Hibiscus sabdariffa Linn. or also known as roselle which is rich in polyphenols, has been demonstrated to cause loweringof blood pressure in animal and clinical settings. However its exact mechanism of action particularly from polyphenoliccompounds is not clearly understood. Therefore, we aimed to determine the effects of H. sabdariffa polyphenol extract(HPE) towards vascular reactivity and its mechanism of action. The HPE was studied on isolated thoracic aortic ringsfrom normal Sprague-Dawley rats, suspended in a 15-ml organ chambers containing Krebs-Henseleit solution. Thechanges in tension were recorded by isometric transducer connected to data acquisition. HPE relaxed the contractioninduced by phenylephrine (PE, 1 μM) in similar pattern for both endothelium-intact and endothelium denuded aorticrings in dose-dependent manner 0.1 ~ 0.9 mg/ml. The pretreatment with atropine (1 μM), a competitive muscarinicantagonist, and propranolol (1 μM), a non-selective beta- blocker did not alter HPE vasorelaxation response. In addition,HPE did not inhibit the contraction induced by extracellular Ca2+ precontracted by PE (1 μM) or KCl (60 mM), in Ca2+-free solution, suggesting that the relaxation effect of HPE was not via inhibition of calcium channels. In conclusion,HPE demonstrated vasorelaxation effects on rat thoracic aorta although the underlying mechanism is still unknown.The vasorelaxation effect could be via angiotensin type 1 receptor inhibition in the vascular smooth muscle cells or theactivation of hyperpolarizing K+ chan

Mutagenic and antimutagenic activities of lactic acid bacteria (LAB) Lactobacillus plantarum isolated from the localfermented durian (tempoyak) was determined by Ames test (Salmonella/microsome mutagenicity assay). Our study alsoinvolved pre-incubation assay against Salmonella typhimurium TA 98 and TA 100 bacterial strain in the presence andabsence of metabolic activator S9 system. It was found that the L. plantarum showed no mutagenic activity on bothS. typhimurium strain TA 98 and TA 100 in the presence and absence of metabolic activator. Significant antimutagenicactivity (p < 0.05) was observed in both cell-free supernatant and bacterial cell suspension of L. plantarum as comparedto the mutagenicity induced by 2-Aminoanthracene in the presence of metabolic activator. Meanwhile, in the absence ofmetabolic activator, only the bacterial cells of L. plantarum showed antimutagenicity acitivity against Sodium Azide and2-Nitrofluorene. In conclusion, L. plantarum could play a vital role as chemopreventive agent by binding to mutagensand suppressing mutagenesis. Thus, L. plantarum could be consider as a good candidate for functional food developmentas a supplement product to prevent development of colon cancer.

Drug Metabolizing Enzyme (DME) has been a target of natural chemopreventive agents to inhibit, retard and reverse theprocess of carcinogenesis. Pterostilbene, an analog to resveratrol has been reported to possess various pharmacologicalbenefits including chemoprevention. In our study, benzo[a]pyrene-induced HT-29 colorectal cell line was used as theDME model. The activity of phase I enzyme CYP1A as determined by the 7-ethoxyresorufin O-deethylation (EROD) assaywas found to be inhibited significantly by pterostilbene at 50 µM, 75 µM and 100 µM (p ≤ 0.01, p ≤ 0.05, p ≤ 0.01respectively) compared to the benzo[a]pyrene treated group. Meanwhile, pterostilbene induced glutathione-S-transferase(GST) activity significantly (p ≤ 0.01) at 50 µM as compared to the untreated. In addition, However, the protein expressionof CYP1A1 and GST in pterostilbene treated group was not significantly affected compared to untreated. On the otherhand, pterostilbene at 25 and 75 µM were able to increase the protein expression of transcription factor Nrf2 significantly(p ≤ 0.01). Results indicated that pterostilbene could reduce metabolic activation of procarcinogens and increase thedetoxification process which can be potentially developed as chemopreventive agent.

Pesticides and chemical fertilizers are widely used in agriculture to increase crop productivity among farmers.However, exposure to pesticides will give potential risk to human health. The aim of this study was to analyze thefrequency of micronucleus (MN) and binucleus (BNu) formation in buccal cells from farmers who were exposedto pesticides using the MN assay. Buccal swabs were collected from the farmers in Tanjung Karang (n = 32) andKelantan (n = 43) using wooden tongue depressor. A structured questionnaire was used to obtain demographic dataof the farmers. Cytogenetic analysis was carried out by Acridin Orange (AO) staining 0.0025% (w/v). The frequencyof MN and BNu as the biomarkers for cytogenetic damage was observed by using a fluorescence microscope.Comparison of frequency of MN and BNu is conducted in two areas namely Tanjung Karang, Selangor and Kelantanbecause of the agricultural activity and the type of pesticides used are different. Results showed that the frequencies of bothMN and BNu among farmers in Tanjung Karang were significantly higher (p < 0.05) compared to farmers in Kelantan.Meanwhile, for the socio-demographic factors (age, smoking status, working period), MN and BNu frequencies amongfarmers in Tanjung Karang were also significantly higher (p < 0.05) as compared to farmers in Kelantan. While in theaspect of pesticide exposure, the frequencies of MN and BNu showed no significant difference between the frequency ofpesticide spraying (p > 0.05) and the practices of PPE (Personal Protective Equipment) (p > 0.05). This may suggeststhat cytogenetic changes were not influenced by these factors. In addition, correlation study shows positive correlationbetween the frequency of MN with the pesticide exposure of farmers in Tanjung Karang (p > 0.05, r = 0.015) and Kelantan(p > 0.05, r = 0.0158). Besides, the frequency of BNu also has a positive correlation with the pesticide exposure amongfarmers in Tanjung Karang (p > 0.05, r = 0.036) and farmers in Kelantan (p > 0.05, r = 0.013). Hence, this present study demonstrated that exposure to pesticides increasedthe formation of MN and BNu among farmers and theprolonged use of pesticides may induce genotoxicity andDNA damage to human.