*3.1. Tomato*

Tomato (*Solanum lycopersicum* L.) is an important fruit vegetable, widely consumed all over the world due to its rich nutrient content, special taste, and diverse ways of consumption (fresh, soups, juices, purees, dried, and sauces) [124]. Fruit color and pigments content are two important traits that largely reflect tomato fruit quality, as well as the antioxidant activity which is mainly correlated to the hydrophilic (e.g., soluble phenolic compounds and vitamin C) than to the lipophilic compounds (e.g., carotenoids, vitamin E, and lipophilic phenols) [125]. Fruit color is mainly related

to pigments content, such as chlorophyll, carotene, lycopene, phytoene and anthocyanin, and their relative proportions at different maturity stage [126]. The most abundant carotenoid is lycopene, followed by phytoene, phytofluene, ζ-carotene, γ-carotene, ß-carotene, neurosporene, and lutein [127]. Color development is due to the chlorophyll degradation and the synthesis of carotenoids as fruit is developed and ripen. Therefore, the genetic development of tomato fruit color and pigments content is an interesting research area to improve fruit quality and satisfy the diverse consumers' demands [128].

The consumption of tomato and related food products is associated with the decrease of various diseases incidence such as chronic degenerative diseases, cardiovascular disease, and age-related macular degeneration (AMD) in human health [129]. Raiola et al. [124] reported the nutritional importance of tomato phytochemicals against inflammation processes and prevention of chronic non-communicable diseases (e.g., obesity, diabetes, coronary heart disease, and hypertension). Anthocyanins normally are not produced in tomato fruit, however, some wild tomato species, such as *S. chilense*, *S. cheesmaniae*, *S. lycopersicoides*, and *S. habrochaites* biosynthesize anthocyanins in the sub-epidermal tissue of the fruit, and some alleles from those genotypes have been introgressed into cultivated genotypes [130]. Therefore, combining the dominant Anthocyanin fruit (Aft) gene from *S. chilense* and the recessive atroviolacea (atv) gene from *S. cheesmaniae* into a cultivated tomato background, anthocyanins biosynthesis has been achieved [131,132].

Purple tomatoes have antioxidants and phytochemical properties in both flesh and peel, often in superior levels than those found in conventional red tomatoes [133]. A genetically modified (GM) purple tomato was found to have additional health-promoting effects by prolonging the life of cancer-susceptible mice compared to tomatoes with conventional (red) color [134]. Extracts from fruit of purple tomato (breeding line V118) showed significant and dose dependent anti-inflammatory effect against paw edema in an in vivo study with rat models (edema inhibition: 7.48%–13.8%), suggesting that anthocyanins may play a role in the anti-inflammatory effect [135]. Interestingly, during the last 20 years there has been an increasing interest in developing highly consumed food, such as flavonoids-rich tomato fruit. To that direction, transgenic approaches have been applied to modify the biosynthesis of phenylpropanoids, in order to alter the tomato flavonoid biosynthesis [130].

Phenolic content is varied at different developmental stages of tomatoes, as sun black (SB) tomato had 5.8 and 8.6 mg GAE/g dw phenolic content at mature green and red ripening stage, respectively, contents that were 152% and 134% higher than wild type (WT) [130]. Li et al. [136] reported similar total phenolic content (659.11 mg GAE/100 g dw) for purple tomato as has been reported for other tomato varieties (from 290 to 500 mg GAE/100 g dw) [137]. Individual components of phenolics may also vary among purple and red varieties, as the main phenolic compounds content (chlorogenic acid, naringenin, and rutin) was higher (65.56, 12.82, and 52.39 mg/100 g dw, respectively) [136] in purple tomatoes compared with red tomatoes were chlorogenic acid, naringenin, and rutin content was 2.67, 1.84, and 6.61 mg/100 g dw [138] and 16.7, 2.2, and 16.9 mg/100 g dw, respectively [139]. Apart from chlorogenic acid, naringenin, and rutin Li et al. [136] reported other phenolic compounds in purple tomatoes such as p-coumaric acid (15.68±0.74 mg/100 g dw), gentistic acid (15.25 ± 0.76 mg/100 g dw), ferulic acid (14.51 ± 0.99 mg/100 g dw), caffeic acid (13.65 ± 0.83 mg/100 g dw), and protocatechuic acid (8.95 ± 0.16 mg/100 g dw). Indeed, chlorogenic acid content depends on the developmental stage of fruit and varied from 0.5 to 1.3 mg/g dw in sun black (SB) tomato extracts [130]. Moreover, composition of flesh and peel in tomato mutants differed as flesh contained chlorogenic acid (7.96 ± 0.75 mg/100 g fw), quercetin (5.03 ± 1.02 mg/100 g fw), luteolin (0.45 ± 0.01 mg/100 g fw), and total phenolics (1.18 ± 0.06 mg/g fw), while in peel the respective compounds content was: chlorogenic acid (8.43 ± 0.15 mg/100 g fw), quercetin (5276.15 ± 15.10 mg/100 g fw), luteolin (21.28 ± 1.07 mg/100 g fw), and total phenolics (5.95 ± 0.27 mg/g fw) [133].

Among the several phytochemicals identified in plants, *cis*- and *trans*-resveratrol (3,4,5-trihydroxystilbene) are polyphenols that belong to the stilbene class; however, only the *trans* form is biologically active in the human body [140]. Numerous biocidal activities exerted by resveratrol have been reported such as antioxidant, antidiabetic and estrogenic activity, anticancer effects through the preservation of the regular cell cycle, the inhibition of tumor invasion and angiogenesis, and cardiovascular effects through the reduction of the expression of endothelial adhesion cells and the inhibition of cell apoptosis and platelet aggregation [141–145]. However, resveratrol's daily intake by humans has still to be established [143]. Vagula et al. [146] quantified *trans*-resveratrol in *S. americanum* Mill. fruit, which ranged between 1.07 and 0.796 μg/g for fruit pulp and peel, respectively, and these levels were significantly higher when compared to freeze-stored fruit (0.1353 μg of *trans*-resveratrol/g of sample) and to other berries [146].

Vasco et al. [147] reported the higher antioxidant capacity of purple (purple-red variety) tamarillo or tree tomato (*Solanum betaceum* Cav.), compared to the golden-yellow variety and reported 9.3 μmol trolox/g fw, 3.0 μmol trolox/g fw and 40 μmol trolox/g fw for seed-jelly, pulp, and peel tissues of purple fruits compared to 3.8 μmol trolox/g fw, 2.3 μmol trolox/g fw and 22 μmol trolox/g fw for seed-jelly, pulp and peel tissues of yellow fruits, respectively. Similarly, Sestari et al. [133] reported increased antioxidant capacity (DPPH) in peel (38.12 ± 4.27 μmol trolox/g fw) compared to flesh (8.64 ± 0.45 μmol trolox/g fw) in tomato mutants. Interestingly, the oxygen radical absorption capacity assay (ORAC) value for the hydrophilic extracts in purple tomato reported by Li et al. [136] was 323.23 μmol trolox/g dw, which was 2-fold higher than the ORAC value of the traditional tomato cultivar San Marzano (140 μmol trolox/g dw) reported by Ninfali et al. [148]. Similar observations were made by Blando et al. [130] who stated 3-fold higher trolox equivalent antioxidant capacity (TEAC) value (31.6 μmol trolox/g dw) in sun black tomatoes compared with the wild type (10.3 μmol trolox/g dw) at the red-ripening stage. Moreover, antioxidant capacity of purple fruit was higher at the ripe (red ripe stage-RR) fruit compared to the unripe (mature green stage-MG) ones, probably explained by the great increase in polyphenols accumulation during ripening (from 5.8 to 8.6 mg GAE/g dw, in MG and RR, respectively) [130]. In the same study, total ascorbic acid content was higher in sun black than wild type fruits (37.3 ± 1.4 vs. 27.1 ± 1.1 mg 100/g fw, respectively) [130].

The antioxidant capacity of fruit is not only related to phenolics and ascorbic acid but also to the carotenoids, flavonoids, and anthocyanins content. Lycopene, the main phytochemical of tomatoes, is known for its important role in human health related functionalities [149]. Lycopene supplementation in an in vivo study with iodoacetamide-induced colitis rats showed reduced tissue malondialdehyde (MDA) levels, the histological signs of colon injury, and increased superoxide dismutase levels in the red blood cells [150]. In the study Li et al. [136], lycopene was the dominant carotenoid (185.01 μg/g dw) in breeding line V118, followed by β-carotene (47.11 μg/g dw) and lutein (2.66 μg/g dw). About 8.1% of the total carotenoids in V118 were *cis*-carotenoids, a lower value compared to that of most of the tomato varieties studied [136]. Moreover, Li et al. [128] reported that purple fruit (cv "Zi Ying") had increased antioxidant capacity compared to green fruit (cv "Lv Ying"), with lycopene content of 36.51 ± 2.86 mg/kg fw and β-carotene 13.38 ± 1.31 mg/kg fw in purple fruit versus lycopene content of 1.35 ± 0.05 mg/kg fw and β-carotene 6.80 ± 0.32 mg/kg fw in green fruit. In a comparative study, Hazra et al. [151] pointed out the dietary role of purple tomato (AftAft dgdg genotype) due to the increased values in ascorbic acid (31.56 ± 2.41 mg/100 g fw), lycopene (6.13 ± 0.39 mg/100 g fw), β-carotene (0.65 ± 0.14 mg/100 g fw), and anthocyanin (20.73 ± 2.86 mg/100 g fw), compared to the overall mean value of 31 hybrids.

Li et al. [136] reported a total carotenoid content of breeding line V118 of 234.78 μg/g dw, being within the range of the average amounts reported for red tomatoes (132–583 μg/g dw) [152]. At the red ripe stage, total carotenoids did not differ between the sun black (SB) and wild type (WT) tomatoes; however, the β-carotene content was significant higher in the SB sample, whereas the lycopene content was lower [130]. Similarly, Vasco et al. [147] reported higher β-carotene levels in purple tamarillo than in yellow tomato variety. Generated double and triple mutants (Anthocyanin fruit/high pigment 2(Aft/hp2) and Anthocyanin fruit/atroviolacium/high pigment 2 (Aft/atv/hp2)) of purple tomatoes had higher lycopene and β-carotene levels and up to 63% of vitamin C compared to tomato cultivar Micro-Tom, suggesting accumulating trends of relevant phytochemicals in near-isogenic lines [133].

Anthocyanins, the most abundant flavonoid constituents in pigmented fruit and vegetables, posse potential health beneficial effects, such as antioxidant, anti-inflammatory, anticancer, and antidiabetic activities [153,154]. Anthocyanins also had notable effects against inflammation by inhibiting cyclooxygenase-2 (COX-2) expression, inducible nitric oxide protein and mRNA expression [155]. The "Giant" and "New Zealand" purple cultivars, had total anthocyanins content of 102.35 ± 1.46 mg/100 g dw and 168.88 ± 2.65 mg/100 g dw, but also revealed high antioxidant activity which might be related to their overall phenolic composition [156]. Zhang et al. [157] reported the role of anthocyanins in postharvest storage of tomatoes as in purple tomatoes, anthocyanins doubled the self-life of fruit by delaying over-ripening and reducing susceptibility to *Botrytis cinerea*.

Li et al. [136] through an LC-MS study reported three major anthocyanins, which were mainly acylglycosides of petunidin and malvidin. Among these anthocyanidins, petunidin was the predominant aglycone (91.9%), and the rest of the minor aglycones accounted for only 9.1% of the total anthocyanidins [136]. Moreover, petunidin is not usually synthesized in vegetables and fruit, and little is known about its health benefits, however in tomato mutants petunidin revealed considerable amounts (>60 mg/100 mg fw) in fruit peels of the lines combining Aft and hp2 genes [133]. The total anthocyanin content in breeding line V118 was 72.31 mg/100 g dw, including 9.04, 50.18, and 13.09 mg/100 g dw of petunidin-3-*O*-caffeoyl-rutinoside-5-*O*-glucoside, petunidin-3-*O*-(*p*-coumaryl)-rutinoside-5-*O*-glucoside, and malvidin-3-*O*-(*p*-coumaryl)-rutinoside-5-*O*-glucoside, respectively [136]. Moreover, Blando et al. [130] reported that petanin (Petunidin 3-(6-(4-(*E*-*p*- coumaroyl)rhamnosyl)glucoside)-5-glucoside (petanin)) and negretein (Malvidin 3-(6-(4-(*E*-*p*-coumaroyl)rhamnosyl)glucoside)-5-glucoside) represented 56.6% and 21.4% of the total anthocyanins content in sun black (SB) fruit peel, respectively, whereas no anthocyanins were detected in wild type (WT) tomato fruit.

The content of anthocyanins in the Del/Ros1 transgenic tomato is equally distributed within fruit, with 5.1 ± 0.5 g/kg dw being detected in the peel and 5.8 ± 0.3 g/kg dw in the flesh, but not detected in seeds [7]. These values are higher than those reported for well-known anthocyanin-rich foods such as red raspberry (3.9 g/kg dw; [158]), strawberry (3.2 g/kg dw; [158]), and mulberry (2.1 g/kg dw; [159]). In a study with transgenic plants, the predominant anthocyanins in the Del/Ros1 transgenic tomato were delphinidin-3-(trans-coumaroyl)-rutinoside-5-glucoside and petunidin-3-(trans-coumaroyl)-rutino side-5-glucoside, which contributed to nearly 86% of the total anthocyanins content, while two new anthocyanins, malvidin-3-(p-coumaroyl)-rutinoside-5-glucoside and malvidin-3-(feruloyl)-rutinoside-5-glucoside making up to 6% of the total anthocyanins content, were also reported [7]. Three mutant genes have been identified that can lead to the production of anthocyanins in the peel of the fruit, namely Anthocyanin fruit (Aft), Aubergine (abg), and atroviolacea (atv), while the Aft gene was also identified in crosses with *Solanum chilense* Dunal [160]. This gene is located in chromosome 10 and its presence in tomato leads to the production of anthocyanin pigments, mainly delphinidin, malvidin and petunidin, as well as to higher levels of the flavonols quercetin (3.6-fold), and kaempferol (2.7-fold), in tomato fruit [160,161].

Tamarillo crop is attracting research interest lately due to the high content in antioxidants and phytochemicals. The tamarillo, a non-climacteric edible fruit, is quite popular in local markets, especially in South America, consumed in juices or fresh and being highly appreciated due to high polyphenols levels [156], β-carotene (provitamin A), vitamin B6, vitamin C (ascorbic acid), vitamin E, and iron contents [162]. Among phenols, the presence of anthocyanins (delphinidin, cyanidin, and pelargonidin glycosides) and hydroxycinnamoyl derivatives (e.g., 3-*O*-caffeoylquinic acids, caffeoyl glucose and feruloyl glucose) have been described in several reports [147,163,164], while recently rosmarinic acid has been also identified [156]. The hydroxycinnamoyl derivatives show antioxidant properties and have been related to protective effects on human health [165]. In particular, the caffeoyl ester of rosmarinic acid has various biocidal activities, such as antiviral, antibacterial, anti-inflammatory, and antioxidant effects [166]. Other compounds were tentatively identified as different rosmarinic acid glucosides, caffeoyl glucoside, feruloyl glucoside, and ferulic acid dehydrodimers. Pelargonidin

3-*O*-rutinoside and delphinidin 3-*O*-rutinoside were the main anthocyanins in purple cultivars of tomato fruit [167]. Vasco et al. [147] reported anthocyanins content of 38 mg/100 g fw in purple tamarillo which was higher than previous reports in yellow fruit (8.5 mg/100 g fw) [167].

Both *Solanum americanum* Mill. and *S. villosum* Mill. are important medicinal plants of the Solanaceae family, however the blackish-purple (*S. americanum*) and reddish-orange (*S. villosum*) colored fruit are mostly consumed in India, Ethiopia, Ghana, China, and Brazil [168]. Mohy-Ud-Din et al. [169] reported the different important steroidal glycoalkaloids like β-Solamargine, α-Solamargine, Solasonine, α-Solanine, solasodine, and Solanidine, with latter being well-recognized for its anticancer activities [170].
