Evaluation of the radioprotective effects of thymoquinone on dynamic thiol-disulphide homeostasis during total-body irradiation in rats

Exploration of medicinal plants as potential therapeutics against COVID-19: molecular insights and drug development prospects with other significant medicinal information a retrospective exposition

OBJECTIVES

The study aims to explore the potential of medicinal plants and their phytoconstituents as effective inhibitors of the coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 virus. The focus is on investigating specific medicinal plants known for their pharmacological properties, such as: antioxidant, anti-inflammatory, and immunomodulatory effects, to determine their viability in developing COVID-19 treatments.

MATERIALS AND METHODS

This study involves a comprehensive study of medicinal plants, including: Withania somnifera (Ashwagandha) and Ocimum sanctum (Holy Basil), known for their beneficial health effects. Molecular docking studies were conducted to assess the interactions between phytoconstituents from these plants and SARS-CoV-2 proteins. The compounds' drug-like characteristics and safety profiles were also evaluated to determine their potential as therapeutic agents.

RESULTS

The molecular docking studies revealed that the phytoconstituents from the studied medicinal plants exhibit favourable interactions with SARS-CoV-2 proteins, suggesting their potential as therapeutic targets. These compounds demonstrated promising drug-like characteristics and safety profiles, indicating their suitability for further development as COVID-19-fighting medications.

DISCUSSION

The results indicate that medicinal plants and their bioactive substances hold significant potential for developing therapies against COVID-19. The ability of these organic substances to interact with key viral proteins and provide various therapeutic benefits highlights their potential as multi-functional treatment options. However, further research is necessary to confirm these findings and to understand the full scope of their therapeutic efficacy and safety in clinical settings.

CONCLUSIONS

Medicinal plants and their phyto-constituents represent a promising avenue for developing effective treatments for COVID-19. The favourable interactions with SARS-CoV-2 proteins and the promising drug-like characteristics observed in this study suggest that these natural compounds could be integral in the fight against the COVID-19 pandemic. Further research and clinical trials are essential to fully validating their potential and translating these findings into practical medical applications.

Continuous Thymoquinone Administration Mitigates Sodium Iodate-Induced Retinal Degeneration in Rats

PURPOSE

This study aimed to investigate the protective or therapeutic effect of thymoquinone (TQ) in a retinal degeneration rat model and its relationships with the retina ultrastructure, heme oxygenase 1 (HO-1), caspase-3, and RPE65 expressions and to determine whether TQ has a therapeutic effect at the biochemical level.

METHODS

A total of 25 adult Wistar albino rats were divided into the following treatment groups: saline (control: CONT), CO (corn oil), sodium iodate (SI), TQ + SI, and SI + TQ injection groups. Retina morphology, RPE65, HO-1, and caspase-3 expression levels were evaluated using immunohistochemistry, and optical density was determined using ImageJ. Ultrastructural evaluations were performed with electron microscopy. Thiol-disulfide homeostatic parameters were examined in serum samples.

RESULTS

Outer nuclear layer (ONL) thickness was significantly higher in the SI + TQ group compared to the SI group. The RPE65 expression significantly decreased in the SI group compared with the CONT and CO groups. A significant increase in RPE65 expression level and a significant decrease in caspase-3 expression level were found in the SI + TQ group compared with the SI group. The increase in HO-1 expression level was significantly higher in the TQ treatment groups, particularly in the SI + TQ group. In the SI and TQ + SI groups, the ONL thickness significantly decreased with a significant increase in caspase-3 expression compared to the CONT and CO groups. In the treatment groups, decreased organelle damage was observed on electron microscopy. In the SI + TQ group, the disulfide/native thiol and disulfide/total thiol ratios were significantly lower than all other groups, while the native/total thiol ratio was significantly higher than the other experimental groups.

CONCLUSIONS

The present study provides evidence that continuous TQ treatment can increase HO-1 and RPE65 expression and decrease apoptosis (caspase-3 levels), thereby preserving the retina at the ultrastructural level. Moreover, TQ administration can maintain thiol/disulfide homeostasis in SI-induced retinal degeneration-modelled rats.

Radioprotective effects of melatonin and thymoquinone on liver, parotid gland, brain, and testis of rats exposed to total body irradiation

BACKGROUND

This study aimed to investigate thymoquinone (TQ), and melatonin's radioprotective effects on liver, parotid gland, brain, and testis of rats which were exposed to total body irradiation (IR).

METHODS

Thirty adult Wistar rats were randomly divided into four groups that are Group 1 (control group): total body IR only, Group 2: IR-Melatonin (10 mg/kg), Group 3: IR-TQ (10 mg/kg), and Group 4 (sham group): nothing. Total body IR dose was 6 Gy. Tissue samples were taken 90 min after IR. The measurements of malondialdehyde (MDA), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) were performed in all groups.

RESULTS

In IR group, GSH-Px and SOD activities significantly decreased whereas MDA levels significantly increased when compared with the sham in all tissues. We recorded a significant decrease in MDA levels in IR-TQ group in liver and parotid gland of rats. Moreover, SOD did not change in IR-TQ group compared with IR only group.

DISCUSSION

Melatonin, a powerful antioxidant, plays role in preventing oxidative stress. We revealed that premedication with TQ significantly inhibited the increase in MDA induced by IR in liver and parotid gland and protected the activities of SOD, an antioxidant enzyme, in all other tissues. It has been revealed that TQ has a potential effect preventing IR-induced damage as much as melatonin.

Thymoquinone: A Review of Pharmacological Importance, Oxidative Stress, COVID-19, and Radiotherapy

Widely consumed worldwide, Nigella sativa (NS) is a medicinal herb commonly used in various alternative medicine systems such as Unani and Tibb, Ayurveda, and Siddha. Recommended for regular use in Tibb-e-Nabwi (Prophetic Medicine), NS is considered one of the most notable forms of healing medicine in Islamic literature. Thymoquinone (TQ), the main component of the essential oil of NS, has been reported to have many properties such as antioxidant, anti-inflammatory, antiviral, and antineoplastic. Its chemical structure indicates antiviral potential against many viruses, including the hepatitis C virus, human immunodeficiency virus, and other coronavirus diseases. Interestingly, molecular docking studies have demonstrated that TQ can potentially inhibit the development of the coronavirus disease 2019 (COVID-19) by binding to the receptor site on the transmembrane serine proteinase 2 (the activator enzyme that attaches the virus to the cell). In addition, TQ has been shown to be effective against cancer cells due to its inhibitory effect by binding to the different regions of MDM2, according to the proposed molecular docking study. Detailed in this review is the origin of TQ, its significance in alternative medicine, pharmacological value, potential as a cancer anti-proliferative agent, use against the coronavirus disease 2019 (COVID-19), and treatment of other diseases.

Radioprotective Effect of Thymoquinone in X-irradiated Rats

BACKGROUND

Thymoquinone, has anti-inflammatory, anti-oxidant, and cardio protection properties. This study aimed to evaluate the radioprotective effect of thymoquinone in whole body X-irradiated rats.

METHODS

This study conducted on 40 male adult Wistar albino rats randomized into the following groups: Group I: Control rats did not receive thymoquinone or ionizing radiation. Group II: Whole-body irradiated rats with 6 Gy of X-ray. Group III: Rats orally intubated with thymoquinone (10 mg/kg/day) for 7 days then subjected to whole-body irradiation with 6 Gy then supplemented with thymoquinone for another 7 days. Group IV: Rats orally intubated with thymoquinone (20 mg/kg/day) for 7 days then subjected to whole-body irradiation with 6 Gy then supplemented with thymoquinone (20 mg/kg/day) for another 7 days. LDH, CK-MB, ALT, AST, MDA, TAC, Catalase activity, GPX, GSR and GSH were measured.

RESULTS

Lipid peroxidation biomarker in the blood of X-irradiated rats significantly increased and accompanied by decrease in the levels of GSH, GSR, GPX, catalase as well as TAC. Moreover, exposure to IR significantly increases cardiac and liver enzymes. However, administration of TQ to X-irradiated rats with either 10 mg/kg or 20 mg/kg have the same reform effects and significantly protects rats against adverse effects of IR.

CONCLUSION

Exposure to X-ray leads to significant changes in cellular biochemical and morphological conditions. Administration of TQ before radiation treatment significantly decreases the adverse effects of IR. TQ can improve cardiac function, decrease myocardial enzyme levels and inhibit oxidative stress.