Rare hydroperoxyl guaianolide sesquiterpenes from Pulicaria undulata Mohamed-Elamir F. Hegazy a,c, *, Seikou Nakamura b , Wafaa A. Tawfik c , Nahla S. Abdel-Azim c , Ahmed Abdel-Lateff d,e , Hisashi Matsuda b , Paul W. Pare ´ f a Phytochemistry Department and Center of Excellence for Advanced Sciences, National Research Centre, 33 El Bohouth St. (Former El Tahrir St.), P.O. 12622, Dokki, Giza, Egypt b Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8412, Japan c Phytochemistry Deptartment, National Research Centre, 33 El Bohouth St. (Former El Tahrir St.), P.O. 12622, Dokki, Giza, Egypt d Department of Natural Products and Alternative Medicine, Faculty of Pharmacy, King Abdulaziz University, PO Box 80260, Jeddah 21589, Saudi Arabia e Pharmacognosy Department, Faculty of Pharmacy, Minia University, Minia 61519, Egypt f Chemistry & Biochemistry Department, Texas Tech University, Lubbock, TX 79409, USA 1. Introduction The genus Pulicaria consists of ca. 100 species with a distribution including Europe, North Africa and Asia; a predomi- nant genus concentration exists in the Mediterranean region (Williams et al., 2003; Liu et al., 2010a,b). The genus belongs to the tribe Inuleae and is a member of the extremely large Asteraceae family. Pulicaria undulata (L.) Kostel [syn. Pulicaria crispa (Forssk.) Benth. et Hook. f.; Francoeuria crispa (Forssk.) Cass.] is an annual herb or perennial sub-shrub that produces small bright yellow flowers; in Egypt, the plant is locally referred to as Dethdath. Plant extracts are commonly employed in traditional medicine to treat inflammation, as an insect repellent and as an herbal tea (Stavri et al., 2008). As part of a long-term project to chemically and biologically characterize metabolites from traditional herbal medicines, sesquiterpenes 1–4 were isolated and identified from a methylene chloride (CH 2 Cl 2 )/methanol (MeOH) (1:1) extract P. undulata. In addition, previously reported compounds 5–14 were chemically characterized (Fig. 1). 13 C NMR data are reported for metabolites 5–7 for the first time. As a series of sesquiterpenes containing a lactone ring in combination with a conjugated exomethylene group (a-methylene-g-lactone) were identified and such chemical functionality is directly associated with inhibition of inducible nitric oxide synthase (iNOS)-dependent nitric oxide (NO) synthesis (Matsuda et al., 2003), the biological activity of isolated metabolites was assayed for iNOS inhibition. Nitric oxide (NO) has been implicated in physiological as well as pathological processes such as vasodilation, microvascular injury and chronic inflamma- tion (Mollace et al., 2005). Inducible NOS is expressed in response to pro-inflammatory agents and inhibition of iNOS enzyme activity may have therapeutic effects with various types of inflammation. 2. Results and discussion As a part of a continuing search for biologically active metabolites from Egyptian medicinal plants belonging to the Asteraceae family (Hegazy et al., 2012, 2014; Elmasri et al., 2014), a solvent extract of aerial tissue was subjected to normal- and reverse-phase chroma- tography to yield fourteen metabolites (Fig. 1). Phytochemistry Letters 12 (2015) 177–181 A R T I C L E I N F O Article history: Received 14 December 2014 Received in revised form 30 March 2015 Accepted 31 March 2015 Available online 14 April 2015 Keywords: Pulicaria undulata Asteraceae Sesquiterpenoids Nitric oxide inhibition RAW264.7 cells A B S T R A C T Pulicaria species, such as Pulicaria undulata, are rich in sesquiterpene lactones. The methylene chloride/ methanol (1:1) extract of P. undulata resulted in the isolation of new sesquiterpenes (1–4), as well as previously reported metabolites (5–14). Structures were elucidated by spectroscopic analyses. Using a mouse peritoneal macrophage bioassay, lipopolysaccharide-induced nitric oxide inhibition was observed with the eudesman-type sesquiterpene 1b,4b-dihydroxy-5aH,7aH,8a-guaia-10(14),11(13)- dien-8b,12-olide (11) at an EC 50 of 7.2 mM. ß 2015 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. * Corresponding author at: Phytochemistry Department and Center of Excellence for Advanced Sciences, National Research Centre, 33 El Bohouth St. (Former El Tahrir St.), P.O. 12622, Dokki, Giza, Egypt. Tel.: +20 1022900036; fax: +20 233370931. E-mail address: elamir77@live.com (M.F. Hegazy). Contents lists available at ScienceDirect Phytochemistry Letters jo u rn al h om ep ag e: ww w.els evier.c o m/lo c ate/p hyt ol http://dx.doi.org/10.1016/j.phytol.2015.03.019 1874-3900/ß 2015 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.