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Biomedical subjects

C J Sih

Publications and source records attributed to C J Sih.

At least 37 records · Page 2Linked to original sources
PubMed1979

Cytotoxic saponins from the Chinese herbal drug Yunnan Bai Yao.

Two cytotoxic saponins were isolated from the acetone extracts of the herbal preparation "Yunnan Bai Yao" by column chromatography. They were identified as a 3-([alpha-L-rhamnopyranosyl()Rha leads to 2Glu)]-[alpha-L-arabinofuranosyl(1Ara leads to 4Glu)]-beta-D-glucopyranosyl)-25(R)-spirost-5-en-3beta-ol (I) and 3-([alpha-L-rhamnopyranosyl(1Rha leads to 4Rha)-alpha-L-rhamnopyranosyl(1Rha leads to 4Glu)]-[alpha-L-rhamnopyranosyl(1Rha leads to 2Glu)]-beta-D-glucopyranosyl)-25(R)-spirost-5-en-3 beta-ol (VI). Both saponins exhibited significant cytotoxicity in the standard P-388, L-1210, and 9KB tissue culture screens.

Animals↗
PubMed1979

Biosynthesis of prostaglandin D2, 15-ketoprostaglandin E2, and hydroxy fatty acids by ram seminal vesicle microsomes.

At high arachidonic acid concentrations (164 micrometer) and without exogenous cofactors, ram seminal vesicle microsomes produced prostaglandin E2 and two less polar products, identified as prostaglandin D2 and 15-ketoprostaglandin E2. The ratio of the biosynthetic products formed depended on the exogenous cofactor and on the arachidonic acid concentration. At high arachidonic acid concentrations (greater than 150 micrometer), tryptophan, phenol, and glutathione stimulated prostaglandin E2 formation, but each affected the formation of the other prostaglandins differently. Ascorbic acid markedly stimulated hydroxy fatty acid formation. GLC-mass spectral analysis of the hydroxy fatty acid fraction indicated the presence of 11-hydroxy-5,8,12,14-eicosatetraenoic acid, 15-hydroxy-5,8,11,13-eicosatetraenoic acid, and 12-hydroxy-5,8,10-heptadecatrienoic acid. At low arachidonic acid concentrations (30 micrometer), glutathione still stimulated prostaglandin E2 biosynthesis, but the other cofactors stimulated 6-ketoprostaglandin F1a and hydroxy fatty acid formation.

Animals↗
PubMed1979

Arachidonic acid is responsible for the smooth muscle-contracting activity of G-acid.

G-acid, a smooth-muscle-contracting substance isolated from human blood plasma, was previously identified as 3-octadecenoic acid. Synthetic cis- and trans-3-octadecenoic acid, however, are biologically inactive. G-acid actually consists of a mixture of fatty acids, characteristic of animal tissues. The biological activity is caused by arachidonic acid, which contracts smooth muscle upon in situ conversion to prostaglandins.

Animals↗
PubMed1976

The absolute configuration of the amino acids in delta-(alpha-aminoadipyl)cysteinylvaline from Penicillium chrysogenum.

Radioactive carbon-14 L-alpha-aminoadipic acid, L-cysteine, or L-valine were readily incorporated into the intracellular tripeptide, delta-(alpha-aminoadipyl)cysteinylvaline (ACV), by washed starved cells of Penicillium chrysogenum. The labeled ACV in each case was oxidized with performic acid and isolated as its corresponding sulfonic acid derivative. After acid hydrolysis, the configuration of the component acids was determined by L- and D-amino acid oxidases, which showed the tripeptide (ACV) from P. chrysogenum to be delta-(L-aminoadipyl)-L-cysteinyl-D-valine.

2-Aminoadipic Acid↗
PubMed1975

On agents favoring prostaglandin f formation during biosynthesis.

The microsomal fraction of bovine vesicular gland catalyzed the conversion of eicosapolyenoic acids exclusively to prostaglandin E in the presence of reduced glutathione, while hydrox fatty acids, prostaglandins D and F, decreased to a negligible level. After solubilizing the microsomal fraction with cutscum, the prostaglandin synthetase activity was purified 11-fold by batchwise absorption and elution of the enzyme activity from DEAE-cellulose. This partially purified enzyme fraction did not respond to reduced glutathione in promoting prostaglandin E formation at the expense of other products. A number of glutathione analogs were examined, but none of these was as effective as reduced glutathione. Dithiol complexes of Cu-2+, Ni-2+, and Zn-2+ exerted pronounced effects on relative amounts of the different prostaglandins biosynthesized. Both the Cu-2+-dithiothreitol (2:1) complex and stannous chloride markedly enhanced prostaglandin F synthesis at the expense of prostaglandin D and prostaglandin E. The following reagents chemically reduced the endoperoxide in ascaridole to p-menth-2-ene-cis-1,4-diol: Cu-2+0dithiothreitol, Cu-2+-epinephrine, and stannous chloride. It is concluded that the enhancement of prostaglandin F formation caused by copper-dithiols and L-epinephrine is due to nonenzymatic reduction of prostaglandin G or prostaglandin H.

5,8,11,14-Eicosatetraynoic Acid↗