## 3 Therapeutic Relevance of Plant-Derived Antioxidants in Aging and Aging-Related Diseases
### Aging-Related Diseases
#### Cancer  
Cancer development in humans is a complex process that is mediated by various endogenous and exogenous stimuli. It has been reported that oxidative DNA damage is responsible for cancer development, involving free radical-induced promotion and oncogene activation [112].  
Polyphenols have been reported to decrease tumor growth in human cancer cell lines [113]. Many polyphenols, such as quercetin, catechins, isoflav, lignans, flavanones, ellagic acid, red wine polyphenols, resveratrol, and curcumin, have been reported to show protective effects in some models, despite their different mechanisms of action [114]. Apigenin, a flavone present in vegetables and in the Egyptian plant _Moringa peregrine_, demonstrates cytotoxic activities against the breast cancer (MCF 7) and colon cell lines (HCT 116), comparable to that of doxorubicin [115]. Curcumin (diferuoylmethane) is the major component of the popular Indian spice turmeric (_Curcuma longa_), which is a member of the ginger family. Its anti-cancer effects have been studied for colon and breast cancers, lung metastases, and brain tumors [116; 117]. Cyandin is a pigment extracted from red berries, such as grapes, blackberries, cranberries, raspberries, or apples, plums, red cabbage, and red onion. It possesses antioxidant and radical-scavenging effects, which may reduce the risk of cancer. It hasbeen reported that cyanidin-3-glucoside (C3G) may prevent or reduce ethanol-induced breast cancer metastasis [118]. Indole-3-carbinol (I3C) is found in _Brassica_ vegetables, such as broccoli, cauliflower, and collard greens. Diindolylmethane (DIM) is a digestion derivative of I3C. I3C and DIM have demonstrated exceptional anti-cancer effects against hormone responsive cancers, like breast, prostate, and ovarian cancers [119]. EGCG is the most abundant catechin compound in green tea. Increasing evidence has shown that EGCG can be beneficial in treating brain, prostate, cervical, and bladder cancers [120; 121; 122]. Theaflavins, thearubigins, and polyphenols, which are present mainly in black tea, have also been shown to possess inhibitory effects against HCT 116 colon cancer cells and HT 460 lung cancer cells [123]. Genistein, an isoflavone that originates from a number of plants, such as lupine, fava beans, soy beans, kudzu, and psoralea, _Flemingia vestila_, and coffee, acts as an antioxidant, and it is also useful in treating leukemia [124].  
Beside this, gingerol (gingers), kaempfer (tea, broccoli, and grapefruit), lycopene (tomato), phenethyl isothiamate (PEITC), sulforaphane (cruicerous vegetable), resveratrol (grapes), rosmarinic acid (rosemary), vitamin D from mushrooms, vitamin E from plant oil, _Aegle marmelos_ (bael), _Vernonia anthellnmitica_ (kalijiri), _Tinospora cordifolia_, and _Phyllanthus acidus_ (amla), have also been reported to have potential anti-cancer properties due to the presence of antioxidants, similar to phenolic compounds [125]. The anti-cancer agents vinblastine and vincristine, from _Catharantthus roseus_ (from the Apocynaceae family), have revolutionized the use of plant material as a medical treatment. These were the first agents put into clinical use for cancer treatment. The isolation of paclitaxel (Taxol(r)) from the bark of the Pacific Yew, _Taxus brevifolia_ Nutt. (_Taxaceae_), was another milestone in the search for novel natural anti-cancer drugs [126].