Identification of Secondary Metabolites Through HR-GC-MS: Antibacterial and Antifungal Activity from Root Fractions of Alstonia scholaris (L.) RBr. from Andhra Pradesh, South India

Abstract

To identify the secondary metabolites from different root extracts of Alstonia scholaris (L) R.Br through HRGCMS. The dried plant material was powdered and extracted with petroleum ether, ethyl acetate, and methanol by using Soxhlet extraction method. The obtained extracts were given to HRGCMS. Gram-positive bacteria are Streptococcus pyogenes, Bacillus pumilus, Staphylococcus aureus, and Micrococcus luteus. Gram-negative bacteria are Escherichia coli, Klebsiella pneumoniae, Corynebacterium diphtheriae, and Pseudomonas aeruginosa. And for antifungal activity Aspergillus niger, Penicillium chrysogenum, Saccharomyces cerevisiae, and Candida albicans were taken. Agar cup plate diffusion method and PDA methods were taken for antimicrobial activity. In the qualitative determination of pharmacologically, biologically, and therapeutically active secondary metabolites obtained from crude extracts, there are a lot of secondary metabolites, different kinds of melting points, unique physicochemical characteristics, and significant quantities of molecules present on the obtained extracts. Moreover, antimicrobial activities showed the best results. From the obtained three extracts, many secondary components were identified. Every molecule has unique characteristics like tetradecanoic acid, limonene, 1-hexadecanol, isomyrestic acid, isoborneol, phenol 2,4-bis(1,1-dimethylethyl), Urs-12-en-24-oic acid, Lup-20(29)-en-3-ol, acetate, 3(β), octa decadienoic acid (Z,Z)-, hydrocinnamic acid, and o-[(1,2,3,4-tetrahydro-2-naphthy, 4,4,6a,6b,8a,11,11,14b-Octamethyl-1,4,4a,5,6,6a,6b. The petroleum ether extract has monoterpenoids, fatty acids, and lipids present; molecule limonene is useful for insecticidal, soaps, and lotions. Isopropyl myristate is an emollient useful for skin conditions, particularly in cosmetics. The metabolite tetradecanoic acid is for antitumor properties. Based on the literature, The molecule of soborneol is for antimicrobial, antitumor and nephroprotective properties. Heptacosane (volatile oil) shows good antibacterial properties. n-Hexadecanoic acid is present in both petroleum ether and methanolic extracts; this molecule is mainly useful for anti-inflammatory and wound healing properties. Ursolic acid, lupeol acetate, and lupol were isolated from ethyl acetate extract, and lupeol acetate is present in both ethyl acetate and methanolic extracts. The molecule ursolic acid is present in all greenery foods, fruits, and seeds. Lupol and lupeol acetate (triterpeniods) are mainly useful as anticancer and anti-inflammatory agents. The methanolic extract of A. scholaris contains Tetradecanoic acid, n-Hexadecanoic acid and Hydrocinnamic acid are present. Hydrocinnamic acid (salicylic acid) shows antimicrobial properties; moreover the metabolite is useful for dandruff and ringworm. At 100 mg/mL dose level, the root extracts showed mild antifungal activity, when compared to 300 mg/mL and 500 mg/mL dose levels. It was observed that the activity has enhanced with increased dose levels as well as with the increased polarity of the solvents.