Thymoquinone attenuates ifosfamide-induced Fanconi syndrome in rats and enhances its antitumor activity in mice

Thymoquinone is a potent superoxide anion scavenger

The antioxidant and pro-oxidant effects of thymoquinone (TQ), a natural main constituent of the volatile oil of Nigella saliva seeds, and a synthetic structurally-related tert-butylhydroquinone (TBHQ), were examined in vitro. Both TQ and TBHQ efficiently inhibited iron-dependent microsomal lipid peroxidation in a concentration-dependent manner with median inhibitory concentration (IC50) values of 16.8 and 14.9 microM, respectively. TBHQ was stronger than TQ as a scavenger of 2,2'-diphenyl-p-picrylhydrazyl radical (DPPH) (IC50 = 5 microM, 200 times more active than TQ) and as a scavenger of hydroxyl radical (OH*) with an IC50 of 4.6 microM (approximately 10 times more active than TQ). TQ was more active than TBHQ as a superoxide anion scavenger with IC50 of 3.35 microM compared to 18.1 microM for TBHQ. Only TBHQ significantly promoted DNA damage in the bleomycin-Fe(III) system. The results suggest that both TQ and TBHQ have strong antioxidant potentials through scavenging ability of different free radicals. Moreover, the data indicate that TQ is acting mainly as a potent superoxide anion scavenger.

Thymoquinone suppresses expression of inducible nitric oxide synthase in rat macrophages

The objective of the present study was to determine the immunomodulatory role of thymoquinone (TQ) regarding its effect on the production of nitric oxide (NO) by rat peritoneal macrophages. Under certain conditions, macrophagesand certain other cells can produce high concentrations of NO from its precursor L-arginine via inducible nitricoxide synthase (iNOS)pathway. TQ has been established as the major component of the oil extracted from Nigella saliva plant seeds, which is being used frequently in herbal medicine. TQ (IC50 1.4-2.76 microM) dose- and time-dependently reduced nitrite production, a parameter for NO synthesis, in supematants of lipopolysaccharide (LPS)-stimulated (5 microg/ml) macrophages without affecting the cell viability. The protein level of iNOS in peritoneal macrophages was also decreased by TQ in a concentration-dependent manner. In addition, TQ inhibited the increase in iNOS mRNA expression induced by LPS indicated by reverse transcription-polymerase chain reaction (RT-PCR). These inhibitory effects of TQ were confirmed by immunofluorescence staining of iNOS in macrophages which showed decreased immunoreactivity for iNOS after treatment with TQ if compared with the control LPS-stimulated cells. These results suggest that TQ suppresses the production of NO by macrophages; an effect which may be useful in ameliorating the inflammatory and autoimmune conditions.

Cytogenetic studies on Nigella sativa seeds extract and thymoquinone on mouse cells infected with schistosomiasis using karyotyping

The protective effect of Nigella sativa seed extract and its main constituents thymoquinone (TQ) was studied on mouse cells infected with schistosomiasis. Bone marrow cells in the in vivo experiments and spleen cells in the in vitro one were used to evaluate the potentially protective effect of these natural compounds on the induction of chromosomal aberrations. Karyotyping of the mice cells illustrated that the main abnormalities were gaps, fragments and deletions especially in chromosomes 2, 6 and some in chromosomes 13 and 14. Both N. sativa extract and TQ were considered as protective agents against the chromosomal aberrations induced as a result of schistosomiasis.

The influence of thymoquinone on doxorubicin-induced hyperlipidemic nephropathy in rats

The effect of thymoquinone (TQ), the main constituent of the volatile oil of Nigella sativa seeds, on the nephropathy and oxidative stress induced by doxorubicin (DOX) in rats was investigated. A single intravenous injection of DOX (6 mg/kg) induced a severe nephrotic syndrome (after 5 weeks) associated with hypoalbuminemia, hypoproteinemia, elevated serum urea, hyperlipidemia, and a high urinary excretion of protein, albumin and N-acetyl-beta-D-glucosaminidase (NAG). In the kidney, DOX induced a significant increase in total triglycerides (TG), total cholesterol (TC), and lipid peroxides and a significant decrease in non-protein sulfhydryl (NPSH) content and catalase (CAT) activity. Treatment of rats with TQ (10 mg/kg per day) supplemented with the drinking water for 5 days before DOX, and daily thereafter, significantly lowered serum urea, TG, and TC. Similarly, TG, TC and lipid peroxides in the kidneys of TQ-treated rats were decreased significantly compared with DOX alone. Moreover, NPSH content and CAT activity in the kidneys of TQ-treated DOX group were significantly elevated compared with DOX alone. Treatment with TQ significantly suppressed DOX-induced proteinuria, albuminuria, and urinary excretion of NAG. The results confirm the involvement of free radicals in the pathogenesis of nephropathy induced by DOX. Likewise, the study demonstrates the high antioxidant potential of TQ and its marked effect on the suppression of DOX-induced nephropathy. The data suggest that TQ might be applicable as a protective agent for proteinuria and hyperlipidemia associated with nephrotic syndrome.