Microemulsion-based topical hydrogels containing lemongrass leaf essential oil (Cymbopogon citratus (DC.) Stapf) and mango seed kernel extract (Mangifera indica Linn) for acne treatment: Preparation and in-vitro evaluations
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by Ngoc Nha Thao Nguyen, Thi Trang Dai Nguyen, Duc Linh Vo, Dang Tuyet Minh Than, Gia Phuoc Tien, Duy Toan Pham
Current treatments for severe acne include combinations of synthetic anti-inflammatory and antibacterial drugs, which possess numerous side effects. Therefore, this study developed microemulsion-based hydrogel containing lemongrass leaf essential oil (Cymbopogon citratus (DC.) Stapf) and mango seed kernel extract (Mangifera indica Linn) as a potential natural therapy for inflammatory acne. To this end, the microemulsions were first prepared using pseudo-ternary phase diagrams with soybean oil and coconut oil, cremophor RH40, and PEG 400. The optimal formula could load 1% lemongrass oil and 10% mango extract, possessed a spherical droplet size of ~18.98 nm, a zeta potential of -5.56 mV, and a thermodynamic stability. Secondly, the microemulsion-based hydrogel was developed by simple mixing the optimal microemulsion in carbopol-940 hydrogel (3.5% w/w). The product showed a viscosity of ~3728 cPs, a pH of 5.4-6.2, a spreadability of ~24 cm, an in-vitro Franz-cell cumulative release rate of ~80% for polyphenol content and ~60% for citral within 12 h, and a good physicochemical stability of > 3 months. Thirdly, the skin compatibility/irritability of the microemulsion-based hydrogel was determined by the HET-CAM assay, which showed non-irritation level. Finally, the anti-inflammatory activities of the hydrogel, using heat-induced BSA denaturation assay and LPS-stimulated RAW 264.7 NO inhibition assay, was 4-times higher than that of the reference drug Klenzit-C® (adapalene and clindamycin gel). Moreover, the hydrogel possessed strong anti-biofilm activity in Cutibacterium acnes, comparable with Klenzit-C®. Conclusively, the microemulsion-based hydrogel containing lemongrass oil and mango seed extract demonstrated much potentials to be a promising natural drug for acne treatment.