Evaluation des effets biologiques des extraits aqueux de plantes médicinales seules et combinées

Abstract

The aqueous extracts of lesser galangal (Alpinia officinarum Hance), ginger (Zingiber officinale Roscoe.), Ceylon cinnamon (Cinnamomum zeylanicum Nees) and clove buds were obtained by two extraction methods, traditional (ethnopharmacology) as a decoction at the temperature of 100°C, and modern (green chemistry) by using superheated water extraction at the temperature of 120°C. These extracts were subjected to evaluate their biological activities, antibacterial and allelopathic, and their chemical composition to compare the efficiency of each extraction method. It has proved that superheated extract of cloves was the most antibacterial with bactericidal effect on multi-resistant strains, followed by the decoction of the same plant with bacteriostatic effect. Superheated extract and decoction of cinnamon and the decoction of mixture of cloves and cinnamon were less effective. The other extracts did not give good results. Concerning the allelopathic activity results indicate that decoctions of ginger and cloves were most effective, and the other decoctions did not have any effect. However, superheated extracts of cloves and the mixture of four spices were the most effective. The phytochamical screening made on aqueous extracts showed a similarity in chemical composition between decoctions and superheated extracts. However the powerful effect of superheated extracts is due to the amount of obtained metabolites, where the water subjected under some conditions of temperature and pressure has a power of extracting less polar molecules. The spectrophotometric profile is an additional proof for the chemical composition of these extracts where polyphenolic molecules predominated.