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Abstract
Laggera crispata (Vahl) Hepper & Wood (Asteraceae), Cyclospermum leptophyllum (Pers.) Eichler (Apiaceae) and Perilla frutescens (L.) Britton (Lamiaceae) are under-explored aromatic plants of western-Himalaya. The hydrodistilled essential oils of L. crispata, C. leptophyllum and P. frutescens were analyzed using gas chromatography-flame ionization detector (GC-FID) and GC-mass spectrometry (GC-MS) and tested against nine pathogenic bacterial strains using disc diffusion assay. Major constituents of L. crispata essential oil were 2,5-dimethoxy-p-cymene (43.2 %), 10-epi-γ-eudesmol (19.7 %), eudesm-7(11)-en-4-ol (4.8 %), α-humulene (3.8 %), 7-epi-α-eudesmol (3.6 %) and (E)-caryophyllene (3.5 %). Major constituents of C. leptophyllum oil were 2,5-dimethoxy-p-cymene (46.8 %), thymol methyl ether (14.6 %), p-cymene (13.9 %), γ-terpinene (8.9 %) and carvacrol methyl ether (7.5 %). However, the essential oil of P. frutescens contained perilla ketone (48.6 %) and isoegomaketone (32.1 %) as main constituents. The essential oil of L. crispata exhibited good activity against Streptococcus mutans and moderate activities against Staphylococcus aureus and Klebsiella pneumoniae. The essential oil of C. leptophyllum showed moderate activity against Gram-positive bacteria, namely, Staphylococcus aureus (MTCC2940), Staphylococcus aureus (MTCC96) and Streptococcus mutans, where as the P. frutescens essential oil showed good activity against Streptococcus mutans and Bacillus subtilis. In general, the examined essential oils exhibited moderate to good activity against most of the tested Gram-positive bacteria, except L. crispata, which also showed moderate activity against Gram-negative strain, Klebsiella pneumoniae.