Chemical composition and biological activities of volatile oil of the stem of Dombeya buettneri K. Schum. (Sterculiaceae)

Abstract

Essential oil, obtained from the stem of Dombeya buettneri and characterized by high resolution GC–MS was tested for antimicrobial (using broth dilution method) and antioxidant (using spectrophotometric methods: DPPH, FRAP and ABTS) properties.Forty-three (43) essential oil components were detected which account for 96.8% of the total oil content comprising mainly: Non-terpene derivatives (31.8%), Apocarotenes (24.3%), Sesquiterpenoids (15.3%), Sesquiterpene hydrocarbons (14.4%), Monoterpenoids (10.1%) and Monoterpene hydrocarbons (0.9%). The major identified compounds in the oil were (E)-geranylacetone (14.8%), δ-cadinene (8.9%), n-hexadecane (7.8%), Tetradecanal (6.2%), β-ionone (4.9%), Borneol (4.2%), Viridiflorol (3.5%), Guaiol (3.4%), caryophyllene oxide (3.4%), Palustrol (2.5%) and Spathulenol (2.5%).The oil displayed antibacterial and antifungal activities on Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Candida albicans ATCC 18804 with respective Minimum Inhibitory Concentration (MIC) of 6.25, 12.5 and 12.5%v/v. The Minimum Bactericidal/Fungicidal Concentrations on the test organisms ranged from 12.5 to 25.0%v/v. The antioxidant assay by DPPH showed a concentration dependent values of 8.0993±0.827 at 25 mg/mL, 14.7657±0.8151 and 19.449±0.6678 at 100 mg/mL with good IC50 value of 1098 µg/mL as compared with reference ascorbic acid standard with IC50 of 23.52 µg/mL. The Ferric reducing antioxidant assay (FRAP) showed activity at concentration of 0.076713±0.001227mg/FeSO4Equiv./g, while ABTS showed an activity at 0.3776±0.0025 mg AA Equiv./g with respect to the standards.The current study showed that the volatile oil of Dombeya buettneri stem possess good antioxidant and antimicrobial properties that could be utilized for cosmetic and pharmaceutical health benefits.