OBJECTIVE:This study was performed to determine the effect of the tocotrienol-rich fraction on the lifespan and oxidative status of C. elegans under oxidative stress.METHOD:Lifespan was determined by counting the number of surviving nematodes daily under a dissecting microscope after treatment with hydrogen peroxide and the tocotrienol-rich fraction. The evaluated oxidative markers included lipofuscin, which was measured using a fluorescent microscope, and protein carbonyl and 8-hydroxy-2′-deoxyguanosine, which were measured using commercially available kits.RESULTS:Hydrogen peroxide-induced oxidative stress significantly decreased the mean lifespan of C. elegans, which was restored to that of the control by the tocotrienol-rich fraction when administered before or both before and after the hydrogen peroxide. The accumulation of the age marker lipofuscin, which increased with hydrogen peroxide exposure, was decreased with upon treatment with the tocotrienol-rich fraction (p<0.05). The level of 8-hydroxy-2′-deoxyguanosine significantly increased in the hydrogen peroxide-induced group relative to the control. Treatment with the tocotrienol-rich fraction before or after hydrogen peroxide induction also increased the level of 8-hydroxy-2′-deoxyguanosine relative to the control. However, neither hydrogen peroxide nor the tocotrienol-rich fraction treatment affected the protein carbonyl content of the nematodes.CONCLUSION:The tocotrienol-rich fraction restored the lifespan of oxidative stress-induced C. elegans and reduced the accumulation of lipofuscin but did not affect protein damage. In addition, DNA oxidation was increased.

Objective: The study was done to determine the effect of Tocotrienol rich fraction (TRF) on the expression of RNAs in C. elegans under oxidative stress. Methods: The nematodes were divided into 4 groups and treated accordingly: control; TRF; hydrogen peroxide (H202); TRF treatment before and after H202-induction (TRF+H202+TRF). Expressions of RNAs were analyzed with Affymetrix Genechip C. elegans Genome Array and Genespring GX11 software where differentially expressed genes were further analyzed using gene ontology (GO). Selected genes (unc-15, cit-1.2, ftn-1, rsks-1, unc-4 and daf-12) were analyzed with RT-qPCR to validate the results. Results: TRF modulated the expression of 314 genes involved in determination of adult lifespan, regulation of growth and lipid modification. A total of 440 genes involved in RNA metabolic processes, transcription, growth and differentiation of muscle and nerve cells were differently expressed following H202 induction. TRF treatment before and after H202- induction resulted in 438 differentially expressed genes involved in RNA metabolic processes, transcription, response to xenobiotic stimulus and protein amino acid phosphorylation. Conclusion: TRF modulates the expression of genes involved in the regulation of lifespan in C. elegans. Bangladesh Journal of Medical Science Vol.18(4) 2019 p.711-721