Selective determination of homocysteine levels in human plasma using a silver nanoparticle-based colorimetric assay.

The first use of silver nanoparticles (AgNPs) for the rapid, simple, and selective determination of homocysteine (Hcy) levels in human plasma was studied. Hcy and five other amino acids, including cysteine (Cys), could be distinguished by their different aggregation kinetics, which caused a change in the visible color and a shift in the UV-vis absorption spectra. The difference in the cross-linking (aggregation) rate between Hcy and Cys was used as the basis for developing a selective probe for Hcy and allowed the detection of Hcy in the linear range of 2-12 μM (R(2)=0.

Structure-activity relationships of trans-cinnamic acid derivatives on alpha-glucosidase inhibition.

trans-Cinnamic acid and its derivatives were investigated for the alpha-glucosidase inhibitory activity. 4-Methoxy-trans-cinnamic acid and 4-methoxy-trans-cinnamic acid ethyl ester showed the highest potent inhibitory activity among those of trans-cinnamic acid derivatives. The presence of substituents at 4-position in trans-cinnamic acid altered the alpha-glucosidase inhibitory activity.

Diterpenoids from the stem barks of Croton robustus.

Three compounds were isolated from the stem barks of Croton 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.

Inhibition of Na+,K+-ATPase activity by (-)-ent-Kaur-16-en-19-oic acid and its derivatives.

The diterpene, (-)- ent-kaur-16-en-19-oic acid, from Croton oblongifolius was identified as an Na +,K +-ATPase inhibitor. This compound exhibits an IC 50 of 2.2 x 10( -5 )M against crude enzyme Na +,K +-ATPase from rat brain.