title: Turmerin, the antioxidant protein from turmeric (Curcuma longa) exhibits antihyperglycaemic effects.
abstract: A wide range of proteinaceous inhibitors are present in plants to protect themselves from hydrolytic enzymes. In this study, turmerin, a water-soluble peptide in turmeric rhizomes, was evaluated for its inhibitory potential against glucosidase and its antioxidant (AO) capacity. Turmerin inhibited α-amylase and α-glucosidase activities with IC₅₀ values 31 and 192 µg mL⁻¹, respectively. Under the experimental conditions, those values for a standard glucosidase inhibitor, acarbose, were 81 and 296 µg mL⁻¹, respectively. The AO capacity of turmerin was evaluated using in vitro assay systems. Turmerin showed good DPPH (IC₅₀ = 29 µg mL⁻¹) and superoxide (IC₅₀ = 48 µg mL⁻¹) and moderate ABTS (IC₅₀ = 83 µg mL⁻¹) radical scavenging and Fe(II) chelation (IC₅₀ = 101 µg mL⁻¹) capacities. The inhibitory potential showed by turmerin against enzymes linked to type 2 diabetes, as well as its moderate AO capacity, could rationalise the traditional usage of turmeric rhizome preparations against diabetes.
authors.affiliation: Agroprocessing and Natural Products Division, National Institute for Interdisciplinary Science and Technology-CSIR, Thiruvananthapuram, Kerala 695019, India.
authors.forename: P C
authors.initials: PC
authors.lastname: Lekshmi
authors.forename: Ranjith
authors.initials: R
authors.lastname: Arimboor
authors.forename: K G
authors.initials: KG
authors.lastname: Raghu
authors.forename: A Nirmala
authors.initials: AN
authors.lastname: Menon
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D052160:Benzothiazoles / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry; D030024:Curcuma / Q000737:chemistry*; D007004:Hypoglycemic Agents / Q000737:chemistry*; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides / Q000737:chemistry*; D010851:Picrates / Q000737:chemistry; D013451:Sulfonic Acids / Q000737:chemistry; D013481:Superoxides / Q000737:chemistry; D000516:alpha-Amylases / Q000378:metabolism; D000520:alpha-Glucosidases / Q000378:metabolism
chemical_list: D000975:Antioxidants; D052160:Benzothiazoles; D001713:Biphenyl Compounds; D007004:Hypoglycemic Agents; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D010851:Picrates; D013451:Sulfonic Acids; C072268:turmerin; D013481:Superoxides; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; C004931:1,1-diphenyl-2-picrylhydrazyl; D000516:alpha-Amylases; D000520:alpha-Glucosidases