Damrong Sommit

Cytotoxic Nor-chamigrane and Chamigrane Endoperoxides from a Basidiomycetous Fungus

A new nor-chamigrane endoperoxide, merulin A (1), and two new chamigrane endoperoxides, merulins B and C (2, 3), were isolated from the culture broth extract of an endophytic fungus of Xylocarpus granatum. Their structures were elucidated on the basis of spectroscopic, mainly NMR and MS, data. X-ray crystallographic analysis confirmed the structure of 1. Compounds 1 and 3 displayed significant cytotoxicity against human breast (BT474) and colon (SW620) cancer cell lines.

11-Hydroxymonocerin from the Plant Endophytic Fungus Exserohilum rostratum

A new analogue of monocerin, 11-hydroxymonocerin (2), along with monocerin (1) and 12-hydroxymonocerin (3) were isolated from cultures of Exserohilum rostratum, a fungal strain endophytic in Stemona sp. The structure of 2 was determined by analysis of NMR and MS data and by comparison of spectroscopic data to those of 1. Monocerin (1) and 11-hydroxymonocerin (2) displayed activity against Plasmodium falciparum (K1, multidrug-resistant strain) with IC50 values of 0.68 and 7.70 microM, respectively. None of the compounds were cytotoxic against any of the tumor cell lines tested.

Protoxylocarpins F−H, Protolimonoids from Seed Kernels of Xylocarpus granatum

Three new protolimonoids, protoxylocarpins F-H (1-3), along with 11 known limonoids, were isolated from seed kernels of Xylocarpus granatum. Their structures were elucidated on the basis of extensive spectroscopic data analyses. All compounds isolated were evaluated for cytotoxic activity against five human tumor cell lines.

Moluccensins H-J, 30-ketophragmalin limonoids from Xylocarpus moluccensis.

Three new phragmalin limonoids, moluccensins H-J (1-3), were isolated from seed kernels of the cedar mangrove, Xylocarpus moluccensis. Their structures were established by extensive spectroscopic analysis. Compound 2 displayed weak antibacterial activity against Staphylococcus hominis and Enterococcus faecalis.

Antiangiogenic effect of chamigrane endoperoxides from a Thai mangrove-derived fungus.

As part of our ongoing efforts to investigate natural products with potential for use as cancer treatments, we have recently disclosed the cytotoxicity of unique nor-chamigrane (1) and chamigrane (2, 3) endoperoxides from a Thai mangrove-derived fungus. Reinvestigation of this fungus in a large-scale fermentation led to the isolation of an additional new chamigrane endoperoxide (4) and one known analogue (5). Among these isolated metabolites, compound 3 (merulin C) exhibited potent antiangiogenic activity mainly by suppression of endothelial cell proliferation and migration in a dose-dependent manner, and its effect is mediated by reduction in the phosphorylation of Erk1/2. Merulin C also displayed promising activity in a rat aortic ring sprouting (ex vivo) and a mouse Matrigel (in vivo) assay.

Weakly Anti-inflammatory Limonoids from the Seeds of Xylocarpus rumphii

Seven new limonoids, namely, xylorumphiins E-J (1-2 and 4-7) and 2-hydroxyxylorumphiin F (3), along with three known derivatives (8-10), were isolated from the seeds of Xylocarpus rumphii. 2-Hydroxyxylorumphiin F (3) and xylorumphiin I (6) displayed moderate inhibitory activity against nitric oxide production from lipopolysaccharide-activated macrophages with IC50 values of 24.5 and 31.3 μM, respectively.

Labdane diterpenoids from Croton oblongifolius

Abstract Four new labdane diterpenoids, labda-7,12( E ),14-triene, labda-7,12( E ),14-triene-17-al, labda-7,12( E ),14-triene-17-ol, labda-7,12( E ),14-triene-17-oic acid, were isolated from the stem bark of Croton oblongifolius . The structure of these compounds were established by spectroscopic data and chemical transformation.

Antiangiogenetic effects of anthranoids from Alternaria sp., an endophytic fungus in a Thai medicinal plant Erythrina variegata

Endophytic fungi are known as a prolific source for the discovery of structurally interesting and biologically active secondary metabolites, some of which are promising candidates for drug development. In the present study, three anthranoids were isolated from an Alternaria sp. endophytic fungus and evaluated for their antiangiogenic activity in a rat aortic sprouting assay, an ex vivo model of angiogenesis. Of these three compounds, altersolanol (2) was further characterized and found to show a promising activity in ex vivo, in vitro and in vivo angiogenesis asssays. Using human umbilical vein endothelial cells as an in vitro model, the angiogenic effect of 2 was found to occur via suppression of all three main functions of endothelial cells, namely proliferation, tube formation and migration.