Meyna spinosa Roxb. ex Link (family: Rubiaceae) is an important folk medicinal plant used by the ethnic people of North-East India. Fruits and barks of the plant are used to treat headache, while the fruits and leaves of the plant are beneficial in diabetes, jaundice and other gastrointestinal disorders. Tender leaves, ripe fruits and seeds are beneficial to cure skin infections, pimples, indigestion and dyspepsia 1-3 . Recently, oleanolic acid were isolated from the fruits of M. spinosa which possess antimicrobial activity against B. subtilis, K. pneuminiae, E. coli, S. aureus and C. albicans 4 . In our recent investigation we reported leaves extracts of M. spinosa especially methanol extract possess significant free radical scavenging activity 2 . The present study was undertaken to isolate few chemical constituent of the plant with antioxidant activity. Leaves of Meyna spinosa Roxb. were collected from Tripura, India and identified by Dr. B.K. Datta, Department of Botany, Tripura University, Tripura, India (TU/BOT/HEB/ SS23072011a). Dried leaves of M. spinosa were pulverized and extracted with methanol using Soxhlet apparatus (yield 15.20 % w/w). Methanolic extract of M. spinosa leaves was further fractionated using petroleum ether, ethyl acetate and methanol in the order of increasing polarity. Preliminary study have showed that methanolic fraction of M. spinosa (MFMS) possess better antioxidant activity, therefore methanolic fraction of M. spinosa was further subfractionated to isolate pure compound using column chromatography (silica gel as NOTE Antioxidant Activity of Flavonoid Isolated from Meyna spinosa Leaves BIPLAB DE 1 , SAIKAT SEN 2,* , N. DEVANNA 3 , RAJA CHAKRABORTY 2 and RATNA CHOUDHURY 4 1 Regional Institute of Pharmaceutical Science and Technology, Agartala-799 005, India 2 Department of Pharmacy, Assam Down Town University, Guwahati-781 026, India 3 JNTU Anantapur-OTRI, Anantapur-515 002, India 4 Henry Derozio Academy, Agartala-799 006, India *Corresponding author: E-mail: saikat.pharm@rediffmail.com Received: 14 January 2014; Accepted: 16 April 2014; Published online: 26 December 2014; AJC-16579 A flavonoid was isolated first time from the leaves of Meyna spinosa (Rubiaceae). Antioxidant study revealed that the isolated flavonoid possess strong antioxidant activity. The isolated compound at 20 μg/mL concentration possesses 42.92 % DPPH • and 40.92 % NO • scavenging effect, respectively. Thus the isolated flavonoid could be a future for drug molecule in the treatment of various oxidative stress related diseases. Keywords: Meyna spinosa, Leaves, Flavonoid, Antioxidant. stationary phase and chloroform as mobile phase). There were 11 bands distinctly visualized for methanolic fraction of M. spinosa which were collected serially. Isolated components of M. spinosa were named as recorded as MS-1 to MS-11. Antioxidant activities of sub-fractions (MS-1 to MS-11) were evaluated using two methods. DPPH • scavenging activity of subfractions (10 and 20 μg/mL) was measured in terms of hydrogen-donating or radical scavenging ability, using stable DPPH • 5 . Nitric oxide radical (NO • ) scavenging activity of subfractions (10 and 20 μg/mL) was also determined using Griess reagent as described by Yen et al. 6 . Based on antioxidant activity 4 sub fractions of M. spinosa were selected for further analysis. MS-9 produced highest DPPH • scavenging activity followed by MS-7, MS-4, MS-10. While, MS-7 showed highest NO • scavenging effect followed by MS-9, MS-10 and MS-4 (Table-1). In our previous investi- gation we have reported that methanolic extract of M. spinosa leaves possess significant antioxidant activity and contain significant amount of total phenolic (90.08 mg GAE/g of dry material) and total flavonoid compound (58.50 mg QE/g of dry material) 3 . In this study, subfractions showed potent scavenging effect, which implies that fractions contain some potent antioxidant components. DPPH scavenging effect by antioxidant compound is based on the principle that antioxidants molecule reduces the stable DPPH • to a yellow coloured diphenyl-picrylhydrazine 7 . MS-4, MS-7, MS-9, MS-10 have exhibited strong activity, ASIAN JOURNAL OF CHEMISTRY ASIAN JOURNAL OF CHEMISTRY Asian Journal of Chemistry; Vol. 27, No. 1 (2015), 389-390 http://dx.doi.org/10.14233/ajchem.2015.17030