Nano-emulsion from Capsaicin: Formulation and Characterization

Capsaicin, abundantly found in hot chilli peppers is reported to have variety of pharmacological effects such as effective role in pain control and can be used as an effective analgesic agent. In the present work, capsaicin extracts were prepared using liquid-liquid extraction technique and solid-liquid extraction techniques. The extracts were then characterized via qualitative and quantitative tests, Thin Layer Chromatography and High Performance Liquid Chromatography. Plant extracts from dried chillies showed better yields and higher alkaloid and capsaicinoids contents as compared to fresh capsaicin extracts. Clear, uniform & stable oil-in-water nano-emulsions of capsaicin were prepared using Oleic acid/Labrasol, Tween-20, glycerol and water using high-speed homogenizer & ultra-sonicator. The developed capsaicin nano-emulsion was characterized for particle size, PDI & zeta potential. The particle size of capsaicin-loaded nano-emulsion (oleic acid) was found to be 35.95 nm with PDI of 0.320 and 7.902 nm with PDI of 0.168 with labrasol basesd nanoemulsion. The zeta potential was determined to be -18.5 mV. Refractive index of optimized nanoemulsion was observed to be 1.33 +/- 0.01 with a pH 6.1 +/- 0.05. Percentage transmittance suggested clear nanoemulsion (99 +/- 0.5 % transmittance) with conductivity of 119.5 +/- 1.5 mu S/cm. Further cytotoxicity was evaluated on Neuro-2a cell using MTT assay. The reported C-max values of capsaicin from topical route is 17.8 ng/ml, results of Cell viability indicated 80% cells to be viable with nano-emulsion prepared from capsaicin at 125 ng/ml and 12.5 ng/ml, which well covers the reported C-max values. (C) 2019 Elsevier Ltd. All rights reserved.