Protective Effect of Perilla Seed Meal and Perilla Seed Extract against Dextran Sulfate Sodium-Induced Ulcerative Colitis through Suppressing Inflammatory Cytokines in Mice

An excessive inflammatory response of the gastrointestinal tract is recognized as one of the major contributors to ulcerative colitis (UC). Despite this, effective preventive approaches for UC remain limited. Rosmarinic acid (RA), an enriched fraction from Perilla frutescens, has been shown to exert beneficial effects on disease-related inflammatory disorders. However, RA-enriched perilla seed meal (RAPSM) and perilla seed (RAPS) extracts have not been investigated in dextran sulfate sodium (DSS)-induced UC in mice. RAPSM and RAPS were extracted using the solvent-partitioning method and analyzed with high-pressure liquid chromatography (HPLC). Mice with UC induced using 2.5% DSS for 7 days were pretreated with RAPSM and RAPS (50, 250, 500 mg/kg). Then, the clinical manifestation, colonic histopathology, and serum proinflammatory cytokines were determined. Indeed, DSS-induced UC mice exhibited colonic pathological defects including an impaired colon structure, colon length shortening, and increased serum proinflammatory cytokines. However, RAPSM and RAPS had a protective effect at all doses by attenuating colonic pathology in DSS-induced UC mice, potentially through the suppression of proinflammatory cytokines. Concentrations of 50 mg/kg of RAPSM and RAPS were sufficient to achieve a beneficial effect in UC mice. This suggests that RAPSM and RAPS have a preventive effect against DSS-induced UC, potentially through alleviating inflammatory responses and relieving severe inflammation in the colon.

Bioefficacy of Nga-Mon (Perilla frutescens) Fresh and Dry Leaf: Assessment of Antioxidant, Antimutagenicity, and Anti-Inflammatory Potential

Perilla leaves are known to be a rich source of polyphenols, which have been shown to exhibit various biological effects. This study aimed to compare the bioefficacies and bioactivities of fresh (PLE_f) and dry (PLE_d) Thai perilla (Nga-mon) leaf extracts. Phytochemical analysis indicated that both PLE_f and PLE_d were abundant in rosmarinic acid and bioactive phenolic compounds. PLE_d, which had higher levels of rosmarinic acid but lower levels of ferulic acid and luteolin than PLE_f, exhibited greater effectiveness in a free radical scavenging assay. Furthermore, both extracts were found to suppress intracellular ROS generation and exhibit antimutagenic activity against food-borne carcinogens in S. typhimurium. They also attenuated lipopolysaccharide-induced inflammation in RAW 264.7 cells by inhibiting the expression of nitric oxide, iNOS, COX-2, TNF-α, IL-1β, and IL-6 through the suppression of NF-κB activation and translocation. However, PLE_f exhibited a higher ability to suppress cellular ROS production and higher antimutagenic and anti-inflammatory activities than PLE_d, which can be attributed to its combination of phytochemical components. Overall, PLE_f and PLE_d have the potential to serve as natural bioactive antioxidant, antimutagenic, and anti-inflammatory agents to achieve potential health benefits.

Molecular Mechanism of Antioxidant and Anti-Inflammatory Effects of Omega-3 Fatty Acids in Perilla Seed Oil and Rosmarinic Acid Rich Fraction Extracted from Perilla Seed Meal on TNF-α Induced A549 Lung Adenocarcinoma Cells

Industrially, after the removal of oil from perilla seeds (PS) by screw-type compression, the large quantities of residual perilla seed meal (PSM) becomes non-valuable waste. Therefore, to increase the health value and price of PS and PSM, we focused on the biological effects of perilla seed oil (PSO) and rosmarinic acid-rich fraction (RA-RF) extracted from PSM for their role in preventing oxidative stress and inflammation caused by TNF-α exposure in an A549 lung adenocarcinoma culture model. The A549 cells were pretreated with PSO or RA-RF and followed by TNF-α treatment. We found that PSO and RA-RF were not toxic to TNF-α-induced A549 cells. Both extracts significantly decreased the generation of reactive oxygen species (ROS) in this cell line. The mRNA expression levels of IL-1β, IL-6, IL-8, TNF-α, and COX-2 were significantly decreased by the treatment of PSO and RA-RF. The Western blot indicated that the expression of MnSOD, FOXO1, and NF-κB and phosphorylation of JNK were also significantly diminished by PSO and RA-RF treatment. The results demonstrated that PSO and RA-RF act as antioxidants to scavenge TNF-α induced ROS levels, resulting in decreased the expression of MnSOD, FOXO1, NF-κB and JNK signaling pathway in a human lung cell culture exposed to TNF-α.

Anti-inflammatory effect of Perilla frutescens seed oil rich in omega-3 fatty acid on dextran sodium sulfate-induced colitis in mice

Background and purpose

Ulcerative colitis is a chronic inflammatory bowel disease that involves diffused inflammation of the large intestine. Omega-3 fatty acid (FA) has been known to regulate the inflammatory response associated with ulcerative colitis pathogenesis. Perilla frutescens is a valuable source of omega-3 FA and α-linolenic acid (ALA) contained in its seed oil. Therefore, the aim of this study was to evaluate the anti-inflammatory effect of Perilla seed oil (PSO) on colitis induced by dextran sulfate sodium (DSS) in a mouse model.

Experimental approach

PSO was extracted using a cold-pressed extractor and FA composition of PSO was analyzed by GC-MS. Acute colitis in mice was induced with 3% DSS in drinking water for 7 days. Some mice were treated with PSO (20, 100, 200 mg/kg BW) for 3 weeks before the DSS administration. Sulfasalazine was used as a positive control. The clinical features, histopathologic, serum, and gene expression of proinflammatory cytokines in the colon were assessed.

Finding/Results

PSO contained the highest proportion of ALA (61.51%). Furthermore, PSO pretreatment evidently reduced body weight loss, diminished diarrhea, gross bleeding, and DSS-induced colon shortening. PSO pretreatment attenuated histopathological changes in response to DSS-induced colitis. PSO pretreatment also markedly decreased inflammatory response in serum and the colon tissue of DSS-induced mice.

Conclusion and implication

ALA in PSO is suggested to be mainly responsible for the reduction of DSS-induced colitis through suppressing inflammatory markers. PSO could be further developed as a functional health supplement, which would be beneficial for anti-inflammation in the colonic mucosa.

Suppressive Effects of Rosmarinic Acid Rich Fraction from Perilla on Oxidative Stress, Inflammation and Metastasis Ability in A549 Cells Exposed to PM via C-Jun, P-65-Nf-Κb and Akt Signaling Pathways

Particulate matter from forest fires (PMFF) is an environmental pollutant causing oxidative stress, inflammation, and cancer cell metastasis due to the presence of polycyclic aromatic hydrocarbons (PAHs). Perilla seed meal contains high levels of polyphenols, including rosmarinic acid (RA). The aim of this study is to determine the anti-oxidative stress, anti-inflammation, and anti-metastasis actions of rosmarinic acid rich fraction (RA-RF) from perilla seed meal and its underlying molecular mechanisms in A549 cells exposed to PMFF. PMFF samples were collected via the air sampler at the University of Phayao, Thailand, and their PAH content were analyzed using GC-MS. Fifteen PAH compounds were detected in PMFF. The PMFF significantly induced intracellular reactive oxygen species (ROS) production, the mRNA expression of pro-inflammatory cytokines, MMP-9 activity, invasion, migration, the overexpression of c-Jun and p-65-NF-κB, and Akt phosphorylation. Additionally, the RA-RF significantly reduced ROS production, IL-6, IL-8, TNF-α, and COX-2. RA-RF could also suppress MMP-9 activity, migration, invasion, and the phosphorylation activity of c-Jun, p-65-NF-κB, and Akt. Our findings revealed that RA-RF has antioxidant, anti-inflammatory, and anti-metastasis properties via c-Jun, p-65-NF-κB, and Akt signaling pathways. RA-RF may be further developed as an inhalation agent for the prevention of lung inflammation and cancer metastasis induced by PM exposure.

Inhibitory Effect of a Rosmarinic Acid-Enriched Fraction Prepared from Nga-Mon (Perilla frutescens) Seed Meal on Osteoclastogenesis through the RANK Signaling Pathway

The aim of this study is to determine antioxidant and anti-inflammatory activities relating to the antiosteoporosis effects of various perilla seed meal (PSM) fractions. The remaining waste of perilla seed obtained from cold oil compression was extracted with 70% ethanol and sequentially fractionated according to solvent polarity with hexane, dichloromethane, ethyl acetate, and water. The results indicated that the seed-meal ethyl acetate fraction (SMEF) exhibited the highest antioxidant and anti-inflammatory activities, and rosmarinic acid (RA) content. The signaling pathways induced by the receptor activator of the nuclear factor kappa B (NF-κB) ligand (RANKL) that trigger reactive oxygen species (ROS) and several transcription factors, leading to the induction of osteoclastogenesis, were also investigated. The SMEF clearly showed attenuated RANKL-induced tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts and TRAP activity. A Western blot analysis showed that the SMEF significantly downregulated RANKL-induced NF-κB, AP-1 activation, and the nuclear factor of activated T-cell 1 (NFATc1) expression. SMEF also suppressed RANKL-induced osteoclast-specific marker gene-like MMP-9 using zymography. Furthermore, the SMEF showed inhibition of RANKL-induced ROS production in RAW 264.7 cells. The results suggest that the SMEF, which contained high quantities of RA, could be developed as a natural active pharmaceutical ingredient for osteoclastogenic protection and health promotion.

The innovation of functional foods in Asia: IFFA 2018

Functional foods (FF) are commonly consumed by Asians, and this trend has increased in recent years. Despite the reported health benefits of FF, it is necessary scrutiny and updates of the underpinning research are important. The first international conference on functional food innovation in Asia (IFFA 2018) took place on January 22nd- 24th, 2018, at the University of Phayao, Thailand. Domestic and international speakers, researchers, nutritionists, dieticians, research scholars and students shared their knowledge and experience in FF research. Key features were the potential beneficial roles of FF in health and disease, the current situation with FF in Asia and innovative trends. The IFFA 2018 involved 2 keynote speakers, 34 invited speakers and 10 sessions. About 250 people from across Asia participated. Key themes, discussions, innovative opportunities, and future directions to link research in academia with health-directed applications as FF are summarised.

Rosmarinic Acid Enriched Fraction from Perilla frutescens Leaves Strongly Protects Indomethacin-Induced Gastric Ulcer in Rats

Gastric ulcers are a common problem in upper gastrointestinal tract (GI) disorders. Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most aggressive factors leading to inducing gastric ulcers. Natural products with lower toxicity and safety are currently sought as a potential source to minimize the effect of the gastric ulcers. Perilla frutescens or Nga-mon (in Thai) leaves are rich in rosmarinic acid (RA), which has antioxidant, anti-inflammatory, and anticancer effects. This study investigates the protective effect of ethanolic extract (EE) and aqueous fraction (AF) from Perilla frutescens leaves, which are rich in RA, on indomethacin- (IND-) induced gastric ulcer in a rat model. The EE at the doses of 50 and 500 mg/kg body weight, AF at the doses of 50, 250, and 500 mg/kg body weight, or famotidine (a standard drug) were administered for 14 days prior to ulcer induction. The ulceration was performed by intragastric administration of IND. Gross gastric ulcers and biological and histological parameters were examined. The pretreatment with AF had more significant effects than EE, including reduced ulcer index, decreased gastric secretion volume and decreased acidity, but it had an elevated gastric pH relative to the IND-induced gastric ulcer. In a histopathological study, the EE and AF decreased mucosal ulcer, inflammatory infiltration, and degenerative lining cells. The IND-induced expression of inflammatory mediators was significantly attenuated with EE and AF. The experiment also remarkably showed the preservation of mucus and apoptosis protection of EE and AF on a gastric mucosal ulcer. The findings demonstrated that the EE and AF of perilla leaves were capable of protecting the stomach against gastric ulcers induced by IND through anti-inflammatory and antiapoptotic mechanisms that should be further investigated. It is suggested that Perilla frutescens leaf could be a potential alternative source of RA as a therapeutic agent and food supplement for NSAID-induced gastric injuries.

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

PURPOSE

In 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.

METHODS

The main experimental results are cited from our publications, and the relevant literature screened from journals and PubMed.

RESULTS AND DISCUSSION

This 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.

CONCLUSION

It is worthwhile to study the future benefits and cancer risks of globally distributed Jatropha curcas L.

A checklist of Recent non-marine ostracods (Crustacea: Ostracoda) from Thailand, including descriptions of two new species

A checklist covering a total of 67 Recent non-marine ostracod species from Thailand, belonging to 33 genera and seven families (Cyprididae, Candonidae, Ilyocyprididae, Notodromadidae, Darwinulidae, Limnocytheridae, Loxoconchidae), is presented. Twenty-five of these are considered endemic to the Oriental region, 17 of which are Thai endemics. Two        species (Hemicypris exiqua Broodbakker, 1983, and Notodromas sinensis Neal & Zhao, 1991) are new records for the Oriental region, and four species (Cypretta seurati Gauthier, 1929, Chrissia ceylonica (Daday, 1898), Chrissia formosa (Klie, 1938), and Dolerocypris fasciata (O.F. Müller, 1776)) are new record for Thailand. The most diverse subfamily in Thailand is the Cypricercinae, with 22 species. The most diverse genera are Strandesia Stuhlmann, 1888 (eight species), followed by Pseudostrandesia Savatenalinton & Martens, 2009 (seven species) and Stenocypris Sars, 1889 (five species). Other enigmatic groups and new taxa occur in the checklist, but these need to be described elsewhere in the future. For example, several species of Cypridopsinae Kaufmann, 1900, Cyclocypridinae Kaufmann, 1900, Candoninae Kaufmann, 1900 and other groups await description. Considering regional distributions based on frequency of occurrences, rare      species constitute a large fraction, whereas very common species are minor elements. Most of the records were reported from the Northern and Northeastern parts of Thailand. Sampled habitat types ranged from ponds, (oxbow) lakes, swamps, reservoirs, springs, canals, rivers, rice fields, waterfalls, and damp leaf litter. Most of the Thai ostracod fauna exists in a wide range of habitats. A brief discussion on the distribution of described species is included with the list.       Additionally, in the present contribution, we describe two new species, Dolerocypris sisaketensis n. sp. and           Hungarocypris suranareeae n. sp., from the Northeastern part of Thailand. The main character of Dolerocypris                   sisaketensis n. sp. is the presence of a spine on the postero-ventral part of the right valve; this feature sets it apart from other Dolerocypris species. Hungarocypris suranareeae n. sp. is the second species of this genus in Thailand and the third one in Southeast Asia. It is clearly distinguished from other Hungarocypris species by the serration on both valves. The genera Dolerocypris and Hungarocypris are briefly discussed and a key to the species of Hungarocypris is provided.

Effects of dietary traditional fermented soybean on reproductive hormones, lipids, and glucose among postmenopausal women in northern Thailand

Isoflavone in soybean and its products have numerous beneficial health effects. A number of clinical studies have demonstrated that dietary soy isoflavone can relieve menopausal symptoms, lower risks of breast cancer, and lower cholesterol and glucose. Among the various effects of isoflavone, the role of cholesterol and glucose reduction seems to be well documented; however, other effects such as reproductive hormones were inconclusive and inconsistent. The main objective of the present study was to investigate the effects of six-month dietary traditional fermented soybean intake on BMI, reproductive hormones, lipids, and glucose among postmenopausal women. Subjects were women with their last menstrual period occurring at least 12 months prior to selection by interview and health screening from Baan Tham Village, Phayao Province, Thailand. A total of 60 women were divided into 2 groups: experimental group (n=31) and reference group (n=29). The experimental group was permitted to continue their usual diet, and supplemented with fermented soybean for 6 months. The fermented soybean provided approximately 60 mg of isoflavone per day. The remarkable findings were that dietary fermented soybean had favorable effects on progesterone and cholesterol, but had no effects on estradiol, glucose, and triglycerides. Although estradiol and glucose in the experimental group did not change, a decrease of estradiol and an increase of glucose were found in the reference group. Our results, therefore, suggest that fermented soybean may have beneficial effects on reproductive hormones and cholesterol, and they would be warrant further detail investigations.

Effect of polyphenols extracted from tamarind (Tamarindus indica L.) seed coat on pathophysiological changes and red blood cell glutathione peroxidase activity in heat-stressed broilers

The purpose of this study was to determine the effect of polyphenols extracted from the tamarind seed coat (PETSC) on glutathione peroxidase (GPx) activity, red blood cell parameters and bilirubin in heat-stressed broilers. One hundred forty-seven broilers, 18-days old were divided into two groups. In group 1, broilers were maintained at an environmental temperature of 26 ± 2 °C throughout the experimental period. In group 2, the broilers were maintained at 38 ± 2 °C (cyclic temperature: 26 ± 2 °C; -38 ± 2 °C; and -26 ± 2 °C, and broilers were maintained at 38 ± 2 °C for 6 h/ day) and received PETSC at a concentration of 0, 100, 200, 300, 400 or 500 mg/kg in their diet ad libitum. Parameters were investigated on days 1, 7, 14 and 21 of the experimental period. Results showed that GPx activity of heat-stressed broilers that received 100 mg/kg of PETSC in their diet was lower (P < 0.05) than that in broilers fed the other concentrations. The mean total red blood cell count and hemoglobin concentration of heat-stressed broilers that received 100 mg/kg PETSC was higher (P < 0.05) than those in broilers in group 1 and those fed the other concentrations. The mean bilirubin level in the excreta of heat-stressed broilers that received 100 mg/kg of PETSC was lower (P < 0.05) than that in broilers that received 0, 300, 400 and 500 mg/kg of PETSC. This showed that PETSC could reduce GPx activity and bilirubin in feces, and increase red blood cell parameters in heat-stressed broilers.

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.

Tannins of tamarind seed husk: preparation, structural characterization, and antioxidant activities

The high content (about 39%) of polymeric tannins in tamarind (Tamarindus indica L.) seed husk (TSH) was demonstrated, and an extract (crude TSE) with a high content (about 94%) of polymeric tannins was prepared from TSH with a one pot extraction using ethanol/water (3:2, v/v). The crude TSE was further purified with Sephadex LH20 to give one fraction (metTSE) eluted with methanol/water (3:2, v/v) and another (acTSE) eluted with acetone/water (3:2, v/v). The tannins of acTSE were established as polymeric proanthocyanidins (PA) by 13C NMR spectroscopy; this was further confirmed by IR and UV spectroscopy, n-BuOH/HCl and vanillin assays, and from HPLC pattern. The ratio of procyanidins to prodelphinidins was 2:3, and the average degree of polymerization of acTSE was 7. Galloylated flavan-3-ols were not detected in acTSE. The main ingredients of metTSE were confirmed to be polymeric PA by 13C NMR spectroscopy. The antioxidant activities using DPPH and ABTS assays were investigated. The IC50 values of acTSE were 4.2 +/- 0.2 (DPPH assay) and 6.2 +/- 0.3 microg/mL (ABTS assay).

Tannins of Tamarind Seed Husk: Preparation, Structural Characterization, and Antioxidant Activities

The high content (about 39%) of polymeric tannins in tamarind ( Tamarindus indica L.) seed husk (TSH) was demonstrated, and an extract (crude TSE) with a high content (about 94%) of polymeric tannins was prepared from TSH with a one pot extraction using ethanol/water (3:2, v/v). The crude TSE was further purified with Sephadex LH20 to give one fraction (metTSE) eluted with methanol/water (3:2, v/v) and another (acTSE) eluted with acetone/water (3:2, v/v). The tannins of acTSE were established as polymeric proanthocyanidins (PA) by 13C NMR spectroscopy; this was further confirmed by IR and UV spectroscopy, n-BuOH/HCl and vanillin assays, and from HPLC pattern. The ratio of procyanidins to prodelphinidins was 2:3, and the average degree of polymerization of acTSE was 7. Galloylated flavan-3-ols were not detected in acTSE. The main ingredients of metTSE were confirmed to be polymeric PA by 13C NMR spectroscopy. The antioxidant activities using DPPH and ABTS assays were investigated. The IC50 values of acTSE were 4.2±0.2 (DPPH assay) and 6.2±0.3 μg/mL (ABTS assay).

Phenolic content and in vitro inhibitory effects on oxidation and protein glycation of some Thai medicinal plants

Fifteen medicinal plant extracts were investigated for: total phenolic content and free radical scavenging effect by DPPH and ABTS assays; anti-lipid peroxidation activity by TBARS; and for antiglycation activity. The results revealed that the total phenolic content showed good correlation with free radical scavenging by ABTS (r = 0.721) and anti-lipid peroxidation by TBARS (r = -0.659), but showed no correlation with antiglycation. Three extracts from Tamarindus indica, Camellia sinensis and Artocarpus lakoocha demonstrated a significant antioxidant effect, and also showed a promising antiglycation effect. The IC50 (mg/ml) were 0.9-0.16 for the DPPH method; TEAC values (mg Trolox/mg sample) of 1.72-2.83 for the ABTS method; IC50 (mg/ml) of 0.64-1.22 for the TBARS method; and IC50 ranging from 0.01 to 3.20 for the antiglycation method. These three herbs were found to possess effective antioxidant and antiglycation activities, and could be further developed for use in anti-aging cosmetics.

Effect of polyphenols extracted from Tamarind (Tamarindus indica L.) seed coat on physiological changes, heterophil/lymphocyte ratio, oxidative stress and body weight of broilers (Gallus domesticus) under chronic heat stress

The aim of this experiment was to determine the effect of polyphenols extracted from tamarind (Tamarindus indica L.) seed coat on physiological changes, oxidative stress and production of male broilers maintained at high environmental temperatures. The results found that body temperature and respiratory rate of broilers maintained at 38 +/- 2 degrees C was higher than broilers maintained at 26 +/- 2 degrees C (P < 0.05). On day 1, the heterophil/ lymphocyte ratio of broilers maintained at 38 +/- 2 degrees C and received polyphenols at 300 and 400 mg/kg in diets was lower than broilers that received polyphenols at 0 and 200 mg/kg in diets (P < 0.05). At week 1, the malondialdehyde of the broilers maintained at 38 +/- 2 degrees C who received polyphenols at 400 mg/ kg in their diet was lower than broilers that received polyphenols at 100 and 200 mg/kg in diets (P < 0.05). At week 1, the body weights of broilers that were maintained at 38 +/- 2 degrees C who received polyphenols at 100-500 mg/ kg in diets, and broilers maintained at 26 +/- 2 degrees C were higher than that of the control group which had not been treated with a polyphenol diet (P < 0.05). This study indicated that polyphenols could reduce heat stress, oxidative stress and improve the growth rate of heat-stressed broilers.

Antioxidative activity, polyphenolic content and anti-glycation effect of some Thai medicinal plants traditionally used in diabetic patients

Ethanolic extracts of 30 Thai medicinal plants, traditionally used as alternative treatments in diabetes, were evaluated for antioxidative activity by the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) method. They were evaluated in vitro for oxidative stress by thiobarbituric acid-reactive substance (TBARS) assay in pooled plasma of diabetic patients compared to without treatment of the extracts (control). The extracts were also assayed for protein glycation. The results showed that five plants had strong antioxidant activity: Phyllanthus emblica Linn. (PE), Terminalia chebula Retz. (TC), Morinda citrifolia Linn. (MC), Kaempferia parviflora Wall. (KP) and Houttuynia cordata Thunb.(HC), respectively. Thirty plant extracts were good correlation between total antioxidant activity and antiradical activity by TBARS as well as by glycation (r = 0.856, p<0.01 and r = 0.810, p<0.01). PE had stronger antioxidative activity as well as inhibition of TBARS and glycation than the other plants. The investigation showed that total polyphenol and tannin content of PE and the flavonoid content of HC were the highest. The results imply that these plants are potential sources of natural antioxidants which have free radical scavenging activity and might be used for reducing oxidative stress in diabetes.

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 microg/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.

Advances in nutrition support for quality of life in HIV+/AIDS

Globally, acquired immunodeficiency syndrome (AIDS) is an epidemic, severe and fatal disease. Along with the etiological factors of human immunodeficiency virus infection (HIV+) and decreased immunity, there are a number of other risk factors including opportunistic infection, malnutrition, wasting syndrome, and oxidative stress. The nutritional problems have been shown to be significant and contribute to health and death in HIV+/AIDS patients. Weight loss, lean tissue depletion, lipoatrophy, loss of appetite, diarrhea, and the hypermetabolic state each increase risk of death. The role of nutrition and how oxidative stress is involved in the pathogenesis of HIV+ leading to AIDS is reviewed. Studies consistently show that serum antioxidant vitamins and minerals decrease while oxidative stress increases during AIDS progression. The optimization of nutritional status, intervention with foods and supplements, including nutrients and other bio-active food components, are needed to maintain the immune system. Various food components may be recommended to reduce the incidence and severity of infectious illnesses by forms of bio-protection which include reduced oxidative stress due to reactive oxygen species which stimulate HIV replication and AIDS progression. Probiotics or lactic acid bacteria and prebiotics are sometimes given on the presumed basis that they help maintain integrity of mucosal surfaces, improve antibody responses and increase white blood cell production. People with HIV+/AIDS can be informed about the basic concepts of optimal nutrition by identifying key foods and nutrients, along with lifestyle changes, that contribute to a strengthened immune system. Moreover, nutritional management, counseling and education should be beneficial to the quality and extension of life in AIDS.

Enhancing the oxidative stability of rice crackers by addition of the ethanolic extract of phytochemicals from Cratoxylum formosum Dyer

Cratoxylum formosum Dyer is consumed throughout the year as food and medicine in Thailand. It contains large amounts of chlorogenic acid and quinic acid derivatives. The antioxidative activity of the extract was studied in refined soybean oil coating on rice crackers without any seasoning. They were stored in accelerated oxidation conditions at 40oC, 80% relative humidity (RH) in the dark for 18 days. The oxidative state of each sample was monitored by analyzing of the peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) as well as by odor analysis by quantitative descriptive analysis (QDA). The C. formosum extract was more effective than alpha-tocopherol due to metal ions present in the crackers, which resulted in alpha-tocopherol being less effective as an antioxidant. Sensory odor attributes of rice crackers were related more closely to TBARS than to PV values by linear regression analysis. The present study indicated that C. formosum extract was a promising source of a natural food antioxidant and was effective in inhibiting lipid oxidation in rice crackers.

Differential Activation of Glucose Transport in Cultured Muscle Cells by Polyphenolic Compounds from Canna indica L. Root

Effects of extracts of a plant, which has been used as a traditional medicine for treating diabetes on glucose transport activity was evaluated in cultured L8 muscle cells. The aqueous extract of Canna indica root (CI) at doses of 0.1-0.5 mg/ml, which contains total phenolic compounds equivalent to 6-30 microg of catechin caused a dose- and time-dependent induction of 2-deoxy-[3H]glucose (2-DG) uptake activity. The induced 2-DG uptake was significantly increased within 8 h and reached a maximum by 16 h. The CI extract increased the amount of glucose transporter isoforms 1 (GLUT1) and 4 (GLUT4) at the cell surface and enhanced expression of GLUT1 protein. Cycloheximide treatment almost completely reversed CI-induced 2-DG uptake to the basal level. Exposure of muscle cells to wortmannin and SB203580 diminished CI-mediated glucose uptake by 38 and 14%, respectively. The effect of CI and insulin was partially additive. Phytochemical analysis detected the presence of flavonoids and catechol in the CI. Taken together, these data provide evidence for differential effects of CI on regulated-glucose transport in muscle cells. Our findings suggest that GLUT1 protein synthesis and the activation of phosphatidylinositol 3-kinase (PI3K) are critical for the increase in glucose transporter activity at the plasma membrane and essential for the maximal induction of glucose transport by CI in L8 muscle cells.

Extract of the seed coat of Tamarindus indica inhibits nitric oxide production by murine macrophages in vitro and in vivo

The seed coat extract of Tamarindus indica, a polyphenolic flavonoid, has been shown to have antioxidant properties. The present studies investigated the inhibitory effect of the seed coat extract of T. indica on nitric oxide production in vitro using a murine macrophage-like cell line, RAW 264.7, and in vitro and in vivo using freshly isolated B6C3F1 mouse peritoneal macrophages. In vitro exposure of RAW 264.7 cells or peritoneal macrophages to 0.2-200 microg/mL of T. indica extract significantly attenuated (as much as 68%) nitric oxide production induced by lipopolysaccharide (LPS) and interferon gamma (IFN-gamma) in a concentration-dependent manner. In vivo administration of T. indica extract (100-500 mg/kg) to B6C3F1 mice dose-dependently suppressed TPA, LPS and/or IFN-gamma induced production of nitric oxide in isolated mouse peritoneal macrophages in the absence of any effect on body weight. Exposure to T. indica extract had no effect on cell viability as assessed by the MTT assay. In B6C3F1 mice, preliminary safety studies demonstrated a decrease in body weight at only the highest dose tested (1000 mg/kg) without alterations in hematology, serum chemistry or selected organ weights or effects on NK cell activity. A significant decrease in body weight was observed in BALB/c mice exposed to concentrations of extract of 250 mg/kg or higher. Oral exposure of BALB/c mice to T. indica extract did not modulate the development of T cell-mediated sensitization to DNFB or HCA as measured by the local lymph node assay, or dermal irritation to nonanoic acid or DNFB. These studies suggest that in mice, T. indica extract at concentrations up to 500 mg/kg may modulate nitric oxide production in the absence of overt acute toxicity.

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 AFB(1) 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 microg kg(-1). The recovery of AFB(1) spiked at 5, 10, 20, 40 and 80 microg 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 microg kg(-1) (85.7%) in corn and 102 microg kg(-1) (67.9%) in peanuts, for which 46.4% of both foods were above the Thailand regulation limit (20 microg kg(-1)).

Effects of a ferrate-containing preparation on diverse metabolic processes in yeast

A plant-sap-derived preparation containing bi- and tervalent ferrate anions was tested on growth, respiration on glucose, and membrane transport of 6-deoxy-D-glucose (6-dGlc) and 2-aminoisobutyric acid (Aib) in several yeast species, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Lodderomyces elongisporus, Rhodotorula gracilis, and Dipodascus magnusii. Growth was enhanced by as much as 65%, respiration was not affected significantly except for a decrease in R. gracilis, transport of 6-dGlc was not affected while that of Aib was increased by up to 45% in R. gracilis and up to 27% in L. elongisporus.

Biochemical and hematological manifestations of HIV/AIDS in Chiang Mai, Thailand

HIV/AIDS is a multifactorial and multi-step disease. No single treatment against AIDS can save a patient. Our last report showed that vitamin A, vitamin E and beta-carotene were decreased while malondialdehyde (MDA) was increased. This report aims to evaluate biochemical and hematological parameters in HIV/AIDS patients in Chiang Mai, Thailand by holistic approaches. Sera from HIV/AIDS patients were examined for sugar, cholesterol, uric acid, total protein, albumin, urea, creatinine, AST, ALT, ALP, total/direct bilirubin, vitamin E, MDA, total antioxidant capacity (TAC), beta-carotene, complete blood cell counts, platelet count, CD4 count, prothrombin time, partial prothrombin time and soluble Fas (sFas). The results found that sFas levels in sera prior to holistic approach was not different from reference values and not significantly correlate with CD4 and absolute lymphocyte count. sFas could not serve as putative marker for CD4 destruction. After 3 months CD4 count, MDA, vitamin E and TAC did not change statistically. This approach had no effect on liver and kidney functions, red blood cell, white blood cell, platelet counts, and blood clotting factors. This presentation may be some alternative approaches to combat HIV infections and AIDS, leading to stabilize or extend survival time which should further be elucidated.

Risk factors for lung cancer among Northern Thai women: epidemiological, nutritional, serological, and bacteriological surveys of residents in high- and low-incidence areas

Lung cancer incidence among Northern Thai women is one of the highest in Asia (an annual age-adjusted incidence rate of 37.4 per 100,000), and the incidence rate significantly differs by geographical districts. Therefore, we conducted a comparative study of women living in the Sarapee area, which showed the highest (crude incidence rate, 40.9), and the Chom Tong area, which had one of the lowest incidence rates (8.5) in Chiang Mai Province, despite the two areas' geographical and cultural closeness. The women in this study were either family members of lung cancer patients or their neighbors. To find clues to the etiology of lung cancer, this study used various epidemiological and biochemical approaches: interviewing on lifestyle factors, duplicate meals, chemical examination of drinking water, biochemical analysis of sera, mutagenicity test of urine, and monitoring of fungi and bacteria in the living environment. We found that tobacco smoking (Khiyo, local cigars) was less frequently observed in Sarapee (high incidence), compared with Chom Tong (low incidence), and that the history of chronic benign respiratory diseases was the most distinct event among women in Sarapee, resulting in a significantly increased percentage of those with a history of both benign respiratory diseases and tobacco smoking. This population revealed increased levels of serum tumor necrosis factor (TNF)-alpha, an endogenous tumor promoter. Furthermore, significantly increased urine mutagenicity was found to be closely associated with history of benign respiratory disease in Sarapee. The fungus which was most commonly found in the air inside houses in Sarapee was identified as Microsporum canis. Additionally, significantly increased serum concentrations of a constituent of the fungus were found in Sarapee women, compared with those in Chom Tong. Our results suggest that tobacco (Khiyo) smoking alone may not be able to explain the very high incidence of female lung cancer in Northern Thailand, and that chronic benign respiratory disease, possibly caused by the infection of fungi such as M. canis, is likely to be involved in the etiology of female lung cancer in North Thailand.

Exposure to N-nitroso compounds in a population of high liver cancer regions in Thailand: volatile nitrosamine (VNA) levels in Thai food

The recent case-control studies in Thailand indicate that a high incidence of liver cancer in Thailand has not been associated with common risk factors such as hepatitis B infection, aflatoxin intake and alcohol consumption. While the infestation by the liver fluke Opisthorchis viverrini (OV) accounted for the high risk in north-east Thailand, there was no such exposure in the other regions of the country where the incidence of liver cancer is also high. Case-control studies suggest that exposure to exogenous and possibly endogenous nitrosamines in food or tobacco in betel nut and cigarettes may play a role in the development of hepatocellular carcinoma (HCC), while OV infestation and chemical interaction of nitrosamines may also be aetiological factors in the development of cholangiocarcinoma (CCA). Over 1800 samples of fresh and preserved food were systematically collected and tested between 1988 and 1996. All the food items identified by anthropological studies to be consumed frequently in four major regions of Thailand were analysed for volatile nitrosamines using gas chromatography combined with a thermal energy analyser. Relatively high levels of N-nitrosodimethylamine (NDMA), N-nitrosopiperidine (NPIP) and N-nitrosopyrrolidine (NPYR) were detected in fermented fish ("Plasalid"). NDMA was also detected at levels ranging from trace amounts to 66.5 microg/kg in several salted and dried fish ("Larb-pla" and "Pla-siu"). NDMA and NPYR were frequently detected in several vegetables, particularly fermented beans ("Tau-chiau") at levels ranging between 1 and 95.1 microg/kg and 0-146 microg/kg, respectively. The possible role of nitrosamines in Thai food in the aetiology of liver cancer (HCC, CCA) is discussed.

Volatile nitrosamines and tobacco-specific nitrosamines in the smoke of Thai cigarettes: a risk factor for lung cancer and a suspected risk factor for liver cancer in Thailand

In Thailand, smoking of commercial cigarettes and of handmade cigarettes has drastically increased in recent decades. Cancer of the lung and of the upper aero-digestive tract have also increased in Thailand as they have in many other countries. It is our working hypothesis that the increase of primary cancer of the liver, especially of cholangiocarcinoma in the north-eastern provinces of Thailand is associated with the use of tobacco in men infested with the liver fluke Opisthorchis viverrini (OV). Bioassays have shown that volatile nitrosamines and tobacco-specific nitrosamines induce cholangiocarcinoma in laboratory animals and that the hepatocarcinogenic action of nitrosodimethylamine in hamsters is significantly increased by infestation with the liver fluke OV. The endogenous formation of nitrosamines is significantly increased by OV infestation. This report presents analytical data on the concentration of volatile nitrosamines and tobacco-specific nitrosamines in mainstream smoke of nine leading brands of commercially produced Thai cigarettes which represent approximately 85% of the market share in Thailand. Observed ranges (ng/cigarette) were 8.5-31.9 for nitrosodimethylamine, 8.8-49.6 for nitrosopyrrolidine and 4.2-18.9 for nitrosodi-n-butylamine. These values are exceptionally high compared with the smoke of light and blended cigarettes from North America and Western Europe. Among the tobacco-specific nitrosamines, the range was 28-730 for nitrosonornicotine and 16-370 for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. There was a correlation between volatile and tobacco-specific nitrosamines, and tar and nicotine deliveries in the mainstream smoke. The analytical data are in line with the rate for lung cancer and support our working hypothesis that nitrosamines, and especially the tobacco-specific nitrosamines, are associated with the increased risk for primary liver cancer among those Thai people who smoke cigarettes and also carry OV infestation.

Developmental toxicity of steviol, a metabolite of stevioside, in the hamster

The developmental toxicity of steviol, a metabolite of stevioside, was studied in hamsters. Pregnant hamsters were intubated with steviol at dose levels of 0, 0.25, 0.5, 0.75 and 1.0 g/kg BW/day on days 6-10 of gestation. Steviol at doses of 0.75 and 1.0 g/kg BW/day were highly toxic to both dams and fetuses. Significant decrease of maternal body-weight gain during the experimental period (days 6-14) and high percentage of maternal mortality indicated the general toxicity of these two high doses. The number of live fetuses per litter and mean fetal weight also significantly decreased in the steviol-treated animals at doses of 0.75 and 1.0 g/kg BW day. The animals treated with an intermediate dose (0.50 g/kg BW/day) exhibited less signs of maternal and developmental toxicity than the two high doses (0.75 and 1.0 g/kg BW/day). One craniomeningocele was found in a fetus under the maternal toxic condition in steviol-treated at a dose of 0.75 g/kg BW/day. Neither the skeleton nor visceral development of the offspring was affected by steviol treatment except delayed ossification of the xiphoid (bifid) and long bones of the limbs and supernumerary thoracic ribs (14th ribs) tended to be increased at doses of 0.5 to 1.0 g/kg BW/day steviol. No dose-related teratogenesis was detected. From the result of the present study concerning maternal toxic condition and embryotoxicity, an oral dose of 0.25 g steviol/kg BW/day is regarded as having no observable effect. This steviol-treated dose is derived from stevioside 625 mg/kg BW/day which is approximately 80 times higher than the suggested acceptable daily intake of stevioside for humans (7.938 mg/kg BW/day).

Comparison of diets among elderly female residents in two suburban districts in Chiang Mai Province, Thailand, in dry season--survey on high- and low-risk districts of lung cancer incidence

By means of duplicate meals, we collected food samples of general female residents, aged 50 to 74 years at two suburban districts in Chiang Mai Province, which are distinguished by very high and low incidence rates of lung cancer. Then, on the basis of analyses of their consumption of foods by food groups, we compared their dietary habits in the dry season of northern Thailand with special reference to the difference in lung cancer incidence. In brief, the following features and difference in their dietary habits were found; 1) Rice, vegetables, and pork were most frequently eaten in both the districts. 2) Consumption of fruits, in both quantity and variety, at a high-risk district was much less than that at a low-risk district. 3) Female residents at a low-risk district consumed more variety of green and yellow vegetables than those at a high-risk district. 4). Potato was not found in food samples of a high-risk district. 5) confectionery was more prevalent in a low-risk district than at a high-risk district.

Total antioxidant capacity in plasma of HIV-infected patients

Total antioxidant capacity (TAC) of fasting EDTA plasma of 33 healthy and 64 HIV-infected patients was determined using H(2)O(2)-peroxidase-ABTS technique. The results revealed that the average TAC in HIV-infected patients was significantly lower than those in healthy normal persons. (0.161 +/- 0.097 vs 0.269 +/- 0.081 mmol/L Trolox equivalent, p < 0.05). Total lymphocytes were also counted using Hycel automatic cell counter and absolute CD4 numbers using Coulter CD4 manual kit. It was interesting that CD4 count was not correlated with the clinical symptoms of the patients. This paper suggests that prediction of severity and monitoring of the disease should be performed by determining both total lymphocyte count and total antioxidant capacity.

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.

Assessment of major carcinogenic tobacco-specific N-nitrosamines in Thai cigarettes

This report presents new findings on the content of cancer-causing tobacco-specific N-nitrosamines (TSNA) in mainstream smoke of nine brands of commercially produced Thai cigarettes, representing about 85% of market share in Thailand. Also tested were two major and popular brands of U.S. cigarettes sold in Thailand, representing about 10% of market share. The cigarettes included filter and nonfilter cigarettes with high, moderate, and low tar and nicotine yields. The observed range for N-nitrosonornicotine (NNN) was from 28 to 730 ng/cigarette and for 4-(methylnitrosamino)-1-(3-pyridyl-1-butanone (NNK) from 16 to 369 ng/cigarette. The relatively highest TSNA values were obtained in filter and nonfilter cigarettes with high tar (22.3-28.1 mg/cigarette) and high nicotine (1.78-2.42 mg/cigarette) deliveries. The results demonstrated that there is a correlation between TSNA and tar and nicotine deliveries in mainstream smoke. The TSNA deliveries, along with the tar and nicotine levels in mainstream smoke depended on the tobacco composition. According to these results, the tar levels alone, while significant, are not a sufficient measure for the biological activity and the carcinogenic potential of cigarettes in Thailand. Consumption of tobacco products nearly quadrupled over the last three decades (1966-1995) in Thailand. Lung cancer is the leading malignancy for men and a common malignancy for women in Thailand. This report provides information that may prove helpful in evaluating the TSNA-carcinogens burden on smokers. Our goal is to offer the scientific basis for voluntary and/or government-regulated reduction of the smoke yields of TSNA in tobacco products in Thailand and in other countries.

Effects of stevioside and steviol on intestinal glucose absorption in hamsters

The effects of stevioside and steviol (a product of enzymatic hydrolysis of stevioside) on intestinal glucose absorption were examined in the hamster jejunum in vitro. By using the jejunal rings technique, we found that stevioside at a high dose of 5 mM had no inhibitory effect on glucose absorption. In contrast, glucose absorption was inhibited 43% by 1 mM steviol. The inhibition of glucose absorption by steviol was related to steviol concentration and incubation time. The inhibitory effect of steviol compared to phlorizin and ouabain was also investigated. Steviol, which caused a decrease in glucose accumulation in the intestinal ring tissues, possibly acts on the brush border membrane as does phlorizin. Furthermore, it was also found that steviol altered the morphology of the intestinal absorptive cells. These results suggest that the possible site of inhibitory action of steviol might be on the mucosal side and/or at the intracellular organelles of intestinal absorptive cells.

Mutagenicity and human chromosomal effect of stevioside, a sweetener from Stevia rebaudiana Bertoni

Leaves of Stevia rebaudiana Bertoni have been popularly used as a sweetener in foods and beverages for diabetics and obese people due to their potent sweetener stevioside. In this report, stevioside and steviol were tested for mutagenicity in Salmonella typhimurium strains TA98 and TA100 and for chromosomal effects on cultured human lymphocytes. Stevioside was not mutagenic at concentrations up to 25 mg/plate, but showed direct mutagenicity to only TA98 at 50 mg/plate. However, steviol did not exhibit mutagenicity in either TA98 or TA100, with or without metabolic activation. No significant chromosomal effect of stevioside and steviol was observed in cultured blood lymphocytes from healthy donors (n = 5). This study indicates that stevioside and steviol are neither mutagenic nor clastogenic in vitro at the limited doses; however, in vivo genotoxic tests and long-term effects of stevioside and steviol are yet to be investigated.

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.