Accepted Article This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/cbdv.201700044 This article is protected by copyright. All rights reserved. Article Type: Full Paper Superbanone, A New 2-Aryl-3-benzofuranone and Other Bioactive Constituents from the Tube Roots of Butea superba Jutatip Boonsombat, * ,a Vilailak Prachyawarakorn, a Acharavadee Pansanit, C Chulabhorn Mahidol, a, b Somsak Ruchirawat, a,b and Sanit Thongnest * ,a a Chulabhorn Research Institute, Kamphaeng Phet 6 Road, Bangkok 10210, Thailand, e-mail: jutatip@cri.or.th, sanit@cri.or.th b Chulabhorn Graduate Institute and Center for Environmental Health and Toxicology, Kamphaeng Phet 6 Road, Bangkok 10210, Thailand c School of Science, Mae Fah Luang University, Tasud, Muang, Chiang Rai 57100, Thailand Phytochemical investigation from the tube roots of Butea superba, led to the isolation and identification of a new 2-aryl-3- benzofuranone named superbanone (1), one benzoin, 2-hydroxyl-1-(2-hydroxy-4-methoxyphenyl)-2-(4-methoxy- phenyl)ethanone (2), eight pterocarpans (3-10), and eleven isoflavonoids (11-21). Compound 2 was identified for the first time as a natural product. The structure of the isolated compounds was elucidated using spectroscopic methods, mainly 1D and 2D NMR. The isolated compounds and their derivatives were evaluated for α-glucosidase inhibitory and antimalarial activities. Compounds 3, 7, 8, and 11 showed promising α-glucosidase inhibitory activity (IC 50 = 13.71 ± 0.54, 23.54 ± 0.75, 28.83 ± 1.02, and 12.35 ± 0.36 μM, respectively). Compounds 3 and 11 were twofold less active than the standard drug acarbose (IC 50 = 6.54 ± 0.04 μM). None of the tested compounds was found to be active against Plasmodium falciparum strain 94. On the basis of biological activity results, structure-activity relationships are discussed. Keywords: Butea superba • Benzofuranone • Pterocarpan • α-Glucosidase Inhibitor • Antimalarial Activity Introduction Butea superba Roxb. (Fabaceae) is one of the two species in the genus Butea found in Thailand. It is locally known as Red Kwao Khruea and is abundantly distributed in the forest of northern and eastern parts, and Kanchanaburi province. In Thailand, Red Kwao Khruea is known to be related to other two plant species under the same generic name “Kwao Khruea” called White Kwao Khruea (Pueraria mirifica) and Black Kwao Khruea (Mucuna collettii Lace); since, they all have long been used in Thai traditional medicines for rejuvenation and aphrodisiac performance. [1] Recently, Red Kwao Khruea is becoming popular as traditional and alternative medicines, as well as dietary supplements for the promotion of male vigor. Previous phytochemical examination from B. superba indicated the presence of flavonoids, isoflavonoids, flavonoid glycosides, [2-4] isoflavonoid lignans, [5] and pterocarpans. [6] The chemical components of this plant show various important biological activities such as antibacterial activity, [3] PDE-inhibition activity for cAMP (albeit with weak activity), [2] Ngn2 promoter activity, [6] and cytotoxic activity. [7] Thus far, there has been no report on the α–glucosidase inhibitory activity from B. superba plant; even though many literatures have reported that pterocarpans constitute a basis for significant α-glucosidase inhibition. [8a,b] In this study, we present the investigation of the isolated compounds from the tube roots of B. superba, leading to the isolation and structure determination of a new 2-aryl-3-benzofuranone designated as superbanone (1) and one benzoin named