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A new alkaloid designated as aspergicin (1), together with a previous secondary metabolite, neoaspergillic acid (2), and a common compound, ergosterol (3), were isolated from the mixed cultured mycelia of two marine-derived mangrove epiphytic Aspergillus sp. fungi. Extensive application of 1D and 2D NMR techniques was made to characterize the structure and to establish the 1 H and 13 C assignments of compound 1. In the antibacterial assays, both compounds 1 and 2 showed significant antibacterial activity against some selected Gram bacteria.Application of mixed fermentation was proved to contribute to the discovery of new natural products from marinederived microorganisms. To date, at least nine new biologically active compounds have been identified by mixed fermentation of marine-derived microorganisms, pestalone [1], libertellenones A-D [2], marinamides A and B [3], and emericellamides A and B [4]. Results of mixed fermentation include increased antibiotic activity in the crude extract, increased yields of previously described metabolites, increased yields of previously undetected metabolites, analogues of known metabolites resulting from combined pathways, and induction of previously unexpected pathways for bioactive constituents [5].Marine-derived mangrove fungi were proved to be an abundant resource for novel natural compounds [6,7]. As part of our ongoing search for new bioactive metabolites from mixed fermentation of marine-derived mangrove fungi from the South China Sea [3,8], two antibacterial compounds, neoaspergillic acid and kojic acid, were obtained as major secondary metabolites from the mixed fermentation liquid of two marine-derived mangrove epiphytic Aspergillus fungi, which were isolated from a rotten fruit of mangrove Avicennia marina in the South China Sea [9]. Further chemical investigations of the mixed fermentation mycelia resulted in the isolation of a new alkaloid designated as aspergicin (1), together with a previous secondary metabolite, neoaspergillic acid (2), and a commom compound, ergosterol (3). We report herein their isolation, structural elucidation, and antibacterial activities. Fig. 1. The structure and key HMBC correlations (from C to H) of compound 1.

A diverse array of bioactive compounds have been isolated and characterized from the mangrove plant Avicennia marina and its endophytes. Extensive chemical investigations of the different parts (barks, leaves, twigs, etc.) of the mangrove plant A. marina and its endophytes (mainly endophytic fungi) resulted in the reporting of the isolation of 123 compounds, and most of them are new or novel compounds. Most of compounds produced by the endophytes were different from the chemical components of the host A. marina, but it can still be found that some metabolites of the endophytes and some chemical components of the host possess the same structure unit. It suggested that there exist some biogenetic relationships between the endophytes and its host. Their biological activities, structural and stereochemical assignments are reported.

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