Gas chromatographic-mass spectral analysis and phytopathogenic activity of theessential oil of Plectranthus tenuiflorus

The chemical composition of the hydrodistilled leaf essential oil from Plectranthus tenuiflorus growing wild in Yemen was determined by GC-MS-analysis and bioautographic assay was used to evaluate the anti-phytofungal activity of the oil against Cladosporium cucumerinum. Thirty-eight components were identified in the essential oil representing 76.2% of the total oil and the major compounds were thymol (47.6.%), τ-cadinol (10.5%), (E)-caryophyllene (3.6%), 1,10-di-epi-cubenol (3.4%), caryophyllene oxide (3.0%), and β-selinene (1.4%). At the application of 400 μg, PTEO exhibited apotent antifungal activity with inhibition zones of 32 (±1.8). TLC-bioautographic assay was used to identify the acetylcholinesterase inhibitory effect, and thymol was isolated and characterized by LC-MS and analytical TLC as the responsible constituent for anticholinesterase activity.