T . Kisnanto et al .: Radioprotection 2024 , 59 ( 2 ), 144 – 151 149
Fig . 4 . Microscopic image of the comet assay results at 1000x magnification in various treatments . Control ( A ), 6 Gy ( B ), Temulawak extract + 6 Gy ( C ), Garlic extract + 6 Gy ( D ), and NAC + 6 Gy ( E ).
We assume that although garlic contains potent antioxidant active substances , insufficient to counteract the quantity of ROS .
Different from several previous studies , garlic plays a role in inhibiting the velocity of lipid peroxidation . Batcioglu et al ( 2012 ) observed that the supplementation of garlic extract ( 500 mg / mL ) for 30 consecutive days significantly declined MDA levels in liver and kidney tissues of rats by 20 Gy gamma radiation-induced . Meanwhile , Bertrand et al . ( 2016 ) reported that Age Garlic Extract ( AGE ) could inhibit lipid membrane damage in the liver , spleen , thymus , kidney , and testes of Wistar rats by 4.5 Gy radiation-induced .
GSH with GPx can catalyze reducing lipid hydroperoxides to OH and H * 2 O . GSH plays a primary role in the endogenous defence system against oxidative damage through its radical scavenging and repair features of protein and nonprotein macromolecules ( Ozcelik et al ., 2018 ). Our study reported that 6 Gy TBI causes tissue damage in the liver and spleen , as demonstrated by a significant drop in GSH levels compared to the control group . IR exposure inflicts the depletion of GSH levels caused by excessive liver and spleen damage resulting in oxidative stress conditions . IR exposure leads to protein denatured , so it undergoes a conformational change that makes it inactive . Eventually , damage to DNA and cell membranes will disrupt GSH synthesis ( Koiram et al ., 2007 ).
Our study also noted a significant enhancement in GSH levels in the radioprotectant agent treatment prior to IR exposure . Significant changes in GSH levels occurred in supplementing temulawak and garlic in liver tissue . While in the spleen tissue , only NAC succeeded in significantly elevated GSH levels . We assume that the active substance curcumin in temulawak is still estimated to be a primary player in the radical scavenging process and trigger an elevated endogenous antioxidant activity . Meanwhile , garlic ’ s protective effect can be mediated by potent antioxidant compounds such as S- allylcysteine , S-allyl mercaptocysteine , allicin , and selenium ( Uzun et al ., 2016 ). In comparison , NAC acts as a source of cysteine and stimulates the formation of GSH , thereby protecting against ROS ( Kilciksiz et al ., 2008 ). However , the inability of this radioprotectant agent to increase GSH levels in all tissues may be due to the limited capacity of active antioxidant substances in these tissues .
Furthermore , our investigation of spontaneous DNA damage by alkaline comet assay showed a significant liven up in all comet parameters in lymphocyte cells after 6 Gy IR exposure . DNA is the most sensitive to damage caused by IR exposure , either directly or indirectly . ROS has critical roles in DNA damage and cytotoxicity , including DNA DSBs , SSBs , and alteration of DNA base structure ( Srinivasan et al ., 2006 ). Our study aligns with Mansour et al . ( 2008 ), who stated that DNA damage in rat liver elevated drastically due to exposure to gamma radiation . Meanwhile , Rady et al . ( 2020 ) concluded that the escalation in DNA damage was proportional to the radiation dose . The higher the dose , the more severe the damage .