Inhibition of α-glucosidase and pancreatic α-amylase is one of the therapeutic approaches for delaying carbohydrate digestion, resulting in reduced postprandial glucose. The aim of this study was to evaluate the phytochemical analysis and the inhibitory effect of various cinnamon bark species against intestinal α-glucosidase and pancreatic α-amylase. The results showed that the content of total phenolic, flavonoid, and condensed tannin ranged from 0.17 to 0.21 g gallic acid equivalent/g extract, from 48.85 to 65.52 mg quercetin equivalent/g extract, and from 0.12 to 0.15 g catechin equivalent/g extract, respectively. The HPLC fingerprints of each cinnamon species were established. Among cinnamon species, Thai cinnamon extract was the most potent inhibitor against the intestinal maltase with the IC(50) values of 0.58 ± 0.01 mg/ml. The findings also showed that Ceylon cinnamon was the most effective intestinal sucrase and pancreatic α-amylase inhibitor with the IC(50) values of 0.42 ± 0.02 and 1.23 ± 0.02 mg/ml, respectively. In addition, cinnamon extracts produced additive inhibition against intestinal α-glucosidase and pancreatic α-amylase when combined with acarbose. These results suggest that cinnamon bark extracts may be potentially useful for the control of postprandial glucose in diabetic patients through inhibition of intestinal α-glucosidase and pancreatic α-amylase.
A methodology for the site-specific attachment of fluorophores to the backbone of pyrrolidinyl peptide nucleic acids (PNAs) with an α/β-backbone derived from D-prolyl-(1S,2S)-2-aminocyclopentanecarboxylic acid (acpcPNA) has been developed. The strategy involves a postsynthetic reductive alkylation of the aldehyde-containing labels onto the acpcPNA that was previously modified with (3R,4S)-3-aminopyrrolidine-4-carboxylic acid on the solid support. The reductive alkylation reaction is remarkably efficient and compatible with a range of reactive functional groups including Fmoc-protected amino, azide, and alkynes. This allows further attachment of readily accessible carboxyl-, alkyne-, or azide-containing labels via amide bond formation or Cu-catalyzed azide-alkyne cycloaddition (CuAAC, also known as click chemistry). The label attached in this way does not negatively affect the affinity and specificity of the pairing of the acpcPNA to its DNA target. Applications of this methodology in creating self-reporting pyrene- and thiazole orange-labeled acpcPNA probes that can yield a change in fluorescence in response to the presence of the correct DNA target have also been explored. A strong fluorescence enhancement was observed with thiazole orange-labeled acpcPNA in the presence of DNA. The specificity could be further improved by enzymatic digestion with S1 nuclease, providing a 9- to 60-fold fluorescence enhancement with fully complementary DNA and a less than 3.5-fold enhancement with mismatched DNA targets.
Clitoria ternatea (commonly known as blue pea) flower petal extract (CTE) is used as a natural colorant in a variety of foods and beverages. The objective of study was to determine the inhibitory effect of CTE on adipogenesis in 3T3-L1 preadipocytes. The phytochemical profiles of CTE were analyzed by liquid chromatography and tandem mass spectrometry (LC-MS/MS). Anti-adipogenesis effect of CTE was measured by using Oil Red O staining, intracellular triglyceride assay, quantitative real-time PCR and western blot analysis in 3T3-L1 adipocytes. Cell cycle studies were performed by flow cytometry. Lipolysis experiments were performed using a colorimetric assay kit. In early stages, CTE demonstrated anti-adipogenic effects through inhibition of proliferation and cell cycle retardation by suppressing expression of phospho-Akt and phospho-ERK1/2 signaling pathway. The results also showed that CTE inhibited the late stage of differentiation through diminishing expression of adipogenic transcription factors including PPARγ and C/EBPα. The inhibitory action was subsequently attenuated in downregulation of fatty acid synthase and acetyl-CoA carboxylase, causing the reduction of TG accumulation. In addition, CTE also enhanced catecholamine-induced lipolysis in adipocytes. These results suggest that CTE effectively attenuates adipogenesis by controlling cell cycle progression and downregulating adipogenic gene expression.
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