Re-examining The Phytochemicals In Tomatoes And Their Contribution To The Antioxidant Activities And Other Potential Health Benefits

Epidemiological and experimental studies have shown that intake of tomato naturally high in phytochemicals is positively associated with health benefits, particularly in reducing risks of many prevalent chronic diseases such as cancer and coronary heart disease.The objectives of the present investigation are to:develop rapid and sensitive UPLC methods to obtain complete, pictures of phytochemicals ineclading carotenoids, phenolics in tomatoes; examine the antioxidant activities of carotenoid and phenolic extracts of20tomato cultivars and breeding lines using the chemical based mthods2,2-diphenyl-l-picrylhydrazyl (DPPH) free radical scavenging capacity; photochemiluminescence (PCL); ferric reducing antioxidant power (FRAP); oxygen radical absorption capacity (ORAC) assays and a cell-based model system using cardiac H9c2cells and H2O2, respectively; and assess the relationships between the antioxidant activity and phytochemical concentration and composition of tomatoes. The information of phytochemical contents and antioxidant activities of different tomato cultivars and breeding lines and their correlations will be useful to plant breeders, food processers and other food industry. Our ultimate goal is to breed designer tomatoes. The main results are shown as followed:1. All-trans lutein, lycopene, β-carotene and their21cis isomers in20tomato breeding were separated and identified by a rapid and sensitive UPLC method using a1.7μm C18column in15min. All-trans carotenoids were predominant, but9-cis,13-cis-lutein,5-cis,9-cis,13-cis,15-cis-lycopene,9-cis,3-cis and15-cis-β-carotene were also found.2. Microwave-assisted extraction (MAE) was investigated for extraction of phenolic compounds from tomato with maximized antioxidant activities using response surface methodology (RSM) coupled with a central composite design, and in vitro antioxidant assays (FRAP and ORAC). MAE was more efficient for greater antioxidant activities and higher total phenolic contents than solvent extraction. The optimal MAE processing parameters were96.5℃,2.06min,66.2%ethanol for FRAP, and96.5℃,1.66min,61.1%ethanol for ORAC.3. The phytochemical content was significantly different among the20^tomato cultivars. The discrepancy is not surprising because genotype can play an important role in the carotenoid and phenolic profiles of tomato. The highest total carotenoid content was found in O258AAAA (261.86μg/g DW), followed by Q105AAAA (242.02μg/g DW) and LA1593(232.12μg/g DW). Red tomatoes had the highest total carotenoid contents, followed by purple, orange, pink and yellow ones. For the individual carotenoids, lycopene had the highest concentrations (total of all-trans and cis isomers) ranging from9.61to227.11μg/g DW, followed by total β-ca(?)ene (6.89to110.40μg/g DW) and total lutein (2.85to9.23μg/g DW). The highest total carotenoid content was found in Q105AAAA (997.45mg GAE/100g DW), followed by O258AAAA (883.72mg GAE/100g DW) and H9478(746.09mg GAE/100g DW). Individual phenolic compounds of the20tomato varieties were ranging from6.10to42.73mg/100g.4. A newly developed non-genetically modified purple tomato V118was investigated for its phytochemical compositions and antioxidant activities. A highly efficient and sensitive UPLC method was developed for both the phenolics and carotenoids. The main carotenoids were lutein, lycopene and β-carotene while the main phenolics were protocatechuic acid, chlorogenic acid, gentistic acid, caffeic acid, p-coumaric acid, ferulic acid, rutin and naringenin. The total carotenoid content of V118was234.78μg/g DW and the total phenolic content was659.11mg GAE/100g DW.5. It showed that in addition to the phytochemicals commonly known for tomatoes, V118had a unique composition of anthocyanins. The LC-MS study showed three major anthocyanins which were petunidin-3-O-caffeoyl-rutinoside-5-O-glucoside (9.04mg petunidin equivalent/100g DW), petunidin-3-O-(p-coumaryl)-rutinoside-5-O-glucoside (50.18mg petunidin equivalent/100g DW) and malvidin-3-O-(p-coumaryl)-rutinoside-5-O-glucoside (13.09mg malvidin equivalent/100g DW).6. The extracts of different tomatoes showed strong but different antioxidant activity. O258AAAA and Q105AAAA exhibited the highest antioxidant activity. The antioxidant activities of the carotenoid extracts of all cultivars tested in the PCL assay ranged from6.01-48.83nmol Trolox equivalent/g DW, and the EC50values in the DPPH assay were from7.76-56.98μg. The FRAP values varied from26.86to57.84μmol AAE/g DW, while the ORAC values ranged from235.42to351.19umol TE/g DW. For purple tomato V118, the antioxidant activities of the lipophilic extract as measured by the PCL and ORAC-L assays were30.11μmol TE/g DW and11.97μmol TE/g DW, respectively; while the hydrophilic extracts as determined by the ORAC-H and FRAP assays were323.23μmol TE/g DW and54.95μmol AAE/g DW, respectively. It showed that purple tomatoes such as V118possess additional phytochemicals like anthocyanins which can potentially have added health benefits.7. The total antioxidant activities as evaluated by PCL and DPPH assays were found to correlate well with the total carotenoid content. The FRAP, but not the ORAC value showed good correlation with the TPC or TPI (p<0.05).8. The lipophilic extracts of pink, red, purple, orange and yellow tomatoes were found to prevent cell death in a cell-based model system using cardiac H9c2cells and H2O2, via attenuation of the caspase-3and matrix metalloproteinase (MMP)-2activities. In both chemical and cell based systems, extracts of different tomatoes showed strong but different antioxidant activities. Lycopene showed the highest correlation in the antioxidant activity.9. Purple tomato showed better chemical-based antioxidant activities, and the phytochemicals in V118can be transported across the MCF cell barrier and showed strong CAA.10. The phytochemicals in purple and red tomatoes had strong anti-inflammatory activity and could significantly inhibite paw oedema formation in a paw oedema rat model. The in vivo antioxidant and anti-inflammatory acitivity of purple tomato was much higher than red one because there was anthocyanin existed in the purple tomato.