Microencapsulation of citronella oil for mosquito-repellent application: Formulation and in vitro permeation studies

Essential oil encapsulations: uses, procedures, and trends

Recently there has been an increased interest towards the biological activities of essential oils (EOs).

Holy basil (Ocimum sanctum Linn.) essential oil delivery to swine gastrointestinal tract using gelatin microcapsules coated with aluminum carboxymethyl cellulose and beeswax

Holy basil essential oil (HBEO) can be applied as a feed additive; however, its benefits depend on the available amount in the gastrointestinal tract. In this study, the physicochemical properties, including the release properties of three different microcapsules, HBEO-loaded gelatin microcapsules (UC), UC coated with aluminum carboxymethyl cellulose (CC), and UC coated with aluminum carboxymethyl cellulose-beeswax composite (CB), were compared. The encapsulation efficiency, HBEO content, and 2,2-diphenyl-2-picrylhydrazyl radical scavenging activity for the microcapsules were 95.4 ± 0.17%, 66.7-67.7%, and 94.3-96.5%, respectively. Scanning electron microscopy and confocal laser scanning microscopy (CLSM) revealed nonuniform HBEO distributions in honeycomb-like networks in the microcapsules. An X-ray diffraction analysis determined that UC and CC microcapsules were amorphous, but CB microcapsules were semicrystalline. UV-vis spectrophotometer and CLSM analyses results determined that HBEO was released from CC and CB microcapsules in greater amounts than from UC microcapsules in simulated intestinal fluid. Therefore, the HBEO amount reaching the intestine can be controlled using the optimal encapsulation system.

Microcapsule preparation of allyl isothiocyanate and its application on mature green tomato preservation

Studies have shown that AITC can effectively control pathogenic fungi, which cause fruits and vegetables decay and rotting during storage. However, because of its strong irritant, AITC has not been conveniently used in fruits and vegetables preservation. Microencapsulation techniques may solve this problem. Up to 2% (w/v) gelatin and 2% (w/v) gum arabic (as wall material and materials), as well as AITC (as core material) were prepared used to form microcapsules with a ratio of 1:2 (the core material: to wall material). On the basis of the microcapsule option conditions, the AITC microcapsule encapsulation efficiency is above 90%, which can effectively control AITC release decrease irritant. Compared with control group, the storage time of the tomato of AITC microcapsule preservation was prolonged significantly, and the sensory quality of the tomato was better. Thus, the AITC microcapsule preservation has broad application prospects and development value prospects.

A novel approach for development and characterization of effective mosquito repellent cream formulation containing citronella oil

Citronella essential oil (CEO) has been reported as an excellent mosquito repellent; however, mild irritancy and rapid volatility limit its topical application. It was aimed to develop a nonirritant, stable, and consistent cream of CEO with improved residence time on skin using an industrial approach. Phase inversion temperature technique was employed to prepare the cream. It was optimized and characterized based on sensorial evaluation, emulsification, and consistency in terms of softness, greasiness, stickiness, and pH. The optimum batch (B5) was evaluated for viscosity (90249.67±139.95 cP), texture profile with respect to firmness (38.67±0.88 g), spreadability (70.33±0.88 mJ), and extrudability (639.67±8.09±0.1 mJ) using texture analyzer along with two most popular marketed products selected as reference standard. Subsequently, B5 was found to be stable for more than 90 days and showed enhanced duration of mosquito repellency as compared to CEO. HS-GC ensured the intactness of CEO in B5. Investigated primary irritation index (PII 0.45) positioned B5 into the category of irritation barely perceptible. The pronounced texture profile and stability of B5 with extended residence time and less PII revealed its potential application in industry and offered a promising alternative to the marketed products of synthetic origin.

Optimisation of rosemary oil encapsulation in polycaprolactone and scale-up of the process

Rosemary essential oil (REO) has many biological activities, such as antioxidant, anticarcinogenic, cognition-enhancing, analgesic and antimicrobial activities. The aim of this study was to prepare, at laboratory scale and larger scale, nanoencapsulating REO in order to reduce its volatilisation, light sensitivity and to enhance its water solubility. The nanoprecipitation method was applied to prepare polycaprolactone (PCL)-based nanocapsules loaded with REO at laboratory scale and then the optimal formulation obtained was scaled-up (×6) using the membrane contactor technique. The effect of several parameters, such as the evaporation method, the type of emulsifiers and the amount of the formulation products (PCL, REO, emulsifiers, etc.) on the REO-loaded nanocapsules properties (mean size, polydispersity index (PdI), zeta potential and REO loss) was evaluated at laboratory scale in order to obtain the optimal formulation. REO-loaded nanocapsules obtained from nanoprecipitation presented a nanometric mean size (220 ± 10 nm) with a PdI below 0.25, indicating an adequate homogeneity of the system, a negative zeta potential (-19.9 ± 4.6 mV) and a high encapsulation efficiency (∼99% for the major components). In addition, the membrane contactor technique gave similar results using an adequate pressure of the organic phase (0.8-1.2 bar). It is then suggested that the nanoprecipitation method can be suitable for the preparation of essential oil-loaded nanocapsules.

Repellent effectiveness of seven plant essential oils, sunflower oil and natural insecticides against horn flies on pastured dairy cows and heifers

Plant essential oils (basil, geranium, balsam fir, lavender, lemongrass, peppermint, pine and tea tree), mixed with either sunflower oil or ethyl alcohol, were applied at 5% concentrations to the sides of Holstein cattle. Pastured cattle treated with essential oils diluted in sunflower oil had less flies than the untreated control for a 24-h period. However, the essential oil treatments were not significantly different than the carrier oil alone. Barn-held heifers treated with essential oils and sunflower oil alone had significantly less flies than the untreated control for up to 8 h after treatment. Basil, geranium, lavender, lemongrass and peppermint repelled more flies than sunflower oil alone for a period ranging from 1.5 to 4 h after treatments applied to heifers. All essential oils repelled > 75% of the flies on the treated area for 6 and 8 h on pastured cows and indoor heifers, respectively. Geranium, lemongrass and peppermint stayed effective for a longer duration. Essential oils mixed with ethyl alcohol demonstrated less repellence than when mixed with the carrier oil. Safer's soap, natural pyrethrins without piperonyl butoxide and ethyl alcohol alone were not efficient at repelling flies. Essential oils could be formulated for use as fly repellents in livestock production.

Essential oils encapsulated in liposomes: a review

In the recent years there has been an increased interest toward the biological activities of essential oils. However, essential oils are unstable and susceptible to degradation in the presence of oxygen, light and temperature. So, attempts have been made to preserve them through encapsulation in various colloidal systems such as microcapsules, microspheres, nanoemulsions and liposomes. This review focuses specifically on encapsulation of essential oils into liposomes. First, we present the techniques used to prepare liposomes encapsulating essential oils. The effects of essential oils and other factors on liposome characteristics such as size, encapsulation efficiency and thermal behavior of lipid bilayers are then discussed. The composition of lipid vesicles membrane, especially the type of phospholipids, cholesterol content, the molar ratio of essential oils to lipids, the preparation method and the kind of essential oil may affect the liposome size and the encapsulation efficiency. Several essential oils can decrease the size of liposomes, homogenize the liposomal dispersions, increase the fluidity and reduce the oxidation of the lipid bilayer. Moreover, liposomes can protect the fluidity of essential oils and are stable at 4-5 °C for 6 months at least. The applications of liposomes incorporating essential oils are also summarized in this review. Liposomes encapsulating essential oils are promising agents that can be used to increase the anti-microbial activity of the essential oils, to study the effect of essential oils on cell membranes, and to provide alternative therapeutic agents to treat several diseases.