ABSTRACT
Academic achievement may be influenced by catechol-O-methyltransferase (COMT)
polymorphism. A common functional polymorphism of COMT, the rs4680 is consistently being
involved in the modulation of dopaminergic pathway and prefrontal cortex function which may
predominantly affect cognitive functions. A total of 197 female participants were recruited in this
study. The score of student’s grade point average (GPA) from the latest previous semester was
used as the measurement of academic achievement. The COMT polymorphism was genotyped
using tetra primer allele specific polymerase chain reaction. The findings indicated that there
were 8 (4.1 %), 72 (36.5 %), and 117 (59.4 %) participants harbouring Met/Met, Met/Val, and
Val/Val genotype for COMT polymorphism respectively. All the genotype distributions of
COMT polymorphism were consistent with Hardy-Weinberg equilibrium (χ2 = 0.495, p > 0.05).
The one-way analysis of variance (ANOVA) result demonstrated that participants bearing
Met/Met genotype had a better achievement in GPA as compared to the other COMT genotypes
(p = 0.001). These findings support evidence that the affective role of COMT polymorphism
might overwhelm cognitive abilities in measures of academic achievement like GPA.
Endothelial cell death due to increased reactive oxygen species (ROS) may contribute to the initial endothelial injury, which promotes atherosclerotic lesion formation. Piper sarmentosum (PS), a natural product, has been shown to have an antioxidant property, which is hypothesized to inhibit production of ROS and prevent cell injury. Thus, the present study was designed to determine the effects of PS on the hydrogen peroxide (H(2)O(2))-induced oxidative cell damage in cultured human umbilical vein endothelial cells (HUVECs). In this experiment, HUVECs were obtained by collagenase perfusion of the large vein in the umbilical cord and cultured in medium M200 supplemented with low serum growth supplementation (LSGS). HUVECs were treated with various concentrations of H(2)O(2) (0-1000 micromol/L) and it was observed that 180 micromol/L H(2)O(2) reduced cell viability by 50% as denoted by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Using the above concentration as the positive control, the H(2)O(2)-induced HUVECs were concomitantly treated with various concentrations (100, 150, 250 and 300 microg/ml) of three different extracts (aqueous, methanol and hexane) of PS. Malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) levels showed a significant increase (P<0.05) in HUVECs compared to the negative control. However, PS extracts showed a protective effect on HUVECs from H(2)O(2)-induced cell apoptosis with a significant reduction in MDA, SOD, CAT and GPX levels (P<0.05). Furthermore, PS had exhibited ferric reducing antioxidant power with its high phenolic content. Hence, it was concluded that PS plays a beneficial role in reducing oxidative stress in H(2)O(2)-induced HUVECs.