Fabrication of quercetin and curcumin bionanovesicles for the prevention and rapid regeneration of full-thickness skin defects on mice

Identification and nanoentrapment of polyphenolic phytocomplex from Fraxinus angustifolia: in vitro and in vivo wound healing potential

The aim of the present study was to elucidate the polyphenolic composition of Fraxinus angustifolia leaf and bark extracts, and to evaluate their efficacy in wound healing. Quercetin, catechin, rutin and tannic acid were identified as the main components of the extracts. In order to improve their skin bioavailability, the polyphenolic phytocomplexes were incorporated in different nanovesicles, namely ethosomes and phospholipid vesicles containing Transcutol(®) P (Trc) or ethylene glycol (EG). The latter had never been used before as a component of phospholipid vesicles, and it was found to play a key role in improving extract efficacy in wound healing. Results of cryogenic transmission electron microscopy (cryo-TEM), Photon Correlation Spectroscopy (PCS) and Small-Angle X-ray Scattering (SAXS) showed that ethosomes and EG-PEVs were small, monodispersed, unilamellar vesicles, while Trc-PEVs were larger, less homogeneously dispersed and multilamellar, with a large bilayer thickness. Free extracts did not show relevant ability to protect in vitro human keratinocytes from H2O2 damages, while when entrapped in nanovesicles, they significantly inhibited H2O2 stress damages, probably related to a higher level of cell uptake. On the other hand, in vivo results showed that the highest antioxidant and anti-inflammatory effects were provided by the phytocomplexes in EG-PEVs, which favoured wound healing. Moreover, non-entrapped F. angustifolia extracts showed a marginal effect, comparable to that of free quercetin dispersion (control). In conclusion, our results depict that these extracts may find potential applications in biomedicine.

Improvement of quercetin protective effect against oxidative stress skin damages by incorporation in nanovesicles

Quercetin was incorporated in glycerosomes, new phospholipid-glycerol vesicles, and their protective effect against oxidative stress skin damages was extensively evaluated. In particular, the concentration-dependent effect of glycerol (from 10 to 50%) on vesicle suitability as cutaneous carriers of quercetin was carefully assessed. All vesicles were unilamellar and small in size (∼80-110 nm), as confirmed by cryo-TEM observation, with a drug incorporation efficiency ranging between 81 and 91%. SAXS studies, performed to investigate the bilayer arrangement, indicated a strong, dose-dependent interaction of glycerol with the polar portions of the phospholipid molecules, while quercetin did not significantly change the bilayer packing. In vitro studies on newborn pig skin underlined the concentration-dependent ability of glycerosomes to promote quercetin accumulation in the different layers, also confirmed by confocal microscopic observation of skin treated with fluorescent vesicles. Quercetin incorporated into liposomal and glycerosomal nanoformulations showed a strong ability to scavenge free radicals (DPPH test) and protect human keratinocytes in vitro against hydrogen peroxide damage. Moreover, quercetin-loaded vesicles were avidly taken up by keratinocytes in vitro. Overall, results indicate 40 and 50% glycerosomes as promising nanosystems for the improvement of cutaneous quercetin delivery and keratinocyte protection against oxidative stress damage.