Studies On Alga Laurencia Okamurai And Nudibranch Glossodoris Atromarginata: Chemistry And Bioactivities

Marine natural materials are prolific source of secondary metabolites with diverse structures and biological properties. In the course of our ongoing research for bioactive compounds, we have chemically investigated two species of marine organisms, including one red alga Laurencia okamurai Yamada collected from the East China Sea and one nudibranch Glossodoris atromarginata collected from the South China Sea.From the two organisms, 29 compounds, including 20 sesquiterpenoids, 3 dimeric sesquiterpenoids, 1 nor-diterpenoid, 3 diterpenoids, 1 sesterterpene and 1 steroid, were isolated by various methods. Such as normal silica gel columns, Sephadex LH-20, RP-HPLC and LC-NMR. Their structures, relative and absolute configurations were elucidated by extensive spectroscopic analysis, such as 1D, 2D NMR, UV, MS, optical rotation, TDDFT-ECD and by comparision of the data with the literature.From the Et2 O extracts of the red alga Laurencia okamurai Yamada, we obtained 23 compounds, they are 20 sesquiterpenoids and 3 dimeric sesquiterpenoids respectively. 7 of them were identified as new compounds, including 2 laurane-type sesquiterpenoids(1-12, 1-14), 2 rearranged laurane-type sesquiterpenoids(1-20, 1-21) and 3 new dimeric sesquiterpenoids(1-22, 1-23, 1-24). It is the first time to isolate the dimeric sesquiterpenoids from the red alga Laurencia okamurai Yamada and to the best of our knowledge it is also the first time to find the laurane-type dimer of different laurane-type monomers from the natural source. we also obtain 3 known compounds by the chemical systhesis, they are laurinterol acetate(1-11), laurebiphenyl(1-25) and dimer of laurinterol(1-26) respectively.From the extracts of the nudibranch Glossodoris atromarginata, we obtain 6 compounds, including 1 nor-diterpenoid, 3 diterpenoids, 1 sesterterpene and 1 steroid. 2 of them were deduced as new compounds.In the bioactivities tests, compound 1-25 showed selective inhibitory activity against Gram-positive bacterias, MIC values anti Staphylococcus aureus Newman, Bacillus subtilis CMCC 63501, Enterococcus faecium Efm-HS0847 and Streptococcus pyogenes ATCC 12344 are 0.6, 2.5, 0.6, 0.6 μg/m L respectively; Compounds 1-14, 1-15, 1-16, 1-17, 1-25 and 1-26 show good PTP1 B inhibitory activity, IC50 values are 13.0, 14.9, 7.0, 4.9, 4.3, 3.3 μg/m L respectively; Compound laurinterol(1-10) show various activities, MIC values of against the four Gram-positive bacterias are 3.9, 1.3, 1.3, 0.6 μg/mL respectively; IC50 values of PTP1 B inhibitory activity, NF-κB inhibitory activity and cytotoxicity are 13.3μg/m L, 6.6μg/mL and 6.0μM, respectively.The above results provided a clue for the discovery of similar structurally interesting and biologically active compounds from marine sources.