The aim of this study was to develop lipid-based nanoparticles that entrapped a high concentration of capsaicin (0.25%) from a capsicum oleoresin extract. The solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were strategically fabricated to entrap capsaicin without a hazardous solvent. Optimized nanosize lipid particles with high capsaicin entrapment and loading capacity were achieved from pair-wise comparison of the solid lipid mixtures consisting of fatty esters and fatty alcohols, representing small and large crystal-structure molecules combined with a compatible liquid lipid and surfactants (crystallinity index = 3%). This report was focused on selectively captured capsaicin from oleoresin in amorphous chili extract-loaded NLCs with 85.27% ± 0.12% entrapment efficiency (EE) and 8.53% ± 0.01% loading capacity (LC). The particle size, polydispersity index, and zeta potential of chili extract-loaded NLCs were 148.50 ± 2.94 nm, 0.12 ± 0.03, and −29.58 ± 1.37 mV, respectively. The favorable zero-order kinetics that prolonged capsaicin release and the significantly faster transdermal penetration of the NLC attributed to the reduction in skin irritation of the concentrated capsaicin NLCs, as illustrated by the in vitro EpiDerm^TM three-dimensional human skin irritation test and hen’s egg test chorioallantoic membrane assay (HET-CAM).

The work aimed to develop Centella asiatica extract-loaded niosomes (CAE-Nio) and surface modified niosomes by hyaluronic acid (CAE-Nio-HA) to enhance transdermal penetration. Niosome formulations were prepared by film hydration method using Tween 60 and Span 60 as nonionic surfactants, cholesterol and various CAE contents. Various HA concentrations were investigated to obtain optimized CAE-Nio enhancing further skin penetration. Results showed that niosomes prepared from Tween 60 yielded suitable CAE encapsulated niosomes with mean particle size and zeta-potential of 155 nm and −15 mV, respectively. The niosomes exhibited high encapsulation efficiency (%EE) and drug loading capacity (%DL) of 71–77% and 3–7%, respectively. Incorporating HA to niosome decreased %DL and caused larger particle size and increased zeta-potential in a dose dependent manner while %EE remained unaffected. The sustained-release behaviour of CAE from all niosomes was under a diffusion controlled mechanism. Asiaticoside, a relatively polar compound from CAE-Nio-HA could penetrate through the stratum corneum and dermis in a larger amount than from CAE-Nio and CAE solution. CAE-Nio-HA formulations showed good stability under low temperature (4 °C and 25 °C) for periods longer than 4 months. In conclusion, the developed Nio-HA is a promising delivery system for asiaticoside to enhanced dermal absorption, permeation and accumulation in viable epidermis and dermis layers. This system can also be applied to other hydrophilic natural active compounds.

Despite the known beneficial impacts of estrogen used as hormone replacement therapy to ameliorate signs of skin aging in postmenopausal women, its compliance rates are low. A significant amount of estrogen may be absorbed into the blood circulation and can lead to systemic actions. Soy isoflavone exhibits biological activities similar to synthetic estrogen because it is a heterocyclic phenolic compound. The disadvantage of most topical ingredients based on isoflavone is that they contain biologically inactive glycoside forms, which must be converted to a readily absorbed aglycone for the topical application. The purposes of this study were to develop niosomes-loaded Aspergillus oryzae-fermented soybean extract (FSE) to enhance skin absorption with proven systemic side effect compared to estrogen application. Skin hydration and viscoelasticity of 75 days post-ovariectomized (OVX) Wistar rats following 84-day topical treatment with various tested gel formulations containing fermented soybean extract (FSE) were evaluated. The tested formulations were gel + FSE nanoniosomes, gel + FSE microniosomes, gel + FSE (200 µg FSE/9 cm²/rat), gel + blank nanoniosomes (a negative control), and gel + 17β-estradiol (E2) nanoniosomes (a positive control, 20 µg E2/9 cm²/rat). Changes in vaginal cornifications and weights of uteri, livers, and kidneys in the OVX rats and signs of primary skin irritation in the rabbits were evaluated for their toxicities. Results showed that FSE-loaded nanoniosomes improved the skin hydration and viscoelasticity better than gel + FSE microniosomes and gel + FSE, respectively, but lower than those of gel + E2 nanoniosomes (p < 0.05). Unlike all gel + E2 nanoniosomes, the FSE formulations showed no changes in vaginal cells and weights of uteri, livers, and kidneys and no signs of skin irritation. In conclusion, The FSE niosome-based gels should be promising candidates for delivering phytoestrogens against signs of skin aging with no systemic toxicities.