Table 3.
Genoprotective properties of plant natural substances in clinical cancer research
| Genoprotective mechanism | Natural substance/dietary supplement | Study design | Participants characteristic (number of participants) | Group distribution, dosage | Genoprotective activities | Reference |
|---|---|---|---|---|---|---|
| Antioxidant activity | Anthocynin/polyphenolic-rich fruit juice | Healthy non-smoking men (n = 27) |
Fruit juice (n = 18, 700 ml/daily); Control (n = 9, polyphenol depleted juice) for 4 weeks |
Fruit juice: ↓ oxidative DNA damage ↑ GSH ↑ GSH status |
[150] | |
| Watercress | A single-blind, randomised, crossover study | Healthy smokers (n = 30), healthy non-smokers (n = 30) | Watercress supplementation: 85 g/daily or control for 8 weeks |
Watercress supplementation: ↓ basal DNA damage (17 %; p = 0.03), ↓ basal plus oxidative purine DNA damage (23.9 %; p = 0.002) ↑ plasma lutein (by 100 %) ↑ plasma β-carotene (33 %) (p < 0.001) |
[149] | |
| Kiwifruits | A randomised crossover study | Healthy non-smokers (n = 14) | 1, 2, or 3 kiwifruits/daily each volunteer |
↑ Antioxidant status of plasma and lymphocytes (↓ DNA breaks) ↓ levels of endogenous oxidation of pyrimidines and purines in DNA ↑ DNA repair activity |
[18] | |
| Ascorbic acid (vitamin C) and D-α-tocopherol (vitamin E) | History of melanoma, BCC or SSC (n = 14), no UV-induced skin cancer (n = 4) | Ascorbic acid 2 g/daily and D-α-tocopherol 1000 IU/daily for 90 days |
↓ Sunburn reaction to UVB irradiation ↓ thymine dimers |
[158] | ||
| GTP | Phase IIa randomised, double-blinded and placebo-controlled chemopreventive trial | High-risk individuals of liver cancer (n = 124) | Low dose (500 mg GTP/daily, n = 42), high dose (1000 mg GTP/daily, n = 41), or placebo (n = 41) | ↓ DNA damage (↓ 8-OHdG level) | [151] | |
| Protection against exposure to carcinogens | Ethiopian kale (Brassica carinata) | Randomised, single blind, controlled crossover intervention trial | Healthy participants (n = 22) |
Cooked B. carinata group (n = 11); Raw B. carinata group (n = 11) for 5 days (15 g of freeze-dried B. carinata leaves/daily cooked/unprocessed) |
Cooked B. carinata: ↓ AFB1-induced DNA damage (+S9 mix: 35%, −S9 mix: 33 %, p ≤ 0.01) Raw B. carinata: ↓ AFB1-induced DNA damage (+S9: 21 %, p = 0.08) |
[152] |
| XAN | Crossover placebo-controlled trial | Healthy non-smokers (n = 22) | XAN-beverage (12 mg of xanthohumol, n = 11); placebo (n = 11) for 2 weeks (1l/daily) | XAN: → α-GST | [154] | |
| Coffee | First trial (n = 10) | Unfiltered coffee (1l/daily over 5 days) | → GSTP | [155] | ||
| Second trial (n = 14) | Unfiltered and paper filtered coffee (1l/daily over 3 days) | → GSTP | ||||
| Third trial (n = 7) | Unfiltered coffee (1l/daily over 5 days) | ↓ BPDE-induced DNA migration | ||||
| Brussel sprouts | Intervention study | Healthy participants (n = 8) | Brussel sprouts for 6 days (300 g/daily) |
Brussel sprouts: ↓ PhIP-induced DNA migration (97%) ↓ endogenous formation of oxidised bases ↓ hydrogen peroxide-induced DNA damage (39 %) |
[156] | |
| DNA damage protection | High-phenol EVOO | Randomised crossover intervention trial | Healthy postmenopausal women (n = 10) | High-phenol EVOO (592 mg total phenols/kg), low-phenol EVOO (147 mg/kg) 50 g/daily | ↓ DNA damage by 30% with high-EVOO vs. low-EVOO | [24] |
| Carotenoid supplementation | Randomised, double-blind, placebo-controlled intervention study | Healthy postmenopausal non-smoking women (n = 37) | Daily dose of mixed carotenoids (β-carotene, lutein, and lycopene; 4 mg each), 12 mg of a single carotenoid (beta-carotene, lutein, or lycopene), or placebo for 56 days | All carotenoid supplemented groups: ↓ endogenous DNA damage | [26] | |
| Broccoli | Randomised crossover study | Healthy young smokers and non-smokers (n = 20) | Broccoli (200 g/daily) or controlled diet for 10 days |
↓ Strand breaks in smokers and non-smokers (− 22.2%; p < 0.0001) ↓ oxidised purines in smokers (− 51.0%; p < 0.0001) |
[157] |
AFB1 aflatoxin B1; BCC basal cell carcinoma; BPDE (±)-anti-B[a]P-7,8-dihydrodiol-9,10- epoxide; EVOO extra-virgin olive oil; GSH reduced glutathione; GSTP glutathione S-transferase P; GTP green tea polyphenols; HCA heterocyclic amines; SSC squamous cell carcinoma; UV ultraviolet radiation; UVB ultraviolet B; XAN xanthohumol; α-GST glutathione S-transferase α; 8-OHdG 8-hydroxydeoxyguanosine
↑increase
↓decrease
→induction