GC/MS Analyses of the Essential Oils Obtained from Different Jatropha Species, Their Discrimination Using Chemometric Analysis and Assessment of Their Antibacterial and Anti-Biofilm Activities

Abstract

The essential oils of <i>Jatropha intigrimma</i>, <i>J. roseae</i> and <i>J. gossypifolia</i> (Euphorbiaceae) were analyzed employing GC/MS (Gas Chromatography coupled with Mass Spectrometry) analyses. A total of 95 volatile constituents were identified from <i>J. intigrimma, J. gossypifolia</i> and <i>J. roseae</i> essential oils, accounting for 91.61, 90.12, and 86.24%, respectively. Chemometric analysis using principal component analysis (PCA) based on the obtained GC data revealed the formation of three discriminant clusters due to the placement of the three <i>Jatropha</i> species in three different quadrants, highlighting the dissimilarity between them. Heneicosane, phytol, nonacosane, silphiperfol-6-ene, copaborneol, hexatriacontane, octadecamethyl-cyclononasiloxane, 9,12,15-Octadecatrienoic acid, methyl ester and methyl linoleate constitute the key markers for their differentiation. <i>In vitro</i> antibacterial activities of the essential oils were investigated at doses of 10 mg/mL against the Gram-negative anaerobe <i>Escherichia coli</i> using the agar well diffusion method and broth microdilution test. <i>J. gossypifolia</i> essential oil showed the most potent antimicrobial activity, demonstrating the largest inhibition zone (11.90 mm) and the least minimum inhibitory concentration (2.50 mg/mL), followed by the essential oil of <i>J. intigrimma</i>. The essential oils were evaluated for their anti-adhesion properties against the Gram-negative <i>E. coli</i> biofilm using a modified method of biofilm inhibition spectrophotometric assay. <i>J. intigrimma</i> essential oil showed the most potent biofilm inhibitory activity, demonstrating the least minimum biofilm inhibitory concentration (MBIC) of 31.25 µg/mL. <i>In silico</i> molecular docking performed within the active center of <i>E. coli</i> adhesion protein FimH showed that heneicosane, followed by cubebol and methyl linoleate, displayed the best fitting score. Thus, it can be concluded that the essential oils of <i>J. gossypifolia</i> and <i>J. intigrimma</i> leaves represent promising sources for antibacterial drugs with antibiofilm potential.