title: Inhibition of key enzymes linked to type 2 diabetes and sodium nitroprusside-induced lipid peroxidation in rat pancreas by water extractable phytochemicals from some tropical spices.
abstract: BACKGROUND
  Spices have been used as food adjuncts and in folklore for ages. Inhibition of key enzymes (α-amylase and α-glucosidase) involved in the digestion of starch and protection against free radicals and lipid peroxidation in pancreas could be part of the therapeutic approach towards the management of hyperglycemia and dietary phenolics have shown promising potentials.
  
  
  OBJECTIVE
  This study investigated and compared the inhibitory properties of aqueous extracts of some tropical spices: Xylopia aethiopica [Dun.] A. Rich (Annonaceae), Monodora myristica (Gaertn.) Dunal (Annonaceae), Syzygium aromaticum [L.] Merr. et Perry (Myrtaceae), Piper guineense Schumach. et Thonn (Piperaceae), Aframomum danielli K. Schum (Zingiberaceae) and Aframomum melegueta (Rosc.) K. Schum (Zingiberaceae) against α-amylase, α-glucosidase, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and sodium nitroprusside (SNP)-induced lipid peroxidation in rat pancreas--in vitro using different spectrophotometric method.
  
  
  METHODS
  Aqueous extract of the spices was prepared and the ability of the spice extracts to inhibit α-amylase, α-glucosidase, DPPH radicals and SNP-induced lipid peroxidation in rat pancreas--in vitro was investigated using various spectrophotometric methods.
  
  
  RESULTS
  All the spice extracts inhibited α-amylase (IC(50) = 2.81-4.83 mg/mL), α-glucosidase (IC(50) = 2.02-3.52 mg/mL), DPPH radicals (EC(50) = 15.47-17.38 mg/mL) and SNP-induced lipid peroxidation (14.17-94.38%), with the highest α-amylase & α-glucosidase inhibitory actions and DPPH radical scavenging ability exhibited by X. aethiopica, A. danielli and S. aromaticum, respectively. Also, the spices possess high total phenol (0.88-1.3 mg/mL) and flavonoid (0.24-0.52 mg/mL) contents with A. melegueta having the highest total phenolic and flavonoid contents.
  
  
  CONCLUSIONS
  The inhibitory effects of the spice extracts on α-amylase, α-glucosidase, DPPH radicals and SNP-induced lipid peroxidation in pancreas (in vitro) could be attributed to the presence of biologically active phytochemicals such as phenolics and some non-phenolic constituents of the spices. Furthermore, these spices may exert their anti-diabetic properties through the mechanism of enzyme inhibition, free radicals scavenging ability and prevention of lipid peroxidation.
authors.affiliation: Department of Biochemistry, School of Sciences, Federal University of Technology, Akure, Ondo State, Nigeria.
authors.forename: Stephen Adeniyi
authors.initials: SA
authors.lastname: Adefegha
authors.forename: Ganiyu
authors.initials: G
authors.lastname: Oboh
mesh_terms: D000818:Animals; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use; D065089:Glycoside Hydrolase Inhibitors; D015227:Lipid Peroxidation / Q000187:drug effects* / Q000502:physiology; D009599:Nitroprusside / Q000633:toxicity; D010179:Pancreas / Q000187:drug effects / Q000201:enzymology; D035261:Plant Components, Aerial; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D017365:Spices; D000516:alpha-Amylases / Q000037:antagonists & inhibitors*
chemical_list: D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; D010936:Plant Extracts; D009599:Nitroprusside; D000516:alpha-Amylases