Microscopic Features, Antioxidant and Antibacterial Capacities of Plants of the Congolese Cosmetopoeia, Raw Materials of Cosmeceuticals

Cosmeceuticals are the fastest growing products in the cosmetics field and represent a hybrid between cosmetics and drugs. The main benefits reported for cosmeceutical herbal extracts, used in skin care, include antioxidant and antimicrobial activities and the tyrosinase inhibiting effect. The aim of this study was to evaluate the antioxidant and antibacterial activities of extracts from Chromolaena odorata, Mitracarpus villosus, Senna alata, Tetradenia riparia, Cannabis sativa and Pterocarpus soyauxii used traditionally in the management of skin and skin annexes pathologies; additionally to determine their microscopical characteristics and their chromatographic fingerprints. Microscopic analyses showed the specific botanical microscopic characters for each plant that constitute the database useful for the identification and authentication of these botanicals. To the best of our knowledge, our work is the first to describe the microscopic histological characters of studied plants except for Cannabis sativa. The results of the TLC chromatographic analysis revealed the richness in phenolic compounds, terpenes in all extracts and Pterocarpus soyauxii contained coumarins. All extracts displayed high ABTS and DPPH radical-scavenging activities connected with their IC50 values at the concentration range of 1 - 125 μg/mL with Cannabis sativa and Pterocarpus soyauxii as the most active. All plant extracts exhibited antibacterial activity on Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus to varying degrees. Cannabis sativa exhibited strong effect on Staphylococcus aureus and Escherichia coli. Chromolaena odorata and Tetradenia riparia showed a marked effect on Escherichia coli. Although certain crude extracts from studied botanicals have been shown to be inactive, fractionation studies are needed to determine the active fractions. Obtained biological activities could be related to phytochemicals present in the organic extracts like phenolic compounds and terpenoids. The antioxidant and antibacterial activities of the studied species may have potential therapeutic interest and could justify their use in traditional medicine and local cosmeceutical resources, but further studies are needed, especially in vivo studies, to demonstrate the benefit of these extracts on skin and skin appendages care.