Background: Currently, there is an increasing interest in developing more efficient techniques for the extraction of phytochemicals. Microwaves and ultrasonic extraction methods are promising techniques that can be used for this purpose.
Objectives: The purpose of this study was to investigate the impact of different extraction methods on yield, antioxidant and antimicrobial activities of volatile oil extracted from Trichodesma africanum.
Materials and methods: Volatile oil was extracted using microwave, ultrasonic, microwave-ultrasonic and conventional hydrodistillation methods. The extracted oil was evaluated for antioxidant and antimicrobial activities. The antioxidant activity was assessed by DPPH scavenging assay, while the antimicrobial activity was assessed by broth micro-dilution method. The antimicrobial activity of the volatile oils were examined against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa American Type Culture Collection reference strains, as well as against Methicillin Resistant Staphylococcus aureus (MRSA) and Candida albicans clinical isolates.
Results: The volatile oil obtained by the four extraction methods in this study exhibited both antioxidant and antimicrobial activities. Among the four extraction methods used, the microwave-ultrasonic method yielded the largest amount (1.8% v/w) and the yield exhibited the highest antioxidant activity in terms of inhibition (91.83% ± 1.1). The minimum inhibitory concentrations for E. coli, P. aeruginosa, S. aureus, MRSA and C. albicans were 3, 5, 6, 3, and 9, respectively.