Discovery of Novel Diterpenoids from Sinularia arborea

Mar. Drugs 2014, 12, 385-393; doi:10.3390/md12010385 OPEN ACCESS

marine drugs

Article

Discovery of Novel Diterpenoids from Sinularia

arborea

Kuan-Hua Chen 1,2, Chang-Feng Dai 3, Tsong-Long Hwang 4, Chun-Yu Chen 5,6, Jan-Jung Li 2, Jih-Jung Chen 7, Yang-Chang Wu 8,9,10, Jyh-Horng Sheu 11,12, Wei-Hsien Wang 2,11 and Ping-Jyun Sung 1,2,9,11,13,*

1 Graduate Institute of Marine Biotechnology, Department of Life Science and Institute of

Biotechnology, National Dong Hwa University, Pingtung 944, Taiwan; E-Mail: [email protected]

2 National Museum of Marine Biology and Aquarium, Pingtung 944, Taiwan; E-Mails:

[email protected] (J.-J.L.); [email protected] (W.-H.W.)

3 Institute of Oceanography, National Taiwan University, Taipei 106, Taiwan; E-Mail:

[email protected]

4 Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan;

E-Mail: [email protected]

5 Department of Anesthesiology, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan;

E-Mail: [email protected]

6 Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan 333,

Taiwan

7 Department of Pharmacy and Graduate Institute of Pharmaceutical Technology, Tajen

University, Pingtung 907, Taiwan; E-Mail: [email protected]

8 School of Pharmacy, College of Pharmacy, China Medical University, Taichung 404,

Taiwan; E-Mail: [email protected]

9 Chinese Medicine Research and Development Center, China Medical University

Hospital, Taichung 404, Taiwan

10 Center for Molecular Medicine, China Medical University Hospital, Taichung 404,

Taiwan

11 Department of Marine Biotechnology and Resources and Division of Marine

Biotechnology, Asia-Pacific Ocean Research Center, National Sun Yat-sen University, Kaohsiung 804, Taiwan; E-Mail: [email protected]

12 Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University

and Academia Sinica, Kaohsiung 804, Taiwan

13 Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung 807,

Taiwan

* Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +886-8-882-5037; Fax: +886-8-882-5087. Mar. Drugs 2014, 12 386

Received: 5 November 2013; in revised form: 23 November 2013 / Accepted: 3 January 2014 / Published: 17 January 2014

Abstract: Two novel diterpenoids, sinularbols A (1) and B (2), which were found to possess a new carbon skeleton were isolated from the soft coral Sinularia arborea. The structures of compounds 1 and 2 were elucidated by spectroscopic methods and 2 displayed a moderately inhibitory effect on the generation of superoxide anion by human neutrophils.

Keywords: sinularbol; sinularborane; diterpenoid; Sinularia arborea; superoxide anion 1. Introduction

Previous studies on the chemical constituents of octocorals, belonging to the genus Sinularia, have led to the isolation of a number of interesting secondary metabolites and some of these were found to possess interesting bioactivities [1,2]. In a previous study on the chemical constituents of the soft coral Sinularia arborea (phylum Cnidaria, class Anthozoa, order Alcyonacea, family Alcyoniidae) (Scheme 1) [3], collected off the waters of Taiwan, two 13-hydroxycembrane diterpenoids, arbolides A and B along with a trihydroxysteroid, crassarosterol A, had been isolated [4]. In the continuing studies on this interesting species, two novel diterpenoids, sinularbols A (1) (Scheme 1 and

Supplementary Figures S1–S8) and B (2) (Scheme 1 and Supplementary Figures S9– S16), which were found to possess a novel sinularborane-type carbon skeleton (3,9-cyclized cembranoid), were obtained (Scheme 1). In this paper, we describe the isolation, structure determination and bioactivity of diterpenoids 1 and 2.

Scheme 1. The soft coral Sinularia arborea and the structures of sinularbols A (1) and B (2). 11 1213 14 17 18 19 20 15 2 3 45 6 7 8 9 16 R OH OH HH1 10

Sinularia arborea Sinularbol A (1): R = β-OH Sinularbol B (2): R = H