Phytochemical characterization of fruit extracts of Rubus adenotrichus and evaluation of their antioxidant power for dermocosmetics formulation

Abstract

There are more than 700 species of the genus Rubus, popularly known as Mora (tropical highland blackberry). In countries like Costa Rica it is commonly used in human food and in others as part of animal feed. In Costa Rica, the species Rubus adenotrichus has been characterized by its high content of antioxidant substances, becoming one of the most cultivated species and that may have characteristics to be used in cosmetics or medicine. The objective of the present study is to identify the main phytochemical groups and to quantify the main markers in order to associate them with cosmetic or medicinal functions in pharmaceutical products. Materials and Methods: Ripe fruits of Rubus adenotrichius were fractionated with solvents of low, medium and high polarity, followed by a phytochemical screening according to the Guidelines for the Control of Quality of Products of Natural Origin of the World Organization of Health, the antioxidant properties were evaluated by means of the H-ORAC and DPPH test; the concentration of total phenols by Follin ciocalteau and antocinanins by differential pH was determined. Finally, the physicochemical properties of the aqueous extract, such as pH, specific gravity, Brix grades, conductimetry, and osmometry were determined and an absorption spectrum from 260 to 700 nm was obtained. Results and Conclusions: Phenolic compounds were found, as condensed and non-condensed tannins, anthocyanins, flavonoids, terpenes, and alkaloids as major phytochemical groups, a high antioxidant power measured in H-ORAC 311 ± 7,63 mg/mol Trolox Equivalent/g of dry fruit, and EC 50 118,46 mg/L for the aqueous extract, the total phenols found were 20,85 ± 0,27 mg/g of dry sample of gallic acid equivalents, which makes the Rubus adenotrichus fruit an excellent active for bacteriostatic, anti-aging, anti-wrinkle, nourishing and moisturizing formulations, and the astrigent effect also allows its application to small superficial wounds on the skin. Likewise, the acidic pH of 3,55 ± 0,1 is beneficial for maintaining the cutaneous acid mantle and thereby favoring the normal flora of the skin, but may be a problem for the formulation of carbomer-based gels or the incorporation of preservatives. The aqueous extract is hyperosmotic (559,66 ± 3,21 mOs / kg) and has a high electrical conductivity (285 ± 2 μS / cm) due to the presence of electrolytes and a considerable amount of sugars, according to brix degrees (7,543° ± 0,005°), finally the 4% w/w aqueous extract shows an absorption of ultraviolet radiation of 25% in the wavelengths from 260 to 400 nm, by which it also could be useful for formulating compositions for sun protection.