Polyalthia longifolia produces sesquiterpene-rich essential oils (EOs) whose compositions varied substantially from sample to sample depending on the origin of the plant (Nigeria and Vietnam). Nothing is known about the phytochemistry of Ivoirian P. longifolia. The aim of the present study was to characterize Ivoirian P. longifolia through the chemical composition of the leaf oil and to develop a strategy that allows the identification of minor oxygenated sesquiterpenes whose MS data are not compiled in commercial or laboratory-constructed MS libraries. The EO was submitted to gas chromatography (GC) retention index (RI), GC-mass spectrometry (MS) and 13 C nuclear magnetic resonance (NMR) analysis. Then hydrocarbons and oxygenated components were separated and the oxygenated fraction was chromatographed on silica gel. The fractions were analysed by GC(RI) and 13 C NMR. Seventy compounds accounting for 91.8% of the EO were identified. Sesquiterpene hydrocarbons, (E)-β-caryophyllene (27.8%), α-zingiberene (20.0%) and allo-aromadendrene (15.0%), were the major components. Various oxygenated sesquiterpenes whose MS data were not compiled in commercial and laboratory-made MS libraries were identified by comparison of their chemical shift values in the spectrum of the fraction of CC with those reported in the literature and compiled in a laboratory-constructed 13 C NMR data library. The composition of the investigated Ivoirian P. longifolia oil sample presented similarities and differences with Nigerian and Vietnamese oils. Combined analysis of Ivoirian P. longifolia EO by chromatographic and spectroscopic techniques including 13 C NMR without isolation of the components, appeared particularly efficient to identify minor components of EOs, whose MS spectra are insufficiently differentiated or MS data are not compiled in commercial and lab-constructed MS libraries.
A detailed analysis of Mentha suaveolens ssp. insularis (Req.) Greuter essential oil (EO) and hydrolate extract (HE) was carried out by combination of GC-RI, GC-MS and 13 C-NMR spectroscopy. After fractionation by column chromatography, 51 components of the EO and 27 components of the HE, accounting for 96.1% and 98.3%, respectively, were identi¼ed. The main components were pulegone (44.4% and 14.8%) and cis-cis-p-menthenolide (27.3% and 67.3%). This a-methylen-g-butyrolactone, reported for the ¼rst time as a natural product, was isolated and its structure elucidated by 1D and 2D NMR spectroscopy. Both EO and HE exhibited a fair antibacterial activity against Staphylococcus aureus and Bacillus cereus.
Quorum sensing (QS) is a bacterial communication mechanism used to express various survival or virulence traits leading to enhanced resistance. Chromobacterium violaceum is a commonly used strain that highlights anti-QS action of bioactive substances. Here, we wanted to see if 12 selected essential oils (EO) could exert anti-QS activity. We measured the sublethal minimal QS inhibitory concentration (MQSIC) by assessing violacein production of C. violaceum along with bacterial growth. To confirm the QS disruption, we also proceed to surface bacterial observations using scanning electron microscopy (SEM). We showed that cis-cis-p-menthenolide extracted and isolated from a plant endemic to occidental Mediterranean Sea islands, Mentha suaveolens ssp. insularis, acts as an inhibitor of violacein production and biofilm formation. Measured MQSIC was much lower than the minimal inhibitory concentration (MIC): 0.10 mg·mL−1 vs. 3.00 mg·mL−1. Moreover, disturbance of QS-related traits was confirmed by the degradation of C. violaceum biofilm matrix. There is a clear structure–activity relationship between cis-cis-p-menthenolide and anti-QS activity. Indeed, its isomer molecule (mintlactone) exerts a poor anti-QS action. These results indicate that inhibition of violacein production and biofilm formation by cis-cis-p-menthenolide might be related to a disruption in the QS mechanism.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.