ABSTRACT
Mustard seed (Sinapis alba Linn) is a brassicaciae plant widely cultivated for its broad agroclimatic survival; culinary and great potentials for pharmacologic usefulness due to its strong linkages with an array of health advantages, including anti-carcinogenic, anti-inflammatory, antibacterial, antioxidant, cardiovascular health, anti-ageing, and lifespan enhancement among others. Emerging research evidence has suggested that antioxidant enzymes which are a part of the first line defense system, the first responders to developing oxidative stress, can inhibit the formation of free radicals and reactive oxygen species while also scavenging already formed ones, towards mitigating oxidative stress, thus promoting health and survival. The aim of this study was to evaluate the effect of mustard seed extract supplementation on the levels of antioxidant enzymes (glutathione peroxidase, superoxide dismutase, catalase) and malondialdehyde (MDA) in Drosophila melanogaster. For the survival study, flies were fed on varying concentrations of mustard seed extract-enriched corn meal diet for 21 days. The meal was changed every 5 days. Survival of the flies was noted by taking daily readings of the number of death in each treatment vial, and the assay was used to estimate their survival rate. For the mustard seed treatment, three treatment groups with varying concentrations of mustard seed extract in the diet were set up excluding the control. Group 1 was fed with 2.5% w/v extracted mustard seed, group 2 was fed with 5% w/v extracted mustard seed, and group 3 was fed with 10% w/v extracted mustard seed. Group 4 was the control containing no mustard seed treatment. Each treatment vial had 30 Drosophila melanogaster flies, and the flies were allowed to feed on the meal all through the course of the study whilst being renewed every 5 days. The numbers of death each day were recorded. The survival rate of flies fed with 2.5% w/v mustard seed extract (M) was higher (74.3%) than control (64.3%), but lower in those fed on 5% w/v (N) and 10% w/v (O) at 61% and 55.3%, respectively. Although the expression of antioxidant enzymes was generally higher in groups fed on mustard seed extract, M (GPx = 4.30±0.51, SOD = 10.11±8.22, CAT = 0.38±0.00), N (GPx = 4.77±1.20, SOD = 18.19±2.04, CAT = 0.18±0.00), and O (GPx = 6.21±3.27, SOD = 9.60±4.63, CAT = 0.51±0.01), compared to the control (GPx = 4.06±0.17, SOD = 2.46±0.64, CAT = 0.27±0.01) (p>0.05; p<0.05; p=0.00), only in group M flies, which were fed on the least amount of mustard seed extract (2.5% w/v) does this response appear to have a role in promoting survival and effective handling of oxidative stress, due to their least expression of malondialdehyde (17.10±6.06), as compared to groups N (45.15±6.21), O (59.12±7.68), and the control (30.09±9.1) (p=0.00). Mustard seed supplementation, at a low concentration, seems to increase the expression of antioxidant enzymes, reduce oxidative stress, and promote the survival of Drosophila melanogaster.
