The activity results of lipid peroxidation [malondialdehyde] antioxidants [APX, CAT, SOD, GPX] of seven days old paeonol pre-treated rice seedling, exposed to applied concentrations (100 µM, 50 µM and 10 µM) of arsenite, paeonol and their dose treatment of paeonol with As III exposure were shown in Fig 1 and 2.
Malondialdehyde [MDA]
The MDA increased by 98%,75%,26% in root while by 90%, 70%, 22% in shoots at 7 day pre-treatment by 100 µM, 50 µM, 10 µM As III respectively as compared to control and positively correlated with As accumulation (R=0.974). Upon paeonol pretreatment under the same day and same concentration as As III treatment, the MDA increased by 27%,15% and 6% in root while in shoot 28%, 14%, 5% as compared to control and was positively correlated with As accumulation (R=0.959). Upon dose treatment of paeonol with As III the increased level of MDA in root was reduced by about 36%, 37%, 38% while in shoot 33%, 35% and 36% as compared to As III treated rice seedling under the same concentration only and was positively correlated with As accumulation (R=0.932) was shown in (Fig 1).
Effect of antioxidant
The APX increased by 79%, 38% and 31% in roots while by 68%, 0 µM,10 µM As III respectively as compared to control with As accumulation (R=0.948). Upon paeonol pretreatment under the same day and same concentration as As treatment, the APX decreased by 34%, 22%,12% in root while in shoot 28%,18%, 8% as compared to control and positively correlated with As accumulation (R=0.939). Upon dose treatment of paeonol along with As III the increased level of APX in root was reduced by about 51%, 44%13% while the shoot by about 44%, 37%, 9% as compared to only As III treated rice seedling under the same concentration only and was positively correlated with As accumulation (R=0.998) was shown in Fig 2(a). The CAT increased by 189%,140%, 55% in root while by 125%, 93%, 43% in the shoot at 7 d pre-treatment with 100 µM, 50 µM,10 µM As III respectively and was positively correlated with As accumulation (R=0.956). Upon paeonol pretreatment under the same concentration as As III treatment, the CAT increased by 42%, 27%, 20% in roots while in shoots 44%, 36%, 31% as compared to control and was positively correlated with As III accumulation (R=0.914). Upon dose treatment of paeonol along with As III the increased level of CAT in root was reduced by about 55%, 52%, 49% while in shoot 53%, 43%, 32% as compared to only As III treated rice seedling under the same concentration only and was positively correlated with As accumulation (R=0.975) was shown in Fig 2(b). The GPX increased by 42%, 29%, 20% in root while by 35%, 26%,17% in the shoot at 7 d pre-treatment 100 µM, 50 µM,10 µM As III respectively as compared to control and was positively correlated with As accumulation (R=0.913). Upon paeonol pretreatment under the same day and same concentration as As III treatment, the GPX increased by 29%, 15% and 13% in roots while in shoots 26%, 11% and 9% as compared to control and was positively correlated with As accumulation (R=0.918). Upon dose treatment of paeonol along with As III the GPX activity in root was decreased on an average, by about 50%, 44%, 20%, while in shoot 45%, 38%, 17% as compared to only As III treated rice seedling under the same concentration only and was positively correlated with As accumulation (R=0.925) were shown in Fig 2(c) The SOD increased by 34%, 28%, 15% in root while by shoot 30%, 22% and 13% at 7 d pre-treatment with 100 µM, 50 µM, 10 µM As III respectively as compared to control and was positively correlated with As accumulation (R=0.982). Upon paeonol pretreatment under the same day and same concentration as As III treatment, the SOD increased by 34%, 28%, 15% in root while in shoot 30%, 22% and 13% as compared to control and was positively correlated with As accumulation (R=0.930). Upon dose treatment of paeonol along with As III, the increased level of SOD in root was reduced by about 27-50% while in shoot 18-37% as compared to only As III treated rice seedling under the same concentration only and was positively correlated with As accumulation (R=0.999) were shown in Fig 2(d).
In the present study, it has been concluded that the MDA level increased with arsenic exposure in rice seedling, which may be attributed to the excessive production of reactive oxygen species such as O
2-, OH, H
2O
2 under stressed condition by the interaction of arsenic with intracellular components and supported by
Chandrakar et al., (2017b). From the present study, it has also be concluded that the increased amount of MDA content in rice seedlings significantly decreased on exposure to paeonol alone and jointly with arsenite.
Significant enhancement of APX activity upon arsenic exposure depends upon more availability of H
2O
2 because of efficient break down in ASC-GSH cycle, while the altogether bringing down the estimation of APX, when pretreatment with paeonol, may be due to neutralizing toxic effect of arsenic by the formation of complex and by the reduction
(Gautam et al., 2019) of O
2.- to molecular oxygen resultantly H
2O
2 levels reduced. Upregulation of APX action in mitigating the harmful impacts of H
2O
2 has likewise been reported in tomatoes, maize,
Vigna mungo L.
(Srivastava et al., 2017), GPX activity was reported in rice seedling plants treated with arsenic and paeonol, suggesting that pretreatment with paeonol induces a significant reduction of oxidative stress caused by arsenic
(Gautam et al., 2019). The CAT activity in root and shoot were decreased on an average as recorded in arsenite treated rice seedlings, which indicate that paeonol pretreatment with arsenic causes a substantive reduction of oxidative stress, which was produced by toxic arsenic. The up-regulation of CAT activity under the introduction of various protocols of arsenic has additionally been accounted for in
Zea may (Gautam
et al., 2019),
Vigna mungo L.
(Srivastava et al., 2017), Results inferred that higher SOD activity during arsenic stress can be a reason for generating H
2O
2. Ameliorate this stress by diminishing the level of H
2O
2 when exposed to paeonol. Therefore paeonol plays a protective role against the oxidative stress brought about by arsenic. High dose treatment of paeonol in a hydroponic medium decreases the enzyme’s activity in arsenic-exposed rice plants and is useful in diminishing arsenic expose rice plant toxicity. The upregulation of SOD under the exposure of various concentration of arsenic has additionally been accounted for in
Vigna mungo L. (
Srivastava, 2017),
Pteris vittata, Vetiveria zizanioides (
Tiwari et al., 2017),
Solanum melongena L.
(Singh et al., 2015), maize
(Requejo et al., 2006) and well supported by
(Dave et al., 2013).