Studies on organomercury(II) complexes of isoniazid

A number of organomercury(II) complexes involving isoniazid (I), of the type RHgCl(L)(II) [R = phenyl(C6H5), o-hydroxyphenyl (o-HOC6H4), p-hydroxyphenyl (p-HOC6H4), p-acetoxyphenyl (p-AcOC6H4), 2-furyl (2-C4H3O); L = isoniazid] have been synthesized and characterized. Conductance measurements indicate that the complexes are nonelectrolytes. From IR and UV studies, it is concluded that isoniazid acts as a bidentate ligand, coordinating through hydrazinic nitrogen and carbonyl oxygen. 1H and 13C NMR support the stoichiometry of the complexes. From fluoroscence studies a number of photochemical parameters have been elucidated. For the C6H5HgCl(L), p-HOC6H4HgCl(L), and p-AcOC6H4HgCl(L) complexes, thermogravimetric studies have been carried out and relevant kinetic and thermodynamic parameters for thermal degradation have been enumerated. In addition, the fragmentation pattern of the complexes has been analyzed on the basis of mass spectra. The C6H5HgCl(L) and p-HOC6H4HgCl(L) complexes have been screened for tuberculosis activity.     

Studies in the cyperaceae of Thailand

Ten species ofCarex and one species ofKobresia from Thailand are taxonomically discussed, and some new range extensions into Thailand are noted. Described as new areCarex subinclinata andC. thailandica, both belonging to the sectionIndicae, andC. speciosa ssp.latifolia of the sectionRadicales. Two new combinations proposed areCarex helferi ssp.mapanifolia, andC. speciosa ssp.platyrhina.     

Studies on immunomodulatory properties of isoniazid: V. Influence of isoniazid on secretion of interleukin-1.

Isoniazid in vitro decreased interleukin-1 production by glass-adherent cells from the blood of healthy donors. The previously described modulation of T cell activation by isoniazid seems to be independent of decreased interleukin-1 secretion.     

Studies on the biocontrol of aflatoxin in maize in Thailand

Aflatoxins in maize and peanuts remain a major cause of liver cancer and other human and animal health issues. The principal causal fungi are Aspergillus flavus and A. parasiticus. Relatively little attention has been paid to reducing aflatoxin formation before harvest. The most promising approach is biocontrol by competitive exclusion. This project aimed to demonstrate the efficacy of locally isolated strains of A. flavus for biocontrol of aflatoxin in maize in Thailand. After a rigorous process utilising molecular methods was used to select non-toxigenic A. flavus strains, field inoculum was produced by using hulled rice coated with A. flavus spores in molasses. Field experiments were conducted over two years in two districts, one of light sandy soil (Chokchai), the other a heavy, close textured, soil (Pakchong). Postharvest treatments representative of local practice were also undertaken. Crops 1 and 2 were not significantly contaminated with aflatoxin at the time of harvest, so any impact of biocontrol could not be assessed. However, wet shelling plus storage before drying resulted in increased aflatoxin contamination; biocontrol had no impact on this increase. In crops 3 and 4, biocontrol had a beneficial impact in some freshly harvested maize. Biocontrol treatments also significantly reduced aflatoxin contamination in samples from some treatments stored for two or four days after shelling, but had minimal effect in others. These experiments demonstrated that biocontrol can be highly effective in reducing aflatoxin contamination in maize in Thailand, both at harvest and during poor postharvest crop handling. However, results were inconsistent.     

Studies on immunomodulatory properties of isoniazid. III. Effect of isoniazid on proliferation of interleukin-dependent and interleukin-independent cell line

The effect of various concentrations of isoniazid on proliferation of the interleukin 2-dependent cell line, HT-2 and continuous T cell line Jurkat was studied. It was found that high doses of isoniazid increased proliferation of the HT-2 cells in presence of suboptimal doses of interleukin 2. Low doses had no effect on proliferation. The unstimulated Jurkat cells increased proliferation in presence of low doses of isoniazid while phytohemagglutinin-stimulated cells responded to high doses of the drug only. It is hypothesized that biphasic effect of isoniazid is caused by cumulation of direct and indirect effects of T cell activation as well as toxic influence on the cells.     

Determination of isonicotinic acid in the presence of isoniazid and acetylisoniazid Studies on isonicotinic acid formation from isoniazid in isolated rat hepatocytes

In comparison with the hepatocytes obtained from intact rats and rats pretreated with phenobarbital or 3-methylchoranthrene, the amount of isonicotinic acid (INA) formed from isoniazid (INH) increased substantially after incubation at 37°C using the pretreated hepatocytes. This suggests an oxidative pathway for INA formation from INH, apart from hydrolysis. In order to explore the exact mechanism of INA formation in the hepatocytes, an HPLC assay for INA in the presence of INH and acetylisoniazid was developed. In this assay, INA was extracted after the preparation of an ion pair with tetra-n-butylammonium hydroxide, and analysed using an ODS column and a mobile phase consisting of 0.067 M potassium dihydrogenphosphate solution-methanol (96:4 v/v). The method is simple, accurate and especially suitable for INA determination after incubation of INH in isolated rat hepatocytes.     

Studies on immunomodulatory properties of isoniazid. II. Effect of isoniazid on interleukin 2 production and interleukin 2-receptor expression

The effect of isoniazid on interleukin 2 production and interleukin 2-receptor expression by phytohemagglutinin-stimulated human T cells was investigated. High concentrations of the drug decreased interleukin 2 production while low doses (10(-5)-10(-6) M) produced a slight increase in interleukin 2 production. Isoniazid did not affect the expression of interleukin 2-receptors on the surface of T cells, except a slight decrease in cells exposed to high levels of the drug.     

Studies on immunomodulatory properties of isoniazid. IV. Effect of isoniazid on T lymphocyte activation by phorbol ester tumor promoter

Human peripheral blood T cells or continuous T cell lines were treated with phorbol myristate (PMA), a direct protein kinase C activator. The effect of isoniazid on PMA-treated cells was investigated. It was found that low doses of isoniazid augmented proliferation of T cells treated with PMA or stimulated with PMA and phytohemagglutinin. Similar results were shown in the Jurkat cell line. There was no influence of isoniazid upon proliferation of PMA-treated HT-2 cells, interleukin 2-dependent cell line. The obtained results suggest that, at least one target mechanism of isoniazid is located in T cell activation pathway after protein kinase C activation.     

Studies of isoniazid metabolism in isolated rat hepatocytes by mass fragmentography

Isoniazid metabolism in isolated rat hepatocytes was studied by mass fragmentography using single ion monitoring. Isoniazid and its metabolites were determined as the trimethylsilylated derivatives of acetylisoniazid and diacetylhydrazine and of the benzaldehyde hydrazones of isoniazid and acetylhydrazine. Deuterated analogues served as internal standards. Hydrazine was quantitated as benzalazine using ¹⁵N-labeled hydrazine as an internal standard. The method is well suited for the microanalysis of isoniazid metabolites in specificity and reliability to demonstrate the overall pathway of isoniazid metabolism, from which it was clarified that the greater part of hydrazine, a hazardous metabolite of isoniazid, was formed through the direct hydrolysis of isoniazid itself as expected.     

秸秆分层多级转化液体燃料新工艺的研究进展

目前,秸秆主要作为性质单一组分的纤维素原料而采用生物转化法或快速热解法加以利用。生物转化法主要利用纤维素,而利用木质素和半纤维素较困难;快速热解生物质又使部分组分低值利用,而且得到的生物油品质低。为解决单一的生物或热转化方式存在的问题,提出秸秆分层多级转化液体燃料的新构思,即以秸秆“组分分离、分级定向转化”为核心,将生物转化和热转化有机结合多级转化生产燃料酒精与生物油。研究结果表明,秸秆经过汽爆处理后,采用高浓度发酵一分离乙醇耦合系统,可降低纤维素酶用量,提高了纤维素酶解效率,而且简化操作过程,使蒸馏前乙醇浓度达到60％以上。发酵乙醇剩余物再经热解后,不但热解温度较原秸秆明显降低,而且所得生物油品质有了明显改观。