title: In vitro studies of Gynura divaricata (L.) DC extracts as inhibitors of key enzymes relevant for type 2 diabetes and hypertension.
abstract: OBJECTIVE
  To evaluate traditionally used herb, Gynura divaricata (L.) DC (Bai Bei San Qi) as in vitro inhibitors of key enzymes involved in the pathogenesis of hyperglycemia and hypertension. We also determined the distribution of enzyme inhibitory activities in different aqueous and non-aqueous extracts.
  
  
  METHODS
  The water extract (extract 1) from the aerial parts of Gynura divaricata (L.) was prepared first and then partitioned sequentially with n-butanol, ethyl acetate, and macroporous adsorptive resin (HPD-40) to yield extracts 2-4; the remaining water phase was named extract 5. Angiotensin-1 converting enzyme (ACE), α-amylase α-glycosidase inhibitory activities of the extracts were determined in vitro and chemical composition including total sugar, protein, flavonoid and total alkaloids in the extract were also evaluated.
  
  
  RESULTS
  The water extract of this herb significantly inhibited (p<0.05) ACE activity (IC(50)=0.37 mg/ml) and showed a moderate potential hypoglycemic effect via in vitro α-amylase (IC(50)=1.36 mg/ml) and α-glycosidase (IC(50)=2.17 mg/ml) inhibition in dose-dependent manner. Further partitioning of the water extract (extracts 2-4) resulted in higher α-amylase inhibitory activities in extract 2 and 3. For α-glycosidase inhibition, extract 3 gave the highest inhibition. ACE inhibitory activities of the extracts were not improved by partitioning. Sugar, protein, flavonoid and alkaloid were found in water extract but only a small portion was partitioned in the n-butanol extract. However, a large portion of the flavonoids and alkaloids were found in ethyl acetate extract.
  
  
  CONCLUSIONS
  The results confirmed potential empirical use of Gynura divaricata (L.) DC for the management of hyperglycemia as well as hypertension. The active compounds for inhibition of α-amylase and α-glycosidase inhibition were flavonoids and alkaloids while ACE inhibition probably resulted from synergic effects of all the herb compounds.
authors.affiliation: Chemistry Institute of Pharmaceutical Resources, College of Pharmaceutical Sciences, Southwest University, Chongqing 400716, People's Republic of China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Wu
authors.forename: Xueting
authors.initials: X
authors.lastname: Zhou
authors.forename: Yafei
authors.initials: Y
authors.lastname: Deng
authors.forename: Qing
authors.initials: Q
authors.lastname: Jing
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Lujaing
authors.initials: L
authors.lastname: Yuan
mesh_terms: D000470:Alkaloids / Q000494:pharmacology / Q000627:therapeutic use; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D019659:Asteraceae / Q000737:chemistry*; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D005419:Flavonoids / Q000494:pharmacology / Q000627:therapeutic use; D065089:Glycoside Hydrolase Inhibitors; D006973:Hypertension / Q000188:drug therapy / Q000201:enzymology*; D007004:Hypoglycemic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D008517:Phytotherapy; D035261:Plant Components, Aerial; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D000516:alpha-Amylases / Q000037:antagonists & inhibitors
chemical_list: D000470:Alkaloids; D000806:Angiotensin-Converting Enzyme Inhibitors; D004791:Enzyme Inhibitors; D005419:Flavonoids; D065089:Glycoside Hydrolase Inhibitors; D007004:Hypoglycemic Agents; D010936:Plant Extracts; D000516:alpha-Amylases