Polyphenol Characterization of the Aqueous Extract from Hubertia ambavilla L. (Asteraceae) by HPLC-DAD-ESI-MSn and Assessment of Its Antioxidant Activity.

In this work, phytochemical components, and the antioxidant properties of an aqueous extract obtained from a medicinal plant Hubertia ambavilla, endemic to Reunion Island, were investigated. A total of 37 compounds were detected and identified by high-performance liquid chromatography (UHPLC) using a photodiode-array detector (DAD) coupled with electrospray ionization/mass spectrometry (ESI/MSn ). From calibration curves, the quantity of secondary metabolites in the aqueous extract was calculated. The mean amounts of phenols, flavonoids, and condensed tannins found were 158.38±1.20 mg GAE/g DE, 60.41±1.65 mg AE/g DE and 23.77±1.36 mg CE/g DE, respectively. The in vitro antioxidant properties of the Hubertia ambavilla plant were measured using three methods: DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging and ferric reducing antioxidant power. The results showed that crude aqueous extract of H. ambavilla had effective radical scavenging and reducing power in comparison with standard antioxidant compounds. In conclusion, the crude extract herein presented offers a natural alternative biosource of antioxidants with potential applications in food and health industries.

Assessment of antioxidant and dermoprotective activities of gold nanoparticles as safe cosmetic ingredient.

Hubertia ambavilla, an endemic plant originating from Reunion Island in the Indian Ocean, is traditionally used as an anti-inflammatory and in healing, both for internal and external use. Polyphenolic compounds from aqueous phase extractions can reduce metal salts into nanoparticles and stabilize them in one step. Although gold nanoparticles are well described in the literature as anti-ageing ingredients, the nanoparticles presented herein are novel and are synthesized using a green process. We demonstrate their efficiency as dermoprotective, free radical scavenger and antioxidant cosmetic ingredients. Comparison with common nanoparticles obtained by the Turkevich method clearly emphasizes the necessity to carefully screen the products used for nanoparticle coatings, as they play a major role in the biological properties of the product. Hubertia ambavilla mediated gold nanoparticles are non-toxic to human dermal fibroblasts, possess free radical scavenging potential, and protect against damage to fibroblast and dermal cells caused by ultraviolet A radiation.