Optimization of Extraction Conditions of Polyphenols and Flavonoids from Olax subscorpioidea leaves, a Medicinal Plant Traditionally Used in Korhogo (Cote d’ivoire)

Secondary metabolites, including polyphenols and flavonoids, play a key role in the expression of the active principles of several medicinal plants from Côte d'Ivoire, such as Olax subscorpioidea Oliv. This study was initiated to help improve conditions for extracting polyphenols and flavonoids from Olax subscorpioidea Oliv leaves harvested in Korhogo. Experimental design methodology was used. The effect of four independent variables on polyphenol and flavonoid content was evaluated: extraction time (12h-24h), evaporation temperature (45°C - 55°C), plant material-solvent ratio (1/20 g/mL - 1/5 g/mL) and ethanol proportion (20% - 100%). The Central Composite Design (CCD) was used to optimize responses after factor screening using the Plackett and Burman design. Optimum extraction conditions were obtained with an ethanolic proportion of 88.29% and 17g of Olax subscorpioidea Oliv leaves dissolved in 100 mL ethanol. The experimental values (96.31 ± 5.29 mg Eq AG/g for polyphenols and 62.44 ± 4.58 mg Eq Q/g) were close to those expected (94.51 mg Eq AG/g for polyphenols and 58.22 mg Eq Q/g for flavonoids), confirming the relevance of the mathematical model used and the success of the response surface methodology in optimizing the extraction conditions of the system studied. These results show that by taking extraction conditions into account in this preliminary study, we can optimize the quantities of secondary metabolites of therapeutic interest.