C: Food Chemistry JFS C: Food Chemistry Antioxidant Activities of Polyphenolic Compounds Isolated from Antidesma thwaitesianum M¨ ull. Arg. Seeds and Marcs D. PUANGPRONPITAG,P.AREEJITRANUSORN,P.BOONSIRI, M. SUTTAJIT, AND P. YONGVANIT ABSTRACT: Antidesma thwaitesianum M¨ ull. Arg. or mao is widely used as commercial products of juice and wine in Thailand. As a result, waste products from the mao plant, such as mao seeds (MS) and mao marcs (MM), are plentiful. We aimed to purify and analyze polyphenolic content in both MS and MM and to investigate the radical scavenging activities of these polyphenolics against 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2 ′ -Azinobis (3- ethylbenzothiazoline 6-sulphonate) (ABTS) radicals and thiobarbituric acid reactive products (TBARP). The results showed MS and MM to be an abundant source of polyphenols (97.32 to 130 mg gallic acid equivalents [GAE]/g) and proanthocyanidins. The radical scavenging activities of MS/MM against DPPH and ABTS radicals (IC 50 of 0.85 to 1.21 μg/mL) were significantly higher (P < 0.05) than that of standard trolox (IC 50 of 5.05 μg/mL). Activity of MS/MM extracts were 3.74 and 3.80 μg/mL trolox eq/g f.w. for the DPPH and ABTS assays, respectively. The oxidation of erythrocyte membranes using 2-thiobarbituric acid demonstrated that the protective effect of MS/MM on lipid per- oxidation is as strong as grape seed proanthocyanidin extract. These findings suggest that polyphenolic compounds and proanthocyanidins isolated from these mao extracts had much higher antioxidant activities than those of stan- dard trolox and exhibited similar antioxidant potential to grape seed proanthocyanidin extract. These findings may also increase value of mao waste products and allow development of commercial health products. Keywords: Antidesma thwaitesianum M¨ ull. Arg., antioxidant activities, lipid peroxidation, polyphenolic com- pounds, proanthocyanidins Introduction N owadays, there is growing interest in the use of polyphe- nolic antioxidant-rich plant extracts as dietary supplements (Alonso and others 2002; Rababah and others 2004) and there has been an upsurge in the exploitation of waste materials generated by the juice and wine industry. Waste products from juice and wine production are commonly characterized by the presence of natural antioxidants much safer than synthetic antioxidants (Bagchi and others 2000), and these waste products have been widely used in the food industry. Mao, or called Mamao or Makmao (Figure 1) is classified in the family Stilaginaceae, genus Antidesma. Thai Antidesma composes of 18 species (Hoffmann 1999); however, A. thwaitesianum M¨ ull. Arg. (mao luang) is favorable to be consumed and sold in the local market in Thailand because of its good color and taste. Mao plant is a medium-sized evergreen tree or shrub plant about 5 to 10 m height with a single, solid trunk. Its branches develop into round- shaped bushes. It sprouts single leaves that whorl into the shape of a spathe with parallel or oval-shaped sides. Leaf edge and base are sharp; both surfaces are smooth and bright green in color. Flowers are dioeciously, yellowish-white and small. The edible part is fruit which is small and is concentrated around the base of the flower MS 20080406 Submitted 5/30/2008, Accepted 8/19/2008. Authors Puang- pronpitag, Areejitranusorn, Boonsiri, and Yongvanit are with Dept. of Bio- chemistry, Faculty of Medicine, Khon Kaen Univ., Khon Kaen 40002, Thai- land. Author Puangpronpitag is also with Dept. of Chemistry, Faculty of Science, Mahasarakham Univ., Mahasarakham 44150, Thailand. Author Suttajit is with School of Science and Technology, Naresuan Univ. (Phayao Campus), Phayao 56000, Thailand. Direct inquiries to author Yongvanit (E-mail: puangrat@kku.ac.th). cluster; it is a light-white color but when ripe display a purplish- red or dark-purple color depending on level of ripeness (Hoffmann 1999). Mao grows well over a variety of soil types and is naturalized in Africa, Australia, tropical Asia, and islands in the Pacific Oceans. Recently, products such as mao juice and mao wine have be- come more popular in Thailand. This industry generates a number of wastes and by-products, most notably mao seeds (MS) and mao marcs (MM). A recent study shows that MS/MM not only induces antioxidant enzymes but also possesses cytoprotective effects in H 2 O 2 -treated human breast epithelial cells (Puangpronpitag and others 2008). Based on the previously mentioned fact, the aim of this study was to characterize the antioxidant properties of polyphenolic compounds, particularly proanthocyanidins (PA), in MS/MM. We purified polyphenolic compounds in MS/MM and analyzed the to- tal polyphenolic and PA content. The antioxidant activities of the crude and purified extract of MS/MM were investigated in vitro us- ing chemical and biological systems. We used grape seed proantho- cyanidin extract (Masquelier’s OPC TM ) as a reference compound to verify the antioxidant properties of MS and MM extracts. Materials and Methods Chemicals and reagents Grape seed proanthocyanidin extract (Masquelier’s OPC TM ) was purchased from Vita Intl. Health Food Co. Ltd., Thailand. Sephadex LH-20 (580 × 25 mm) was prod- uct of Pharmacia Biotech, Sweden. Gallic acid mono- hydrate (3,4,5-trihydroxybenzoic acid), Folin–Ciocalteau’s reagent, vanillin (4-hydroxy-3-methoxybenzaldehyde), catechin, C648 JOURNAL OF FOOD SCIENCE—Vol. 73, Nr. 9, 2008 C  2008 Institute of Food Technologists R  doi: 10.1111/j.1750-3841.2008.00951.x Further reproduction without permission is prohibited