Encapsulation of Rosmarinus officinalis essential oil and of its main components in cyclodextrin: application to the control of the date moth Ectomyelois ceratoniae (Pyralidae).

BACKGROUND: Synthetic insecticides are the most useful tools for preventing losses caused by insect pest's infestation during storage. However, the use of pesticides should be limited because of the development of insect resistance and their adverse effects on human health and environment. In the last decades, natural insecticidal products, principally essential oils (EOs) and their active components, exhibited potential alternatives for pest control. Nevertheless, due to their volatile nature, encapsulation could be considered as the most appropriate solution. Therefore, this work aims to investigate the fumigant ability of inclusion complexes of Rosmarinus officinalis EO and its major constituents (1,8-cineole, α-pinene and camphor) with 2-hydroxypropyl-beta-cyclodextrin (HP-ß-CD) against Ectomyelois ceratoniae (Pyralidae) larvae. RESULTS: The encapsulation within HP-ß-CD reduced greatly the release rate of the encapsulated molecules. Therefore, free compounds were more toxic than those encapsulated. Moreover, results revealed that encapsulated volatiles exhibited interesting insecticidal toxicity towards E. ceratoniae larvae. In fact, after 30 days mortality rates were 53.85, 94.23, 3.85 and 42.31% for α-pinene, 1,8-cineole, camphor and EO, respectively, encapsulated within HP-ß-CD. In addition, results showed also that 1,8-cineole free and encapsulated was more effective toward E. ceratoniae larvae than the other tested volatiles. Additionally, the HP-ß-CD/volatiles complexes exhibited best persistence compared to the volatiles components. The half-life of the encapsulated α-pinene, 1,8-cineole, camphor and EO (7.83, 8.75, 6.87 and 11.20 days) was significantly longer than that of the free ones (3.46, 5.02, 3.38 and 5.58 days). CONCLUSION: These results sustain the utility of R. officinalis EO and its main components encapsulated in CDs as treatment to stored-date commodities. © 2023 Society of Chemical Industry.

Molecular Composition and Antibacterial Effect of Five Essential Oils Extracted from Nigella sativa L. Seeds against Multidrug-Resistant Bacteria: A Comparative Study.

Nigella sativa L. (NS) and its volatile compounds are well known for their broad spectrum of effects. This study aimed to investigate the variability of the chemical composition and the in vitro antibacterial activity of five essential oils (Eos) originated from Morocco, Saudi Arabia, Syria, India, and France. These five samples were grown under different edaphic and climatic conditions. The agar diffusion method and microdilution method in 96-well plates were used to test the sensitivity of multidrug-resistant strains clinically isolated from patients (methicillin-resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii), for the determination of the minimum inhibitory concentration and bactericidal concentration. Among all the investigated Eos, the monoterpenes were highly present in the chemical composition. Moroccan, Saudi Arabian, and Syrian seeds were characterized by the presence α-phellandrene (20.03-30.54%), ß-cymene (12.31-23.82 %), and 4-caranol (9.77-14.27%). The Indian seeds were rich with 4-caranol (18.81%), ß-cymene (14.22%), α-phellandrene (10.58%), and ß-chamigrene (9.54%), while France NS was rich with estragole (20.22%) and D-limonene (14.63%). The minimum inhibitory (MIC) and bactericidal concentration (MBC) obtained for the four Eos (with the exception of France because of the low yield) tested were ranging from 3 to 40 µl/ml. Gram-positive (+) bacteria were slightly sensitive to the Eos tested than the Gram-negative (-) bacteria. The results of this study showed that the Eos of NS seeds show interesting antibacterial activity which could be associated to the existence of different bioactive compounds. Indeed, these compounds can be used for preventive or curative purposes in the face of the noncontrolled emergence of resistance to antibiotics.