Process optimization for pigments extraction from Vitis vinifera using response surface methodology

The flavonoid pathway produces water-soluble pigments known as anthocyanins in the cytoplasm of colored plant cells. The present study focused on evaluation of Vitis vinifera (black grapes) pigments. Maximum pigment (18.2 mg/g) was extracted with optimized parameters (Methanol 35%; pH-4; temperature-65 degrees degrees C) using response surface methodology. The obtained ANOVA quadratic model was statistically significant. Interactive variables such as AB (methanol vs pH), AC (methanol vs temperature) and BC (pH vs temperature) were highly significant due to its p-value < 0.05. Especially, temperature playsa significant role in pigment extraction compared to other variables. The model was shown to be very significant with a coefficient of variation(C.V 0.6156) by the overall determination of the coefficient (R2 = 0.9999) and adjusted coefficient value (adj R2 = 0.9998).Instrumental analysis confirmed that pigment belonged to anthocyanin. The toxicity of pigment at different concentrations were evaluated by using plants (Vigna radiata) and animal (Zebra fish) as model. Pigments did not show toxicity on the plant as well as the animal model throughout the study. In addition, pigments showed 58% of DPPH radical scavenging activity and 55% anti-diabetic activity by inhibiting alpha -glucosidase activity. Further, Isosorbide dinitrate and Tridecanoic acid obtained from GC-MS was docked with EGFR kinase and glucagon like peptide 1 (GLP-1) protein respectively. The Isosorbide dinitrate and Tridecanoic acid binding affinity was -6.7 and -7.6 for EGFR and GLP-1 respectively. Therefore, Vitis vinifera pigments havepotential therapeutic properties that can be used for making natural food supplements for improving human health.