Phytochemical analysis and antimicrobial activity of Cardaria draba (L.) Desv. volatiles

Two different volatile isolates from the aerial parts of Cardaria draba (L.) Desv., obtained either by hydrodistillation (Extract I) or by CH(2) Cl(2) extraction subsequent to hydrolysis by exogenous myrosinase (Extract II), were characterized by GC-FID and GC/MS analyses. The main volatiles obtained by hydrodistillation, i.e., 4-(methylsulfanyl)butyl isothiocyanate (1; 28.0%) and 5-(methylsulfanyl)pentanenitrile (2; 13.8%), originated from the degradation of glucoerucin. In Extract I, also volatiles without sulfur and/or nitrogen were identified. These were mostly hexadecanoic acid (10.8%), phytol (10.2%), dibutyl phthalate (4.5%), and some other compounds in smaller percentages. Extract II contained mostly glucosinolate degradation products. They originated from glucoraphanin, viz., 4-(methylsulfinyl)butyl isothiocyanate (3; 69.2%) and 5-(methylsulfinyl)pentanenitrile (4; 4.5%), glucosinalbin, viz., 2-(4-hydroxyphenyl)acetonitrile (5; 7.2%), and glucoerysolin, viz., 4-(methylsulfonyl)butyl isothiocyanate (6; 5.0%). Moreover, the volatile samples were evaluated for their antimicrobial activity using the disc-diffusion method and determining minimum inhibitory concentrations (MIC). All volatile isolates expressed a wide range of growth inhibition activity against both Gram-positive and Gram-negative bacteria and fungi. The MIC values varied between 4 and 128 μg/ml.