Secondary Metabolite Profiling in Various Parts of Tomato Plants

Contents of carotenoids, phenolic compounds, volatile organic compounds, and alkaloids in leaves, internodes, fruits, and roots of tomatoes in different developmental stages were measured. Lycopene, ${\beta}$-carotene, and lutein were detected in all the tested parts except roots and green fruits. Lycopene content in red fruits was $49.04{\mu}g{\cdot}g^{-1}$ FW, while that in the other parts was below $40{\mu}g{\cdot}g^{-1}$ FW. ${\beta}$-Carotene and lutein contents in 24th leaves were 5.81 and $6.40{\mu}g{\cdot}g^{-1}$ FW, respectively, and were greater than those in the other parts. Caffeic, chlorogenic, and vanillic acids were detected in all the tested parts except roots. The content of chlorogenic acid in the 18th leaves was $40.11{\mu}g{\cdot}g^{-1}$ FW, while that in the other parts was lower than $31.00{\mu}g{\cdot}g^{-1}$ FW. The contents of caffeic and vanillic acids in the 24th leaves were 9.18 and $1.64{\mu}g{\cdot}g^{-1}$ FW, respectively, and were greater than those in the other parts. Moreover, younger leaves contained the more diverse volatile organic compounds including monoterpenes and sesquiterpenes. Contents of dehydro-tomatine and ${\alpha}$-tomatine were greatest in leaves, followed by internodes, roots and fruits. Younger leaves and internodes contained more dehydro-tomatine and ${\alpha}$-tomatine than older leaves and internodes. The contents of dehydro-tomatine and ${\alpha}$-tomatine in the 24th leaves were 0.89 and $1.42mg{\cdot}g^{-1}$ FW, respectively, and were greatest among all the tested parts. Our results indicated that, except lycopene, tomato leaves included greater secondary metabolites contents than red fruits. The results suggest that inedible parts of tomato plants can be used as raw material for antioxidants, anti-inflammatory agents, fungistats, and pesticides.