**1. Introduction**

Cucumber (*Cucumis sativus* L.) is cultivated throughout the world because of its ability to thrive in both temperate and tropical conditions. As a result, fresh cucumbers are available throughout the year [1]. Historically, cucumber is one of the oldest cultivated crops and believed to be a native of the Asia continent [2]; parts of China with temperate climates and parts of southern regions of India with tropical climates. At present, cucumber is the fourth most widely cultivated vegetable crop in the world (after tomatoes, onions and cabbage) and China is by far the world's largest producer of it [1].

*C. sativus* belongs to the gourd family of Cucurbitaceous, which also includes cantaloupes, squash, pumpkins, melon and water melon [3, 4]. *C. sativus*is a tender creeping vine and hairy leaves with 3 to 5 pointed lobes. In general, it bears roughly cylindrical fruits and may be as large as 60 cm long and 10 cm in diameter with dark-green skin, crispy moisture rich flesh, and small edible seeds concentrated at its core [5]. There are close to 100 varieties, but common ones include the English, garden, Persian, mini, and lemon. Cucumbers are mainly eaten in the unripe green form when they taste sweet, have crunchy texture, and unique flavor. Thus, they are best-harvested young, tender and just short of reaching maturity. On getting to full maturity, the cucumber skin becomes tougher and turns yellow-white with an accompanied bitter and sour [1, 5].

Relative to other vegetables that have been widely researched and reported on, cucumber seems to have received little interest probably because of seemingly lack of concentrated levels of well-known bioactive compounds presents in garlic, onion, tomatoes and the likes. Generally, cucumbers are consumed because of their refreshing quality, in part due to their very high water content and crunchy texture. Studies have shown that cucumbers contain lignans, vitamin K, cucurbitacins and their derivatives (triterpenoids), flavonoids (apigenin, luteolin, quercetin, and kaempferol), antioxidants (beta carotene and vitamin C) and B vitamins among other trace elements and minerals [6–8]. With a 95% level of water content saturated with naturally-occurring nutrients and trace elements meshed in high dietary fiber, cucumbers are beginning to gain attention in therapeutic, culinary and cosmetic uses.
