Phytochemical Studies on Premna Schimperi Engl (Lamiaceae)
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Date
2021-09-20
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Addis Ababa University
Abstract
In this study, attempts were made to isolate secondary metabolites from the solvent extracts of the dried leaves of Premna schimperi Engl. The essential oil obtained by hydrodistillation of the dried leaves of P. schimperi was also analyzed by GC-MS. A total of six compounds were isolated from the solvent extracts, of which ent-8,12α-epidioxy-12-hydroxylabda-9(11),13-dien-15-oic acid -lactone (71), 3,5,5'-trihydroxy-6,7,3',4'-tetramethoxyflavone (157) and 3,5,7,5'-tetrahydroxy-6,3',4'-trimethoxyflavone (158) were isolated from the chloroform extract, while a straight chain primary alcohol (165) was isolated from the petroleum ether extract, and luteolin (159) and p-hydroxycinnamic acid (164) were isolated from the ethyl acetate portion of the methanol extract. Per acetylation of compound 157 using acetic anhydride and pyridine gave triacetate 157-Ac. The GC-MS analysis of the essential oil revealed 36 compounds, of which the major compositions were caryophyllene (9), caryophyllene oxide (10), terpinen-4-ol (33), -curcumene (166), eugenol (167), -sesquiphellandrene (168), -gurjunene (169), 2-isopropyl-5-methyl-9-methylene-bicyclo[4.4.0]dec-1-ene (170), -eudesmol (171). The antioxidant activities of the MeOH extract of the leaves of P. schimperi and compound 71 were assessed using the DPPH radical scavenging assay. The MeOH extract reduced the stable DPPH radical by 95.3% whereas compound 71 reduced the stable DPPH radical by 62.2% at 100 μg/mL, which suggested that they are potential radical scavengers.
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Phytochemical, Studies on Premna, Schimperi Engl, Lamiaceae