Trinorditerpenes from the roots of Flueggea virosa Chih-Hua Chao a,b,⇑ , Ju-Chien Cheng c , Tsong-Long Hwang d , De-Yang Shen e , Tian-Shung Wu e,⇑ a School of Pharmacy, China Medical University, Taichung 404, Taiwan b Chinese Medicine Research and Development Center, China Medical University Hospital, Taichung 404, Taiwan c Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung 404, Taiwan d Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan e Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan article info Article history: Received 23 September 2013 Revised 11 December 2013 Accepted 13 December 2013 Available online 20 December 2013 Keywords: Flueggrene A Flueggrene B Flueggea virosa Anti-HCV abstract Two trinorditerpenes, flueggrenes A and B (1 and 2), have been isolated from the roots of Flueggea virosa. Their structures were established by extensive analyses of spectroscopic data. The isolates were evalu- ated for anti-HCV activity, as well as the inhibition of superoxide anion generation and elastase release in response to FMLP/cytochalasin B. Ó 2013 Elsevier Ltd. All rights reserved. The roots of Flueggea virosa Roxb. ex Willd. (Euphorbiaceae) have been traditionally used to treat rheumatism, pruritus, cepha- lic eczema, leucorrhoea, and bruising in China. 1 Securinine-type alkaloids, the main constituents in F. virosa, attracted considerable interest due to their wild spectrum of biological activities and no- vel skeleton. 2–5 However, the nonalkaloid part of this plant has been rarely studied. 6 During the course of our investigation on the bioactive chemical constituents from medicinal plants, two no- vel trinorditerpenes, flueggrenes A and B (1 and 2)(Fig. 1), have been isolated from the roots of F. virosa. Herein, we report the iso- lation, structural elucidation, and biological activity of these two compounds. The roots of F. virosa were collected in September 2011 from Pingtung County, Taiwan. A voucher specimen (specimen no. FV- Chao001) was deposited in Chinese Medicine Research and Devel- opment Center, China Medical University Hospital. The air-dried roots of F. virosa (13 kg) were minced and extracted exhaustively with MeOH (3  20 L). The organic extract was concentrated to an aqueous suspension and was further partitioned between CHCl 3 and H 2 O. The CHCl 3 extract was washed with 3% aqueous tartaric acid three times to remove alkaloids and subsequently obtained a nonalkaloid extract (93 g). This extract was fractionated by open column chromatography on silica gel using n-hexane–EtOAc and EtOAc–MeOH mixtures of increasing polarity to afford a main frac- tion (3.2 g). This fraction was fractioned by silica gel column chro- matography (n-hexane–EtOAc, 13:1 to 5:1), Toyopearl HW-40 (C) column chromatography (2  60 cm, MeOH), and RP-18 column chromatography (MeOH–H 2 O, gradient 75–79%) to yield com- pounds 1 (2.5 mg) and 2 (4.5 mg). The molecular formula of flueggrene A (1) was found to be C 17 H 18 O 2 , as determined from ()-HRESIMS 7 and 13 C NMR data (Table 1), appropriate for nine degrees of unsaturation. The IR spec- trum showed absorption bands of hydroxy (3383 cm 1 ), ketonic (1712 cm 1 ), and aromatic (1633, 1427 cm 1 ) groups. The UV absorptions at 272, 283, 294, 317, and 331 nm suggested the pres- ence of an extended aromatic conjugation. In the 1 H NMR spectrum of 1, one downfield singlet methyl (d H 2.43), two aromatic protons (d H 7.58 and 7.26), and two mutually coupled aromatic protons (d H 7.64 and 7.28) were observed (Table 1). The aforementioned data coupled with 10 aromatic carbons in the 13 C NMR spectrum 0960-894X/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.bmcl.2013.12.051 ⇑ Corresponding authors. Tel.: +886 4 22053366x5157; fax: +886 4 22078083 (C.-H.C.); tel.: +886 6 2747538; fax: +886 6 2740552 (T.-S.W.) E-mail addresses: chaochihhua@hotmail.com (C.-H. Chao), tswu@mail.ncku. edu.tw (T.-S. Wu). OH O 1 OMe HO 2 1 3 5 7 10 9 11 13 14 15 18 19 Figure 1. Structures of compounds 1 and 2. Bioorganic & Medicinal Chemistry Letters 24 (2014) 447–449 Contents lists available at ScienceDirect Bioorganic & Medicinal Chemistry Letters journal homepage: www.elsevier.com/locate/bmcl