This article was downloaded by: [FU Berlin] On: 02 July 2015, At: 07:13 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: 5 Howick Place, London, SW1P 1WG

Natural Product Research: Formerly Natural Product Letters Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gnpl20

A new steroid from the Red Sea soft coral Lobophytum lobophytum a

a

Mohamed-Elamir F. Hegazy , Tarik A. Mohamed , Abdelsamed I. b

c

d

Elshamy , Abuzeid A. Hassanien , Nahla S. Abdel-Azim , Mohamed e

c

e

A. Shreadah , Ibrahim I. Abdelgawad , Eman M. Elkady & Paul W. Paré

f

a

Phytochemistry Department and Center of Excellence for Advanced Sciences, National Research Centre, P.O. 12622, 33 El Bohouth st. (Former El Tahrir st.) Dokki, Giza, Egypt b

Click for updates

Natural Compounds Chemistry Department, National Research Centre, P.O. 12622, 33 El Bohouth st. (Former El Tahrir st.) Dokki, Giza, Egypt c

Department of Chemistry, Faculty of Science, Suez University, Egypt d

Phytochemistry Department, National Research Centre, P.O. 12622, 33 El Bohouth st. (Former El Tahrir st.) Dokki, Giza, Egypt e

National Institute of Oceanography & Fisheries, Alexandria, Egypt f

Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA Published online: 02 Jul 2015.

To cite this article: Mohamed-Elamir F. Hegazy, Tarik A. Mohamed, Abdelsamed I. Elshamy, Abuzeid A. Hassanien, Nahla S. Abdel-Azim, Mohamed A. Shreadah, Ibrahim I. Abdelgawad, Eman M. Elkady & Paul W. Paré (2015): A new steroid from the Red Sea soft coral Lobophytum lobophytum, Natural Product Research: Formerly Natural Product Letters, DOI: 10.1080/14786419.2015.1046871 To link to this article: http://dx.doi.org/10.1080/14786419.2015.1046871

PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions

and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content.

Downloaded by [FU Berlin] at 07:13 02 July 2015

This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions

Natural Product Research, 2015 http://dx.doi.org/10.1080/14786419.2015.1046871

SHORT COMMUNICATION A new steroid from the Red Sea soft coral Lobophytum lobophytum

Downloaded by [FU Berlin] at 07:13 02 July 2015

Mohamed-Elamir F. Hegazya*, Tarik A. Mohameda, Abdelsamed I. Elshamyb, Abuzeid A. Hassanienc, Nahla S. Abdel-Azimd, Mohamed A. Shreadahe, Ibrahim I. Abdelgawadc, Eman M. Elkadye and Paul W. Pare´f a Phytochemistry Department and Center of Excellence for Advanced Sciences, National Research Centre, P.O. 12622, 33 El Bohouth st. (Former El Tahrir st.) Dokki, Giza, Egypt; bNatural Compounds Chemistry Department, National Research Centre, P.O. 12622, 33 El Bohouth st. (Former El Tahrir st.) Dokki, Giza, Egypt; cDepartment of Chemistry, Faculty of Science, Suez University, Egypt; dPhytochemistry Department, National Research Centre, P.O. 12622, 33 El Bohouth st. (Former El Tahrir st.) Dokki, Giza, Egypt; eNational Institute of Oceanography & Fisheries, Alexandria, Egypt; fDepartment of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA

(Received 17 March 2015; final version received 22 April 2015)

Chemical investigation of the soft coral Lobophytum lobophytum collected from the Red Sea led to the isolation of a new compound gorgostan-5,25-dien-3b-ol (1), and two known compounds gorgosterol (2), and alismol (3). Structures were elucidated by employing extensive NMR and HR-ESI-MS experiments. Keywords: Red Sea; Lobophytum lobophytum; steriods; sesquiterpene

1. Introduction Soft coral isolated from diverse marine souces have proven to be a rich basis of biologically active secondary metabolites (Blunt et al. 2011). With the high concentration of marine diversity present in the Red Sea, this marine habitat represents one of the most promising areas of medicinal natural products (Hegazy et al. 2011). Soft corals belonging to the genus Lobophytum (class Coelenterata, subclass Octocorallia, and family Alcyonaceae) are a source of macrocycliccembrane-type diterpenes and their cyclised derivatives, germacrenediterpene, steroids (Cheng et al. 2008; Lu et al. 2010; Hegazy et al. 2011; Minh et al. 2011; Govindam et al. 2012) and zoanthamine-type alkaloids (Fattorusso et al. 2008). Some of these metabolites have been shown to exhibit significant cytotoxic activity against the growth of various cancer cell lines (Cheng et al. 2008, 2009; Hegazy et al. 2011; Quang et al. 2011) as well as anti-inflammatory (Chao et al. 2008; Lin et al. 2009; Lin et al. 2009; Lu et al. 2010; Quang et al. 2011) and/or antioxidant activity (Minh et al. 2011). Here we

*Corresponding author. Email: [email protected] q 2015 Taylor & Francis

2

M.-E.F. Hegazy et al.

report on chemical constituents of the species Lobophytum lobophytum which has not been previously chemically characterised.

Downloaded by [FU Berlin] at 07:13 02 July 2015

2. Results and discussion The chemical investigation of the CH2Cl2:MeOH (1:1) extract of Lypophytum lypophytum, led to the isolation of a new steroid, gorgosten-5,25(26)(E)-3b-ol (1), along with two known compounds, gorgosterol (2) (Hale et al. 1970) and (þ )-alismol (3) (Xu et al. 2011) (Figure 1). Positive ion mode HR-ESI-FT-MS analysis of 1 showed a molecular ion peak [M þ Na]þ at m/z 447.2924, corresponding to the molecular formula C30H48O. The NMR spectrum was similar to the previous reported steroid, gorgostan-5-(E)-3b-ol from a Heteroxenia species, also collected from the Red Sea (Hegazy et al. 2011; Elshamy et al. 2013), except for the presence of two olefinic bonds. This unsaturation was evidenced by three proton signals at dH 5.33 (1H, m, H-6), dH 4.64 (1H, s, H-26a) and dH 4.69 (1H, s, H-26b) characteristic of olefinic bonds at C-5/C-6 and C-25/C-26, respectively; double bond formation also resulted in an absence of proton signals associated with C-5. Thirty signals were identified in the 13C NMR consistent with a doublely unsaturated gorgostan-5-(E)-3b-ol in the presence of characteristic olefinic carbon signals at dC 140.8 (C-5), 121.7 (C-6), 156.9 (C-25) and 106.0 (C-26). The dC 50.2 (C-24) upfield shift by 1.6 ppm in 1 versus gorgostan-5-(E)-3b-ol in addition to a dC 22.0 (C-27) downfield shift by 0.5 ppm was also expected in the presence of a C-25/C-26 double bond. Characteristic signals for a cyclopropane-bearing gorgostane-type side chain were observed at dH 2 0.14 (1H, dd, J ¼ 4.0, 4.0, H-30a), dH 0.45 (1H, dd, J ¼ 4.0, 9.0, H-30b) and dH 0.15 (1H, ddd, J ¼ 4.0, 6.0, 9.0, H-22) and six observed methyl signals were also consistent with a gorgostane-type skeleton (Tanaka et al. 1982; Elshamy et al. 2013). DEPT experiment confirmed 6 methyl, 10 methylene and 9 methine signals and protonated carbons were assigned by HMQC analysis. The 1H – 1H COSY (Figure 2) showed correlations between H-3 (dH 3.51, m) with both H-4 at dH 1.27 (m) and H-2 at dH 1.49, confirming the location of hydroxyl group at C-3. Also the

21 18 12 19

11

13 14

1

HO

9 10

2 3

5 4

6

20 17 16 15

28

30

22 23

24

27 25

29 26

8 7

HO

1

2

OH

3

Figure 1. Structures of metabolites 1 – 3.

Natural Product Research

3

spectrum exhibited a clear correlation between H-6 (dH 5.33, m) with H-7 at dH 1.82 (m) confirming the presence of C5vC6(H)ZC7(2H) moiety. The position of the C-25nC-26 was confirmed by the HMBC (Figure 2) correlations. The HMBC showed correlations between H-26 at dH (4.64, s, & 4.69, s) with signals at dC 156.9 (C-25, J 2), 156.9 (C-27, J 3) and 50.2 (C-24, J 3). Addititionally, the correlation between H-24 at dH 0.22 (dq) with signals at dC 15.4 (C-28, J 2), 156.9 (C-25, J 2), 106.0 (C-26, J 3), 156.9 (C-27, J 3), and 25.8 (C-23, J 2). The stereochemistry of the side chain was determined by comparison of NMR data of 1 with those of gorgosterol (Tanaka et al. 1982; Elshamy et al. 2013), as well as by NOESY experiment. NOESY correlations in which identified alpha protons as 1 (dH 2.27) correlated with H-3 allowing for the beta hydroxyl assignment at C-3. From the above data, the structure of this compound was deduced as gorgostan-5,25-dien-3b-ol, a new natural product compound. 3. Experimental 3.1 General experimental procedures

Downloaded by [FU Berlin] at 07:13 02 July 2015

1

H and 13C NMR spectra were recorded in CDCl3 on a JEOL ECA-600 spectrometer (JEOL, Kyoto Pharmaceutical university, Japan) (600 MHz for 1H and 150 MHz for 13C, respectively). All chemical shifts (d) are given in ppm units with reference to TMS as an internal standard and coupling constants (J) reported in Hz. HRESI-FT-MS experiments were performed on HR-ESIFT-MS: Thermo Fisher Scientific LTQ Orbitrap XL mass spectrometer. Silica gel 60 (230 – 400 mesh, Merck, Darmstadt, Germany) was used for purification and compounds monitored by TLC on pre-coated silica gel plates (Merck, Kieselgel 60 F254, 0.25 mm) after spraying with 10% H2SO4 and heating.

3.2 Animal material Soft coral L. lobophytum was collected from the Egyptian Red Sea off the coast of Hurghada in March, 2013.The soft coral was identified by Dr. M. Alhammady with a voucher specimen (03RS35) deposited in the National Institute of Oceanography and Fisheries, Marine Biological Station, Hurghada, Egypt. 3.3 Extraction and separation Frozen soft coral (5.0 kg, total wet weight) was chopped into small pieces and extracted with at room temperature (4 L £ 5). The combined dichloromethane-methanol (1:1) extract was concentrated in vacuo to a brown gum. The concentrated dichloromethane-methanol (1:1) extract (310 g) was subjected to gravity chromatography in a silica gel column (6 £ 120 cm) eluting with n-hexane (4 L) followed by a gradient of n-hexane-CH2Cl2 up to 100% CH2Cl2 and CH2Cl2-MeOH up to 50% MeOH (4 L each of the solvent mixture) to afford nine major fractions (LL-1, LL-2, LL-3, LL-4, LL-5, LL-6, LL-7, LL-8 and LL-9). The n-hexane-CH2Cl2 (2:1) fraction (LL-2) (5.3 g) eluted with n-hexane – EtOAc (8:1) was subjected to silica gel column separation (100 cm £ 5 cm) to afford compound 3 (50 mg). The n-hexane-CH2Cl2 (1:1) (LL-3) fraction (4.2 g) eluted with n-hexane – EtOAc (8:1) was subjected to silica gel column separation (100 cm £ 5 cm) to afford 1 (40 mg) and 2 (60 mg). 3.3.1 Gorgostan-5, 25-dien-3b-ol (1): Amorphous powder, 1H NMR [CDCl3] dH 2.27, 1.45 (2H, m, H-1), 1.84, 1.49 (2H, m, H-2), 3.51 (1H, m, H-3), 2.21, 1.27 (2H, m, H-4), 5.33 (1H, m, H-6), 1.82, 1.42 (2H, m, H-7), 1.92 (1H, m, H-8), 1.07 (1H, m, H-9), 1.12 (2H, m, H-11), 1.62, 1.30 (2H, m, H-12), 1.22 (1H, m, H-14), 1.49,

4

M.-E.F. Hegazy et al.

1.04 (2H, m, H-15), 1.64, 1.15 (2H, m, H-16), 1.27 (1H, m, H-17), 0.66 (3H, s, Me-18), 0.99 (3H, s, Me-19), 1.10 (1H, m, H-20), 0.99 (3H, s, Me-21), 0.15 (3H, ddd, J ¼ 9.0, 6.0, 4.0, H-22), 0.22 (1H, dq, J ¼ 7.0, 8.0, H-24), 4.64, 4.69 (2H, s, H-26), 0.97 (3H, d, Me-27), 1.82 (3H, s, Me-28), 0.88 (3H, s, Me-29), 0.43 (1H, dd, J ¼ 4.0, 9.0 Hz, H-30a), 2 0.14 (1H, dd, J ¼ 4.0, 4.0 Hz, H30b). 13C NMR [CDCl3] dC 37.3 (CH2, C-1), 31.7 (CH2, C-2), 71.9 (CH, C-3), 42.3 (CH2, C-4), 140.8 (C-5), 121.7 (CH, C-6), 31.9 (CH2, C-7), 32.0 (CH, C-8), 50.2 (CH, C-9), 35.8 (C-10), 24.3 (CH2, C-11), 39.8 (CH2, C-12), 42.8 (C-13), 56.7 (CH, C-14), 24.6 (CH2, C-15), 28.2 (CH2, C-16), 58.0 (CH, C-17), 11.9 (CH3, C-18), 19.4 (CH3, C-19), 36.6 (CH, C-20), 21.1 (CH3, C-21), 31.7 (CH, C-22), 25.8 (C-23), 50.2 (CH, C-24), 156.9 (CH, C-25), 106.0 (CH3, C-26), 22.0 (CH3, C-27), 15.4 (CH3, C-28), 14.3 (CH3, C-29), 22.2 (CH2, C-30).

Downloaded by [FU Berlin] at 07:13 02 July 2015

Supplementary material Supplementary material relating to this paper is available online at http://dx.doi.org/10.1080/ 14786419.2015.1046871. Disclosure statement No potential conflict of interest was reported by the authors.

Funding This project was supported financially by the Science and Technology Development Fund (STDF), Egypt [grant number 1102].

References Blunt JW, Copp BR, Munro MH, Northcote PT, Prinsep MR. 2011. Marine natural products. Nat Prod Rep. 28:196–268. doi:10.1039/C005001F. Chao CH, Wen ZH, Wu YC, Yeh HC, Sheu JH. 2008. Cytotoxic and anti-inflammatory cembranoids from the soft coral Lobophytum crassum. J Nat Prod. 71:1819–1824. doi:10.1021/np8004584. Cheng S, Wen Z, Chiou S, Hsu C, Wang S, Dai C, Chiang M, Duh C. 2008. Durumolides a– e, anti-inflammatory and antibacterial cembranolides from the soft coral Lobophytum durum. Tetrahedron. 64:9698–9704. doi:10.1016/j. tet.2008.07.104. Cheng S, Wen Z, Wang S, Chiou S, Hsu C, Dai C, Chiang M, Duh C, Lin ST, Wang SK. 2009. Unprecedented hemiketal cembranolides with anti-inflammatory activity from the soft coral lobophytum durum. J Nat Prod. 72:152–155. doi:10.1021/np800686k. Elshamy AI, Abdel-Razik AF, Nassar MI, Mohamed TK, Ibrahim M, El-Kousy S. 2013. A new gorgostane derivative from the Egyptian Red Sea soft coral Heteroxenia ghardaqensis. Nat Prod Res. 27:1250–1254. doi:10.1080/ 14786419.2012.724417. Fattorusso E, Romano A, Taglialatela-Scafati O, Janib achmad MJ, Bavestrello G, Cerrano C. 2008. Lobozoanthamine, a new zoanthamine-type alkaloid from the Indonesian soft coral Lobophytum sp. Tetrahedron Lett. 49:2189– 2192. doi:10.1016/j.tetlet.2008.02.028. Govindam SV, Yoshioka Y, Kanamoto A, Fujiwara T, Okamoto T, Ojika M. 2012. Cyclolobatriene, a novel prenylated germacrene diterpene, from the soft coral Lobophytum pauciflorum. Bioorg Med Chem. 20:687–692. doi:10. 1016/j.bmc.2011.12.012. Hale RT, Leclercq J, Tursch B, Djerassi C, Gross RA, Weinheimer AJ, Gupta K, Scheuer PJ. 1970. Demonstration of a biogenetically unprecedented side chain in the marine sterol, gorgosterol. J Am Chem Soc. 92:2179– 2180. doi:10.1021/ja00710a089. Hegazy ME, Su JH, Sung PJ, Sheu JH. 2011. Cembranoids with 3,14-ether linkage and a secocembrane with bistetrahydrofuran from the dongsha atoll soft coral Lobophytum sp. Mar Drugs. 9:1243–1253. doi:10.3390/ md9071243. Lin SY, Wang ZH, Cheng SK, Duh SF, Hsu CH, Dai CF, Chiang MY, Duh CY. 2009. Lobocrasol, a new diterpenoid from the soft coral Lobophytum crassum. Org Lett. 11:3012–3014. doi:10.1021/ol901070e. Lu Y, Lin Y, Wen Z, Su J, Sung P, Hsu C, Kuo Y, Chiang M, Dai C, Sheu J. 2010. Steroid and cembranoids from the dongsha atoll soft coral Lobophytum sarcophytoides. Tetrahedron. 66:7129–7135. doi:10.1016/j.tet.2010.06.094.

Natural Product Research

5

Downloaded by [FU Berlin] at 07:13 02 July 2015

Minh CV, Kiem PV, Nhiem NX, Cuong NX, Thao NP, Nam NH, Anh HLT, Thung DC, Thuy DTT, Kang H, Jang H-D, Kim YH. 2011. Cytotoxic and antioxidant activities of diterpenes and sterols from the vietnamese soft coral Lobophytum compactum. Bioorg Med Chem Lett. 21:2155–2159. doi:10.1016/j.bmcl.2011.01.072. Quang TH, Ha TT, Minh CV, Kiem PV, Huong HT, Ngan NTT, Nhiem NX, Tung NH, Tai BH, Thuy DTT, Song SB, Kang H-K, Kim YH. 2011. Cytotoxic and anti-inflammatory cembranoids from the vietnamese soft coral Lobophytum laevigatum. Bioorg Med Chem. 19:2625–2632. doi:10.1016/j.bmc.2011.03.009. Tanaka J, Higa T, Tachibana K, Iwashita T. 1982. Gorgost-5-ene-3.beta.,7.alpha.,11.alpha.,12.beta.-tetraol 12monoacetate, a new marine sterol from the gorgonian isis hippuris. Chem Lett. 8:1295–1296. doi:10.1246/cl. 1982.1295. Xu X, Jin J, Shi S, Ma M, Yang Y, Zhao Z, Guo G. 2011. Sesquiterpenes from vladimiria souliei and their inhibitory effects on no production. Fitoterapia. 82:508–511. doi:10.1016/j.fitote.2011.01.004.