Effect Of Short-chain Fatty Acids On Lifespan And Its Mechanism On C.elegans

The short-chain fatty acids?SCFAs?are mainly produced by anaerobic glycolysis colon from un-digested carbohydrates,which are well studied bioactive molecules with anti-inflammatory activities.They affect the metabolism of intestinal flora and prevent the development of the early type I diabetes.However,the related biological effects are not perfect and the mechanism is not clear enough.There are few studies of SCFAs with branched chain.In this study,juglone was used as oxidant to evaluate the anti-antioxidant effect of short branched chain-fatty acids?SBCFAs?by model organism Caenorhabditis elegans?C.elegans?.This dissertation is aimed to explore the anti-oxidant stress resistance and anti-aging biological activity of the 2?-Methyl-butyric acid and its mechanism.The main results are as follows.?1?Antioxidant activities of short-chain fatty acidsJuglone was used as oxidant to evaluate the anti-antioxidant effect of short chain-fatty acids by model organism C.elegans.The results showed that SCFAs?formic acid,acetic acid,propionic acid,butyric acid and valeric acid?and 2'-methylpropionic acid,3'-methyl-butyric acid,2'-ethylbutyric acid,2'-ethylvaleric acid had no anti-oxidant activities,while 2?-methyl substituted SCFAs?n=4-6?have significant anti-oxidant activities in C.elegans.The position of methyl substitution and the length of substituted alkyl groups were critical for the antioxidant activity of short-branched fatty acids.?2?Study on the antioxidation mechanism of 2?-Methyl-butyric acidCysteine was used as positive control to evaluate the free radical scavenging of2?-Methyl-butyric acid by ABTS and DPPH in vitro.The results showed that2?-Methyl-butyric acid could not scavenge the reactive oxygen species?ROS?in vitro.However,2?-Methyl-butyric acid could reduce the endogenous ROS level of C.elegans in H₂DCFDA experiment.The inactivated metabolism of bacteria by using of ampicillin and penicillin had no effect on the experimental results.Consequently,the anti-oxidant activities of 2?-Methyl-butyric acid in C.elegans was due to it's actions in vivo.We showed that 2?-Methyl-butyric acid could increase anti-oxidant stress resistance and improve the heat stress resistance.Next,we performed genetic analysis with a series of worm mutants and found that 2?-Methyl-butyric acid did not further extend the lifespans and ROS resistance of glp-1 single mutants.Furthermore,the relative GFP fluorescence intensity washigher than the control group?gst-4,hsp-16.2?.2?-Methyl-butyric acid increased ROS resistance through germline signalling to extend the lifespan of C.elegans.?3?2?-Methyl-butyric acid can delay the aging process of C.elegansLongevity is the most important index to evaluate the aging of nematodes.In addition,the aging of worms is accompanied by the decrease of reproduction ability,movement ability and external resistance.In this study,on the basis of aging index evaluation2?-Methyl-butyric acid to the effects of aging.We found that 2?-Methyl-butyric acid extend the lifespan and improve the healthy span.In terms of the reproductive capacity ofC.elegans,the oviposition cycle and number of nematodes were observed and counted.It was found that 2'-methylbutyric acid could prolong the oviposition cycle of nematodes and increase the number of nematodes.In the exercise ability experiment of nematodes,the swallowing frequency and head swing frequency of nematode swallowing pump were counted.The experimental results showed that 2'-methyl butyric acid could increase the swallowing frequency of nematode swallowing pump and head swing frequency of C.elegans.As for the resistance ofC.elegansto external environment,the effects of 2'-methylbutyric acid on the ultraviolet radiation and high temperature stress ability of worms were further examined by ultraviolet and high temperature stress experiments.It was found that 2'-methylbutyric acid could enhance the stress ability of nematodes to ultraviolet and high temperature.In terms of the longevity of worms,the effects of 2'-methylbutyric acid on the longevity of wild-type nematode N2 and glp-1 mutant of germline signaling pathway were tested.It was found that 2'-methylbutyric acid could significantly prolong the longevity of wild-type N2,but had no effect on the longevity of glp-1 mutant worms.The above results suggest that2?-Methyl-butyric acid regulate germline signalling and extend the lifespan of C.elegans.