Microencapsulation Preservation of the Stability and Efficacy of Citrus Grandis Oil-Based Repellent Formulation against Aedes aegypti during Storage

Abstract

Essential oils have been widely used as an active ingredient in mosquito repellent products. However, essential oils are highly unstable and prone to degradation when exposed to the environment during storage. Microencapsulation techniques help to maintain the stability of molecules in essential oils that are sensitive to environmental stress, and therefore improve shelf life. In this study, the physical stability and efficacy of a repellent formulation consisting of encapsulated Citrus grandis essential oil (CGEO) were evaluated under different storage conditions over a 12-month period by comparing the formulation with a non-encapsulated formulation. The formulations were both stored under two different storage conditions, i.e., 25 ± 2 °C/60% ± 5% relative humidity (RH) and 40 ± 2 °C/75% RH ± 5%, for 12 months. Droplet size, zeta potential, and pH value were measured after 1, 6, and 12 months of storage to determine their stability. For the study of efficacy, each formulation was tested against Aedes aegypti under laboratory conditions. We found that the microencapsulated formulation’s physical characteristics showed insignificant changes as compared with the non-encapsulated formulation during storage. The microencapsulated formulation demonstrated better repellent effects, sustaining high protection (>80%) for 4 more hours of exposure after 12 months of storage as compared with the non-encapsulated formulation that demonstrated high protection for only an hour post application. Microencapsulation helped to preserve the stability of the formulation, which resulted in high protection being maintained for over 12 months of storage.

Repellent activity of trans‐anethole and tea tree oil against Aedes aegypti and their interaction with OBP1, a protein involved in olfaction

“…Organic extracts and essential oil of plants such as clove, coconut, lemongrass, and tea tree have been documented to prevent insect bites such as from Ae. aegypti , German and American cockroaches, and common bed bug (Terriquez et al, 2013; Pavela, 2015; Nentwig et al, 2016; Peach et al, 2019; Afify & Potter, 2020; González‐Morales et al, 2021; Jannatan & Rahayu, 2021; Misni et al, 2021; Ubulom et al, 2021).…”

Citrus By-Products as a Valuable Source of Biologically Active Compounds with Promising Pharmaceutical, Biological and Biomedical Potential

“…Citrus-based essential oils exhibit significant antimicrobial activity against foodborne bacteria and also antioxidant activity to prevent the effects of oxidation; hence, citrus-based essential oils could act as natural preservatives [ 39 , 40 , 41 ]. Furthermore, several studies have reported the high repellent activity [ 42 , 43 , 44 ] and fumigant toxicity [ 45 , 46 ] of citrus-based essential oils against different insects.…”