Notes Bull. Korean Chem. Soc. 2013, Vol. 34, No. 7 2207 http://dx.doi.org/10.5012/bkcs.2013.34.7.2207 Sesquiterpenes from the Rhizomes of Cyperus rotundus and Their Potential to Inhibit LPS-induced Nitric Oxide Production Su Jung Kim, a Byeol Ryu, a Ha-Yeong Kim, Yeong-In Yang, Jungyeob Ham, † Jung-Hye Choi, and Dae Sik Jang * College of Pharmacy, Kyung Hee University, Seoul 130-701, Korea. * E-mail: dsjang@khu.ac.kr † Natural Medicine Center, Korea Institute of Science and Technology, Gangneung 210-340, Korea Received April 22, 2013, Accepted April 30, 2013 Key Words : Cyperus rotundus, Cyperaceae, Sesquiterpene, Nitric oxide, Inflammation The rhizomes of Cyperus rotundus L. (Cyperaceae) have been used in traditional Chinese medicine as an estrogenic and anti-inflammatory agent for the treatment of women's diseases and also used for treatment of stomach ache, bowel disorders, and menstrual disorders. 1 The extract of the rhizomes of C. rotundus has been showed a broad range of biological activities, such as anti-diabetic activity, 2 acetyl- cholinesterase inhibitory activity, 3 and inhibitory activities on nitric oxide and superoxide production. 4 Previous phyto- chemical investigations on C. rotundus have resulted in the isolation of a series of sesquiterpenes possessing diverse skeletons 5-7 as well as sesquiterpene alkaloids, triterpenes, sterols, and flavonoids. 7-9 Recently, new patchoulane-type sesquiterpenes were isolated from the rhizomes of C. rotundus by our group. 10 We also investigated the inhibitory effect of the n-hexane fraction of the 80% EtOH extract on LPS-induced nitric oxide (NO), a pro-inflammatory mediator, in RAW 264.7 cells. 11 In the present study, further investi- gation of the n-hexane-soluble fraction from the rhizomes of C. rotundus led to the isolation and characterization of a new natural (1) and a new (2) patchoulane-type sesquiterpenes, along with seven known eudesman-type sesquiterpenes (3- 9). The structures of 1 and 2 were determined by spectro- scopic data interpretation, particularly by extensive 1D and 2D NMR studies. To our knowledge, this is the first report on the 13 C NMR assignment of 1. The structures of other known compounds were identified to be α-rotunol (3), 5 β- rotunol (4), 5 (-)-eudesma-3,11-diene-5-ol (5), 12 ligucyper- onol (6), 13 14-hydroxy-α-cyperone (7), 14 britanlin E (8), 15 and 1β,4β-dihydroxyeudesma-11-ene (9) 16 by physical (mp, [α] D ) and spectroscopic data ( 1 H NMR, 13 C NMR, 2D NMR, and MS) measurement and by comparison with published values. Compound 1 was obtained as a colorless solid. Its HR- DART-MS gave a pseudo-molecular ion peak at m/z = 319.1910 [MH–H 2 O] + (calcd for C 19 H 27 O 4 : 319.1909), indicated a molecular formula of C 19 H 28 O 5 . The 1 H-NMR spectrum of 1 (Table 1) showed the presence of three oxy- methine protons [δ 5.57 (1H, d, J = 6.0 Hz), δ 4.96 (1H, br t, J = 7.0 Hz), and δ 4.66 (1H, td, J = 10.5 and 7.0 Hz)] and two acetoxyl methyl groups [δ 2.17 (3H, s) and δ 2.03 (3H, s)]. The 13 C-NMR and DEPT spectra of 1 (Table 2) allowed the identification of 19 carbon atoms: six methyl groups, two methylene groups, five methine groups, and six quaternary carbon atoms. The chemical shifts of the latter indicated two ester carbonyl (δ 171.2 and 170.9), two aliphatic (δ 61.6 and 41.5), and two sp 2 carbons (δ 140.9 and 139.1). The presence of two acetoxyl groups in 1 was supported by HR-DART- MS spectrum of 1 which showed two fragment ion peaks at m/z 277.1794 [MH–Ac] + and 217.1623 [MH–2Ac] + . Further examination of the 1 H-NMR spectrum of 1 revealed some signals common to patchoulane-type sesquiterpenes, namely the two geminal methyl groups H-12 and H-13 (δ 0.88 and 1.07, respectively; each 3H, s), the methyl group H-15 at δ 0.81, appearing as a doublet (3H, J = 6.5 Hz) and coupling with the methine proton H-10 (δ 2.12, 1H, dq, J = 10.5 and 6.5 Hz), and the vinyl methyl group H-14 at δ 1.74, appear- ing as a singlet. The 1 H- and 13 C-NMR spectra of 1 exhibited strong similarities with those of sugetriol triacetate 10,17 (Tables 1 and 2), which was isolated from the same plant in the previous study. 10 The inspection of the 1 H- and 13 C-NMR spectra of 1 readily indicated the absent of an acetyl group (δ H 2.05, δ C 21.1 and δ C 170.7) of sugetriol triacetate. It was also observed that both the oxymethine proton at δ H 5.90 and the oxymethine carbon at δ C 84.8 in the 1 H- and 13 C-NMR spectra of sugetriol triacetate were shifted to upfield in the those of 1 (δ H 4.96 and δ C 83.2) due to deacetylation. The COSY and HMBC correlations (Figure 2) confirmed the a These authors contributed equally to this work. Figure 1. Structures of 1-9 isolated from the rhizomes of C. rotundus.