Sensitive high-performance liquid chromatographic assay for pilocarpine in biological fluids using fluorescence derivatisation

A sensitive assay for pilocarpine in biological fluids has been developed involving HPLC of a fluorescent derivative of 4-bromomethyl-7-methoxycoumarin. Pilosine as internal standard was added before the derivatisation step. The fluorescent derivatives were well resolved and separated from excess reagent and endogeneous compounds on a cyanopropyl silica column. The detection limit of pilocarpine in biological fluids was 1.0 ng/ml and the assay was linear up to a concentration of 150 ng/ml. The assay was applied to a preliminary study of pilocarpine disposition in man after a single oral dose. This is the first report of pilocarpine excretion into saliva.     

Histopathological Changes in Tissues of Bithynia siamensis goniomphalos Incubated in Crude Extracts of Camellia Seed and Mangosteen Pericarp

The present study was performed to observe histopathological changes in tissues of Bithynia siamensis goniomphalos (Gastropoda, Bithyniidae) incubated in crude extract solutions of camellia (Camellia oleifera) seed and mangosteen (Garcinia mangostana) pericarp, and furthermore to estimate the molluscicidal effects of 2 plant substances. Substantial numbers of bithyniid snails were incubated in various concentrations of 2 plant solution for 24 hr. As the positive control, snails incubated in various concentrations of niclosamide, a chemical molluscicide, were used. The histopathological findings were observed in sectioned snail specimens of each experimental and control groups. The results showed that both camellia and mangosteen extracts had molluscicidal effects at 24 hr with 50% lethal concentration (LC₅₀) at concentrations of 0.003 and 0.002 g/ml, respectively, while niclosamide had LC₅₀ at concentrations 0.599 ppm. B. siamensis goniomphalos snail tissues (foot, gill, and digestive system) showed disruption of columnar muscle fibers of the foot, reduction of the length and number of gill cilia, numerous mucous vacuoles, and irregularly shaped of epithelial cells. Irregular apical and calciferous cells, dilatation of the digestive gland tubule, and large hemolymphatic spaces, and irregular apical surfaces, detachment of cilia, and enlargement of lysosomal vacuoles of epidermis were also shown in all groups. By the present study, it is confirmed that 2 plants, camellia and mangosteen, are keeping some substance having molluscicidal effects, and histopathological findings obtained in this study will provide some clues in further studies on their action mechanisms to use them as natural molluscicides.     

Serotype and PCR-fingerprints of Clinical and Environmental isolates of Cryptococcus neoformans in Chiang Mai,Thailand

From May 1999 to April 2000, serotypes of clinical and environmental isolates of Cryptococcus neoformans were studied in Chiang Mai province, northern Thailand. Three hundred and eighty-five environmental samples, of which 100 were dove droppings, 55 pigeon droppings and 230 eucalyptus flower, were collected from 7 Amphoes in Chiang Mai. C. neoformans was isolated from 45 of 100 (45.0%) dove dropping samples, 9 of 55 (16.4%) pigeon dropping samples and 2 of 230 (0.9%) eucalyptus flower samples. Serotypes of 56 environmental isolates and 75 clinical isolates of C. neoformans,obtained during the same period, were determined by the slide agglutination test. Fifty-six environmental and 74 clinical isolates belonged to C. neoformans serotype A (C. neoformans var. grubii), and only one clinical isolate belonged to C. neoformans serotype AD. The isolation of C. neoformans var. grubii from eucalyptus flower samples suggests contamination of avian droppings. PCR-fingerprinting, using (GACA)4 as a primer, discriminated 131 clinical and environmental isolates into 2 groups (group I and II). Seventy-five clinical and 54 environmental isolates were of group I, which had two major specific bands of approximately 1,250 and 960 base pairs. Two environmental isolates, one from pigeon excreta and the other from a eucalyptus flower sample were of group II, which had two major specific bands of approximately 1,180 and 500 base pairs.     

Chroman amide and nicotinyl amide derivatives: Inhibition of lipid peroxidation and protection against head trauma

A series of chroman amide and nicotinyl amide derivatives was designed and synthesized for the treatment of traumatic and ischemic CNS injury. Five compounds were significantly more potent inhibitors of lipid peroxidation in vitro than the reference antioxidant, trolox (p < 0.01). Quantitative structure activity studies demonstrated that the inhibitory action was related to the ability to donate electrons, charge on hydroxy group and E_LUMO, to scavenging radicals and to the lipophilicity log P, which determines penetration of membrane lipids. ESR study indicated the ability of 12 to scavenge the hydroxyl radicals. The most promising compound, [(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2yl)carbonyl]-3′-(aminoethyl) indole (12), inhibited ex vivo lipid peroxidation in a head injury model and showed potent in vivo neuroprotective efficacy. Improvement of neurological recovery within 1 h of injury (grip test score) by as much as 200% was observed together with significant anti-anoxia activity. Compound 12 was a potent antagonist of methamphetamine-induced hypermotility resulting from dopamine release in the mouse brain. These results support the importance of cerebroprotective radical-scavenging agents for the treatment of traumatic injury and anoxia as well as provide additional evidence for the role of oxygen radicals and dopamine in brain damage.     

A novel neuroprotective agent with antioxidant and nitric oxide synthase inhibitory action

N^α-vanillyl-N^ω-nitroarginine (N ? 1) that combines the active functions of natural antioxidant and nitric oxide synthase inhibitor was developed for its neuroprotective properties. N ? 1 exhibited protective effects against hydrogen peroxide-induced cell damage and the inhibitory effect on nitric oxide ‘NO’ production induced by calcium ionophore in NG 108-15 cells. N ? 1 inhibited the constitutive NOS isolated from rat cerebellar in a greater extent than constitutive NOS from human endothelial cells. Low binding energy ( ? 10.2 kcal/mol) obtained from docking N ? 1 to nNOS supported the additional mode of action of N ? 1 as an nNOS inhibitor. The in vivo neuroprotective effect on kainic acid-induced nitric oxide production and neuronal cell death in rat brain was investigated via microdialysis. Rats were injected intra-peritonially with N ? 1 at 75 μmol/kg before kainic acid injection (10 mg/kg). The significant suppression effect on kainic acid-induced NO and significant increase in surviving cells were observed in the hippocampus at 40 min after the induction.     

Aging Effect of a Cu(In,Ga)(S,Se)2 Absorber on the Photovoltaic Performance of Its Cd‐Free Solar Cell Fabricated by an All‐Dry Process: Its Carrier Recombination Analysis

Cd‐free Cu(In,Ga)(S,Se)₂ (CIGSSe) solar cells are fabricated by an all‐dry process (a Cd‐free and all‐dry process CIGSSe solar cell) with aged CIGSSe thin film absorbers. The aged CIGSSe thin films are kept in a desiccator cabinet under partial pressure of oxygen of ≈200 Pa for aging time up to 10 months. It is reported for the first time that aged CIGSSe thin film with increased aging time results in significant enhancement of photovoltaic performance of Cd‐free and all‐dry process CIGSSe solar cells, regardless of the alkali treatment. Based on carrier recombination analysis, carrier recombination rates at the interface and in the depletion region of the Cd‐free and all‐dry process CIGSSe solar cells are reduced owing to avoidance of sputtering damage on CIGSSe absorber surface, which is consistent with the strong electron beam‐induced current signal near CIGSSe surface after the increased aging time. It is implied that the interface and near‐surface qualities are clearly improved through the increased aging time, which is attributable to the self‐forming of In_x(O,S)_y near CIGSSe surface, which acts as a buffer layer. Ultimately, the 22.0%‐efficient Cd‐free CIGSSe solar cell fabricated by all‐dry process is achieved with the aged Cs‐treated CIGSSe absorber with the aging time of 10 months.     

Triazolyl tryptoline derivatives as β-secretase inhibitors

Tryptoline, a core structure of ochrolifuanine E, which is a hit compound from virtual screening of the Thai herbal database against BACE1 was used as a scaffold for the design of BACE1 inhibitors. The tryptoline was linked with different side chains by 1,2,3-triazole ring readily synthesized by catalytic azide-alkyne cycloaddition reactions. Twenty two triazolyl tryptoline derivatives were synthesized and screened for the inhibitory action against BACE1. JJCA-140 was the most potent inhibitor (IC(50)=1.49 μM) and was 100 times more selective for BACE1 than for Cat-D.     

Architectural changes of heated mungbean, rice and cassava starch granules: Effects of hydrocolloids and protein-containing envelope

Architectural changes of starch granules induced by heat were demonstrated using light microscopy and confocal laser scanning microscopy. Heat treatment (80 °C, 30 min) on mungbean starch, cassava starch and rice flour suspensions resulted in the rearrangement of amylose and granule-associated proteins within the deformed granules. The presence of alginate and carrageenan influenced the RVA pasting characteristics of starch/flour-hydrocolloid mixed suspensions by maintaining the granular structure of amylose-rich swollen granules or inducing the aggregation of the swollen ones. Generally, the addition of hydrocolloid increased peak viscosity, lowered breakdown and reduced setback of the flour-hydrocolloid mixed paste. This study demonstrated that the heat treatment in excess water generated the protein-containing granule envelope encasing the mungbean and cassava starch content within the deformed granules.