Chemical Composition, Antimicrobial and Cytotoxic Activity of the Essential Oil of Platostoma hispidum, an Unexplored Species of Lamiaceae

Platostoma hispidum (Syn: Acrocephalus hispidus), an aromatic herb of the family Lamiaceae, is used in traditional folk medicine but remained unexplored till date for its essential oil composition and biological activities. The present study is aimed at determining the chemical composition, antimicrobial and cytotoxic activities of the essential oil of the plant for the first time. The GC-MS analysis led to the identification of fifty-one compounds, accounting for 97.62 % of the total essential oil. The major volatile components were limonene (35.35 %), piperitenone oxide (13.96 %), terpinolene (10.19 %), beta-bisabolene (5.02 %), alpha-humulene (4.65 %) and beta-caryophyllene (4.38 %). The essential oil of P. hispidum showed significant antimicrobial activity against all tested bacterial strains such as Staphylococcus aureus, Basillus subtilis, Staphylococcus saprophyticus, Krebsiella pneumoniae, Eschrichia coli, Shigella flexneri and Salmonella enterica serovar typhimurium showing a range of inhibitory zone from 7-25 mm. In vitro MTT assay revealed that the essential oil of P. hispidum had cytotoxicity against HCT 116 and PC-3 cancerous cell lines with an IC50 value of 37.25 mu g/ml and 35.62 mu g/ml, respectively. Thus, the present report on essential oil composition and bioactivities of Platostoma hispidum would be useful for further bioprospecting of the species to exploit its full pharmaceutical potential.