 1-5 were lignan glycosides, which were identified as lyoniside ½a 21 D þ 22 (c 1.0, MeOH) [8],

RETRACTED ARTICLE: A new antifungal labdane diterpene from the leaves of Saraca indica

“…This plant has shown many pharmacological properties such as antidiabetic (Preethi et al 2010), oxytocic (Satyavati et al 1970), antiulcer (Maruthappan & Shree 2010), antimicrobial (Sainath et al 2009;Hawas et al 2012) and anthelmintic (Sharma et al 2011) activities. Previous phytochemical studies on the leaves of S. indica have led to the isolation of quercetin, quercetin 3-O-a-rhamnoside, kaempferol 3-O-a-rhamnoside, amyrin, ceryl alcohol and b-sitosterol (Darwish & Khalifa 1992;Sadhu et al 2007;Pradhan et al 2009). …”

Phytochemical studies of the endangered tree, Saracaasoca (Roxb.) De Wilde

“…Hence, quantitative estimations of the same were taken up for intensive study. The results are in agreement with the reports of Sadhu et al (2007), Panchawat and Sisodia (2010), Pradhan et al (2010), and Manohar et al (2012) in S. asoca. Toxicity of some secondary metabolites of various plant parts was tested by while the antioxidant properties of bark and flower extracts were reported by Sadhu et al (2007), Panchawat and Sisodia (2010), Pandey et al (2011) and Pal et al (2014).…”

“…The values obtained presently were much higher than earlier reports by Sadhu et al (2007), Pradhan et al (2010), Pandey et al (2011) and Ghatak et al (2015). Therefore, the Sa-O accession was chosen for the HPLC analysis of quercetin and catechin.…”

“…The phenolic compounds are one of the largest and most ubiquitous groups of plant metabolites that possess an aromatic ring bearing one or more hydroxyl constituents (Sadhu et al, 2007). The values obtained presently were much higher than earlier reports by Sadhu et al (2007), Pradhan et al (2010), Pandey et al (2011) and Ghatak et al (2015).…”

Floral Morphology and HPTLC Fingerprint Profile of <i>Saraca asoca</i> (Roxb.) De Wilde (Caesalpiniaceae): A Consecrated Tree of India

“…[3] Scientifically the plant is to be proven as Antibacterial, Antimicrobial, [4], Anthelmintic, [5] Analgesic, [6] Antihyperglycemic / Antioxidant, [7,8] CNS Depressant Activity, [9] Anti-Arthritic / Anti-Inflammatory, [10] Cytotoxicity, [11] Anti-Platelet Aggregation, [12] AntiDiarrheal, [13] Larvicidal [14], antifungal [15]. Chemically it contain Labdane Diterpene, 6,9-epoxy marrubiinic acid, steroids, Flavonoids, lignin glycosides, Gallic acid, [16,17] The present investigation deals with the study of pharmacognostical characteristics of the flowers and phytochemical analysis by high performance thin layer chromatography. …”