Adebajo A.C., Ayoola M.D., Odediran S.A., Aladesanmi A.J., Schmidt T.J., Verspohl E.J.
Department of Pharmacognosy, Faculty of Pharmacy, Obafemi Awolowo University, Ile Ife, Nigeria; Institute of Pharmaceutical Biology and Phytochemistry, Westfälische Wilhelms-Universität, Munster, Germany; Department of Pharmacology, Institute of Pharmaceu
Adebajo, A.C., Department of Pharmacognosy, Faculty of Pharmacy, Obafemi Awolowo University, Ile Ife, Nigeria, Institute of Pharmaceutical Biology and Phytochemistry, Westfälische Wilhelms-Universität, Munster, Germany, Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität, Munster, Germany; Ayoola, M.D., Department of Pharmacognosy, Faculty of Pharmacy, Obafemi Awolowo University, Ile Ife, Nigeria; Odediran, S.A., Department of Pharmacognosy, Faculty of Pharmacy, Obafemi Awolowo University, Ile Ife, Nigeria; Aladesanmi, A.J., Department of Pharmacognosy, Faculty of Pharmacy, Obafemi Awolowo University, Ile Ife, Nigeria; Schmidt, T.J., Institute of Pharmaceutical Biology and Phytochemistry, Westfälische Wilhelms-Universität, Munster, Germany; Verspohl, E.J., Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität, Munster, Germany
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 (100mg/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 (100mg/kg) than A6, agreed with their in vivo antihyperglycemic activities and confirmed insulin release as a mechanism of action of the plant. Compared with 5.6mmol/L glucose (negative control), the extract and the A3, A6, and C1 (all at 100.0μg/mL) elicited significantly higher in vitro insulin release that was similar to that of glibenclamide (1.0μg/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 (100.0μg/mL) demonstrated the highest insulinotropic activity that was comparable (P>0.05) to that of glibenclamide (1.0μg/mL). Conclusions: The results confirm pancreatic activity as a mechanism underlying the antidiabetic action of G. latifolium and justify its ethnomedical use. © 2013 Wiley Publishing Asia Pty Ltd and Ruijin Hospital, Shanghai Jiaotong University School of Medicine.
alpha amyrin; antidiabetic agent; beta amyrin; cinnamic acid; glibenclamide; glucose; Gongronema latifolium extract; insulin; lupeol acetate; plant extract; triterpenoid; unclassified drug; animal cell; animal experiment; antidiabetic activity; Apocynaceae; article; column chromatography; comparative study; controlled study; diabetes mellitus; female; glucose blood level; Gongronema latifolium; in vitro study; in vivo study; insulin release; insulin response; liquid chromatography; male; nonhuman; oral glucose tolerance test; plant root; plant stem; priority journal; rat; antihyperglycemic; Gongronema latifolium; insulin release; α-amyrin cinnamate; β-amyrin cinnamate; Animals; Asclepiadaceae; Blood Glucose; Cell Line, Tumor; Chromatography, Liquid; Drug Evaluation, Preclinical; Drug Therapy, Combination; Female; Glucose; Glyburide; Hyperglycemia; Hypoglycemic Agents; Insulin; Insulinoma; Male; Methanol; Oleanolic Acid; Phytotherapy; Plant Extracts; Plant Roots; Plant Stems; Rats; Rats, Wistar; Treatment Outcome