Chemical Constituents of Muehlenbeckia tamnifolia (Kunth) Meisn (Polygonaceae) and Its In Vitro α-Amilase and α-Glucosidase Inhibitory Activities

Abstract

Abstract:The phytochemical investigation of Muehlenbeckia tamnifolia, collected in Loja-Ecuador, led to the isolation of nine known compounds identified as: lupeol acetate (1); cis-p-coumaric acid (2); lupeol (3); β-sitosterol (4) trans-p-coumaric acid (5); linoleic acid (6) (+)-catechin (7); afzelin (8) and quercitrin (9). The structures of the isolated compounds were determined based on analysis of NMR and MS data, as well as comparison with the literature. The hypoglycemic activity of crude extracts and isolated compounds was assessed by the ability to inhibit α-amylase and α-glucosidase enzymes. The hexane extract showed weak inhibitory activity on α-amylase, with an IC 50 value of 625 µg·mL −1 , while the other extracts and isolated compounds were inactive at the maximum dose tested. The results on α-glucosidase showed more favorable effects; the hexanic and methanolic extracts exhibited a strong inhibitory activity with IC 50 values of 48.22 µg·mL −1 and 19.22 µg·mL −1 , respectively. Four of the nine isolated compounds exhibited strong inhibitory activity with IC 50 values below 8 µM, much higher than acarbose (377 uM). Linoleic acid was the most potent compound (IC 50 = 0.42 µM) followed by afzelin, (+)-catechin and quercitrin.

Antidiabetic potential: in vitro inhibition effects of some natural phenolic compounds on α‐glycosidase and α‐amylase enzymes

“…IC 50 values of phenolic compounds and acarbose as positive control exhibited the following order: Rosmarinic acid (137.36 nM) < Curcumin (168.73 nM) ≈ Isoliquiritigenin (169.52 nM) < Tetrakis (187.80 nM) < Olivetol (204.24 nM) < CAPE (314.42 nM) < Resveratrol (376.22 nM) < p‐Coumaric acid (737.23 nM) < Acarbose (10.00 μM). Additionally, it was reported that acarbose with a proper diet and exercise program to control high blood sugar in T2DM recorded IC 50 value of 10.00 μM . All natural phenolic compounds had effective IC 50 values than that acarbose (10.00 μM) toward α‐amylase.…”

“…On the other hand, it was reported that acarbose used as a positive inhibitor for the medical therapy of diabetic potential had K i value of 12.60 ± 7.80 M. [48] (ii) Inhibition of -amylase enzyme that plays an important role in digestion of glycogen and starch is evaluated as strategy for the therapy of disturbances in carbohydrate uptake, such as obesity and diabetes, as well as, periodontal diseases and dental caries. [49] For -amylase, natural phenolic compounds had IC 50 [51] The hypoglycemic agents decelerate the digestion and assimilation of simple carbohydrates in intestine throughglycosidase inhibition. Commercially accessible oral AGIs, such as acarbose, have been extensively prescribed to treat T2DM.…”

The impact of some natural phenolic compounds on carbonic anhydrase, acetylcholinesterase, butyrylcholinesterase, and α‐glycosidase enzymes: An antidiabetic, anticholinergic, and antiepileptic study

“…In current medical science, therapeutic drugs, such as voglibose, acarbose, and miglitol, are used as α‐amylase and α‐Gly inhibitors. The important difficulty of these drugs is their side effects such as bloating, abdominal distention, possibly diarrhea, meteorism, and flatulence …”

Synthesis, characterization, antioxidant, antidiabetic, anticholinergic, and antiepileptic properties of novel N‐substituted tetrahydropyrimidines based on phenylthiourea

“…These results clearly indicated that newly synthesized compounds as well as future similar derivatives may function as drugs for the treatment of AD. For the ?‐glycosidase enzyme, the novel N‐substituted tetrahydropyrimidines based on phenylthiourea ( 1a‐d ) had IC 50 values in the range of 56.18 to 70.31 nM and K i values in the range of 48.95 ± 11.00 to 91.03 ± 9.21 nM (Table and Figure ). The results obviously showed that all these novel derivatives (1a‐d) demonstrated efficient ?‐glycosidase inhibitory effects than that of acarbose (IC 50 : 22.8 M) as standard ?‐glycosidase inhibitor. However, the most effective K i values were obtained by 1‐(4‐(2‐hydroxyphenyl)‐6‐methyl‐1‐phenyl‐2‐thioxo‐1,2,3,4‐tetrahydropyrimidin‐5‐yl) ethanone ( 1a ) and methyl‐3‐(4‐hydroxybutyl)‐4‐(2‐hydroxyphenyl)‐6‐methyl‐1‐phenyl‐2‐thioxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carboxylate ( 1d ), with K i values of 48.95 ± 11.00 and 52.47 ± 8.43 nM, respectively. Reducing capability of novel N‐substituted tetrahydropyrimidines based on phenylthiourea ( 1a‐d ) was evaluated by reduction of Fe([CN] 6 ) 3 to Fe([CN] 6 ) 2 .…”