Ek Sangvichien

Cytotoxic activity of four xanthones from Emericella variecolor, an endophytic fungus isolated from Croton oblongifolius.

Four xanthones were isolated from mycelia ofEmericella variecolor, an endophytic fungus isolated from the leaves ofCroton oblongifolius. Their structures were elucidated by spectroscopic analysis to be shamixanthone, 14-methoxytajixanthone-25-acetate, tajixanthone methanoate, and tajixanthone hydrate. All compounds were tested for cytotoxic activity against various human tumor cell lines including gastric carcinoma, colon carcinoma, breast carcinoma, human hepatocarcinoma, and lung carcinoma. The antitumor activities of these xanthones were compared with that of doxorubicin hydrochloride, a chemotherapeutic substance. All of them showed moderate activities and were selective against gastric carcinoma, colon carcinoma, and breast carcinoma. Only tajixanthone hydrate exhibited moderate activity against all cancer cell lines. Furthermore, under the test conditions it was found that 14-methoxytajixanthone-25-acetate and tajixanthone hydrate are almost as active as doxorubicin hydrochloride against gastric carcinoma (KATO3) and breast carcinoma (BT474).

Ascospore discharge, germination and culture of fungal partners of tropical lichens, including the use of a novel culture technique

A total of 292 lichen samples, representing over 200 species and at least 65 genera and 26 families, were collected, mainly in Thailand; 170 of the specimens discharged ascospores in the laboratory. Generally, crustose lichens exhibited the highest discharge rates and percentage germination. In contrast, foliose lichen samples, although having a high discharge rate, had a lower percentage germination than crustose species tested. A correlation with season was indicated for a number of species. Continued development of germinated ascospores into recognizable colonies in pure culture was followed for a selection of species. The most successful medium tried was 2 % Malt-Yeast extract agar (MYA), and under static conditions using a liquid culture medium, a sponge proved to be the best of several physical carriers tested; this novel method has considerable potential for experimental work with lichen mycobionts.

First Record of Viridothelium virens (Trypetheliales, Ascomycota) in the Southeast Asian Tropics

Abstract: Luangsuphabool, T., Piapukiew, J., Lumbsch, H. T. & Sangvichien, E. 2017. First record of Viridothelium virens (Trypetheliales, Ascomycota) in the Southeast Asian tropics. — Herzogia 30: 317–321. Viridothelium virens was found growing on tree bark at 1500 m altitude in an oak forest in northern Thailand. Phenotypical and molecular data (mtSSU and nuLSU rDNA sequences) supported the identification of the sample as V. virens. This is a new record for Thailand and extends the distributional range from temperate regions (North America and Japan) to the tropics.