Kasem Soytong

Cytotoxic pentacyclic and tetracyclic aromatic sesquiterpenes from Phomopsis archeri.

Three new sesquiterpenes, named phomoarcherins A-C (1-3), and four known compounds, kampanol A (4), R-mevalonolactone, ergosterol, and ergosterol peroxide, were isolated from the endophytic fungus Phomopsis archeri. These structures were established on the basis of spectroscopic evidence. The structure and absolute configuration of 1 were confirmed by X-ray crystallographic analysis of its p-bromobenzoate derivative (1a). Compounds 1-4 showed cytotoxicity against five cholangiocarcinoma cell lines (0.1-19.6 μg/mL), while 1 and 2 exhibited weak cytotoxicity against the KB cell line with IC(50) values of 42.1 and 9.4 μg/mL, respectively. In addition, compound 2 showed antimalarial activity against Plasmodium falciparum with an IC(50) value of 0.79 μg/mL.

Antimalarial and cytotoxic depsidones from the fungus Chaetomium brasiliense.

Four new depsidones, mollicellins K-N (1-4), and six known depsidones, mollicellins B (5), C (6), E (7), F (8), H (9), and J (10), along with two known sterols were isolated from the fungus Chaetomium brasiliense. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopic data and chemical transformation. Among these isolates, 1-3, 5-7, and 10 exhibited antimalarial activity against Plasmodium falciparum. Only 1 exhibited antimycobacterial activity against Mycobacterium tuberculosis and antifungal activity against Candida albicans using in vitro assays. In addition, 1-10 showed cytotoxicity against the KB, BC1, NCI-H187, and five cholangiocarcinoma cell lines.

Prenylxanthones and a Bicyclo[3.3.1]nona-2,6-diene Derivative from the Fungus Emericella rugulosa

Five new prenylxanthones, ruguloxanthones A-C (1-3), 14-methoxytajixanthone (4), and tajixanthone ethanoate (5), a new bicyclo[3.3.1]nona-2,6-diene derivative, rugulosone (6), and seven known compounds, shamixanthone, tajixanthone, 14-methoxytajixanthone-25-acetate, tajixanthone hydrate, tajixanthone methanoate, isoemericellin, and ergosterol, were isolated from the fungus Emericella rugulosa. The structures of 1-6 were established using spectroscopic techniques. Compound 6 exhibited antimalarial and antimycobacterial activities, as well as cytotoxicity against three cancer cell lines.

Fungal diversity on fallen leaves of Ficus in northern Thailand

Fallen leaves of Ficus altissima, F. virens, F. benjamina, F. fistulosa and F. semicordata, were collected in Chiang Mai Province in northern Thailand and examined for fungi. Eighty taxa were identified, comprising 56 anamorphic taxa, 23 ascomycetes and 1 basidiomycete. Common fungal species occurring on five host species with high frequency of occurrence were Beltraniella nilgirica, Lasiodiplodia theobromae, Ophioceras leptosporum, Periconia byssoides and Septonema harknessi. Colletotrichum and Stachybotrys were also common genera. The leaves of different Ficus species supported diverse fungal taxa, and the fungal assemblages on the different hosts showed varying overlap. The fungal diversity of saprobes at the host species level is discussed.

Sutorius: a new genus for Boletus eximius

Sutorius is described as a new genus of Boletaceae to accommodate Boletus robustus originally named illegitimately by C.C. Frost from eastern North America. The legitimate name, Boletus eximius, provided by C.H. Peck, has been used since for a dark purple to chocolate brown bolete with finely scaly stipe and reddish brown spore deposit. This iconic taxon has been documented on five continents. Despite the straightforward species identification from morphology, the interpretation of stipe macro-morphology and spore color has led to equivocal generic placement. Phylogenetic analyses of genes encoding large subunit rRNA and translation elongation factor 1α confirm Sutorius as a unique generic lineage in the Boletaceae. Two species are recognized based on multiple accessions: S. eximius, represented by collections from North America, Costa Rica, Guyana, Indonesia and Japan (molecular data are lacking for only the Guyanan and Japanese material); and S. australiensis, represented by material from Queensland, Australia. Additional collections from Zambia and Thailand represent independent lineages, but sampling is insufficient to describe new species for these entities.

Cytotoxic 10-(indol-3-yl)-[13]cytochalasans from the fungus Chaetomium elatum ChE01.

Nine 10-(indol-3-yl)-[13]cytochalasans such as a new chaetoglobosin V (1); two new natural products, prochaetoglobosin III (2) and prochaetoglobosin IIIed (3); six known chaetoglobosins B-D (4–6), F (7), and G (8) and isochaetoglobosin D (9) in addition to two known sterols, 24(R)-5α,8α-epidioxyergosta-6–22-diene-3β-ol (10) and ergosterol (11), were isolated from the fungus Chaetomium elatum ChE01. The structures of these compounds were elucidated by spectroscopic methods. Compounds 1–9 showed cytotoxicity against the human breast cancer (IC50 2.54–21.29 μM) and cholangiocarcinoma cell lines (IC50 3.41–86.95 μM).

A monograph of Micropsalliota in Northern Thailand based on morphological and molecular data

Using a combination of morphological and molecular data, the genus Micropsalliota is shown to represent a monophyletic lineage in the Agaricaceae sister to Hymenagaricus. Features that distinguish the genus from Agaricus and allied genera include usually small, gracile basidiomes with a membranous partial veil, dextrinoid basidiospores with an apically thickened endosporium and lack of a germ pore, capitate or subcapitate, conspicuous cheilocystidia, and incrusted pileipellis hyphae that turn green in ammonia solution. We provide a monographic treatment of 23 taxa of Micropsalliota from Northern Thailand, of which 13 taxa represent new distribution reports for Thailand and 10 represent new taxa, including M. allantoidea, M. bifida, M. furfuracea, M. lateritia var. vinaceipes, M. megarubescens, M. megaspora, M. pusillissima, M. rubrobrunnescens var. rubrobrunnescens, M. rubrobrunnescens var. tibiicystis, and M. suthepensis. Included in this monograph are comprehensive descriptions, illustrations of micromorphological features, photographs of basidiomes, comparisons with allied species, phylogenetic trees inferring relationships amongst Thai species based on nrITS and nrLSU sequence datasets, and a key to aid in diagnosis.

Affinities of the Boletus chromapes group to Royoungia and the description of two new genera, Harrya and Australopilus

Abstract. Harrya is described as a new genus of Boletaceae to accommodate Boletus chromapes, a pink-capped bolete with a finely scabrous stipe adorned with pink scabers, a chrome yellow base and a reddish-brown spore deposit. Phylogenetic analyses of large-subunit rDNA and translation elongation factor 1α confirmed Harrya as a unique generic lineage with two species, one of which is newly described (H. atriceps). Some Chinese taxa were recently placed in a separate genus, Zangia, supported by both morphology and molecular data. Multiple accessions from Queensland, Australia, support the synonymy of at least three species in a separate Australian clade in the new genus, Australopilus. The truffle-like Royoungia is also supported as a separate lineage in this clade of boletes. Even though it lacks stipe characters, it possesses the deep, bright yellow to orange pigments in the peridium. Additional collections from Zambia and Thailand represent independent lineages of uncertain phylogenetic placement in the Chromapes complex, but sampling is insufficient for formal description of new species. Specimens from Java referable to Tylopilus pernanus appear to be a sister group of the Harrya lineage.

Cytotoxic lasiodiplodin derivatives from the fungus Syncephalastrum racemosum

Chemical investigation of fungal biomass of the fungus Syncephalastrum racemosum led to the isolation of new natural products (3R),(5S)-5-hydroxy-de-O-methyllasiodiplodin (1), 6-oxode-O-methyllasiodiplodin (2), in addition to five known compounds, de-O-methyllasiodiplodin (3), lasiodiplodin (4), (3R),(5R)-5-hydroxy-de-O-methyllasiodiplodin (5), ergosterol (6), and ergosterol peroxide (7). Their structures were elucidated by spectroscopic techniques. The absolute configuration of 1 was determined by a modified Mosher’s method. Compound 1 showed cytotoxicity against cholangiocarcinoma, KKU-M139, KKU-M156, and KKU-M213 cell lines with IC50 values in the range of 14–19 μg/mL, while 3 showed cytotoxicity against KB, BC1, and NCI-H187 cell lines with IC50 values of 12.67, 9.65, and 11.07 μg/mL, respectively.

The phylogeny of selected Phylloporus species, inferred from NUC-LSU and ITS sequences, and descriptions of new species from the Old World

The phylogeny of Phylloporus (Boletaceae) has not been well studied, and the taxonomic relationships of this genus have varied considerably among authors. The following study presents phylogenetic relationships of Phylloporus based on two nuclear ribosomal DNA regions, ITS and LSU. The ITS dataset includes 39 collections and the LSU dataset contains 50 collections of Phylloporus. A combined analysis of both genes did not resolve the deeper nodes in the phylogeny, but the results suggest that Phylloporus is monophyletic and a sister group of the Xerocomus subtomentosus group. The lamellate hymenophore configuration is a synapomorphy that distinguishes Phylloporus from the other genera in the family. The placement of a lamellate genus within Boletaceae suggests that hymenophore evolution is not well understood in the family. This is the first phylogeny of Phylloporus and includes 20 species from different geographic regions. Six taxa of Phylloporus from the Old World are here presented. Phylloporus cyanescens is a new combination for an Australasian taxon formerly named as a variety of P. bellus (Massee) Corner. Phylloporus pumilus is described from Indonesia, and 4 species are described from Thailand: P. castanopsidis, P. dimorphus, P. infuscatus, and P. rubiginosus.