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Further chemical investigation of the fruit of the mangrove Avicennia marina led to the isolation of a new caffeic acid derivative, maricaffeolylide A (1), and a new megastigmane derivative, maricyclohexene A (2). The structures of the isolates were elucidated on the basis of extensive spectroscopic analysis. The antioxidant activity of 1 and 2 was also evaluated using a cellular antioxidant activity assay, and catechol 1 showed antioxidant activity with an EC50 value of 24 ± 0.3 μm.

Further chemical investigation of the fruits of the mangrove, Avicennia marina, afforded three new phenylethyl glycosides, marinoids J–L (1–3), and a new cinnamoyl glycoside, marinoid M (4). The structures of isolates were elucidated on the basis of extensive spectroscopic analysis and by comparison of the data with those of related secondary metabolites. The antioxidant activity of the isolates was evaluated using the cellular antioxidant assay (CAA), and compounds 1–4 showed antioxidant activities, with EC50 values ranging from 23.0 ± 0.71 μM to 247.8 ± 2.47 μM.

Two new avermectin derivatives, avermectins B1c and B1e (1 and 2, resp.), as well as two known compounds, avermectin B2a (3) and ivermectin A1a (4), were isolated from a Beibu Gulf gorgonian coral, Anthogorgia caerulea. The structures of the new compounds were established by detailed spectroscopic analysis and by comparison with spectral data of related known compounds. Compounds 1-4 showed moderate antifouling activities against the larval settlement of Balanus amphitrite.

Two new avermectin derivatives, avermectin B1c (Ia) and B1e (Ib) are isolated along with the known compounds, avermectin B2a and ivermectin A1a.

In March, June, September, and December 2007, investigations were conducted on the species composition, dominant species, community structure, and abundance distribution of phytoplankton in the Fangchenggang Bay of Guangxi. Based on the investigation data, the phytoplankton abundance, biotic index, and their correlations with environmental factors were analyzed. A total of 138 species of 54 genera were identified, among which, 112 species belonged to 37 genera of diatoms, 21 species belonged to 12 genera of dinoflagellates, 2 species belonged to chrysophyta, 2 species belonged to chlorophyta, and 1 species belonged to cyanophyta. In whole year, the dominant species was Skeletonema costatum. The species number had a trend decreasing from the outer to the inner of the Bay and from spring to winter, while the cell abundance was decreased from the inner to the outer of the Bay. There was an obvious annual change in the cell abundance, being the highest (151.39 x 10(4) cells x dm(-3)) in summer (June) and the lowest (0.35 x 10(4) cells x dm(-3)) in winter (December). In spring, both the diversity and the species number were higher. Correlation analysis demonstrated that the distribution of phytoplankton community had definite correlations with water nutrient content, temperature and salinity. At the observation stations 1 and 2 in west Bay, due to the effects of Fangcheng River runoff and hydrodynamic forces such as tide, water salinity was lower and nutrient content was higher, and accordingly, S. costatum cells in summer could greatly reproduce, even result in high probability of red tide.