A New Tomato Pregnane Glycoside from the Overripe Fruits

Discovery of Flazin, an Alkaloid Isolated from Cherry Tomato Juice, As a Novel Non-Enzymatic Protein Glycation Inhibitor via in Vitro and in Silico Studies

Both overproduced reactive oxygen species/reactive nitrogen species and hyperglycemic conditions accompany a significant increase in protein glycation and nitration that contribute to the initiation and progression of diabetic complications and neuronal disorders. In this study, 19 compounds, including steroidal saponins, alkaloids, cerebroside, phenolic compounds, sterols, and nucleosides, were isolated from cherry tomato (Solanum lycopersicum var. cerasiforme) juice, of which flazin showed good inhibition on monosaccharide-induced non-enzymatic bovine pancreas insulin and bovine serum albumin (BSA) glycation. Molecular dynamics simulations revealed that flazin continuously interacts with Phe1, Val2, Tyr26, and Lys29 insulin residues, which play a key role in insulin glycation/dimerization. In addition, depending upon the flazin dose, this blocked the tyrosine nitration of BSA via scavenging peroxynitrite anions. Taken together, our novel findings suggest that flazin could be a lead compound for the treatment of diabetes and neuronal disorders via the inhibition of non-enzymatic protein glycation and the elimination of peroxynitrite.

Unexplored nutritive potential of tomato to combat global malnutrition

Tomato, a widely consumed vegetable crop, offers a real potential to combat human nutritional deficiencies. Tomatoes are rich in micronutrients and other bioactive compounds (including vitamins, carotenoids, and minerals) that are known to be essential or beneficial for human health. This review highlights the current state of the art in the molecular understanding of the nutritional aspects, conventional and molecular breeding efforts, and biofortification studies undertaken to improve the nutritional content and quality of tomato. Transcriptomics and metabolomics studies, which offer a deeper understanding of the molecular regulation of the tomato's nutrients, are discussed. The potential uses of the wastes from the tomato processing industry (i.e., the peels and seed extracts) that are particularly rich in oils and proteins are also discussed. Recent advancements with CRISPR/Cas mediated gene-editing technology provide enormous opportunities to enhance the nutritional content of agricultural produces, including tomatoes. In this regard, genome editing efforts with respect to biofortification in the tomato plant are also discussed. The recent technological advancements and knowledge gaps described herein aim to help explore the unexplored nutritional potential of the tomato.

Metabolomics-Inspired Insight into Developmental, Environmental and Genetic Aspects of Tomato Fruit Chemical Composition and Quality

Tomato was one of the first plant species to be evaluated using metabolomics and remains one of the best characterized, with tomato fruit being both an important source of nutrition in the human diet and a valuable model system for the development of fleshy fruits. Additionally, given the broad habitat range of members of the tomato clade and the extensive use of exotic germplasm in tomato genetic research, it represents an excellent genetic model system for understanding both metabolism per se and the importance of various metabolites in conferring stress tolerance. This review summarizes technical approaches used to characterize the tomato metabolome to date and details insights into metabolic pathway structure and regulation that have been obtained via analysis of tissue samples taken under different developmental or environmental circumstance as well as following genetic perturbation. Particular attention is paid to compounds of importance for nutrition or the shelf-life of tomatoes. We propose furthermore how metabolomics information can be coupled to the burgeoning wealth of genome sequence data from the tomato clade to enhance further our understanding of (i) the shifts in metabolic regulation occurring during development and (ii) specialization of metabolism within the tomato clade as a consequence of either adaptive evolution or domestication.

A new hemiterpene glycoside from the ripe tomatoes

A new hemiterpene glycoside (1) was isolated from ripe tomatoes (the fruit of Lycopersicon esculentum, Solanaceae) along with eight known compounds. The chemical structure of 1 was determined to be 2-methylbutan-1-ol β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranoside, based on spectroscopic data as well as chemical evidence. In addition, the radical-scavenging activities of the isolated compounds on the free radical of 1,1-diphenyl-2-picrylhydrazyl were examined. Among the tested compounds, tryptophan, 4-O-β-d-glucopyranosyl caffeic acid and dihydro-p-coumaryl alcohol γ-O-β-d-glucopyranoside demonstrated 42.0%, 50.1% and 76.0% scavenging activities, respectively, at a concentration of 0.5 mM.

Metabolomics-assisted refinement of the pathways of steroidal glycoalkaloid biosynthesis in the tomato clade

Steroidal glycoalkaloids (SGAs) are nitrogen-containing secondary metabolites of the Solanum species, which are known to have large chemical and bioactive diversity in nature. While recent effort and development on LC/MS techniques for SGA profiling have elucidated the main pathways of SGA metabolism in tomato, the problem of peak annotation still remains due to the vast diversity of chemical structure and similar on overlapping of chemical formula. Here we provide a case study of peak classification and annotation approach by integration of species and tissue specificities of SGA accumulation for provision of comprehensive pathways of SGA biosynthesis. In order to elucidate natural diversity of SGA biosynthesis, a total of 169 putative SGAs found in eight tomato accessions (Solanum lycopersicum, S. pimpinellifolium, S. cheesmaniae, S. chmielewskii, S. neorickii, S. peruvianum, S. habrochaites, S. pennellii) and four tissue types were used for correlation analysis. The results obtained in this study contribute annotation and classification of SGAs as well as detecting putative novel biosynthetic branch points. As such this represents a novel strategy for peak annotation for plant secondary metabolites.

On the regulation and function of secondary metabolism during fruit development and ripening

The maturation and development of tomato fruit has received much attention due both to the complexity and intricacy of the changes which occur during this process and to the importance of these fruits as a component of the human diet. Whilst great advances have been made in understanding molecular genetic aspects of fruit development, our knowledge concerning the metabolic shifts underpinning this process remains largely confined to primary metabolism. Conversely, the majority of the metabolites considered to have health benefits are secondary or specialized metabolites. Prior to assessing the role (if any) of these metabolites in tomato fruit development, considerable effort will be required in order to better describe the complement of secondary metabolites in the tomato and to elucidate the metabolic pathways involved in their synthesis and degradation. Advances in tomato secondary metabolism will be reviewed here focusing on the use of metabolomics strategies and, where applicable, the enabling of these strategies by their coupling to information resident in the tomato genome sequence.

The tomato saponin, esculeoside A

Esculeoside A (2), a spirosolane steroidal glycoside, is a major constituent isolated from Solanum lycopersicum, a commercial strain of mini tomatoes. The content variability of esculeoside A (2) was examined in mini, midi, and Momotaro tomatoes and various processed tomato products. In the green immature tomato fruit, tomatine (1) is oxidized at C-23 and C-27 to produce esculeoside A (2) in the ripe fruit. Further, esculeoside A (2) is partly converted to 3β-hydroxy-5α-pregn-16-en-20-one 3-O-β-lycotetraoside (6), a pregnane glycoside, in the overripe fruit. Esculeogenin A (3), the sapogenol of 2, is easily converted into 3β,16β-dihydroxy-5α-pregn-20-one (17). Metabolic studies showed excretion of androstane derivatives in the urine of human volunteer subjects after tomato consumption. Esculeogenin A (3) inhibited the accumulation of cholesterol esters in macrophages through its effects on acyl-CoA:cholesterol acyl transferase (ACAT). Oral administration of esculeoside A (2) to apoE-deficient mice significantly reduced serum levels of cholesterol, triglycerides, and LDL-cholesterol and ameliorated the severity of atherosclerotic lesions.

Three new aromatic glycosides from the ripe fruit of cherry tomato

Three new aromatic glycosides were isolated from the ripe fruit of cherry tomato [Lycopersicon esculentum var. cerasiforme (Dunal) Alef. (Solanaceae)] along with six known aromatic glycosides and one known steroidal alkaloid glycoside. Their chemical structures were determined on the basis of spectroscopic data as well as chemical evidence.

Involvement of ethylene in the accumulation of esculeoside A during fruit ripening of tomato (Solanum lycopersicum)

The composition of glycoalkaloids in tomato fruit changes with ripening. However, it has not been clarified whether the accumulation of glycoalkaloids is controlled by the ripening-inducing phytohormone, ethylene. Here, we report the effect of ethylene on the accumulation of tomato fruit glycoalkaloids. We investigated the effect of exogenously applied ethylene. In response to ethylene treatment, the content of alpha-tomatine decreased, whereas the content of esculeoside A increased. Next, we analyzed the fruits of ripening mutants, rin, nor, and Nr. In fruits of these mutant lines, the level of accumulation of esculeoside A decreased, whereas alpha-tomatine accumulated to higher levels than in wild-type fruit. These results demonstrated that the esculeoside A accumulation was associated with production and perception of ethylene. Additionally, the accumulation profiles of the intermediate metabolites of esculeoside A biosynthesis in ripening mutant fruits suggest that a glycosylation step in the putative pathway from alpha-tomatine to esculeoside A depends on ethylene.

Steroidal Alkaloid Glycosides, Esculeosides C and D, from the Ripe Fruit of Cherry Tomato

Two new steroidal alkaloid glycosides, esculeosides C and D, have been isolated from the ripe fruit of Cherry tomato [Lycopersicon esculentum var. cerasiforme (DUNAL) ALEF.], along with three known steroidal alkaloid glycosides, esculeoside A, esculeoiside B, and lycoperoside G. Their chemical structures were determined on the basis of spectroscopic data.