Response Surface Method for Recovering Flavonoid / Flavonone Rich Small Red Bean Extracts that Inhibit of alpha-Amylase, alpha-Glucosidase and Lipase in Isolation and Combined with Acrobose and Orlistat

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The red bean is a rich source of health promoting components with polyphenols playing a significant role. The objective of this project, is to determine the ability of phenolic rich extracts obtained from a red beans to inhibiting α-A, α-G and PL. Because phenolic compounds are chemical diverse compounds classified by the presence of one or more phenolic groups that are bonded to one or more hydroxyl groups, different extraction methods are needed to determine the different amounts present in dietary system (Chapter 1). Therefore, a three-factor, three-level, face-centered cube design was used for the response surface method approach, which resulted in 17 extracts per solvent system prepared in triplicate, each of which were tested for total flavonoids (TF) and total flavanone (TFN). The highest TF 1.56 mg/g was predicted by the ensuing model by using 50:50 acetone:water, 5% solid:solvent and 60 minutes of mixing. Alternatively, ethanol extractions represented the highest TFN with 1.3 mg/g being the optimal level. The factors that resulted in the optimum TFN yields (predicted) were 25:75 ethanol:water, 10% solid:solvent and 180 minutes of mixing. However, knowledge remains limited on the ability of polyphenolic compounds from small red beans to inhibit these enzymes despite the high levels of TF and TFN. In case of α-A, extracts with high TF levels represented provided the optimal inhibition that was strongly correlated (59.8 % /mg extract, R=0.817). In case of α-G, TFN representing the highest inhibition with a strong correlation (3.3 % /mg extract, R= 0.768). In case of PL, acetone TFN represent the most effective (38.05 % /mg, R=0.285) (Chapter 2). As many phenols act effectively with common used treatment methods in combination, the next study (Chapter 3) consisted of using the three most potent extract produced from Chapter 2 to test their efficacy with the pharmaceutical drugs, acarbose and orlistat. All three Extracts could potentiate inhibition caused by acarbose or orlistat at select levels. Extract 2, 9, and 11, were identified by high-performance liquid chromatography (HPLC) and consisted of gallic, chlorogenic, caffeic acids and keampferol, whereas catechin and quercetin are two other compounds determined in Extract 11