Optimized extraction of a-glucosidase inhibitors from Phyllantus niruri

GONZALEZ MIRAGLIOTTA ANA; OJEDA GONZALO ADRIAN; GONZALEZ ROMINA BELEN; TORRES ANA MARÍA

Goias

Conferencia; 8th Brazilian Conference Natural Products/XXXIV RESEM; 2021

Sociedade Brasileira de Quimica

Type 2 diabetes is a globally prevalent chronic disease that accounts for 90-95% of diabetes cases. Although there is a wide variety of drugs on the market for its treatment, there is an increasing demand for substitute approaches, either because of the adverse effects of insulin or to reduce the side effects of the drugs. One interesting possibility is to inhibit intestinal glucosidase enzymes to reduce postprandial glycemia. Phyllanthus niruri (chanca piedra) is used in ethnomedicine as a hypoglycemic (Beidokhti et al., 2017), antioxidant, hepatoprotective and hypolipidemic; properties related to polyphenol content and antioxidant potential (Kumaran et al.,2005). 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. Extracts were prepared with a 1:4 solid : solvent ratio. Total phenolic compounds content (TPC) was spectrophotometrically determined (Folin Ciocalteau). Alpha glucosidase (APG) inhibitory assay was determined using p-Nitrophenol-a-Dglycopyranoside as substrate in pH 7.5 buffer and acarbose a positive control of inhibition. The comparison of linear and quadratic models for inhibition of APG 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 indicates that the chemical nature of involved compounds could be diverse. Other authors have implicated polyphenols as inhibitors of the enzyme; these observations are in coincidence with our results. TPC presented maximum values in ternary mixtures (33.3 : 33.3 : 33.3). In the optimization stage it was desirable to maximize inhibition of APG and TPC 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 a TPC of 253.24 mg gallic acid/ g extract. Experimental design, 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 APG inhibitory effect, an interesting strategy for the discovery and validation of phytopreparations.