In vitro antioxidant and antistaphylococcal properties of leaf extracts of Ocotea comorensis Kosterm (Lauraceae)

Abstract

This study focused on the determination of phenolic compounds and the evaluation of the biological activity of Ocotea comorensis Kosterm (Lauraceae) extracts, an endemic and the only species of Ocotea genus from the Comoros archipelago. Leaf Extracts of O. comorensis were obtained by maceration in 50% hydro-methanol, acetone and cyclohexane. Their total phenolic and flavonoids contents were quantified and their antioxidant activity, determined by both the Ferric Reducing Power and the DPPH radical scavenging assays. The hydromethanolic extract (MEOc) exhibited the highest DPPH radical scavenging activity (IC50 = 9.28 ± 0.58 μg. mL−1) and the largest reducing capacity of ferrous ions. The most relevant contents in total phenolics (733.33 ± 20.272 µg Gallic Acid Equivalent. mg−1) and flavonoids (142.6 ± 8.20 μg catechin equivalent. mg−1) were also observed in the MEOc. Significant correlations were established between antioxidant activity and total phenolic and flavonoids contents. The antibacterial activity was carried out using microdilution method on Methicilin-Resistant Staphylococcus aureus (MRSA) isolates from burn wounds. The results revealed remarkable anti-MRSA activities with MICs ranging from 0.08 mg mL−1 to 13.41 mg.mL−1and the MEOc displayed the most important anti-MRSA activity. While this is the first study concerning extracts from O. Comorensis, our findings highlighted the richeness in phenolic compounds of these extracts and their great potential as source of antioxidants and antibacterial agents.