Formulation and Evaluation of Solid Lipid Nanoparticles containing Kappaphycus alvarezii Extract in A Cosmetic Gel

Abstract

Objectives: The objective of the research was to prepare and evaluate the cosmetic gel containing SLNs of Kappaphycus alvarezii chloroform extract to localize the extract topically to exert its antimicrobial properties. Methodology: The antimicrobial activity evaluation for the chloroform, methanol, and aqueous K. alvarezii extracts were carried out using disc-diffusion agar plate method. The extract with maximum antimicrobial action was selected for the preparation of SLNs. Pre-formulation studies using ATR-FTIR spectrophotometer was carried out to check the compatibility of the extract with excipients in the range of 400–4000 cm−1.The SLNs were prepared by the film hydration technique with ultrasonication. The dried SLNs were evaluated for its physical characteristics, zeta potential and for the duration taken to release the encapsulated extract for the antimicrobial action. Carbopol and HPMC were chosen as the gelling agent after compatibility studies with nanoparticle dispersions.The extract loaded SLNs based gel was analysed for its pH, visual appearance, and in-vitro drug release. Results: Chloroform extract of K. alvarezii (120μg) showed maximum antimicrobial activity with cloudy and blurry zone of inhibition. The zone of inhibition was smaller for SLNs when compared to the extract. This was due to the low diffusion of encapsulated drug through the outer lipid layer of SLNs. SLNs showed a zeta potential ranging between –11.0 to –37.4mV. The formulated gel containing solid lipid nanoparticles of chloroform extract of K. alvarezii had an average pH value of 5.37, which was suitable to be used on human skin. The maximum drug release was 60.28% for over a period of 25 hours. Conclusion: In this study algal extracts were successfully encapsulated within the SLNs and when applied topically the SLNs could reside on the surface of the skin for localized action as evident from the drug release study.The zeta potential obtained for the SLNs was approximately within the limit of –30mV that yields a formulation with fairly good physical stability.