title: Helichrysum and grapefruit extracts inhibit carbohydrate digestion and absorption, improving postprandial glucose levels and hyperinsulinemia in rats.
abstract: Several plant extracts rich in flavonoids have been reported to improve hyperglycemia by inhibiting digestive enzyme activities and SGLT1-mediated glucose uptake. In this study, helichrysum ( Helichrysum italicum ) and grapefruit ( Citrus × paradisi ) extracts inhibited in vitro enzyme activities. The helichrysum extract showed higher inhibitory activity of α-glucosidase (IC50 = 0.19 mg/mL) than α-amylase (IC50 = 0.83 mg/mL), whereas the grapefruit extract presented similar α-amylase and α-glucosidase inhibitory activities (IC50 = 0.42 mg/mL and IC50 = 0.41 mg/mL, respectively). Both extracts reduced maltose digestion in noneverted intestinal sacs (57% with helichrysum and 46% with grapefruit). Likewise, both extracts inhibited SGLT1-mediated methylglucoside uptake in Caco-2 cells in the presence of Na(+) (56% of inhibition with helichrysum and 54% with grapefruit). In vivo studies demonstrated that helichrysum decreased blood glucose levels after an oral maltose tolerance test (OMTT), and both extracts reduced postprandial glucose levels after the oral starch tolerance test (OSTT). Finally, both extracts improved hyperinsulinemia (31% with helichrysum and 50% with grapefruit) and HOMA index (47% with helichrysum and 54% with grapefruit) in a dietary model of insulin resistance in rats. In summary, helichrysum and grapefruit extracts improve postprandial glycemic control in rats, possibly by inhibiting α-glucosidase and α-amylase enzyme activities and decreasing SGLT1-mediated glucose uptake.
authors.affiliation: Department of Nutrition, Food Science and Physiology, University of Navarra , Pamplona, Spain.
authors.forename: Ana Laura
authors.initials: AL
authors.lastname: de la Garza
authors.forename: Usune
authors.initials: U
authors.lastname: Etxeberria
authors.forename: María Pilar
authors.initials: MP
authors.lastname: Lostao
authors.forename: Belén
authors.initials: B
authors.lastname: San Román
authors.forename: Jaione
authors.initials: J
authors.lastname: Barrenetxe
authors.forename: J Alfredo
authors.initials: JA
authors.lastname: Martínez
authors.forename: Fermín I
authors.initials: FI
authors.lastname: Milagro
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D032083:Citrus paradisi / Q000737:chemistry*; D004063:Digestion; D015536:Down-Regulation / Q000187:drug effects; D065089:Glycoside Hydrolase Inhibitors; D036562:Helichrysum / Q000737:chemistry*; D006801:Humans; D006943:Hyperglycemia / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism / Q000503:physiopathology; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007408:Intestinal Absorption / Q000187:drug effects; D008297:Male; D010936:Plant Extracts / Q000008:administration & dosage*; D019518:Postprandial Period / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D000516:alpha-Amylases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000520:alpha-Glucosidases / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D065089:Glycoside Hydrolase Inhibitors; D007004:Hypoglycemic Agents; D010936:Plant Extracts; D000516:alpha-Amylases; D000520:alpha-Glucosidases