Optimized extraction of alfa-glucosidase inhibitors in Phyllantus niruri

GONZALEZ MIRAGLIOTA, ANA MELISA .; OJEDA, GONZALO; GONZALEZ, ROMINA; PERUCHENA, N. M.; TORRES, ANA

Goias

Congreso; 8th Brazilian Conference on Natural Product; 2021

Brazilian Society on Natural Product

Design Expert Software (version 11.0) was used to generate a randomized mixture simplex lattice design. Twelve extraction mixtures were prepared using methanol, water and ethyl acetate in different proportions. Using these mixtures 12 extracts were obtained with a 1:4 solid : solvent ratio. Total phenolic compounds content was spectrophotometrically determined (Folin Ciocalteau). Alpha glucosidase inhibitory assay was determined using p-Nitrophenol a-D-glycopyranoside as substrate in buffer pH 7,5 and acarbose a positive control of inhibition. The comparison of linear and quadratic models for inhibition of -glucosidase activity showed that the quadratic model was significant (p < 0.05). The highest inhibition values were obtained by binary mixtures of methanol : ethyl acetate (50 : 50) and methanol : water (50 : 50). This result indicate that the chemical nature of involved compounds could be diverse. Other authors have implicated compounds of phenolic nature as inhibitors of the enzyme; these observations are in coincidence with our results. Total phenolic compounds presented maximum values in ternary mixtures (33.3 : 33.3 : 33.3). In the optimization stage it was desirable to maximize inhibition and keep phenolic content in range, therefore, numerical and graphical optimizations were evaluated to select the mixtures that best adjust to those requirements. The adopted criteria for numerical optimization were: inhibition >40%, using the maximum importance in weight this factor and maximum desirability (D). Numerical optimization indicated maximum desirability of D=1 for a mixture containing 70% methanol, 15% of water and 15% of ethyl acetate. Similarly, graphical optimization indicated that the same mixture would achieve inhibition of 46% with 253.24 mg gallic acid/ g extract. Experimental design and particularly mixture design represents a powerful strategy to objectively select the most suitable conditions for extracting phytochemicals with bioactive potential. In this way, we have optimized the preparation of extracts with in vitro alpha-glucosidase inhibitory effect, an interesting strategy for the discovery and validation of phytopreparation