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Highlights To avoid L-dopa side effects it’s administration is delayed. Natural antioxidants have wide range of medicinal properties. The natural antioxidants might inhibit oxidation and toxin formation. The L-dopa use with antioxidants, may be a necessary approach in modern PD therapy.

A semiquinone glucoside derivative (SQGD) was isolated from a radioresistant bacterium Bacillus sp. INM-1 and its antioxidant and radioprotective activities were evaluated using in vitro assays. Natural stable free radical properties of SQGD in solid as well as in solution form were estimated using Electron Paramagnetic Resonance (EPR) spectrometry. Results of the study were demonstrated high reducing power (1.267 ± 0.03356 U(abs)) and nitric oxide radicals scavenging activity (34.684 ± 2.132%) of SQGD. Maximum lipid peroxidation inhibitory activity of SQGD was found to be 74.09 ± 0.08% at 500 μg/ml concentration. Similarly, significant (39.54%; P < 0.05) protection to the liposomal artificial membrane against gamma radiation was observed by SQGD in terms of neutralization of gamma radiation-induced TBARS radicals in vitro. OH(-) radicals scavenging efficacy of SQGD was estimated in terms of % inhibition in deoxy D: -ribose degradation by non-site-specific and site-specific assay. The maximum (54.01 ± 1.01%) inhibition of deoxy D: -ribose degradation was observed in non-site-specific manner, whereas, site-specific inhibition was observed to be 46.36 ± 0.5% at the same concentration (250 μg/ml) of SQGD. EPR spectroscopic analysis of the SQGD indicated ~80% reduction of DPPH radicals at 6.4% concentration. EPR spectral analysis of SQGD was revealed an appearance of very strong EPR signal of 2.00485 (crystalline form) and 2.00520 (solution form) g(y) tensor value, which were an established characteristic of o-semiquinone radicals. Therefore, it can be concluded that SQGD is a natural stable o-semiquinone-type radical, possessing strong antioxidant activities and can effectively neutralize radiation induced free radicals in biological system.

Curcuma longa L. (CLL) extract has previously been reported to alleviate liver damage. The current study examined the antioxidant activity of CLL by which the extract protects the liver against bleomycin (BLM)-induced hepatotoxicity in mice. The hypothesis was that CLL extract would protect the liver by reducing oxidative stress (induced superoxide dismutase (SOD) and catalase (CAT) activity), inhibiting lipid peroxidation, lowering biochemical parameters, and decreasing ROS production. Hepatic toxicity was induced by intraperitoneal injection of mice once daily with BLM (0.069 U/mL; 0.29 U/kg bw.) for a period of 4 weeks. The CLL was administered once a day for 4 weeks, 2 h prior at dose (40 mg/mL; 0.187 mg/kg/day). CLL extract significantly protected the liver, it decreased plasma bilirubin (BL) and gamma glutamyl transpeptidase (GGT), and it reduced lipid peroxidation levels. BLM intoxication produced oxidative stress, in which the antioxidant system functioned incorrectly and ROS production significantly increased. The CLL extract provided significant hepatic protection against BLM toxicity by improving SOD, CAT (p < 0.05), and MDA levels and decreasing ROS in the group receiving BLM (p < 0.05), leading to reduced membrane lipid peroxidation. Throughout this study, the CLL extract facilitated recovery from BLM-induced hepatic injury by suppressing oxidative stress. Therefore, the CLL extract has the potential to serve as an antioxidant compound to treat chronic hepatotoxicity.

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