Antimicrobial Activity of Seeds and Leaves of Myristica fragrans against Multi-resistant Microorganisms

Myristica fragrans, known as nutmeg, is used in food applications. In traditional medicines, the seeds and leaves are used to treat skin, respiratory and gastrointestinal diseases. Limited antibacterial activity has been reported for this plant. The present study aimed to screen the decoction and methanolic extracts of the seeds and leaves of M. fragrans against Staphylococcus aureus NCTC 6571, five strains of methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa NCTC 10662, Escherichia coli NCTC 10418, as well as essential oils from both parts against a panel of resistant bacteria and Candida spp. in order to identify potential antimicrobial activity. Antimicrobial activity was evaluated using well (well diameter: 12 mm) and disc diffusion methods (disc diameter: 6 mm). The decoction and methanolic extract of leaves and methanolic extract of seeds of M. fragrans showed inhibitory activity against S. aureus and all five MRSA strains with zones of inhibition (ZOI) = 16.0 ± 0.0 mm to 19.0 ± 0.0 mm. The decoction and methanolic extract of both parts did not show inhibitory activity against E. coli and P. aeruginosa. However, both essential oils showed inhibitory activity against S. aureus and the five MRSA strains, as well as E. coli (ZOI = 9-15 mm). The essential oils from seed showed activity against all tested multi-resistant bacteria (ZOI = 7-12 mm). The essential oils from leaves showed activity against Klebsiella pnemoniae, Acinetobacter spp., Enterobacter cloacae and group A beta-haemolytic streptococcus (ZOI = 8-12 mm). The essential oils showed inhibitory activity against all tested Candida species (ZOI = 8-15 mm). The decoction, methanolic extract and essential oils of leaves have potential activity against sensitive and resistant S. aureus. This is the first report of inhibition of multi-resistant bacteria and Candida spp. by the essential oils of leaves and seeds of M. fragrans which could be utilized for pharmaceutical applications.