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Aiming at finding natural sources of antidiabetics agents, 15 extracts from Brazilian medicinal plants of the Atlantic Forest and Amazon region were tested against α-glucosidase enzyme. Plants were selected based on the taxonomic relationships with genera including several species with antidiabetic activity. In this screening, the extracts obtained from the flowers of Hyptis monticola and the leaves of Lantana trifolia and Lippia origanoides resulted endowed with promising anti-α-glucosidase activity. The extracts from H. monticola and from L. origanoides collected in two different areas, were characterised by ultra-high performance liquid chromatography coupled to mass spectrometry. Bioassay-guided fractionation led to the identification of several enzyme inhibiting compounds, among them the mechanism of action of naringenin and pinocembrin was investigated. The two L. origanoides extracts showed differences in bioactivity and in the phytochemical profiles. The fractionation of the extract from H. monticola led to a partial loss of the inhibitory effect.

Ethnopharmacological Relevance: species of Terminalia (Combretaceae) are used to treat diabetes and metabolic disorders in Asia, Africa, and America. Terminalia phaeocarpa Eichler is an endemic tree from Brazil, popularly known as capitão. This species is closely related to Terminalia argentea Mart., also vulgarly known as capitão, a native but not endemic tree. Due to their phenotype similarity, these species might eventually prove inseparable and they are indistinctly used by locals to treat diabetes, among other diseases. The potential antidiabetic effect of T. argentea has been previously reported, whereas the biological effects and chemical composition of T. phaeocarpa have never been addressed so far., Aim of the Study: investigate the hypoglycaemic effect of an ethanol extract (EE) of T. phaeocarpa leaves and its ethyl acetate (FrEtOAc) and hydromethanolic (FrMEOH) fractions, in addition to their activity on the release of pro-inflammatory mediators and inhibition of lipase, α-amylase, and α-glucosidase enzymes. Additionally, it aimed to characterize the chemical composition of the extract and fractions, seeking to identify the compounds related to the biological activities., Materials and Methods: The effect on the release of TNF-α, IL-1β, and CCL-2 was evaluated in LPS-stimulated THP-1 cells (ATCC TIB-202). The inhibition of lipase, α-amylase, and α-glucosidase was tested in vitro, whereas the hypoglycemic effect was assayed in the oral starch tolerance test. The chemical composition was investigated by extensive UHPLC-DAD-ESI-MS/MS analyses., Results: The extract and derived fractions reduced TNF-α (EE pIC 50  = 4.58 ± 0.01; FrEtOAc pIC 50  = 4.69 ± 0.01; FrMeOH pIC 50  = 4.54 ± 0.02) and IL-1β (EE pIC 50  = 4.86 ± 0.02; FrEtOAc pIC 50  = 4.86 ± 0.02; FrMeOH pIC 50  = 4.75 ± 0.01) release by LPS-stimulated THP-1 cells in a concentration-dependent manner, whereas the inhibitory effect on CCL-2 release did not reach a clear linear relationship for the tested concentrations. The extract and fractions also inhibited in vitro the activity of lipase (EE pIC 50  = 3.97 ± 0.12; FrEtOAc pIC 50  = 3.87 ± 0.04; FrMeOH pIC 50  = 3.67 ± 0.14), α-amylase (EE pIC 50  = 4.46 ± 0.27; FrEtOAc pIC 50  = 5.47 ± 0.27; FrMeOH pIC 50  = 4.26 ± 0.22), and α-glucosidase (EE pIC 50  = 5.46 ± 0.05; FrEtOAc pIC 50  = 5.79 ± 0.11; FrMeOH pIC 50  = 5.74 ± 0.05). The pIC 50 values of the test samples were lower than those obtained with orlistat (7.59 ± 0.08) and acarbose (6.04 ± 0.37 and 7.63 ± 0.04) employed as the positive controls respectively in the lipase, α-amylase, and α-glucosidase assays. When assayed in the oral starch tolerance test, the extract and fractions also reduced animal glycaemia. UHPLC-DAD-ESI-MS/MS analyses of the extract and fractions led to the identification of 38 phenolic compounds, mainly phenolic acids, ellagitannins and flavonoids, among others, all of them first-time described for the species., Conclusion: Based on our findings, T. phaeocarpa has hypoglycaemic activity and polyphenols are the probable bioactive compounds, which support the ethnomedical use of the species., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Brazilian native fruits are reported to be promising sources of bioactive compounds; however their bioactivity depends on their stability along the digestive process. This study evaluated the α-glucosidase inhibition, antioxidant activity and total phenolic content (TPC) stability of araçá, butiá and pitanga fruit extracts using an in vitro digestion model. Additionally, the individual phenolic compound recovery of the most stable and active extract was evaluated by HPLC-DAD-ESI-MS/MS. Overall, the antioxidant activity of all extracts decreased along the process. Araçá fruit extracts, at the end of digestion, showed α-glucosidase inhibition values similar to their non-digested extracts and the highest TPC recovery (28%). Recovery of individual phenolic compounds of red araçá fruit extract revealed a negative impact on the stability of ellagitannins. Araçá fruit extract seems to provide phenolic compounds with α-glucosidase inhibitory properties after the gastrointestinal digestion, indicating their potential to be used in the control of type II diabetes.

Brazilian native fruits have been shown as excellent sources of polyphenols which are associated with multiple biological activities including inhibition of carbohydrate-hydrolyzing enzymes, α-amylase and α-glucosidase. Postmeal blood glucose elevations and high glycemic index diets can play a major role in the development of type 2 diabetes, therefore alternative approaches to reduce postprandial hyperglycemia are of growing interest in order to reduce diabetes risk. Here we investigated the effect of six Brazilian native clarified fruit juices from Amazon, Savannah and Atlantic Forest biomes on postprandial glycemia after consumption of a carbohydrate meal. For this, 23 healthy subjects were selected to consume seven meal tests, with a 1-week interval among them, consisting in 50g white bread plus 300mL of water (control) or cambuci, cagaita, maracujá-alho, cupuaçu, camu-camu and jaboticaba clarified fruit juices. The results showed that serum glucose concentrations were significantly lower after consumption of cambuci, cagaita, camu-camu and jaboticaba juices, whereas maracujá-alho and cupuaçu juices did not decrease the amount of glucose absorbed, compared to control (p<0.05). In addition, cagaita, cambuci, cupuaçu and jaboticaba juices increased the oxygen radical absorbance capacity in plasma, whereas all juices augmented the ferric reducing ability of plasma, except for cambuci (p<0.05). These results indicate that juices from Brazilian native fruits may be considered as adjuvant treatment for reduction of postprandial glycemia in healthy subjects., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Diabetes mellitus is the most common disease in the world. One therapeutic approach for treating diabetes is inhibition of α-amylase and α-glucosidase activities to reduce postprandial blood glucose levels. In vitro tests showed that several plant extracts from Brazilian cerrado species can inhibit the activity of α-amylase and α-glucosidase. The extracts of Eugenia dysenterica, Stryphnodendron adstringens, Pouteria caimito, Pouteria ramiflora, and Pouteria torta showed strong α-amylase and α-glucosidase inhibitory activity. Eugenia dysenterica, P. caimito, P. ramiflora, and P. torta aqueous extracts exerted the highest activity against α-amylase (IC₅₀) values of 14.93, 13.6, 7.08, and 5.67 µg/mL, respectively) and α-glucosidase (IC₅₀ values of 0.46, 2.58, 0.35, and 0.22 µg/mL, respectively). Stryphnodendron adstringens ethanol extract also exhibited inhibitory activity against both enzymes (IC₅₀) 1.86 µg/mL against α-amylase and 0.61 µg/mL against α-glucosidase). The results suggest that the activity of these cerrado plants on α-amylase and α-glucosidase represents a potential tool for development of new strategies for treatment of diabetes., (© Georg Thieme Verlag KG Stuttgart · New York.)

Nutrient digestion and absorption after blood feeding are important events for Lutzomyia longipalpis, which uses these nutrients to produce eggs. In this context, the pH inside the digestive tract is an important physiological feature as it can markedly influence the digestive process as well as interfere with Leishmania development in infected phlebotomines. It was described previously that unfed females have an acidic midgut (pH 6). In this study, the pH inside the midgut of blood-fed females was measured. The abdominal midgut (AM) pH varied from 8.15+/-0.31 in the first 10 h post-blood meal to 7.7+/-0.17 after 24 h. While the AM was alkaline during blood digestion, the pH in the thoracic midgut (TM) remained acidic (5.5-6.0). In agreement with these findings, the enzyme alpha-glucosidase, which has an optimum pH of 5.8, is mainly encountered in the acidic TM. The capacity of unfed females to maintain the acidic intestinal pH was also evaluated. Our results showed the presence of an efficient mechanism that maintains the pH almost constant at about 6 in the midgut, but not in the crop. This mechanism is promptly interrupted in the AM by blood ingestion. RT-PCR results indicated the presence of carbonic anhydrase in the midgut cells, which apparently is required to maintain the pH at 6 in the midgut of unfed females. Investigations on the phenomenon of alkalization observed after blood ingestion indicated that two mechanisms are involved: in addition to the alkalization promoted by CO2 volatilization there is a minor contribution from a second mechanism not yet characterized. Some inferences concerning Leishmania development and pH in the digestive tube are presented.

Enzyme activities associated with the labial glands, midgut and rectum of adult Acromyrmex subterraneus were investigated in order to understand their role in digestion of plant and fungal material. High chitinolytic activity was detected in the labial glands, indicating a possible role in the degradation of fungus ingested by the ants. Chitinolytic activity seen in other compartments of the alimentary canal probably originated in the labial glands. The highest activity detected in the midgut was for alpha-glucosidase, which was considered to be of insect origin due to its association with midgut epithelium and it is probably involved in glucose assimilation from nutrient sources such as maltose and sucrose present in plant material. A large range of enzyme activities were detected in the rectal lumen contents, and as in the midgut the highest values were for alpha-glucosidase activity. The absence of activity associated with the epithelium, in the particulate fraction, indicates that the rectal epithelium does not have a secretory function. The detection of enzymes in the rectal lumen contents, which were not detected in the midgut lumen contents, indicates that the rectum acts as a reservoir, accumulating enzymes. The major digestive enzymes were partially characterized using hydrophobic interaction chromatography, gel filtration and SDS-PAGE. The pH of the adult intestinal tract and flow rate of dye through the tract was investigated. A gradual acidification of the intestinal tract was noted commencing with the crop (pH 6-8.2) and terminating with the rectum (pH 3-5). The flow of dye through the different compartments of the tract showed a rapid fill time for all the gut compartments and a short residence time in the crop. In all other compartments, the dye remained detectable for 10 days or longer.