Unlocking Natureʼs Pharmacy: Composition and bioactivity of essential oil of bog-myrtle (Myrica gale) grown on Irish boglands

Abstract

Myrica gale is an acidic soil loving aromatic shrub that grows throughout parts of the Northern Hemisphere in bogs, fens and heaths and at lake edges. Its catkins and leaves secrete an aromatic oil known historically to repel insects. Commonly known as bog-myrtle, its branches were placed in bedroom cupboards and stuffed into mattresses to repel moths and bed bugs and a twig of bog-myrtle worn in a shirt buttonhole was thought to keep biting midges at bay. Many insecticides, from both natural and synthetic sources, exert their action through modulation of cholinesterases. This work examined the anticholinesterase activity of essential oil from Irish Myrica gale leaves and a Canadian commercial preparation by TLC-bioautography with detection by both a diazotization method and the Ellman method with determination of IC50s by colorimetric assay. The chemical composition of the essential oils was examined by GCMS and compared. The essential oils of Irish and Canadian M. gale were partially similar in qualitative profile with α-pinene, β-myrcene, α-phellandrene, o-cymene, limonene, cineole and γ-elemene as major compounds in common. Qualitative as well as quantitative differences between the oils were observed ([Fig. 1]). Irish M. gale essential oil and the Canadian oil were both found to be low potency inhibitors of acetylcholinesterase with IC50s of 0.36 mg/mL and 0.55 mg/mL respectively. Assessment of the inhibitory activity of individual oil components is in progress.