Antioxidant Potential of Spices and Their Active Constituents

A wide variety of phenolic substances derived from spice possess potent antimutagenic and anticarcinogenic activities. Examples are curcumin, a yellow colouring agent, contained in turmeric (Curcuma longa L., Zingiberaceae), [6]-gingerol, a pungent ingredient present in ginger (Zingiber officinale Roscoe, Zingiberaceae) and capsaicin, a principal pungent principle of hot chili pepper (Capsicum annuum L, Solanaceae). The chemopreventive effects exerted by these phytochemicals are often associated with their antioxidative and anti-inflammatory activities. Cyclo-oxygenase-2 (COX-2) has been recognized as a molecular target of many chemopreventive as well as anti-inflammatory agents. Recent studies have shown that COX-2 is regulated by the eukaryotic transcription factor NF-kappaB. This short review summarizes the molecular mechanisms underlying chemopreventive effects of the aforementioned spice ingredients in terms of their effects on intracellular signaling cascades, particularly those involving NF-kappaB and mitogen-activated protein kinases.

The present study was carried out to investigate the effects of onion (Allium cepa Linn) and garlic (Allium sativum Linn) juices on biochemical parameters, enzyme activities and lipid peroxidation in alloxan-induced diabetic rats. Alloxan was administered as a single dose (120 mg/kg BW) to induce diabetes. A dose of 1 ml of either onion or garlic juices/100 g body weight (equivalent to 0.4 g/100 g BW) was orally administered daily to alloxan-diabetic rats for four weeks. The levels of glucose, urea, creatinine and bilirubin were significantly (p<0.05) increased in plasma of alloxan-diabetic rats compared to the control group. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and alkaline and acid phosphatases (AlP, AcP) activities were significantly (p<0.05) increased in plasma and testes of alloxan-diabetic rats, while these activities were decreased in liver compared with the control group. Brain LDH was significantly (p<0.05) increased. The concentration of thiobarbituric acid reactive substances and the activity of glutathione S-transferase in plasma, liver, testes, brain, and kidney were increased in alloxan-diabetic rats. Treatment of the diabetic rats with repeated doses of either garlic or onion juices could restore the changes of the above parameters to their normal levels. The present results showed that garlic and onion juices exerted antioxidant and antihyperglycemic effects and consequently may alleviate liver and renal damage caused by alloxan-induced diabetes.