Maitree Suttajit

Survey of microcystins in environmental water by a highly sensitive immunoassay based on monoclonal antibody

By using a highly sensitive enzyme-linked immunosorbent assay (ELISA) based on a monoclonal antibody, microcystin (MC) concentration was analyzed in environmental water samples (total, 134), collected in 1993-1995 from ponds, lakes, reservoirs, and rivers in Japan, Thailand, Germany, and Portugal. MCs detected in the water samples filtered over a glass filter were designated as free MCs, and those samples that were freeze-thawed twice before the filtration were designated as total MCs. MCs (> 50 pg/ml) were detected in 14 of 24 samples collected from the lakes that were used as recreation and water supply in Japan in different regions. In the MC-positive samples, the concentration of free MCs was only a few percentages of the total MCs, indicating that the most part of MCs found in the water samples was present in algal cells. An additional trial on 33 samples collected continuously from Lake Inbanuma, Japan, during June-September 1994-1995 revealed that the total MCs were in a range of 52-52,000 pg/ml. In Chiang Mai, Thailand, 6 of 10 samples were positive, with the mean and highest of 161 and 354 pg/ml, respectively. In the Frankfurt area. Germany, 4 of 10 and 7 of 8 samples collected in the same lakes for recreation in July 1993 and November-December 1994 showed the presence of MCs, with their mean and highest values of 257 and 407 pg/ml, respectively. Another survey of MCs in dense bloomed samples collected with plankton net revealed a contamination of MCs up to 36,000 pg/ml. In Portugal, 28 of 29 samples from 4 lakes, 20 rivers, and 5 reservoirs were positive for MCs, with the respective means of 13,664, 11,048, and 2,278 pg/ml. These data indicated that MCs contaminate environmental water in ponds, rivers, lakes, and reservoirs worldwide. The present ELISA is considered to be a reliable tool for the mass monitoring and risk assessment of MCs in water supplies.

Specific binding of okadaic acid, a new tumor promoter in mouse skin.

The tumor promoteradaic acid binds specifically to a particulate as well as a cytosolic fraction of various mouse tissues, e.g., skin, brain, lung and colon. The K D value was 21.7 nM for receptors in the particulate fraction and 1.0 nM for those in the cytosolic fraction of mouse skin. The specific binding of [3H]okadaic acid to the particulate fraction of mouse skin was inhibited dose‐dependently byadaic acid, but notaidaic acid tetramethyl ether, an inactive compound, or by other tumor promoters, such as 12‐O‐tetradecanoylphorbol‐13‐acetate and teleocidin. The results suggest a new pathway of tumor promotion mediated through theadaic acid receptor(s).

5α-reductase inhibition and hair growth promotion of some Thai plants traditionally used for hair treatment.

ETHNOPHARMACOLOGICAL RELEVANCE Many Thai traditional herbs have been used for hundreds of years for hair treatment and nourishment, including hair loss. However, scientific evidence about their mechanisms of action has not yet been elucidated. AIMS OF THE STUDY The purpose of this research is to define the possible mechanisms involved in hair loss treatment of the selected plants by determining the 5α-reductase enzyme inhibition and hair growth promoting activities, and the relationship between these two activities. MATERIALS AND METHODS Seventeen Thai plants traditionally used for hair treatment were selected. The plants were dried, ground and extracted by maceration with ethyl alcohol. These extracts were further tested for 5α-reductase inhibition using enzymes from rat livers. Hair growth promoting activity was tested in C57BL/6 mice. RESULTS Carthamus tinctorius L. was the most potent 5α-reductase inhibitor, with a finasteride equivalent 5α-reductase inhibitory activity (FEA) value of 24.30±1.64 mg finasteride equivalent per 1g crude extract. Phyllanthus emblica L. was the second most potent inhibitor, with FEA of 18.99±0.40. Rhinacanthus nasutus (L.) Kurz. was the least potent 5α-reductase inhibitor (FEA 10.69±0.96). Carthamus tinctorius also was the most potent hair growth promoter in C57BL/6 mice. There were strong relationships between 5α-reductase inhibitory activity and hair growth promoting activity (r=0.719), and between 5α-reductase inhibitory activity and hair follicle count (r=0.766). CONCLUSIONS Ethanolic extract of Carthamus tinctorius was the most potent 5α-reductase inhibitor and hair growth promoter. This discovery may lead to the development of new alternative medicines for hair loss prevention and treatment.

Geographic Distribution of Liver and Stomach Cancers in Thailand in Relation to Estimated Dietary Intake of Nitrate, Nitrite, and Nitrosodimethylamine

It is our working hypothesis that the high rate of the liver and gastric cancers in North and Northeast Thailand is associated with increased daily dietary intake of nitrate, nitrite, and nitrosodimethylamine (NDMA). Samples of fresh and preserved Thai foods were systematically collected and analyzed from 1988 to 1996 and from 1998 to 2005. Consumption frequencies of various food items were determined on the basis of a dietary questionnaire given to 467 adults (212 males and 255 females) from 1998 to 2005. Food consumption data for the preceding and current year were collected and intakes (day, week, and month) of nitrate, nitrite, and NDMA were calculated. The trends in liver and stomach cancer age-standardized incidence rates (ASR) in four regions of Thailand were compared with the dietary intake of nitrate, nitrite, and NDMA in those same geographic regions. Mean daily intakes of nitrate of 155.7 mg/kg, of nitrite of 7.1 mg/kg, and of NDMA of 1.08 μ g/kg per day were found. Significant differences in dietary nitrate, nitrite, and NDMA intakes were seen between various Thai regions (P < 0.0001), and these corresponded to the variations in liver and stomach cancer ASR values between the regions. Dietary factors are likely to play key roles in different stages of liver and stomach carcinogenesis in Thailand.

In-house direct cELISA for determining aflatoxin B1 in Thai corn and peanuts.

To overcome the problem of aflatoxins (AF) in Thai foods, a sensitive in-house direct cELISA using monoclonal antibody (mAb) was established and compared with a commercial ELISA kit and thin-layer chromatography for the determination of AFB1 levels in corn and peanuts. Among eight in-house mAbs (AF1-8), AF5 was used in the direct cELISA owing to its excellent specificity and sensitivity with the detection limit of 4 µg kg−1. The recovery of AFB1 spiked at 5, 10, 20, 40 and 80 µg kg−1 ranged from 88.1 to 99.5%. Correlation coefficients of the ELISA with the commercial ELISA kit and thin-layer chromatography were 0.912 and 0.802 for corn, and 0.941 and 0.832 for peanuts, respectively (p<0.05). The cost per sample was estimated to be about 16 times lower than the commercial ELISA kit. Subsequently, the in-house direct cELISA was successfully applied to screen the contamination of AFB 1 in Thai corn and peanuts. Mean levels of AFB 1 (per cent positive) were 73 µg kg−1 (85.7%) in corn and 102 µg kg−1 (67.9%) in peanuts, for which 46.4% of both foods were above the Thailand regulation limit (20 %g kg−1).

Effects of Phenolic Compounds of Fermented Thai Indigenous Plants on Oxidative Stress in Streptozotocin-Induced Diabetic Rats

We investigated the effects of antioxidant activity of fermentation product (FP) of five Thai indigenous products on oxidative stress in Wistar rats with streptozotocin (STZ)-induced diabetes type II. The rats were fed with placebo and with the FP (2 and 6 mL/kg body weight/day) for 6 weeks. Rutin, pyrogallol and gallic acid were main compounds found in the FP. Plasma glucose levels in diabetic rats receiving the higher dose of the FP increased less when compared to the diabetic control group as well as the group receiving the lower FP dose (13.1%, 29%, and 21.1%), respectively. A significant dose-dependent decrease in plasma levels of thiobarbituric acid reactive substance (P < .05) was observed. In addition, the doses of 2 and 6 mL FP/kg/day decreased the levels of erythrocyte ROS in diabetic rats during the experiment, but no difference was observed when compared to the untreated diabetic rat group. Results imply that FP decreased the diabetes-associated oxidative stress to a large extent through the inhibition of lipid peroxidation. The FP also improved the abnormal glucose metabolism slightly but the difference was not statistically significant. Thus, FP may be a potential therapeutic agent by reducing injury caused by oxidative stress associated with diabetes.

Microchemical Components and Antioxidant Activity of Different Morphological Parts of Thai Wild Purslane (Portulaca oleracea)

Abstract Purslane weed has long been used for animal feed in Thailand but has been underutilized, and no published data exist on the chemical and nutritional qualities of Thai wild purslane. In this study, we aimed to determine the microchemical components of purslane stem, leaf, and flower, including the phenolic acid, flavonoid, ascorbic acid, β-carotene, and fatty acid content. The water extract of the flower fraction contained the highest total phenolic acid content and had the highest O2-scavenging activities, whereas leaf contained the highest amount of total flavonoids and ascorbic acid. The β-carotene content was not significantly different in leaf and flower fractions but was significantly greater than that in stem (P < 0.05). The predominant phenolic acid was chlorogenic acid for all fractions. Rutin was the major flavonoid found in leaf, and myricetin was highest in flower and stem. Alpha linolenic acid (18 : 3n-3) content ranged from 16% (149 mg per 100-g sample) of total fatty acid in stem to 50% (523 mg per 100-g sample) in leaf. We suggest that Thai wild purslane could be considered a nutritional source for animal feed or an excellent vegetable in the human diet. Nomenclature: Thai wild purslane (common purslane), Portulaca oleracea L.

Suppressive effect of soybean milk protein on experimentally induced skin tumor in mice

We studied the effect of soybean milk protein (SMP) in a two-stage carcinogenesis experiment on mouse skin. Mice were given soybean protein isolate (SPI) diet or SPI diet supplemented with SMP. After 4 weeks on the diets, the mice were shaved and a tumor initiator was applied. A tumor promotor was then applied twice a week on the same area of the skin throughout the experiment. After 20 weeks on the treatment, the percentage of tumor-bearing mice and the volume of tumor tended to be lower in the mice on the SMP diet than those on the SPI diet. The number of tumor was also significantly lower in the former group as compared to the latter group. There was no difference in growth between mice of the SPI and SMP groups. The results indicate the safety and the anti-carcinogenic effect of SMP in mice.

Phorbol esters in seed oil of Jatropha curcas L. (saboodam in Thai) and their association with cancer prevention: from the initial investigation to the present topics

PurposeIn 1988, we first reported the complete chemical structure of a new type of phorbol ester, abbreviated to DHPB, found in seed oil of Jatropha curcas L. (Saboodam in Thai) and its tumor-promoting activity on mouse skin. Although this seed oil contains toxic phorbol ester, it was planned to use it as a feasible renewable oil and the extracted seed cake as fertilizer. This utilization value opened a new science of Jatropha curcas.MethodsThe main experimental results are cited from our publications, and the relevant literature screened from journals and PubMed.Results and discussionThis paper begins with our original work on the structural elucidation of a new phorbol ester, 12-deoxy-16-hydroxyphorbol (DHPB): its tumor-promoting activity was compared with that of TPA. We think that it is timely to review the following research advances with Jatropha curcas, so numerous topics are classified as follows: (1) historical development of phorbol esters in seed oil; (2) toxicity of phorbol ester based on various bioassays; (3) degradation of phorbol ester; (4) a new pharmaceutical compound in seed; and (5) tumor promotion and progression with endogeneous tumor promoters in human carcinogenesis. The discovery of phorbol ester in seed oil raised awareness of the danger of public use of seed oil and seed cake in Thailand, and also indicated the necessity of discussing the concept of primary and tertiary cancer preventions.ConclusionIt is worthwhile to study the future benefits and cancer risks of globally distributed Jatropha curcas L.

Impact of different pre-treatment strategies on the quality of fatty acid composition, tocols content and metabolic syndrome related activities of Perilla frutescens seed oil.

Article history: Received on: 02/11/2015 Revised on: 23/12/2015 Accepted on: 09/01/2016 Available online: 27/02/2016 Perilla frutescens (Nga-Mon) is an annual herbaceous plant, reported for its antioxidant, anti-allergic, antiinflammatory and neuroprotective properties. The current study was conducted to compare the different pretreatment techniques followed by hexane extraction for perilla seed oil and its pharmaceutical values. There are no significant differences in the yield of seed oil after pre-treatments except sonication. All the pre-treatments diminish the endogenous lipase activity, peroxidation and degradation of the oil. Fatty acid content analysis revealed that the nutrient quality, with respect to fatty acid content, of perilla seed was not compromised with any of the pre-treatments of current study. The results of αamylase, αglucosidase and protein glycation inhibition assays suggested that tested perilla seed oils are pharmaceutical candidate for the treatment of carbohydrate related diseases, especially for diabetes. Selection of appropriate pre-treatment strategies will helps to extract the perilla seed oil without any compromise in its quality. The current study suggested that moist heat with pressure can be an appropriate pre-treatment method for perilla seed oil extraction.