Micrometam C Protects against Oxidative Stress in Inflammation Models in Zebrafish and RAW264.7 Macrophages.

Micrometam C is a core of novel marine compound isolated from the mangrove associates Micromelum falcatum. In this study, we investigated the protective effects of micrometam C in inflammation models in the transgenic zebrafish line Tg (corola: eGFP) and RAW264.7 macrophages. We found that micrometam C significantly suppressed the migration of immune cells in tail-cutting-induced inflammation in transgenic zebrafish and reduced lipopolysaccharide (LPS)-induced reactive oxygen species (ROS) in both zebrafish and macrophages. In addition, micrometam C also restored LPS-induced reduction of endogenous antioxidants, such as catalase (CAT), glutathione (GSH) and superoxide dismutase (SOD). The protective effects of micrometam C were in parallel to its inhibition of NADPH oxidase and nuclear factor-kappa-binding (NF-κB) activity. Thus, the present results demonstrate that micrometam C protects against LPS-induced inflammation possibly through its antioxidant property.

Detection of polyketide synthase and nonribosomal peptide synthetase biosynthetic genes from antimicrobial coral-associated actinomycetes.

The diversity and properties of actinobacteria, predominant residents in coral holobionts, have been rarely documented. In this study, we aimed to explore the species diversity, antimicrobial activities and biosynthetic potential of culturable actinomycetes within the tissues of the scleractinian corals Porites lutea, Galaxea fascicularis and Acropora millepora from the South China Sea. A total of 70 strains representing 13 families and 15 genera of actinobacteria were isolated. The antimicrobial activity and biosynthetic potential of fifteen representative filamentous actinomycetes were estimated. Crude fermentation extracts of 6 strains exhibited comparable or greater activities against Vibrio alginolyticus than ciprofloxacin. Seven of the 15 actinomycetes strains possess type I polyketide synthases (PKS-I) and/or nonribosomal peptide synthetases (NRPS) genes. Nine tested strains possess type II polyketide synthases (PKS-II). Phylogenetic analysis based on 16S rRNA gene sequences indicated that these PKS and NRPS gene screening positive strains belong to genera Nocardiopsis, Pseudonocardia, Streptomyces, Micromonospora, Amycolatopsis and Prauserella. One PKS-I and four NRPS fragments showed <70% similarity to their closest relatives, which suggested the novelty of these genes. This study helps uncover the genetic capacity of stony coral-associated actinomycetes to produce bioactive molecules.

Marine compound catunaregin inhibits angiogenesis through the modulation of phosphorylation of akt and eNOS in vivo and in vitro.

Angiogenesis is the formation of blood vessels from pre-existing vasculature. Excessive or uncontrolled angiogenesis is a major contributor to many pathological conditions whereas inhibition of aberrant angiogenesis is beneficial to patients with pathological angiogenesis. Catunaregin is a core of novel marine compound isolated from mangrove associate. The potential anti-angiogenesis of catunaregin was investigated in human umbilical vein endothelial cells (HUVECs) and zebrafish. HUVECs were treated with different concentrations of catunaregin in the presence or absence of VEGF. The angiogenic phenotypes including cell invasion cell migration and tube formation were evaluated following catunaregin treatment in HUVECs. The possible involvement of AKT, eNOS and ERK1/2 in catunaregin-induced anti-angiogenesis was explored using Western blotting. The anti-angiogenesis of catunaregin was further tested in the zebrafish embryo neovascularization and caudal fin regeneration assays. We found that catunaregin dose-dependently inhibited angiogenesis in both HUVECs and zebrafish embryo neovascularization and zebrafish caudal fin regeneration assays. In addition, catunaregin significantly decreased the phosphorylation of Akt and eNOS, but not the phosphorylation of ERK1/2. The present work demonstrates that catunaregin exerts the anti-angiogenic activity at least in part through the regulation of the Akt and eNOS signaling pathways.

[Study on the chemical constituents from ethyl acetate extract of Micromelum falcatum].

OBJECTIVE: To study the chemical constituents from ethyl acetate extract of Micromelum falcatum. METHODS: The constituents were separated and purified by silica gel, Sephadex LH-20 and HPLC. Their structures were elucidated by spectral analysis (NMR, MS). RESULTS: Ten compounds were isolated and identified as micropubescin (1), phebalosin (2), scopoletin (3), citrubuntin (4), thamnosmonin (5), hopeyhopin (6), arnottinin (7), casegravol (8), 2-methoxy-5-hydroxy cinnamate (9), threo-syringoylglycerol (10). CONCLUSION: Compounds 1 - 10 are obtained from this plant for the first time.

Alkaloids from the stem bark of Micromelum falcatum.

Two new quinoldione alkaloids, methyl 2-(3-hydroxy-1-methyl-2,4-dioxo-1,2,3,4-tetrahydroquinolin-3-yl)acetate (1) and 3-hydroxy-1-methyl-3-(2-oxopropyl)quinoline-2,4(1H,3H)-dione (2), and two quinolinone alkaloids previously synthesized but first isolated as natural products, N-methylflindersine (3) and 4-hydroxy-3-methoxy-1-methyl-2(1H)-quinolinone (4), were isolated from the stem bark of Micromelum falcatum, together with the known N-methylswietenidine-B (5). Their structures were established mainly on the basis of 1D- and 2D-NMR techniques. All compounds were evaluated for toxicity towards brine shrimp larvae, and 3 showed strong toxicity with an LD(50) value of 1.39 microg/ml.