Two antoxidant elements of Allium vegetables: germanium and selenium

Abstract

Germanium (Ge) and Selenium (Se) are two elements naturally found in many plant. Germanium is a rare element, and present two forms as organic and inorganic forms. Germanium can have beneficial effects or toxic effects depending on its form present. The inorganic form of germanium or germanium dioxide is normally associated with toxicity and can lead to conditions some disorder. The organic forms such as germanium sesquioxide and spirogermanium have antioxidant properties and anticancer effects and immunostimulatory medicine that are used to inhibit the progress of cancer and destroy cancer cells. The organic forms of germanium could capture and discharge the heavy metal toxins such as cadmium and lead. It also protect against radiation damage in humans. Carboxyethylgermanium sesquioxide (Ge-132) has been shown to have antiinflammatory, antiarthritic and photo protective effects. Selenium is an essential micronutrient for many organisms including plants, animals, and humans. It has antioxidant properties and plays a main role in prevention of cancer and cardiovascular diseases. It is beneficial to human and other animal health in trace amount, but it's toxic in excess. Among Allium vegetables, garlic is in rich both germanium and selenium. In literature, it has been reported germanium and selenium contents of garlic are 2.78 and 0.276 µg g-1, respectively. Also, it has been reported germanium and selenium contents of onion are 0.29 and 0.052 µg g-1, respectively. The content of selenium in the vegetables is highly dependent upon both the amount and the availability of selenium in the soil and this can vary geographically. Especially, germanium and selenium contents of garlic are higher than many fruits and vegetables, including tomato, potato, carrot, peach, apple etc. This review discusses the allium vegetables as source of theirs and effect of germanium and selenium on human health.