Antimicrobial Activities and Chemical Compositions of Daniellia oliveri and Leptoderris micrantha (Fabaceae) Essential Oils From Nigeria

The stem bark and leaves of Daniellia oliveri were obtained from two sites, Batsari and Zurmi, in Nigeria. Leaves of Leptoderris micrantha were obtained from Agbagi, Nigeria. Essential oils of these plants were obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. The major components in the bark essential oil of D. oliveri were δ-cadinene (12.8%), α-muurolene (6.7%), α-calacorene (5.9%), and caryophyllene oxide (5.5%). The major components in the leaf essential oils from Batsari and Zurmi, respectively, were humulene epoxide II (8.0% and 16.3%), caryophyllene oxide (7.4% and 12.4%), pentadecanal (8.9% and 6.0%), phytone (6.5% and 2.2%), δ-cadinene (5.3% and 3.0%), and α-muurolene (5.3% and 2.6%). The major components in the leaf essential oil of L. micrantha were incensole (16.2%), phytone (15.4%), pentadecanal (13.7%), α-pinene (7.7%), and iso-phytol (5.2%). The essential oils were screened for antibacterial activity against Bacillus cereus, Cutibacterium acnes, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Pseudomonas aeruginosa, and Serratia marcescens, and for antifungal activity against Aspergillus fumigatus, Aspergillus niger, Cryptococcus neoformans, Microsporum canis, Microsporum gypseum, Trichophyton mentagrophytes, Trichophyton rubrum, and Candida albicans, using the microbroth dilution method. The leaf essential oils of D. oliveri and L. micrantha showed only marginal activity against the panel of microorganisms. However, D. oliveri bark essential oil showed notable antifungal activity against Aspergillus niger and Trichophyton rubrum with a minimum inhibitory concentration of 78.1 µg/mL for each. This is the first report on the essential oil compositions of D. oliveri and L. micrantha from Nigeria and their antimicrobial activities.