## 4 Potential Plant Extracts and Plant By-Products as Alternative Sources of Vitamins in Animal Feeds
### Monogastrics
Young growing pigs that were fed a high- polyunsaturated fatty acids (PUFA) diet presented oxidative DNA damage in peripheral blood lymphocytes (measured with the comet assay) and increased plasma and 24 h urinary malondialdehydedehyde (MDA) content, which indicates lipid peroxidation [58; 59]. Dietary supplementation with Marigold extracts whole flower tops or petals (at 3 mL/day) [58], which is one of the best commercial sources of pure lutein and zeaxanthin [60], or a plant extract mixture (carvacrol, cinnamaldehyde, and capsicum oleoresin; at 0.027% of the diet) [59] for 14 days reduced the DNA percentage in the tail of the comet and olive tail moment (OTM)--indicators of DNA oxidation damage--similarly to VitE. The decrease induced by Marigold extract from petals was similar in magnitude to the one observed for the plant extracts mixture being around 45% for the DNA percentage in the tail of the comet and around 70% for OTM (Table 1). However, only the Marigold extract from petals and the plant extract was able to reduce the urinary 8-hydroxy-2\(\epsilon\)-deoxyguanosine (8-OHdG) excretion compared with the group without supplementation (by an average of 45.6%), while VitE was not effective (Table 1). The dietary supplementation with Marigold extract, plant extract, or VitE could not prevent the increase of plasma and 24-h MDA values when pigs were fed a high-PUFA diet [58; 59]. Comparing both studies, the same trend and similar values were observed for the 24-h urinary iPF2\(\alpha\)-VI (urine isoprostanes) among the low-PUFA diet, high-PUFA diet, Marigold extract from petals or plant extract mixture, and VitE enriched ones. Although the 24-h urinary iPF2\(\alpha\)-VI did not statistically differ among the feeding groups when evaluating the Marigold extract from petals enriched diet compared with the low-PUFA control one, a numerical decrease in the 24-h urinary iPF2\(\alpha\)-VI was found. These results indicate that Marigold extract from petal and plant extracts containing carvacrol, cinnamaldehyde, and capsicum oleoresin was as effective as VitE in preventing DNA oxidation. Treated lens epithelial cells with lutein or zeaxanthin can effectively block H\({}_{2}\)O\({}_{2}\) induced protein oxidation, lipid peroxidation, and DNA damage as demonstrated in vitro [61]. In addition, dietary supplementation of albino rats with the same moleculesled to a significant elevation of anti-oxidant enzyme levels in dose-dependent manner, concomitant with a similar increment of the total anti-oxidant capacity [60]. Moreover, the few differences between the two Marigold extracts used revealed that an extract from petals was more effective in protecting DNA than the extract from flower tops. On the other side, cinnamaldehyde is a phenylpropanol that demonstrated considerable metal ion chelating ability, which is an important mechanism of antioxidant action, and lower to moderate free radical scavenging activity [62]. A diet enriched with linseed oil, which induced a state of n-3 PUFA oxidative stress in young pigs, was supplemented over a period of 14 days with sweet chestnut wood extract (_Castanea sativa_ Mill., SCW; at 0.075%, 0.15%, and 0.3% of the diet) [63]. Chestnut wood extract (CWE) is a source of hydrolyzable tannic acid, a naturally occurring plant polyphenol, composed of a central glucose molecule derivatized at its hydroxyl groups with one or more galloyl residues. Its capacity to inhibit lipid peroxidation has been demonstrated to be comparable to those of butylated hydroxyanisole, butylated hydroxytoluene, \(\alpha\)-tocopherol, and trolox in vitro [64]. Despite the antioxidant supplementation, pigs fed the high PUFA diet in the SCW groups, along with the VitE one, had a higher (by 80.5% on average) urinary MDA content compared with those on a low PUFA control diet, while the same parameter was lower (by 31.7%) only in the high SCW group compared with the high PUFA control group.