Abstract
BackgroundThe stem bark aqueous alcohol extract of Poincianella pluviosa (PPSB extract) is rich in bioactives including gallic acid, gallic acid methyl ester, pyrogallol, ellagic acid, corilagin, 1,4,6-tri-O-galloyl-glucose, 1,2,3,6-tetra-O-galloyl-glucose, 1,2,3,4,6-penta-O-galloyl-glucose, tellimagrandin I, tellimagrandin II, mallotinic acid, mallotusinic acid, and geraniin. The aim of the present study was to evaluate the antioxidant activity of the PPSB extract as well as its inhibitory action on carbohydrate digestive enzymes relevant to type 2 diabetes.ResultsThe PPSB extract was prepared using a mixture of 40% ethanol and 60% distilled water. The PPSB extract showed high antioxidant activities and inhibited several carbohydrate digestive enzymes. The IC50 values for inhibiting in vitro salivary amylase, pancreatic amylase, intestinal β-galactosidase and intestinal invertase were, respectively, 250 ± 15, 750 ± 40, 25 ± 5, and 75 ± 8 μg/mL. In vivo inhibition of the intestinal starch absorption was confirmed by determination of blood glucose levels in rats before and after administration of starch by gavage with or without different amounts of PPSB extract. Docking simulations performed on three different programs to rank the extract compounds most likely to bind to porcine pancreatic α-amylase suggest that geraniin is likely to be the P. pluviosa extract compound that presents the greatest binding potential to the pancreatic alpha-amylase. However, the total inhibitory action of the PPSB extract is likely to result from a summation of effects of several molecules. Furthermore, the PPSB extract did not present acute toxicity nor did it present mutagenic effects.ConclusionIt can be concluded that the PPSB extract is potentially useful in controlling the postprandial glycaemic levels in diabetes. Further clinical studies with the extract are needed, however, to confirm its potential use in the management of type 2 diabetes.
Highlights
Diabetes mellitus is one of the most common public health problems in the world, and type 2 diabetes accounts for 90–95% of all cases of diabetes [1]
The antioxidant activity of the PPSB extract was evaluated by two methods, DPPH radical scavenging and FRAP (Table 1)
The stem bark of the Poincianella pluviosa extract contains high amounts of phenolics and flavonoids. Such richness in phenolics and flavonoids is in agreement with data reported for similar extracts including Caesalpinia spinosa extract (551 mg of GAE/g) [30], Caesalpinia decapetala methanolic extract (13.28 mg of GAE/g of phenolics and 3.93 mg quercetin/g of flavonoids) [31] and ethanolic extracts of seeds of Caesalpinia bonducella (62.50 mg of GAE/g of phenolics) [32]
Summary
Diabetes mellitus is one of the most common public health problems in the world, and type 2 diabetes accounts for 90–95% of all cases of diabetes [1]. A practical approach to control blood glucose levels is through natural products isolated from plants that act by retarding the absorption of carbohydrates during digestion and decrease glucose release into blood. This could be achieved through the inhibition of carbohydrate hydrolysing enzymes, such as salivary and pancreatic amylases, and intestinal disaccharidases, αglucosidase, β-galactosidase, and β-fructofuronosidase (invertase). The aim of the present study was to evaluate the antioxidant activity of the PPSB extract as well as its inhibitory action on carbohydrate digestive enzymes relevant to type 2 diabetes
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