Constituents of the essential oil from aerial parts of Chromolaena odorata from Thailand.

The chemical composition of the essential oil from the aerial parts of Chromolaena odorata, collected from Phitsanulok, Thailand was analyzed by means of GC-(FID) and GC-MS. Twenty-two constituents were identified. The major components were pregeijerene (17.6%), germacrene D (11.1%), alpha-pinene (8.4%), beta-caryophyllene (7.3%), vestitenone (6.5%), beta-pinene (5.6%), delta-cadinene (4.9%), geijerene (3.1%), bulnesol (2.9%), and trans-ocimene (2.2%).

Pharmacokinetics and bioavailability studies of generic ondansetron, and the innovator preparation, in healthy Thai male volunteers.

The pharmacokinetics and bioequivalence of two oral formulations of ondansetron were evaluated; Zetron (Biolab Pharmaceutical, Bangkok, Thailand), as the test formulation and Zofran (Glaxo Wellcome Operations, Greenford, UK), as the reference formulation. The two products were administered as a single oral dose of 8 mg according to a randomized two-way crossover design to 12 healthy Thai male volunteers. The washout period between treatment was 1 week. Ondansetron plasma concentrations were measured using HPLC. The oral bioavailability of ondansetron averaged 67 per cent and the elimination half-life after oral administration was 5.6 hours. The means and parametric 90 per cent CI of the ratios of Cmax and AUC 0-alpha [mu Zetron (Test)/mu Zofran (Reference)] were 0.95 (0.84-1.07) and 0.94 (0.80-1.10), respectively. These values were well within the bioequivalence range of 0.8-1.25 as established by the US-FDA. The mean difference of Tmax (Test-Reference) was approximately 20 per cent. Thus, our study demonstrated bioequivalence of the two products (Zetron and Zofran) regarding the rate and extent of absorption.

Dual effects of quercetin on contraction in cardiac and skeletal muscle preparations.

The effects of quercetin, a plant flavonoid, on contraction in cardiac and skeletal muscle preparations were examined. Higher concentrations of quercetin increased mean arterial blood pressure in anesthetized rats. Quercetin showed positive inotropic action on spontaneous contraction in a dose-dependent manner in isolated rat atria. Quercetin prevented the negative inotropism evoked by acetylcholine in isolated rat atria. On the other hand, quercetin inhibited the twitch contraction in isolated rat hemidiaphragm muscles. The addition of Ca2+ to extracellular medium recovered the inhibitory effects of twitch contraction in Ca2+-free medium but did not prevent the inhibitory effects of twitch contraction in Ca2+-free medium containing quercetin. The present results suggest that quercetin have a positive inotropic action in cardiac muscle but inhibitory effects on contraction in skeletal muscle.

The comparative bioavailability of a generic and the innovator fluconazole preparations in healthy Thai volunteers.

We studied the pharmacokinetics and compared the oral bioavailability of the "generic" (Biozole, Biolab Company, Thailand) and the "innovator" (Diflucan, Pfizer Incorporation, U.S.A.) fluconazole preparations in 12 healthy Thai volunteers. A 200 mg single oral dose of each preparation was given to the subjects in a randomized double-blind 2-period crossover design with 2 weeks washout period. Blood samples were collected just before and at 0.5, 1, 2, 2.5, 3, 4, 24, 48, 56 and 72 hours after drug administration. Serum fluconazole concentrations were determined by using high performance liquid chromatography. Individual concentration-time profiles and the pharmacokinetic parameters were analyzed by the noncompartmental pharmacokinetic method [TOPFIT, a pharmacokinetic data analysis program]. The pharmacokinetic parameters (Tmax, Cmax, Vd, Cl) of fluconazole in Thai healthy volunteers were comparable to those values observed in Caucasian subjects. The relative bioavailability of the generic Biozole was 102.38 +/- 9.79 per cent of Diflucan. The means and 90 per cent confidence intervals (90% CI) of the [Biozole/Diflucan] ratio of AUC0-72, AUC0-inf and Cmax were 1.02 (0.98-1.06), 0.99 (0.95-1.03) and 1.13 (1.03-1.25), respectively. These values were well within the acceptable bioequivalence ranges of 0.8-1.25 proposed by the US FDA. The means and 90 per cent CI of Tmax differences [Biozole-Diflucan] were -0.46 [(-1.03)-(0.12)]. This value was outside the stipulated bioequivalence range of +/- 0.41 h (+/- 20% of the Tmax of the reference formulation). Nevertheless, the Tmax difference was not expected to be related to the differences in safety and efficacy of the drug. Hence, Biozole and Diflucan were bioequivalent with respect to the extent of absorption (AUC), and the Cmax, and could be used interchangeably.

Inhibitory effect of dietary curcumin on skin carcinogenesis in mice.

Laboratory animal model studies have suggested that curcumin may play an important role in inhibiting the process of carcinogenesis. Curcumin, the yellow pigment that is obtained from rhizomes of the plant Curcuma longa Linn (Family Zingiberaceae), is commonly used as a spice and food coloring agent. The present study was designed to investigate the chemopreventive action of dietary curcumin on 7,12-dimethylbenz[a]anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted skin tumor formation in male Swiss ablino mice. At 6 weeks of age, groups of animals were fed the standard (modified AIN-76 A) diet or a diet containing 1% curcumin. At 8 weeks of age, all animals, except those in the vehicle (acetone)-treated groups, received 100 microg of DMBA dissolved in 100 microl of acetone in a single application to the skin of the back. From 1 week after DMBA application, tumor promoter (2.5 microg of TPA dissolved in 100 microl of acetone) was applied to the same areas on mouse skin twice a week for 26 weeks. All groups continued on their respective dietary regimen until the termination of the experiment. The results indicate that dietary administration of curcumin significantly inhibited the number of tumors per mouse (P < 0.05) and the tumor volume (P < 0.01). The percentage of tumor-bearing mice tended to be lower in the mice on the curcumin diet than those on the standard diet. There was no difference in growth between mice of the standard and 1% curcumin groups. The results indicate the safety and the anti-carcinogenic effect of curcumin in mice.

Antifungal activity of turmeric oil extracted from Curcuma longa (Zingiberaceae).

Turmeric oil and curcumin, isolated from Curcuma longa L., were studied against fifteen isolates of dermatophytes, four isolates of pathogenic molds and six isolates of yeasts. The inhibitory activity of turmeric oil was tested in Trichophyton-induced dermatophytosis in guinea pigs. The results showed that all 15 isolates of dermatophytes could be inhibited by turmeric oil at dilutions of 1:40-1:320. None of the isolates of dermatophytes were inhibited by curcumin. The other four isolates of pathogenic fungi were inhibited by turmeric oil at dilutions of 1:40-1:80 but none were inhibited by curcumin. All six isolates of yeasts tested proved to be insensitive to both turmeric oil and curcumin. In the experimental animals, turmeric oil (dilution 1:80) was applied by dermal application on the 7th day following dermatophytosis induction with Trichophyton rubrum. An improvement in lesions was observed in 2-5 days and the lesions disappeared 6-7 days after the application of turmeric oil.