It is better known for the Biblical ‘Parable of the Mustard Seed.’ But it has become an article of trade in the country. Marketers advertise it even on ‘Molue’ buses in Lagos as a potential ‘cure all’ natural medicine. However, recent studies have validated mustard seed as a remedy for liver and kidney damage, epilepsy, and a possible substitute for insulin injections to treat diabetes, among other benefits. CHUKWUMA MUANYA writes. 

MUSTARD seeds are the small round seeds of various mustard plants. The seeds are usually about one or two millimetres in diameter. Mustard seeds may be coloured from yellowish white to black. They are important spices in many regional foods. 

        The seeds can come from three different plants: black mustard (Brassica nigra), brown Indian mustard (B. juncea), and white mustard (B. hirta/Sinapis alba).    

       Mustard seed belongs to the plant family Brassicaceae (Cruciferae). It is commonly used as a spice and a cheap source of antimicrobial agents for bacterial infections.

       Black mustard is a many-branched, aromatic, weedy annual plant, growing up to four meters in height. It has showy, smallish yellow flowers. Its seeds grow in long, slender pods. Each pod contains ten to 12 brown or black seeds. 

       Phytochemical analysis shows that mustard seeds contain omega-3 fatty acids, essential oils, the minerals selenium, phosphorus, manganese, magnesium, iron, calcium, zinc, vitamins A, B-complex, and C, dietary fibre, protein, and phytonutrients. 

       Earlier studies indicate that Brassica nigra seed has been used as a sedate for neurotic pain and rheumatoid arthritis, treatment of the brain and lung edema, paralysis, migraine and epilepsy. 

        Experimental reports have shown the antioxidant, hypoglycemic, anticancer and antimicrobial effect of Brassica nigra seed. The effect of this plant on oxidative stress and free radicals production has also been reported. 

        However, Indian researchers from M.G.R. College, Hosur, Periyar University, Salem, Pondicherry University, Puducherry, and Siddah Central Research Institute, Chennai, have demonstrated the protective effect of the methanol extract of B. nigra leaves against d-galactosamine (d-GalN)-induced hepatic (liver) and nephro (kidney) toxicity in Wistar rats.

        Galactosamine is a hepatotoxic, or liver-damaging, agent that is sometimes used in animal models of liver failure.

      Wistar rat is a laboratory rat of the species Rattus norvegicus (brown rat), which is bred and kept for scientific research.

         The researchers in a study published recently concluded: “The crude methanol extract of B. nigra leaf lacks inherent toxicity and exhibits hepatic and nephro-protective effects against d-GalN-induced toxicity in Wistar rats.”

      The study is titled “Brassica nigra plays a remedy role in hepatic and renal damage.”

     The researchers used as the standard, activity of the methanol extract of B. nigra at doses of 200 and 400 mg/kg b.wt. against d-GalN (500 mg/kg b.wt.) induced toxicity, with silymarin. 

       Silymarin exerts membrane-stabilizing and antioxidant activity, and promotes liver regeneration.

      They assessed the histological damage, activities of serum marker enzyme, haematological changes, metabolites such as bilirubin, urea, uric acid, and creatinine levels, tissue thiobarbutric acid reactive substance, enzymic and non-enzymic antioxidants and inflammatory marker enzymes such as myeloperoxidase, cathepsin D, and acid phosphatase.

      The haematological system consists of the blood and bone marrow.

      Bilirubin is a yellowish pigment found in bile, a fluid made by the liver. 

       Urea is the major end product of nitrogen metabolism in humans and mammals. 

       Uric acid is a chemical created when the body breaks down substances called purines. Purines are found in some foods and drinks. 

       Creatinine is a by-product of normal muscle contractions, which becomes a chemical waste product filtered from the blood through the kidneys Thiobarbituric acid reactive substances - TBARS - are formed as a byproduct of lipid peroxidation (that is as degradation products of fats) which can be detected by the TBARS assay using thiobarbituric acid as a reagent. The results read: “The d-GalN-induced toxicity was evident from a significant increase (p < 0.001) in the serum and tissue inflammatory markers in toxic rats, when compared with the control (saline alone treated animals). The B. nigra pretreated groups (200 and 400 mg/kg b.wt.) showed significant reduction in the d-GalN-induced toxicity as obvious from biochemical parameters. Histopathological observations confirm the protective effect of B. nigra leaf extract by reduction in hepatic and renal tissue damage. Experimentals extract showed a similar effect as the standard.”   Indian researchers have also shown that extract of Brassica nigra seed can be used to treat seizure, epilepsy and convulsion because of its antioxidant properties and action via enzyme activity mechanism. The study is titled “Antiepileptic and Antioxidant Effect of Brassica nigra on Pentylenetetrazol-Induced Kindling in Mice.”  The researchers wrote: “Considering the high rate of epilepsy today, with respect to the insufficiency of the available therapies, new strategies and methods are recommended for medical treatment of epileptic patients. Therefore, the present study experimentally investigated the anticonvulsant effect of a herbal medicine candidate Brassica nigra, by using kindling method. 

       “Sixty male mice were randomly selected and divided into six experimental groups (n = 10) including: 1-control, 2-pentylentetrazole (PTZ)-kindled mice, 3-positive control group received valproate (100 mg/Kg) as anti-convulsant drug, 4-5 and 6 received brassica nigra seed extract in three doses (75, 150 and 300 mg/Kg; IP). 

       “All groups except for the control ones were kindled by 11 period injections of PTZ (35 mg/Kg; IP). In the 12th injection, all groups except for the control group were tested for PTZ challenge dose (75 mg/Kg). However, the exhibited phases of seizure (0-6) were observed and noted till 30 min after the PTZ injection. At last, the brains of all the mice were removed and then malondialdehyde (MDA), superoxide dismutase (SOD) and nitric oxide (NO) levels of the brain tissues were determined.    

      “Statistical analysis of the data shows that the seed extract could reduce the intensity, improvement and duration of seizure. In addition, the Brassica nigra extract increased the SOD and NO levels and decreased the MDA level in the brain tissues. 

      “Attained results show that the extract of Brassica nigra seed can be used in grand mal seizure treatment. Moreover, the antiepileptic effect of this extract is probably caused by its antioxidant properties and acts via enzyme activity mechanism.”

       Epilepsy is one of the most prevalent neurological disorders, which affects about 0.5 to one percent of the world’s population. Epilepsy is resulted from a recurrent spontaneously abnormal electrical discharge of a group of neurons in the brain and exhibits as seizure occurrence in the patients. 

       Glutamate and γ-aminobutyric acid (GABA) are two important excitatory and inhibitory neurotransmitters in epilepsy. In spite of the generally acceptable treatment of epilepsy by anticonvulsant drugs, about one-third of this population suffers from un-prevented neurological changes induced by epileptic seizures and also exhibit some accompanied side effects. The long time seizure-induced neuronal activity might result in neurological changes and finally is ended by neuronal death.    

        Oxidative stress and free radicals production are of the most important mechanisms by which neurological disorders such as epileptic seizure occur. Nitric oxide (NO) is known as a neurotransmitter in the brain that has shown paradoxical role in seizure modulation, as an inhibitor and promoter in different cases. 

       The final product of lipid peroxidation is malondialdehyde (MDA), while MDA level could be considered as an index of lipid peroxidation. Increased level of MDA, as an index of lipid peroxidation in the PTZ mice may lead us to the conclusion that free fatty acids and free radicals are made from membrane phospholipid metabolism. Superoxide dismutase (SOD) is an intracellular antioxidant enzyme that catalyses converting the peroxidase to hydrogen peroxide (H2O2) in order to protect the cell from superoxide radicals and oxidative stress.

       The researchers concluded: “In conclusion, the present research indicates that hydro-alcoholic Brassica nigra extract have anti-seizure effect on PTZ-induced kindling in mice. In addition, since the experimental epilepsy is mediated by oxidative stress and free radicals, it could be suggested that Brassica nigra is able to prevent seizures by an antioxidant mechanism. However, the involvement of GABA receptor agonists in the Brassica nigra anti-seizure effect should not be ruled out.”

        Indian researchers have also found that mustard seed could be a possible new therapeutic agent for the treatment of diabetes.

         The study published in Experimental, Clinical and Endocrinology Diabetes is titled “Insulinotropic effect of aqueous extract of Brassica nigra improves glucose homeostasis in streptozotocin induced diabetic rats.”

     The researchers wrote: “Aqueous extract of BRASSICA NIGRA (AEBN) has been shown to have good anti-diabetic effect along with significant decrease of abnormal serum lipid levels in our previous study. To understand the mechanism of action, effect of oral administration of AEBN for two months on glycolytic and gluconeogenic enzymes was studied in liver and kidney tissues of rats with streptozotocin (STZ) induced diabetes mellitus.”

 “The activities of gluconeogenic enzymes were higher and of glycolytic enzymes were decreased in both the liver and kidney tissues during diabetes. However, in diabetic rats treated with AEBN for two months, decrease of serum glucose, increase of serum insulin and release of insulin from pancreas (shown in vitro from isolated pancreas) along with the restoration of key regulatory enzyme activities of carbohydrate metabolism and glycogen content were observed. 

      “The therapeutic role of AEBN in STZ induced diabetes as exemplified in this study can be attributed to the release of insulin from pancreas and change of glucose metabolizing enzyme activities to normal levels, thus stabilizing glucose homeostasis in the liver and kidney. The LD50 was found to be more than 15 times the effective dose (ED) implying higher margin of safety for AEBN. These biochemical effects indicate that AEBN could be a possible new therapeutic agent for the treatment of diabetes.”