Thymoquinone Ameliorates Indomethacin-Induced Gastric Ulcers in Rats: A Dose Response Study

Nigella sativa L. essential oil is a widely used medicinal plant throughout the world. It is very popular in various traditional systems of medicine like Unani and Tibb, Ayurveda and Siddha. Acute and chronic use of non-steroidal anti-inflammatory drugs (NSAIDs) is considered a significant cause of peptic ulcers. Different doses (20-60 mg/kg body weight) of thymoquinone (TQ), the main constituent of Nigella sativa L. essential oil, have been shown to protect gastric tissue from NSAID-induced peptic ulcers. Researchers attributed the protective effect of TQ to its antioxidant properties. This study aimed to determine effective antiulcer dose range of TQ. In this study, we conducted a series of experiments to determine the optimal dosage of TQ in indomethacin-induced gastric ulcers in rats. Additionally, we investigated the effect of TQ on superoxide dismutase (SOD) activity, glutathione (GSH) levels, and malondialdehyde (MDA) levels. Our results showed that, when administered at 40 and 20 mg/kg body weight, TQ was ineffective in preventing indomethacin-induced gastric ulcers. Moreover, TQ itself induced gastric ulcers at 40 mg/kg dose. As the doses of TQ decreased, the protective effect increased. 0.5 mg/kg TQ provided the best protection in terms of gastric ulcer area and antioxidant parameters, having statistically the same result with famotidine. Low dose TQ is an efficient protector of indomethacin-induced gastric damage, and it significantly enhances antioxidant parameters of gastric tissue. High dose TQ administration does not produce any desirable effects.