Further report on the chemical constituents of the n-hexane extract of Leonotis nepetaefolia (L.) R. Br (Lamiaceae)

Abstract

Introduction: Leonotis nepetifolia (L.) R. Br, a species of the family Lamiaceae, has some interesting biological activities, such as antibacterial, antioxidant, and anti-inflammatory activities. This paper describes the structural elucidation of seven compounds isolated from Leonotis nepetifolia collected in Xuyen Moc district, Ba Ria–Vung Tau Province, in June 2018. Methods: Phytochemical investigations of the n-hexane extract of Leonotis nepetifolia led to the isolation of seven pure compounds. Their chemical structures were elucidated by extensive MS, 1D and 2D-NMR spectroscopic analysis and comparison with previously published data. Results: Seven compounds, namely, (E)-10-oxooctadeca-8-enoic acid (1), ergosterol peroxide (2), turmeronol A (3), methyl (E)-3-(3,4-dimethoxyphenyl)propenoate (4), methyl 4-hydroxybenzoate (5), methyl (E)-3-(4-hydroxy-3-methoxyphenyl)propenoate (6), and alpinumisoflavone (7), were identified. Conclusions: Although these compounds are known in other species, this is the first time they have been reported in Leonotis nepetifolia.