Methods: Chemical compounds fromDendrocalamus asperbamboo shoots were purified and identified as major palmitic acids mixed with other minor fatty acids, palmitic acid, 4-hydroxybenzaldehyde, lauric acid, 4-hydroxybenzoic acid and cholest-4-ene-3-one. The response of synthetic 4-hydroxybenzoic acid was tested on Kv1.4 potassium channel which was injected into viable oocytes that was extracted fromXenopus laevis. The current were detected by the two-microelectrode voltage clamp, holding potential starting from -80 mV with 20 mV step-up until +80 mV. Readings of treatments with 0.1% DMSO, 4-hba concentrations and K channel blockers were taken at +60 mV. The ratio of tail/peak amplitude is the index of the activity of the Kv1.4 channels withn≥ 6 (number of oocytes tested). The decreases of the ratios of five different concentrations (1 μM, 10 μM, 100 μM, 1 mM and 2.5 mM) were compared with 0.1% DMSO as the control.
Results: All concentration showed statistically significant results withP< 0.05 except for 100 μM. The normalised current of the 4-hba concentrations were compared with potassium channel blockers (TEA and 4-AP) and all groups showed statistically significant results. This study also showed that time taken for each concentration to affect Kv1.4 does not play any significant roles.
Conclusion: 4-hydroxybenzoic acid was found to be able to enhance the inactivation of Kv1.4 by lowering the membrane potential so that the abnormal neuronal firing can be inhibited. With IC50 slightly higher than 10 μM, increasing concentrations (100 μM, 1 mM and 2.5 mM) had shown to exhibit toxicity effects. The best concentration from this study is 10 μM with Hill slope of 0.1799.
Methods: This cross-sectional study involved 227 adults aged 40 to 59 years at low-cost housing flats in suburban area of Cheras, Kuala Lumpur. Data collection involved food frequency questionnaire (FFQ) for polyphenols and international physical activity questionnaire (IPAQ). Subjects were measured for anthropometric parameters including height, weight, waist and neck circumferences (NC), and body fat percentage. The polyphenol intake from the diet was estimated using local polyphenol database built according to PHENOL-EXPLORER.
Results: The average intake of polyphenol of subjects was 1815 (672) mg/day. The main food sources of polyphenol were coffee with milk, followed by chocolate milk and red beans. A higher polyphenol intake according to quartile was significantly associated with a lower neck circumference (χ2 = 8.30, P = 0.040), waist circumference (χ2 = 8.45, P = 0.038) and body fat percentage (χ2 = 8.06, P = 0.045). Binomial logistic regression analysis showed that the association remained significant for the neck circumference (P = 0.032), after controlling for age, household income, energy intake and physical activity level. More subjects with normal NC had higher intake of polyphenols (50th percentile and above). In contrast, subjects with high NC showed lower percentiles of polyphenols intake (50th percentile and below).
Conclusion: The result showed that polyphenol intake was associated with neck circumference and thus it can be suggested that polyphenol intake is associated with obesity.