Nongluksna Sriubolmas

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.

Aromatase inhibitory, radical scavenging, and antioxidant activities of depsidones and diaryl ethers from the endophytic fungus Corynespora cassiicola L36

Isolation of a broth extract of the endophytic fungus Corynespora cassiicola L36 afforded three compounds, corynesidones A (1) and B (3), and corynether A (5), together with a known diaryl ether 7. Compounds 1, 3, 5, and 7 were relatively non-toxic against cancer cells, and inactive toward normal cell line, MRC-5. Corynesidone B (3) exhibited potent radical scavenging activity in the DPPH assay, whose activity was comparable to ascorbic acid. Based on the ORAC assay, compounds 1, 3, 5, and 7 showed potent antioxidant activity. However, the isolated natural substances and their methylated derivatives (1-8) neither inhibited superoxide anion radical formation in the XXO assay nor suppressed TPA-induced superoxide anion generation in HL-60 cell line. Corynesidone A (1) inhibited aromatase activity with an IC(50) value of 5.30 microM.

Curvularides A–E: Antifungal Hybrid Peptide–Polyketides from the Endophytic Fungus Curvularia geniculata

Five new hybrid peptide-polyketides, curvularides A-E (1-5), were isolated from the endophytic fungus Curvularia geniculata, which was obtained from the limbs of Catunaregam tomentosa. Structure elucidation for curvularides A-E (1-5) was accomplished by analysis of spectroscopic data, as well as by single-crystal X-ray crystallography. Curvularide B (2) exhibited antifungal activity against Candida albicans, and it also showed synergistic activity with a fluconazole drug.

Metabolites from the endophytic mitosporic Dothideomycete sp. LRUB20

The endophytic mitosporic Dothideomycete sp. LRUB20 was found to produce pyrone derivatives, dothideopyrones A-D (1, 3, 4, and 5), together with seven known compounds, including questin (9), asterric acid (10), methyl asterrate (11), sulochrin (12), and eugenitin (13), 6-hydroxymethyleugenitin (14), and cis, trans-muconic acid (15). Dothideopyrone D (5) and its acetate derivative 6 exhibited moderate cytotoxic activity. This is the first report on a naturally occurring muconic acid, which is commonly known as a biomarker in environments after exposure to benzene and phenol (or derivatives). Interestingly, the LRUB20 fungus could produce muconic acid in relatively high yield (47.8mg/L). The utility of endophytic fungi in the field of white biotechnology is discussed.

Cytotoxic Activities of Trichothecenes Isolated from an Endophytic Fungus Belonging to Order Hypocreales

Bioassay-guided fractionation of the extract of the endophytic fungus KLAR 5 belonging to order Hypocreales, which was isolated from the twig of Knema laurina (Blume) Warb., resulted in the isolation of brefeldin A (1), 8-deoxy-trichothecin (2), trichothecolone (3), 7α-hydroxytrichodermol (4), and 7α-hydroxyscirpene (5). Compound 5 was isolated from natural source for the first time. Compound 1 was very highly active against human epidermoid carcinoma of the mouth, human breast cancer (BC-1), and human small cell lung cancer (NCI-H187) cells whereas compounds 2 and 4 were selectively active against BC-1 and NCI-H187 cells. Compounds 3 and 5 were moderately active against these three cancer cell lines.

A new pterocarpan from Erythrina fusca

A new pterocarpan, 3-hydroxy-10-(3-hydroxy-3-methylbutyl)-9- methoxypterocarpan (1), together with seven known compounds, sandwicensin (2), erythrisenegalone (3), citflavanone (4), liquiritigenin (5), lonchocarpol A (6), lupinifolin (7) and 8-prenyldaidzein (8), were isolated from the stem bark of Erythrina fusca. The structure of 1 was determined on the basis of spectroscopic analyses. Among these compounds, lonchocarpol A (6) exhibited strongly antibacterial activities in vitro against Staphylococcus aureus, Bacillus subtilis and Enterococcus faecalis. Compounds (2, 3, 6 and 7) exhibited weakly antimycobacterial activity with minimum concentrations (MICs) of 100, 50, 50 and 25 µg/mL, respectively.

Effect of the derivatives of andrographolide on the morphology of Bacillus subtilis

Andrographis paniculata has been reported to have antiviral, antipyretic and anticancer activities. Andrographolide, an ent-labdane diterpene, is an active constituent in this plant. In this study, andrographolide (1) and its natural derivative 14-deoxy-11,12-didehydroandrographolide (2) and 5 other semisynthetic derivatives were tested for their activity against Grampositive and Gram-negative bacteria and Candida albicans. Only derivatives bearing a 14-acetyl group showed activity, and this activity was only against Gram-positive bacteria. 14-Acetylandrographolide showed the highest potency against Bacillus subtilis; the other 14-acetylandrographolides with additional substitution at the 3- and 19-hydroxyl groups showed lower activity against Gram-positive bacteria. The morphology of B. subtilis after being treated with 14-acetylandrographolide was investigated with TEM. This is the first report on 14-acetylandrographolide’s quantified antibacterial activity, and the crucial functional group of this ent-labdane that plays an important role in perturbing the morphogenesis of B. subtilis leading to cell death.

Azole-synergistic anti-candidal activity of altenusin, a biphenyl metabolite of the endophytic fungus Alternaria alternata isolated from Terminalia chebula Retz.

In this study, a tropical endophytic fungus, Alternaria alternata Tche-153 was isolated from a Thai medicinal plant Terminalia chebula Rezt. The ethyl acetate extract prepared from the fermentation broth exhibited significant ketoconazole-synergistic activity against Candida albicans. Bioassay-directed fractionation of the ethyl acetate extract led to the isolation of altenusin (1), isoochracinic acid (2), and altenuic acid (3) together with 2,5-dimethyl-7-hydroxychromone (4). Using the disc diffusion method and the microdilution chequerboard technique, only altenusin (1) in combination with each of three azole drugs, ketoconazole, fluconazole or itraconazole at their low sub-inhibitory concentrations exhibited potent synergistic activity against C. albicans with the fractional inhibitory concentration index range of 0.078 to 0.188. This first discovery of altenusin (1) as a new azole-synergistic prototype possessing a biphenyl structure is of significance for further development of new azole-synergists to treat invasive candidiasis.

Chemical composition, antibacterial and antifungal activities of essential oil from Heracleum Siamicum Craib

Heracleum siamicum Craib (Apiaceae), is an important herbal species having wide application in food flavoring processes. The flat-oval shaped fruit of H. siamicum Craib from North Thailand was hydrodistilled, and the chemical composition of the essential oil was analyzed by GC and GC-MS. The essential oil yield based on dried plant material was 1.25%, and twenty-five compounds (corresponding to 97.69% of the total weight) were identified. The main components were: n-octyl acetate (65.30%), o-cymene (10.35%), limonene (7.52%), δ-2-carene (6.87%), cis-thujone (1.92%), isobornyl acetate (0.94%), n-octanol (0.73%), 1,8-cineol (0.62%), n-tridecanol (0.44%), and safrole (0.37%). H. siamicum essential oil demonstrated bactericidal and fungicidal activity against five bacterial strains and two fungal strains, as evaluated using agar diffusion in terms of the minimum inhibitory concentration.

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.