In vitro studies on a-glucosidase inhibition, antioxidant and free radical scavenging activities of Hedyotis biflora L. I.V.S. Nimal Christhudas a , P. Praveen Kumar a , Christudas Sunil b , S. Vajravijayan a , R. Lakshmi Sundaram c , S. Jenifer Siril a , P. Agastian a,⇑ a Department of Plant Biology and Biotechnology, Loyola College, Chennai 600 034, India b Division of Ethnopharmacology, Entomology Research Institute, Loyola College, Chennai 600 034, India c Central Research Facility, Sri Ramachandra University, Porur, Chennai 600 116, India article info Article history: Received 25 May 2012 Received in revised form 3 November 2012 Accepted 9 November 2012 Available online 20 November 2012 Keywords: Hedyotis biflora a-Glucosidase DPPH b-Carotene Metal chelating abstract Aim of this study was to evaluate the in vitro a-glucosidase inhibition and antioxidant activity of hexane, ethyl acetate and methanol extracts of Hedyotis biflora L. (Rubiaceae). In in vitro a-glucosidase inhibition and antioxidant activity, the methanol extract showed potent effect compared to hexane and ethyl ace- tate extracts. The methanol extract of H. biflora (HBMe) showed 50% a-glucosidase inhibition at the con- centration of 480.20 ± 2.37 lg/ml. The total phenolic content of HBMe was 206.81 ± 1.11 mg of catechol equivalents/g extract. HBMe showed great scavenging activity on 2,2-diphenyl-picrylhydrazyl (DPPH) (IC 50 520.21 ± 1.02 lg/ml), hydroxyl (IC 50 510.21 ± 1.51 lg/ml), nitric oxide (IC 50 690.20 ± 2.13 lg/ml) and superoxide (IC 50 510.31 ± 1.45 lg/ml) radicals, as well as high reducing power. HBMe also showed a strong suppressive effect on lipid peroxidation. Using the b-carotene method, the scavenging values of HBMe was significantly lower than BHT, and metal chelating ability of HBMe also showed a strong inhibition effect when compared to the reference standard. The active compound ursolic acid from HBMe was identified using various spectroscopical studies. The results obtained in this study clearly indicate that HBMe has a significant potential to use as a natural a-glucosidase inhibition, antioxidant agent. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Diabetes mellitus (DM) is a metabolic disorder characterised by hyperglycemia resulting from defects in insulin secretion, insulin action or both. Along with hyperglycemia and abnormalities in ser- um lipids, diabetes is associated with micro- and macro-vascular complications, which are the major causes of morbidity and death in diabetic subjects (Kumar & Murugesan, 2008). There are many articles related to antidiabetic compounds from plants (Matsui, Ueda, Oki, Sugita, & Terahara, 2001). However, normalising blood glucose level is a formidable challenge in clinical practice. The pharmacological agents with greatest effect on postprandial hyper- glycemia include insulin, lispro, amylin analogues, and a-glucosi- dase (acarbose and voglibose) inhibitors (Goda, Yamada, Hosoya, & Moriuchi, 1981). It has been well acknowledged that plant- derived extracts and phytochemicals are potential alternatives to synthetic inhibitors against a-glucosidase. Oxidative stress is an important contributor to the pathophysi- ology of a variety of pathological conditions including diabetes, cardiovascular dysfunctions, atherosclerosis, inflammation, carci- nogenesis, drug toxicity, reperfusion injury and neurodegenerative diseases (Aruoma, 1998). Antioxidants help organisms to deal with oxidative stress, caused by free radical damage. Free radicals are chemical species, which contains one or more unpaired electrons due to which they are highly unstable and cause damage to other molecules by extracting electrons from them in order to attain sta- bility. Reactive oxygen species (ROS) include free radicals such as superoxide (O 2 ), hydroxyl radical (OH), peroxyl radical (RO 2 ) as well as nonradical species such as hydrogen peroxide (H 2 O 2 ) (Cerutti, 1991). These free radicals are formed as part of the normal metabolic processes (Halliwell & Gutteridge, 1989). Our body has multiple mechanisms especially enzymatic and nonenzymatic antioxidant systems to protect the cellular molecules against reac- tive oxygen species (ROS) induced damage by antioxidant en- zymes, such as superoxide dismutase, catalase, glutathione dependent enzymes such as glutathione peroxidase, and glutathi- one reductase, as well as compounds such as ascorbic acid, a- tocopherol and glutathione (Datta, Sinha, & Chattopadhyay, 2000). However these induced damage disrupted by various path- ological phenomena; antioxidant supplements are essential to 0308-8146/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodchem.2012.11.051 ⇑ Corresponding author. Address: Research Department of Plant Biology and Biotechnology, School of Life Science, Loyola College, Chennai 600 034, India. Tel.: +91 9444433117; fax: +91 44 28175566. E-mail addresses: agastian@loyolacollege.edu, past_hod@rediffmail.com (P. Agastian). Food Chemistry 138 (2013) 1689–1695 Contents lists available at SciVerse ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem