New Strongylophorines from the Okinawan Marine Sponge Petrosia (Strongylophora) corticata Ayako Hoshino, † Hidemichi Mitome, † Hiroaki Miyaoka,* ,† Akinori Shintani, † Yasuji Yamada, † and Rob W. M. van Soest ‡ School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan, and Institute for Systematics and Ecology, University of Amsterdam, P.O. Box 94766, 1090 GT Amsterdam, The Netherlands Received July 10, 2003 New strongylophorines-22 (1), -23 (2), -24 (3), and -25 (4) were isolated from the Okinawan sponge Petrosia (Strongylophora) corticata along with other known strongylophorines. The structures of these strongy- lophorines were determined on the basis of spectroscopic analysis and chemical conversions. Assessment was also made of the cytotoxicity of strongylophorines-1, -2, -3, -4, -22 (1), -23 (2), and -24 (3) toward HeLa cells. Strongylophorines are meroditerpenoids, each possessing a hydroquinone situated on an isocopalane-type diterpene skeleton. 1-6 Strongylophorines-1, -2, and -3 were initially isolated from the Papua New Guinean sponge Strongylo- phora durissima, and the absolute configurations of strongy- lophorines-1 and -3 were determined on the basis of chemical correlation with (+)-manool. 1a Twenty-one strongy- lophorines are reported in the literature. 1-6 Most of strongy- lophorines have been found to possess biological activity, in the form of ichthyotoxic, antimicrobial, antifungal, and cytotoxic activity. While investigating the chemical con- stituents present in Okinawan marine invertebrates, 7 four new strongylophorines, strongylophorines-22 (1), -23 (2), -24 (3), and -25 (4), were isolated from the Okinawan sponge Petrosia (Strongylophora) corticata (Wilson, 1925) along with other known strongylophorines. The isolation and structure determinations are discussed below. Results and Discussion Sponge specimens of Petrosia (Strongylophora) corticata, obtained in June 2001 from the coral reef of Hatoma Island (Okinawa, Japan), were extracted with MeOH and then acetone. The combined extracts were partitioned between H 2 O and EtOAc. The EtOAc-soluble portion was parti- tioned between hexane and 80% MeOH. Repeated chro- matographic separations of the 80% MeOH-soluble portion gave strongylophorines-22 (1), -23 (2), -24 (3), and -25 (4) along with the known strongylophorines-1, 1 -2, 1 -3, 1 -4, 2 -8, 2 -15, 6 and -16. 6 The molecular formula of strongylophorine-22 (1) was found to be C 26 H 38 O 2 on the basis of the HREIMS spectrum. IR and UV spectra of 1 indicated the presence of a hydroxy group (IR: 3435 cm -1 ) and aromatic ring (IR: 1496 cm -1 , UV: λ max 298, 229, 221 nm). Twenty six carbons of 1 were identified as five methyls, eight sp 3 methylenes, three sp 3 methines, three sp 2 methines, four sp 3 quaternary carbons, and three sp 2 quaternary carbons, from 13 C NMR and DEPT spectra. 1 H and 13 C NMR correlations were noted in the HMQC spectrum (Table 1). 1 H and 13 C NMR indicated a 1,2,4-trisubstituted benzene [δ H 6.62 (1H, d, J ) 8.4 Hz), 6.56 (1H, dd, J ) 8.4, 2.9 Hz), 6.55 (1H, br s), δ C 148.5 (C), 147.2 (C), 123.3 (C), 117.5 (CH), 115.8 (CH), 114.2 (CH)], one oxygenated sp 3 quaternary carbon [δ C 76.6 (C)], and five methyls [δ H 1.16 (3H, s), 0.88 (3H, s), 0.86 (3H, s), 0.85 (3H, s), 0.82 (3H, s), δ C 33.3 (CH 3 ), 21.4 (CH 3 ), 20.5 (CH 3 ), 16.4 (CH 3 ), 16.0 (CH 3 )]. COSY cross-peaks indicated linkages of vicinal protons to give rise to the following carbon sequences: C-1 to C-3, C-5 to C-7, C-9 to C-12, C-14 to C-15, and C-18 to C-19. These partial structures were connected to each other via quaternary carbons, as evident from the following HMBC spectrum correlations: Me-23/C-1, C-5, C-9, C-10; Me-24/C-7, C-8, C-9, C-14; Me-25/C-12, C-13, C-14; Me-26/C-3, C-4, C-5, C-22; H-15/C-16, C-17, C-21; H-18/C-16, C-17, C-20; H-21/ C-15, C-17, C-20. A cyclic ether moiety was demonstrated by the degree of unsaturation of 1. The relative configu- ration of 1 was deduced from the following NOESY cor- relations: H-6 (δ H 1.57)/Me-23, Me-26; H-11 (δ H 1.32)/ Me-23, Me-24, Me-25; H-9/H-5, H-14. The structure of 1 was thus determined to be that shown in 1. The molecular formula of strongylophorine-23 (2) was C 26 H 38 O 3 according to the HREIMS spectrum. IR, UV, and NMR spectra of 2 were similar to those of 1. NMR spectra of 2 suggested that a methyl group of 1 had been replaced with a hydroxymethyl group [δ H 4.05 (1H, d, J ) 11.8 Hz), 3.92 (1H, d, J ) 11.8 Hz), δ C 62.9 (CH 2 )] in the case of 2 (Table 1). The position of the hydroxymethyl group of 2 was clearly confirmed by COSY and HMBC spectra as C-10, and the relative configuration of 2 was demonstrated by the NOESY spectrum. * To whom correspondence should be addressed. Tel: +81 426 76 3080. Fax: +81 426 76 3073. E-mail: miyaokah@ps.toyaku.ac.jp. † Tokyo University of Pharmacy and Life Science. ‡ University of Amsterdam. Figure 1. 1600 J. Nat. Prod. 2003, 66, 1600-1605 10.1021/np030312q CCC: $25.00 © 2003 American Chemical Society and American Society of Pharmacognosy Published on Web 11/26/2003