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The unique marine environment (high-pressured, high-salted, anoxygenous, and lucifugal, etc.) endows the marine organisms with special survival mechanisms, generating various of secondary metabolites with novel structures and potent bioactivities in their metabolic progress. And these compounds provided the valuable resources for the research on new drugs and the lead compounds.In this paper, the secondary metabolites and their bioactivities of the sponge Carteriospongia foliascens (Pallas) from the South China Sea and the brown alge Kjellmaniella Crassifolia (Miyabe) from the Hokkaido, Japan Sea were investigated according to modern technology of marine natural products. The bioactive secondary metabolites were isolated and elucidated from the two species by the methods of chromatography (silica gel, Sephadex LH-20, ODS and HPLC) and spectroscopy (NMR, MS, IR, UV). Fifty-one compounds in total were isolated, 45 of which were identified, including 16 new compounds.Thirty compounds were evaluated from C. foliascens, including sesterterpenes 1–14, phyllofenone C (15), phyllofenone B (16), phyllolactone E (17), furospongin-1 (18), 12,13-didehydrofurospongin-1 (19) , (2Z,6R,8R,9E)-methyl-3,6-epoxy-4,6,8-triethyl-2,4,9- dodecatrienoate (20), 6β-acetyl-4β,5β-dimethyl-1(10)-α-epoxy-7-oxodecalin (21), 6α-acetyl- 4β,5β-dimethyl-1(10)-α-epoxy-7-oxodecalin (22), 6β-acetoxy-9β-hydroxy-1α,5β-dimethy-2- oxodecalin (23), 5α,8α-epidioxy-cholesta-6,22-dien-3β-ol (24), 5α,8α-epidioxy-cholest-6-en-3β-ol (25), rhodoptilometrin (26), uracil (27), thymine (28), xanthine (29), and 3-nonen-2-ol (30). Compounds 1–15 and 21 were new componds, and compound 26 was also isolated and elucidated from sponge for the first time.Fifteen compounds were identified from K. Crassifolia, and all of them were isolated from this species for the first time. They were cholesterol (31), ergosta-5,22-dien-3-ol (32), lobophytol A (33), 24-methylenecholest-5-en-3-ol (34), saringosterol (35), fucosterol (36), 24-ethylcholesta-4,24(28)-dien-3-one (37), 24-ethyl-5α-cholesta-24(28)Z,25-dien-3β-ol (38), 3β, l5β-dihydroxycholest-5-ene (39), 3-epicyclomusalenol (40), cyclosadol (41), 24,25- dihydrocimicifugenol (42), phytol (43), bis-(2-ethylhexyl)phthalate (44), and Hexadecan-1-ol (45). Compound 40–42 were isolated from the algae for the first time.The bioactivities of these compounds were evaluated by screening programs on various of screening modles including antifouling, ichthyotoxic, lethality to brine shrimp, microalgae-growth inhibition, antibacterial as well as antitumor activities. Compounds 4, 18, 20, 26 from C. foliascens exhibited significant antifouling activities against barnacle Balanus amphitrite. The IC50 values of 4 and 18 were less than 2.5μg·mL-1. Compounds 14 and 26 also showed strong ichthyotoxic activity. These results confirm that the sesterterpenes play a key role as eco-physiological mediators in the sponge of C. foliascens. These bioactive compounds demonstrated high values for further research.The study of the secondary metabolites from C. foliascens and K. Crassifolia and their bioactivities not only provided a basis for the research on the chemical defense substances and their mechanisms of the sponges and algaes, but also supplied much initial value for the research of chemoecology and related drugs.
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