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

Myristicafragrans, 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 ofM. 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.

Biotransformation of malabaricone C by rat hepatic microsomes and cytotoxic activities against gastric cancer cells in vitro

Malabaricone C （1）, isolated from the seeds ofMyristicafragrans Houtt., belongs to a kind of diarylnonanoid compounds that are only found in Myristicaceae till now. In this study, biotransformation of 1 was investigated using rat hepatic microsomes for the first time and the main biotransformation product was elucidated as malabaricone B （2） according to the spectroscopic data. Further evaluation on human gastric cancer cell lines showed that the cytotoxic effects of malabaricone C and its metabolite malabaricone B were comparable to those of vinorelbine, with the values of IC50 of （42.62±3.10） and （19.80±1.70） μg/mL on NCI-N87, and （22.94±1.33） and （19.60±2.21） μg/mL on MGC803, respectively. Statistical analysis revealed that malabaricone B had significantly stronger cytotoxicity than the parent compound （P〈0.01 on NCI-N87 and P〈0.05 on MGC803）, which may indicate a bioactivation of malabaricone C by hepatic microsomes. These results suggest that malabaricone C has a simple biotransformation pathway by hepatic microsomes and provide valuable information for further investigation on both the parent compound and its biotransformation product as anti-gastric cancer agents or lead compounds.

Biotransformation of methyleugenol by rat hepatic microsomes

Methyleugenol （1）, one of the main bioactive constituents of the seeds of Myristicafragrans Houtt. （family： Myristicaceae）, was incubated with rat hepatic microsomes from rats pretreated with sodium phenobarbital. Eight biotransformation products named （R）-l＇-methoxymethyleugenol （2）, 3-（3,4-dimethoxyphenyl）-l-methoxyprop-2-ene （3）, cis-3,4-dimethoxycinnamyl acetate （4）, trans-3,4-dimethoxycinnamyl acetate （5）, （R）-I hydroxymethyleugenol （6）, trans-3,4-dimethoxycinnamyl alcohol （7）, cis-3,4-dimethoxycinnamyl alcohol （8）, and （R）-3-（3,4-dimethoxyphenyl）-propane-l,2-diol （9） were obtained and their structures were elucidated by NMR and MS data analysis and by comparison with the previously reported data. The biotransformation of 1 may provide valuable information for the use of methyleugenol. The NMR data of compounds 4 and 6 were reported for the first time.