title: Synergisms in Alpha-glucosidase Inhibition and Antioxidant Activity ofCamellia sinensisL. Kuntze andEugenia unifloraL. Ethanolic Extracts.
abstract: BACKGROUND
  Camellia sinensis, the most consumed and popular beverages worldwide, andEugenia uniflora, a Brazilian native species, have been already confirmed to have beneficial effects in the treatment of diabetes mellitus. However, their potential acting together against an enzyme linked to this pathology has never been exploited.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the inhibitory properties of individual and combined ethanolic extracts of the leaves ofC. sinensisandE. unifloraover alpha-glucosidase, a key digestive enzyme used on the Type 2 diabetes mellitus (T2DM) control. In addition, their inhibitory activity against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) and peroxyl radicals was also assayed.
  
  
  METHODS
  Enzyme inhibition and antioxidant potential were assessed based onin vitroassays. Total phenolic compounds, carotenoids, and chlorophylls A and B were achieved using spectrophotometric methods.
  
  
  RESULTS
  E. uniflorawas almost 40 times more active on alpha-glucosidase thanC. sinensisand combined extracts showed a significant synergistic effect with an obtained IC50value almost 5 times lower than the theoretical value.C. sinensisextract was twice more active thanE. unifloraconcerning DPPH•, in contrast,E. uniflorawas almost 10 times more effective thanC. sinensison inhibition of peroxyl radicals with a significant synergistic effect for combined extracts. The extracts activities may be related with their phytochemicals, mainly phenolic compounds, and chlorophylls.
  
  
  CONCLUSIONS
  CombinedC. sinensisandE. unifloraethanolic extracts showed synergistic effect against alpha-glucosidase and lipid peroxidation. These herbal combinations can be used to control postprandial hyperglycemia and can also provide antioxidant defenses to patients with T2DM.
  
  
  CONCLUSIONS
  Alfa-glucosidase and antioxidant Interaction betweenCamellia sinensisL. Kuntze andEugenia unifloraL. ethanolic extracts was investigated.Extracts showed synergistic effect over alpha-glucosidase and peroxyl radicals.Total phenolic, carotenoids and chlorophylls A and B can be responsible by the observed activities.Extracts could be used as alternative to control postprandial hyperglycemia.Extracts could increase antioxidant defenses to patients with T2DM.Abbreviations Used: T2DM: Type 2 diabetes mellitus; DPPH: 2,2-diphenyl-1-picrylhydrazyl radical; PNPG: 4-Nitrophenyl β-D-glucuronide; LOO: Lipid peroxidation; SEM: Standard error of the mean; CAE: Chlorogenic acid equivalent.
authors.affiliation: Embrapa Clima Temperado, Rodovia BR-392, Km 78, 9° Distrito, Monte Bonito Caixa Postal 403, CEP: 96010-971 - Pelotas, RS, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: Vinholes
authors.affiliation: Embrapa Clima Temperado, Rodovia BR-392, Km 78, 9° Distrito, Monte Bonito Caixa Postal 403, CEP: 96010-971 - Pelotas, RS, Brazil.
authors.forename: Márcia
authors.initials: M
authors.lastname: Vizzotto
keywords: Additive effect; antihyperglycemic effect; antiradical activity; diabetes; phytochemicals; synergistic effect