**6. Other bioactive compounds**

Phytosterols are plant-based steroid molecules with cardioprotective and antitumor activities. Seeds are a rich source of bioactive phytosterols, such as radish seeds with good phytosterol profiles mainly consisting of brassicasterol, campesterol, and sitosterol [97]; however, considerable quantities of phytosterols are also reported in edible roots. A study has shown 366.16 mg/100 g phytosterol content in carrots with campesterol and sitosterol as major constituents [98]. Radish sprouts also have shown campesterol (947 μg/g) and β-sitosterol (899 μg/g) in considerable amounts [99]. Sweet potato contains anticancer phytosterol, daucosterol linolenate, daucosterol linoleate, and daucosterol palmitate that regulate gut microbiota [100]. Saponins compounds such as steroidal saponins are reported to possess anti-proliferative activities. Yams are an excellent source of saponins with a content range of 37.36–129.97 mg/g. While individual steroidal saponins include dioscin, gracilllin, protodioscin, and protoracillin [101]. Dioscin, a steroidal saponin, has been extracted from wild yams and has shown a promoting effect on GATA 3 expression, a tumor suppressor in breast cancer [102]. Diosgenin is also a major steroidal saponin in yam with high antioxidant activity [103]. Other than steroidal saponins, root vegetables have reported triterpenoid saponins with antioxidant activity. Beetroot is a rich source of triterpenoid saponins. Triterpenoid aglycones of saponins include oleanolic acid, hederagenin, akebonoic acid, and glycogenin, which were linked with hexose, uronic, deoxyhexose, and pentose sugar to generate terpenoid saponins [104]. Other than beetroot, sweet potatoes also have reported triterpene saponin with antioxidant properties. Sandrosaponin is a major triterpene saponin of sweet potatoes with a content value of 161.20 mg/100 g, constituting approximately 81% of the total saponins of sweet potatoes [105]. Volatile fractions of plants contain useful alcohols, terpenes, and hydrocarbons, among which terpenes are the most important due to their significant role in providing aroma and the flavor to vegetables. The accumulation of terpenes in root vegetables varies depending upon the color variation. Orange carrots have a high accumulation of β-caryophyllene, α-humulene, and bornyl acetate, while the yellow variety contains β-bisabolene and γ-bisabolene in higher amounts [106]. Likewise, hydrodistillation of radish has also identified phytol as a major terpene with the highest abundance (69.7% of total compounds identified) in the white variety, followed by neophytadiene (1.5%) in the black variety and β-damascone (1.4%) in the red variety [49].
