Phytochemical studies of Premna schimperi, and antioxidant activities of the extract and an isolated compound

ABSTRACT. In this study, the attempts were made to isolate secondary metabolites from the solvent extract of the dried leaves of Premna schimperi (P. schimperi). Thus, six compounds, namely, ent-8b,12-epidioxy-12b-hydroxylabda-9(11),13-dien-15-oic acid-g-lactone (1), 3,5,5'-trihydroxy-6,7,3',4'-tetramethoxyflavone (2) and 3,5,7,5'-tetrahydroxy-6,3',4'-trimethoxyflavone (3), p-hydroxycinnamic acid (4), luteolin (5) and 1-nonacosanol (6) were isolated and characterized by NMR, UV-Vis, MS and FTIR spectroscopic techniques. All the compounds; except luteolin (5) were reported for the first time from the leaves of P. schimperi. In addition, the GC-MS analysis of the essential oil of the plant leaves revealed 47 compounds, of which a-curcumene (16.38%), caryophyllene (10.73%), eugenol (6.85%), b-sesquiphellandrene (4.65%), g-gurjunene (4.55%), terpinen-4-ol (2.9%), g-eudesmol (4.43%), linalool (2.2%) and caryophyllene oxide (2.67%) were the major compounds. Furthermore, assessment of the antioxidant activities of the MeOH extract and compound 1 using the DPPH assay revealed 95.3% and 62.2% DPPH inhibition, respectively, at concentration of 100 μg/mL.  KEY WORDS: P. schimperi, GC-MS, DPPH radical scavenging assay, Antioxidant activity, Acetylation Bull. Chem. Soc. Ethiop. 2023, 37(6), 1471-1486.DOI: https://dx.doi.org/10.4314/bcse.v37i6.14