Siripun Narongchai

Inhibitory effects of caffeic acid ester analogues on free radicals and human liver microsome CYP1A2 activities

Ethyl caffeate (EC), octyl caffeate(OC), benzyl caffeate(BC) and phenethyl caffeate(PC) were synthesized and evaluated for scavenging of superoxide anion, nitric oxide radical and 1,1-diphenyl-1-picrylhydrazyl radical (DPPH). Antioxidant activity was investigated with reducing power method. Pooled human liver microsome was used for investigating the effects on cytochrome P450 1A2 (CYP1A2) catalytic activities by using phenacetin as a substrate. Dixon and Cornish-Bowden plots were used for enzyme kinetic analysis. The EC, OC, BC and PC potentially inhibited superoxide anion, nitric oxide and DPPH radicals. IC(50) values of superoxide anion scavenging of EC, OC, BC and PC were 16.42, 79.83, 123.69 and 123.69 µg/ml, respectively. EC was more potent than OC and BC in terms of nitric oxide radical scavenger: IC(50) values of EC, OC and BC were 24.16, 37.34 and 52.64 µg/ml, respectively. In addition, the IC(50) values of EC, OC, BC and PC on DPPH radical scavenging were 70.00, 184.56, 285.34 and 866.54 µg/ ml, respectively. The IC(50) values of EC, OC, BC and PC on phenacetin O-deethylation were 124.98, 111.86, 156.68 and 31.05 µg/ml, respectively. Enzyme kinetics showed that the type of inhibition mechanism was mixed-type. The result of this study shows that caffeic acid ester analogues potentially scavenge free radicals and inhibit catalytic activity of CYP1A2. This may lead to important implications in the prevention of CYP1A2-mediated chemical carcinogenesis.

Deactivation Study of ñ-Amanitin Toxicity in Poisonous Amanita spp. Mushrooms by the Common Substances In Vitro

The purpose of this research was to find out the substance which deactivate α-Amanitin Toxicity The materials and methods used in the study include analysis with high performance liquid chromatography (HPLC) to: 1.Demonstrate the standard α-amanitin at concentrations of 25, 50 and 100 μg/ml 2.Determine the deactivation of α-amanitin with 1) 18% acetic acid 2), calcium hydroxide 40 mg/ml, 3) potassium permanganate 20 mg/ml, 4) sodium bicarbonate 20 mg/ml 3.Report the statistical analysis as the mean ± standard deviation (SD) and paired t-test. The result revealed that potassium permanganate could eliminate 100 percent of the α-amanitin at 25, 50 and 100 μg/ml. Calcium hydroxide, sodium bicarbonate and acetic acid had lower elimination rates at those concentrations: 68.43 ± 2.58 (-71.4, -67.2, -66.7%), 21.48 ± 10.23 (-29.4, -25.2, -9.9%) and 3.21 ± 0.02% (-3.2, -3.2, +1.1%), respectively. The conclusion of this study was suggested that potassium permanganate could be applied as an absorbent substance during gastric lavage in patients with mushroom poisoning. It also might be effective as a cleansing wash for uncooked mushrooms. Investigation of potassium permanganate’s ability to absorb α-amanitin in animal models and humans should be considered. .