Sophon Roengsumran

An oxygen index evaluation of flammability for zinc hydroxystannate and zinc stannate as synergistic flame retardants for acrylonitrile–butadiene–styrene copolymer

Abstract This article describes a study on zinc hydroxystannate (ZHS) and zinc stannate (ZS) in combination with 1,2-bis(tribromophenoxy)ethane (BTBPE) for increasing flame retardancy and reduced smoke emission in an acrylonitrile-butadiene-styrene (ABS) copolymer. The combination between BTBPE, synergist and chlorinated polyethylene (CPE) yield a high value of LOI which for some proportions is higher than for commercial ABS.

Inhibitory Activity of Cyanidin-3-rutinoside on α-Glucosidase

Cyanidin-3-rutinoside, a natural anthocyanin, inhibited α-glucosidase from bakers yeast in dose-responsive manner. The IC50 value was 19.7 μM ± 0.24 μM, compared with the IC50 value of voglibose (IC50 = 23.4 ± 0.30 μM). Cyanidin-3-rutinoside was found to be a non-competitive inhibitor for yeast α-glucosidase with a Ki; value in the range of 1.31–1.56 × 10−5M. These results indicated that cyanidin-3-rutinoside could be classed as a new α-glucosidase inhibitor.

Cytotoxic labdane diterpenoids from Croton oblongifolius

Three labdane diterpenoids, 2-acetoxy-3-hydroxy-labda-8(17),12(E)-14-triene, 3-acetoxy-2-hydroxy-labda-8(17),12(E)-14-triene, and 2,3-dihydroxy-labda-8(17),12(E),14-triene were isolated from stem bark of Croton oblongifolius. Their structures were established by spectroscopic data, and each was also tested for cytotoxicity against various human tumor cell lines. The latter compound showed non-specific, moderate, cytotoxicities against all the cell lines; whereas the first two compounds were less active.

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).

Encapsulated AlCl3: a convenient catalyst for the alkylation of benzene with dodecene

Abstract A novel method for the encapsulation of AlCl 3 was successfully carried out using an insoluble polymer wall. The polymer wall was formed by the reaction of poly(styrene- co -dimethylaminoethyl methacrylate) and hydrogenated telechelic polybutadiene containing -COOH groups. The encapsulated AlCl 3 was used to catalyze the Friedel–Crafts alkylation of benzene with dodecene. The alkylbenzenes were obtained in excellent yields and the encapsulated AlCl 3 catalyst was separated by simple filtration.

Cassane diterpenoid from Caesalpinia major.

A new cassane diterpenoid, 14-deoxy-epsilon-caesalpin was isolated from the seed kernels of Caesalpinia major and its structure was determined by spectroscopic data.

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.

Diterpenoids from the stem barks ofCroton robustus

Three compounds were isolated from the stem barks ofCroton robustus. Their structures were elucidated as trachyloban-19-oic acid, trachyloban-19-ol and poilaneic acid by spectroscopic analysis. Among them, trachyloban-19-ol and methyl trachyloban-19-oate exhibited weak cytotoxic activity against gastric carcinoma and colon carcinoma with ED50 of 9.2, 9.6 and 8.3, 9.1 μg/mL, respectively.

Biotransformation of ent-kaur-16-en-19-oic acid by Absidia blakesleeana and Rhizopus oligosporus

Biotransformation of ent-kaur-16-en-19-oic acid was carried out with Absidia blakesleeana and Rhizopus oligosporus. Absidia blakesleeana produced two novel metabolites, ent-(7α, 9α)-dihydroxy-kaur-16-en-19-oic acid and ent-(1β, 7α)-dihydroxy-kaur-16-en-19-oic acid, together with three known compounds: ent-7α-hydroxy-kaur-16-en-19-oic acid, ent-(7α, 11β)-dihydroxy-kaur-16-en-19-oic acid and ent-(7α, 13)-dihydroxy-kaur-16-en-19-oic acid. The ent-7α-hydroxy-kaur-16-en-19-oic acid and ent-(7α, 9α)-dihydroxy-kaur-16-en-19-oic acid were obtained from R. oligosporus. The structures were established by spectroscopic techniques and X-ray crystallography.

New labdane-type diterpenoids from Croton oblongifolius and their cytotoxic activity

Eight new labdane-type diterpenoids (1-3) and (5-9) and hardwickiic acid (4), a clerodane, were isolated from the stem bark of Croton oblongifolius. Their structures were established to be 3-oxygenated ent-manoyl oxide derivatives with a 8,13-epoxytricyclic ring system and hydroxylabdandienes on the basis of spectroscopic and X-Ray crystallographic analysis. The absolute stereochemistry of the core labdane skeleton was deduced to be (5S,8S,9S,10R,13S) from the X-Ray crystallographic analysis of the p-bromobenzoate of ent-3α-hydroxymanoyl oxide (3) and mutual chemical correlation. Cytotoxicity of these compounds was tested against a panel of human tumor cell lines.