Preparation of nanoemulsion of Cinnamomum zeylanicum oil and evaluation of its larvicidal activity against a main malaria vector Anopheles stephensi.

PURPOSE: There is a growing need to use green and efficient larvicidal as alternatives for conventional chemicals in vector control programs. Nanotechnology has provided a promising approach for research and development of new larvicides. Larvicidal potential of a nanoemulsion of Cinnamomum zeylanicum essential oil reports against Anopheles stephensi. METHODS: The nanoemulsion of was formulated in various ratios comprising of C. zeylanicum oil, tween 80, span 20 and water by stirrer. It was characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). All components of C. zeylanicum essential oil were identified by GC-MS analysis. The larvicidal potential of the oil and its nanoformulation were evaluated against larvae of An. stephensi. The stability and durability of nanoemulsion was observed over a period of time. RESULTS: Sixty one components in the oil were identified, cinnamaldehyde (56.803%) was the main component. The LC90 and LC50 values of C. zeylanicum essential oil were calculated as 49 ppm and 37 ppm, respectively. The nanoemulsion droplets were found spherical in shape. It was able to kill 100% of larvae in up to 3 days. It was stable after dilution and increased its larvicidal activity up to 32% compared with the essential oil. CONCLUSIONS: A novel larvicide based on nanotechnology introduced. This experiment clearly showed increasing larvicidal activity and residual effect of the nanoformulation in comparison with the bulk essential oil. It could be concluded that this nanoemulsion may be considered as safe larvicide and should be subject of more research in this field.

Preparation of a Nanoemulsion of Essential Oil of Acroptilon repens Plant and Evaluation of Its Larvicidal Activity agianst Malaria Vector, Anopheles stephensi.

Background: Extensive use of chemical larvicides to control larvae, has led to resistance in vectors. More efforts have been conducted the use of natural products such as plant essential oils and their new formulations against disease vectors. Nanoformulation techniques are expected to reduce volatility and increase larvicidal efficacy of essential oils. In this study for the first time, a larvicide nanoemulsion from the essential oil of Acroptilon repens was developed and evaluated against Anopheles stephensi larvae under laboratory conditions. Methods: Fresh samples of A. repens plant were collected from Urmia, West Azarbaijan Province, Iran. A clevenger type apparatus was used for extracting oil. Components of A. repens essential oil (AEO) were identified by gas chromatography-mass spectrometry (GC-MS). All larvicidal bioassay tests were performed according to the method recommended by the World Health Organization under laboratory condition. Particle size and the morphologies of all prepared nanoformulations determined by DLS and TEM analysis. Results: A total of 111 compounds were identified in plant. The LC50 and LC90 values of AEO calculated as 7 ppm and 35 ppm respectively. AEO was able to kill 100% of the larvae in 4 days. Conclusion: The nanoemulsion of AEO showed a weak effect on the larvar mortality. It may therefore be suggested that this kind of nanoemulsion is not appropriate for the formulation as a larvicide. It is important to screen native plant natural products, search for new materials and prepare new formulations to develop alternative interventions with a long-lasting impact.

Evaluation of the alum-naloxone adjuvant activity against experimental murine leishmaniasis due to L. major.

Leishmaniasis is caused by intracellular parasites of Leishmania species, which are transmitted by the bite of the sandfly. Recovery and protection against the infection depends on the induction of a strong Th1 type of immune response. Vaccination of mice with the opioid antagonist naloxone can promote the activation of the Th1 responses. We studied the efficacy of the mixture of naloxone and alum, as an adjuvant, to enhance immune responses and induce protection against Leishmania major infection in BALB/c as a susceptible mouse model. BALB/c mice were immunized with Ag-naloxone-alum, Ag-alum, Ag-naloxone or PBS subcutaneously three times at 2-week intervals. The humoral and cellular specific immune responses were assessed 2 weeks after the last immunization and compared with the control mice. Our results indicated that the administration of alum-naloxone as an adjuvant increased the capability of L. major promastigote antigens to enhance lymphocyte proliferation, the levels of IFN-γ, and the IFN-γ/IL-5 ratio. The results of DTH showed that there were no significant differences in footpad swelling between the groups of immunized mice as compared with the non-vaccinated control group; however, no significant differences were observed in the survival rate among groups. It can be concluded that although immunization with the alum-naloxone mixture in combination with the autoclaved L. major promastigote antigens could enhance cellular immunity and shift the immune response to a Th1 pattern, it could not protect the mice against Leishmania major infection.