Two new diterpenoids, pachydictyol B ( 1a/ 1b) and C ( 2), were isolated from the dichloromethane extract of the marine brown alga, Dictyota dichotoma, collected from the Red Sea coast of Egypt, along with the known metabolites, pachydictyol A ( 3a), dictyol E ( 4), cis-africanan-1α-ol ( 5a), fucosterol ( 6), tetrahydrothiophen-1,1-dioxide and poly-β-hydroxybutyric acid. GC-MS analysis of the nonpolar fractions also indicated the presence of β-bourbonene and nonanal, along with three hydrocarbons and five fatty acids or their simple derivatives, respectively. GC-MS analysis of the unsaponifiable algal petroleum ether extract revealed the presence of a further eight compounds, among them 2,2,6,7-tetramethyl-10-oxatricyclo[4.3.0.1(1,7)]decan-5-one ( 7), N-(4-bromo- n-butyl)-pipe ridin-2-one ( 8) and tert-hexadecanethiol. Structures 1– 6 were assigned by 1D and 2D NMR, mass spectra (EI, CI, HREI and HRESI) and by comparison with data from related structures. The crude algal extract was potently active against the breast carcinoma tumor cell line, MCF7 (IC 50 = 0.6 μg mL ？1); pachydictyol B ( 1a) and dictyol E ( 4) showed weak antimicrobial properties, and the other compounds were inactive. Pachydictyols B ( 1a) and C ( 2) demonstrated a weak and unselective cytotoxicity against twelve human tumor cell lines with a mean IC 50 of >30.0 μM.
References
[1]
Vashishta, B.R. Botany for Degree Students, Part 1, Algae, 7th ed. ed.; S. Chand & Company Ltd.: New Delhi, India, 1984; p. 5.
[2]
Duran, R.; Zubia, E.; Ortega, M.J.; Salva, J. New diterpenoids from the alga Dictyota dichotoma. Tetrahedron 1997, 53, 8675–8688, doi:10.1016/S0040-4020(97)00537-1.
[3]
Gedaraa, S.R.; Abdel-Halim, O.B.; El-Sharkawya, S.H.; Salama, O.M.; Shier, T.W.; Halim, A.F. Cytotoxic hydroazulene diterpenes from the brown alga Dictyota dichotoma. Z. Naturforsch. 2003, 58b, 17–22.
[4]
Freitas, O.S.P.; Santos de Oliveira, A.; de-Paula, J.C.; Pereira, R.C.; Cavalcanti, D.N.; Teixeira, V.L. Chemical variation in the diterpenes from the Brazilian brown alga Dictyota mertensii (Dictyotaceae, Phaeophyta). Nat. Prod. Commun. 2007, 2, 13–15.
[5]
Teixeira, V.L.; Almeida, S.A.; Kelecom, A. Chemsystematic and biogeographic studies of the diterpenes. Biochem. Syst. Ecol. 1990, 18, 87–92, doi:10.1016/0305-1978(90)90041-D.
[6]
De-Paula, J.C.; Bueno, L.B.; Cavalcanti, D.N.; Yoneshigue-Valentin, Y.; Teixeira, V.L. Diterpenes from the brown alga Dictyota crenulata. Molecules 2008, 13, 1253–1262, doi:10.3390/molecules13061253.
[7]
Suzuki, M.; Yamada, H.; Kurata, K. Dictyterpenoids A and B, two novel diterpenoids with feeding-deterrent activity from the brown alga Dilophus okamurai. J. Nat. Prod. 2002, 65, 121–125, doi:10.1021/np010234b.
[8]
Schmitt, T.M.; Lindquist, N.; Hay, M.E. Seaweed secondary metabolites as antifoulants. Effects of Dictyota spp. diterpenes on survivorship, settlement, and development of marine invertebrate larvae. Chemoecology 1998, 8, 125–131, doi:10.1007/s000490050017.
[9]
Soto, R.H.; Rovirosa, R.J.; San Martin, A.; Argandona, V. Secondary metabolites of Dictyota crenulata. Bol. Soc. Chil. Quim. 1994, 39, 173–178.
[10]
Patil, A.D.; Berry, D.; Brooks, D.P.; Hemling, M.E.; Kumar, N.V.; Mitchell, M.P.; Ohlstein, E.H.; Westley, J.W. A diterpene epoxide from the marine brown alga Dictyota sp.: Possible vasopressin V1 receptor antagonist. Phytochemistry 1993, 33, 1061–1064, doi:10.1016/0031-9422(93)85023-K.
[11]
Cavalcanti, D.N.; Rezende, C.M.; Pinto, A.C.; Teixeira, V.L. Diterpenoid constituents from the brown alga Dictyota menstrualis (Dictyotaceae, Phaeophyta). Nat. Prod. Commun. 2006, 1, 609–611.
[12]
Teixeira, V.L.; Cavalcanti, D.N.; Pereira, R.C. Chemotaxonomic study of the diterpenes from the brown alga Dictyota menstrualis. Biochem. Syst. Ecol. 2001, 29, 313–316, doi:10.1016/S0305-1978(00)00055-7.
[13]
Pereira, R.C.; Teixeira, V.L.; Kelecom, A. Chemical defenses against herbivores in marine algae. 1. The brown alga Dictyota dichotoma (Hudson) Lamouroux from Brazil. An. Acad. Bras. Cienc. 1994, 66, 229–235.
[14]
Danise, B.; Minale, L.; Riccio, R.; Amico, V.; Oriente, G.; Piattelli, M.; Tringali, C.; Fattorusso, E.; Magno, S.; Mayol, L. Further perhydroazulene diterpenes from marine organisms. Experientia 1977, 33, 413–415, doi:10.1007/BF01922182.
[15]
Ovenden, S.P.B.; Nielson, J.L.; Liptrot, C.H.; Willis, R.H.; Tapiolas, D.M.; Wright, A.D.; Motti, C.A. Update of spectroscopic data for 4-hydroxydictyolactone and dictyol E isolated from a Halimeda stuposa-Dictyota sp. Assemblage. Molecules 2012, 17, 2929–2938, doi:10.3390/molecules17032929.
[16]
Fricke, C. Terpenoide Inhaltsstoffe von Lebermosen und Heilpflanzen. Ph.D. Thesis, University Hamburg, Germany, 1999.
[17]
SPARTAN'08; Wavefunction, Inc.: Irvine, CA, USA, 2009.
[18]
Del Coronel, A.; Cerda-García-Rojas, C.M.; Joseph-Nathan, P.; Catalán, C.A.N. Chemical composition, seasonal variation and a new sesquiterpene alcohol from the essential oil of Lippia integrifolia. Flavour Fragr. J. 2006, 21, 839–847.
[19]
Abou-ElWafa, G.S.E.; Shaaban, M.; Shaaban, K.A.; El-Naggar, M.E.E.; Laatsch, H. Three new unsaturated fatty acids from the marine green alga Ulva fasciata Delile. Z. Naturforsch. 2009, 64b, 1199–1207.
[20]
Maskey, R.P.; Kock, I.; Shaaban, M.; Grün-Wollny, I.; Helmke, E.; Mayer, F.; Wagner-D？bler, I.; Laatsch, H. Low molecular weight oligo-β-hydroxybutyric acids and 3-hydroxy-N-phenethyl-butyramide new products from microorganisms. Polym. Bull. 2002, 49, 87–93.
[21]
Anderson, A.J.; Dawes, E.A. Occurrence, metabolism, metabolic role, and industrial uses of bacterial polyhydroxyalkanoates. Microbiol. Rev. 1990, 54, 450–472.
[22]
Takahashi, A.; Kurasawa, S.; Ikeda, D.; Okami, Y.; Takeuchi, T. Altemicidin, a new acaricidal and antitumor substance. I. Taxonomy, fermentation, isolation and physico-chemical and biological properties. J. Antibiot. 1989, 32, 1556–1561.
[23]
Sajid, I.; Fondja Yao, C.B.; Shaaban, K.A.; Hasnain, S.; Laatsch, H. Antifungal and antibacterial activities of indigenous Streptomyces isolates from saline farmlands: Prescreening, ribotyping and metabolic diversity. World J. Microbiol. Biotechnol. 2009, 25, 601–610, doi:10.1007/s11274-008-9928-7.
[24]
Burkholder, P.R.; Burkholder, L.M.; Almodovar, L.R. Antibiotic activity of some marine algae of Puerto Rico. Bot. Mar. 1960, 2, 149–156.
[25]
Biabani, M.A.F.; Baake, M.; Lovisetto, B.; Laatsch, H.; Helmke, E.; Weyland, H. Anthranilamides: New antimicroalgal active substance from a marine Streptomyces sp. J. Antibiot. 1998, 51, 333–340, doi:10.7164/antibiotics.51.333.
[26]
Zinad, D.S.; Shaaban, K.A.; Abdalla, M.A.; Islam, T.; Schüffler, A.; Laatsch, H. Bioactive isocoumarins from a terrestrial Streptomyces sp. ANK302. Nat. Prod. Commun. 2011, 6, 45–48.
[27]
Nasr, A.H. The Marine Algae of Alexandria. 1—A Report on Some Marine Algae Collected from the Vicinity of Alexandria. Notes and Memoirs No. 36; Government Press: Cairo, Egypt, 1940; p. 33.
[28]
Abou-El Wafa, G.S.E.; El-Naggar, M.E.E. Studies on the biological activities of some species of Egyptian marine algae. 2005.
[29]
Abou-El Wafa, G.S.E. Comparative Studies on Biogenic Compounds in Some Species of Egyptian Marine Algae. Ph.D. Thesis, El-Mansoura University, Egypt, 2011.
[30]
Skehan, P.; Storeng, R.; Scudiero, D.; Monks, A.; McMahon, J.; Vistica, D.; Warren, J.T.; Bokesch, H.; Kenney, S.; Boyd, M.R. New colorimetric cytotoxicity assay for anticancer-drug screening. J. Natl. Cancer Inst. 1990, 82, 1107–1112, doi:10.1093/jnci/82.13.1107.
[31]
Dengler, W.A.; Schulte, J.; Berger, D.P.; Mertelsmann, R.; Fiebig, H.H. Development of a propidium iodide fluorescence assay for proliferation and cytotoxicity assays. Anticancer Drugs 1995, 6, 522–532, doi:10.1097/00001813-199508000-00005.
