title: Evaluation of ethnomedical claim III: anti-hyperglycemic activities of Gongronema latifolium root and stem.
abstract: BACKGROUND
  The insulinotropic activity of the combined root and stem of Gongronema latifolium (Asclepiadaceae) was evaluated to justify its African ethnomedicinal use in the management of diabetes.
  
  
  METHODS
  A methanolic extract and its chromatographic fractions (A1 -A6 ) were tested for glucose-reducing and in vitro insulin-stimulating abilities using glucose-loaded rats and INS-1 cells, respectively. In vivo insulin-releasing activities for the significantly (P<0.05) active antihyperglycemic A5 and A6 and in vitro insulinotropic activity of the C1 fraction and its isolated constituents were also similarly determined.
  
  
  RESULTS
  The extract (100 mg/kg) had higher in vivo antihyperglycemic activity than the individual A1 -A6 , indicating a synergistic effect of the plant constituents. Higher in vivo insulin release in response to A5 (100 mg/kg) than A6 , agreed with their in vivo antihyperglycemic activities and confirmed insulin release as a mechanism of action of the plant. Compared with 5.6 mmol/L glucose (negative control), the extract and the A3 , A6 , and C1 (all at 100.0 μg/mL) elicited significantly higher in vitro insulin release that was similar to that of glibenclamide (1.0 μg/mL; P>0.05). Fraction C1 yielded a 1:1 mixture of α-amyrin and β-amyrin cinnamates (1a:1b), lupenyl cinnamate (2), lupenyl acetate (3), and two unidentified triterpenoids, Y and Z. The 1a:1b mixture (100.0 μg/mL) demonstrated the highest insulinotropic activity that was comparable (P>0.05) to that of glibenclamide (1.0 μg/mL).
  
  
  CONCLUSIONS
  The results confirm pancreatic activity as a mechanism underlying the antidiabetic action of G. latifolium and justify its ethnomedical use.
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Obafemi Awolowo University, Ile Ife, Nigeria. caadebajo@yahoo.com
authors.forename: Adeleke Clement
authors.initials: AC
authors.lastname: Adebajo
authors.forename: Marcus Durojaye
authors.initials: MD
authors.lastname: Ayoola
authors.forename: Samuel Akintunde
authors.initials: SA
authors.lastname: Odediran
authors.forename: Adetunji Joseph
authors.initials: AJ
authors.lastname: Aladesanmi
authors.forename: Thomas Jürgen
authors.initials: TJ
authors.lastname: Schmidt
authors.forename: Eugene Joseph
authors.initials: EJ
authors.lastname: Verspohl
mesh_terms: D000818:Animals; D029062:Apocynaceae / Q000737:chemistry*; D001786:Blood Glucose / Q000378:metabolism; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004359:Drug Therapy, Combination; D005260:Female; D005947:Glucose; D005905:Glyburide / Q000494:pharmacology; D006943:Hyperglycemia / Q000097:blood / Q000139:chemically induced / Q000188:drug therapy; D007004:Hypoglycemic Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007340:Insulinoma / Q000378:metabolism / Q000473:pathology; D008297:Male; D000432:Methanol / Q000737:chemistry; D009828:Oleanolic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D008517:Phytotherapy / Q000379:methods; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D018517:Plant Roots / Q000737:chemistry*; D018547:Plant Stems / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D016896:Treatment Outcome
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D010936:Plant Extracts; D009828:Oleanolic Acid; D005947:Glucose; C036380:beta-amyrin; D005905:Glyburide; D000432:Methanol