title: Triterpenes as uncompetitive inhibitors of α-glucosidase from flowers of Punica granatum L.
abstract: The α-glucosidase and maltase inhibitory effects of Punica granatum L. flowers (PGF) were investigated. The methanol extract (PGFMe), n-hexane extract (PGFH), chloroform extract (PGFC) and the remaining water fraction (PGFW) were assayed for their α-glucosidase and maltase inhibitory effects. PGFW showed potent α-glucosidase inhibition with IC₅₀ of 0.8 μg/mL followed by PGFMe (IC₅₀ of 4.0 μg/mL) then PGFC (IC₅₀ of 5.21 μg/mL) in comparison to acarbose (0.9 μM). Due to its selectivity towards α-glucosidase, PGFC was subjected to bioactivity-guided isolation of its main active constituents. Five known compounds (1-5) were identified as β-sitosterol (1), oleanolic acid (2), ursolic acid (3), p-coumaric acid (4) and apigenin (5). Ursolic and oleanolic acids showed potent α-glucosidase inhibition (IC₅₀ of 39.0 and 35.0 μM, respectively), while they did not show significant maltase inhibition. Kinetic study using the double Lineweaver-Burk plot revealed that ursolic acid uncompetitively inhibited α-glucosidase in comparison with acarbose as a competitive inhibitor.
authors: a Department of Pharmacognosy , Faculty of Pharmacy, Cairo University , 11562 Cairo , Egypt.
authors: Riham
authors: R
authors: Salah El Dine
authors: Qiong
authors: Q
authors: Ma
authors: Zeinab A
authors: ZA
authors: Kandil
authors: Ali M
authors: AM
authors: El-Halawany
mesh_terms: D003373:Coumaric Acids / Q000737:chemistry / Q000302:isolation & purification; D004305:Dose-Response Relationship, Drug; D035264:Flowers / Q000737:chemistry*; D065089:Glycoside Hydrolase Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D007004:Hypoglycemic Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D029561:Lythraceae / Q000737:chemistry*; D009828:Oleanolic Acid / Q000031:analogs & derivatives / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D011422:Propionates; D012855:Sitosterols / Q000737:chemistry / Q000302:isolation & purification; D014315:Triterpenes / Q000737:chemistry / Q000302:isolation & purification; D000520:alpha-Glucosidases / Q000378:metabolism; D000097245:Ursolic Acid
chemical_list: D003373:Coumaric Acids; D065089:Glycoside Hydrolase Inhibitors; D007004:Hypoglycemic Agents; D009828:Oleanolic Acid; D011422:Propionates; D012855:Sitosterols; D014315:Triterpenes; D000520:alpha-Glucosidases; D000097245:Ursolic Acid; C025473:gamma-sitosterol; C495469:p-coumaric acid
keywords: Punica granatum flower; α-glucosidase; uncompetitive; ursolic acid