Topical delivery of Withania somnifera crude extracts in niosomes and solid lipid nanoparticles

Background: Withania somnifera is a medicinal plant native to India and is known to have anticancer properties. It has been investigated for its anti-melanoma properties, and since melanoma presents on the skin, it is prudent to probe the use of W. somnifera in topical formulations. To enhance topical drug delivery and to allow for controlled release, the use of niosomes and solid lipid nanoparticles (SLNs) as delivery vesicles were explored. Objective: The objective of this study is to determine the stability and topical delivery of W. somnifera crude extracts encapsulated in niosomes and SLNs. Materials and Methods: Water, ethanol, and 50% ethanol crude extracts of W. somnifera were prepared using 24 h soxhlet extraction which were each encapsulated in niosomes and SLNs. Franz cell diffusion studies were conducted with the encapsulated extracts to determine the release and skin penetration of the phytomolecules, withaferin A, and withanolide A. Results: The niosome and SLN formulations had average sizes ranging from 165.9 ± 9.4 to 304.6 ± 52.4 nm with the 50% ethanol extract formulations having the largest size. A small particle size seemed to have correlated with a low encapsulation efficiency (EE) of withaferin A, but a high EE of withanolide A. There was a significant difference (P Abbreviations used: API: Active pharmaceutical ingredient, ANOVA: Analysis of variance, ED: Epidermis-dermis, HPLC: High-performance liquid chromatography, HLB: Hydrophilic-lipophilic balance, NMR: Nuclear magnetic resonance spectroscopy, PDI: Polydispersity index, SLN: Solid lipid nanoparticle, SD: Standard deviation, SCE: Stratum corneum-epidermis, TEM: Transmission electron microscopy.