Metabolism of Tomato Steroidal Glycosides in Humans

Ripe Tomato Saponin Esculeoside A and Sapogenol Esculeogenin A Suppress CD4+ T Lymphocyte Activation by Modulation of Th2/Th1/Treg Differentiation

We report that esculeoside A (EsA), a glycoside and a major component in ripe tomato fruit, ameliorated experimental dermatitis in mice. However, the underlying immunologic molecular mechanisms are unknown. The present study examined its underlying immune nutrition mechanism using concanavalin A (ConA)-blast mouse splenocyte primary culture. We found that EsA and its sapogenol esculeogenin A (Esg-A) concentration-dependently suppressed T-lymphoproliferation using CFSE-labeled flow-cytometry and water-soluble tetrazolium (WST) assay. Using ELISA and q-PCR methods, EsA/Esg-A showed profound decreases in T helper 2 (Th2)-relevant interleukin-4 (IL-4) secretion and mRNA expression, and GATA3 expression. Moreover, EsA/Esg-A suppressed CD4+ T-lymphocyte activation by decreasing IL-2 secretion and mRNA expression and CD25+ cell proportion. Further, EsA/Esg-A alleviated Treg suppressive activity by reducing IL-10 secretion, Foxp3 mRNA expression, and cell numbers. We suggest the immune nutrition function by tomato component, and highlight that EsA/Esg-A are capable of reducing CD4+ T-lymphocyte activation via a reduction in Th2-lymphocyte activity by modulation of Th2/Th1/Treg subunit differentiation.

Decrease of Hyaluronidase Activity and Suppression of Mouse CD4+ T Lymphocyte Activation by Tomato Juice Saponin Esculeoside B, and Its Sapogenol Esculeogenin B

(1) Background: A naturally occurring glycoside, esculeoside B (EsB), has been identified as a major component in juice or canned tomato. We reported how EsB ameliorated mice experimental atopic dermatitis by a decrease in serum IgE levels. However, the underlying immunologic molecular mechanisms are unknown. (2) Methods: The present study tested the effects of EsB on hyaluronidase activity and CD4+ T lymphocyte activation using concanavalin A (ConA)-blast mouse splenocyte primary culture. (3) Results: We found that EsB and its sapogenol esculeogenin B (Esg-B) decreased hyaluronidase activity by a modified Morgan–Elson method. We demonstrated that EsB/Esg-B dose-dependently suppressed T-lymphoproliferation using CFSE-labeled flow-cytometry and water-soluble tetrazolium (WST) assay. Using ELISA and q-PCR methods, EsB/Esg-B suppressed the cytokine secretion and mRNA expression of Th2-relevant IL-4 and Th1-relevant IFN-γ. Moreover, both EsB/Esg-B showed a reduction in IL-10 secretion, but only Esg-B decreased IL-2 secretion. (4) Conclusions: Our study is the first to demonstrate how EsB/Esg-B inhibit hyaluronidase activity and reduce CD4+ T-lymphocyte activation via a reduction in Th2-lymphocyte activity by modulation of Th2/Th1/Treg subunits differentiation.

Plant in vitro cultures: A promising and emerging technology for the feasible production of antidiabetic metabolites in Caralluma tuberculata

Caralluma tuberculata, a medicinal and edible plant of the genus Caralluma, belongs to the family Asclepiadaceae. Traditionally, its succulent stems are used as folk medicine for life-threatening diabetes mellitus (DM) disease. Its antidiabetic potential is ascribed to the presence of various secondary metabolites (e.g., pregnane glycosides, flavone glycosides, megastigmane glycosides, polyphenols, ferulic acid, quercetin, and bitter principles, among others) that act as effective and safe antidiabetic agents. The mechanisms of these bioactive secondary metabolites in C. tuberculata herbal medicine include lowering the blood glucose level, stimulating B cells of the pancreas to release more insulin, enhancing the sensitivity of the insulin receptor, inhibiting the action of glucagon and the hydrolysis of glycogen, and increasing the use of glucose in tissues and organ. However, overexploitation, alterations in natural environmental conditions, lower seed viability, and slow growth rate are responsible for the extinction of species from natural habitats, then becoming critically endangered species according to the International Union for Conservation of Nature Red List categories. Therefore, its limited availability does not meet the higher worldwide market demand of C. tuberculata as an antidiabetic drug. Thus, for its conservation and sustainable utilization, researchers across the globe are working on devising strategies to conserve and improve biomass along with the secondary metabolite profiles of C. tuberculata using in vitro approaches. The current review describes the recent progress on antidiabetic phytoconstituents, their cellular mechanisms, and their subsequent clinical outcomes in the drug discovery management of DM. Moreover, in vitro methods such as callus culture, micropropagation, and nano-elicitation strategies for conserving and producing bioactive secondary metabolites have been concisely reviewed and discussed.

Russelioside B, a pregnane glycoside ameliorates hyperglycemia in streptozotocin induced diabetic rats by regulating key enzymes of glucose metabolism

An alternative strategy to treat diabetes mellitus is the use of various natural agents possessing hypoglycemic effect. Caralluma quadrangula has been used in Saudi traditional medicine in cases of thirst and hunger and for the treatment of diabetes. The present study was designed to evaluate the improving effect of russelioside B, a pregnane glycoside isolated from Caralluma quadrangula on glucose metabolism in the liver of streptozotocin-induced diabetic rats. Diabetes mellitus was induced in rats by a single intraperitoneal injection of streptozotocin (50 mg/kg body weight). Experimental rats were administered russelioside B at a dose of 50 mg/kg body weight once a day for 30 days. The results showed that RB improved the fasting serum glucose level, glycated hemoglobin percent, serum insulin level and lipid profile. A significant improvement was observed upon the administration of russelioside B on the activities of the key enzymes of carbohydrate metabolism (glucokinase, glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, and glycogen phosphorylase) in the liver of diabetic rats. Further, russelioside B administration to diabetic rats reverted gene expression of glucokinase, glucose-6-phosphatase, glycogen synthase and glycogen synthase kinase-3β to near normal levels. In conclusion, russelioside B possess antidiabetic and antihyperlipidemic effect in streptozotocin induced diabetic rats. Hence, administration of russelioside B may represent a potentially useful strategy for the management of diabetes.

Anti-hyaluronidase Activity in Vitro and Amelioration of Mouse Experimental Dermatitis by Tomato Saponin, Esculeoside A

The increasing incidence of atopic dermatitis during recent decades has prompted the development of safe and effective agents for prevention of atopic diseases. Esculeoside A, a glycoside of spirosolane type, is identified as a major component in ripe tomato fruits. The present study investigated the effects of esculeoside A and its aglycon esculeogenin A on hyaluronidase activity in vitro and antiallergy in experimental dermatitis mice. Esculeogenin A/esculeoside A (esculeogenin A equivalent) with an IC50 of about 2 μM/9 μM dose-dependently inhibited hyaluronidase activity measured by a modified Morgan-Elson method. Oral treatment with esculeoside A 10 mg/kg of experimental dermatitis mice for 4 weeks significantly decreased the skin clinical score to 2.5 without any detectable side effects compared with 6.75 of the control. The scratching frequency of esculeoside A 100 mg/kg application was decreased significantly as 107.5 times compared with 296.67 times of the control. Thus, the present study showed that esculeoside A/esculeogenin A significantly blocks hyaluronidase activity in vitro and that esculeoside A ameliorates mouse experimental dermatitis.

Steroidal Aglycones from Stems of Marsdenia tenacissima that Inhibited the Hedgehog Signaling Pathway

Two novel steroidal aglycones, together with four known ones, were isolated from the hydrolysis extract of the CHCl3 soluble extract of the stems of Marsdenia tenacissima. Their structures were determined on the basis of chemical evidence and extensive spectroscopic methods, including 1D and 2D NMR spectroscopy. These compounds displayed inhibition of the Hedgehog signaling pathway in vitro.

Stephanthraniline A inhibits the proliferation and activation of T cells in vitro and in vivo

Stephanthraniline A (STA) isolated from the stems of Stephanotis mucronata (Blanco) Merr. was evaluated for their suppression on T cells' immune responses in vitro and in vivo. In vivo, oral administration of STA significantly inhibited T cell-mediated delayed-type hypersensitivity (DTH) response. In vitro, STA has inhibitory effects on T cell proliferation induced by CD3/CD28 cross-linking or Con A; additionally, CD4(+) T cells are more sensitive to this inhibition than CD8(+) T cells. STA also suppressed the production of cytokines (IL-2, IFN-γ, IL-4 and IL-17) and mRNA expression of the genes associated with T cell activation, proliferation and differentiation. Our data indicate that STA inhibits the proliferation of T cells by inducing cell cycle arrest but not inducing apoptosis. The inhibitory mechanism of STA on T cells was correlated with the gene change related to multi-signal transduction pathways. Furthermore, we also provided lines of evidence that STA, distinct from glucocorticoids, did not activate the glucocorticoid receptor. These findings would be beneficial for further understanding the therapeutic effects of S. mucronata in the treatment of autoimmune diseases. It also suggested the potential of the natural steroid STA as the effective candidate compounds for use in the treatment of inflammatory and autoimmune diseases.

New spirostanol glycosides from Solanum nigrum and S. jasminoides

A new characteristic steroidal glycoside possessing a hydroxyl group at C-23, inunigroside A (1), was isolated from the withered berries of Solanum nigrum L. On the basis of spectroscopic analysis, the structure of 1 was characterized as (5α,22S,23S,25R)-3β,23-dihydroxyspirostane 3-O-β-lycotetraoside. Next, a major steroidal sapogenol, (22R, 25S)-3β,15α-dihydroxy-spirost-5-ene (3), was obtained from the acid hydrolysate of the methanolic extract of the aerial parts of Solanum jasminoides L. A new bisdesmoside, 3-O-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl (22R,25S)-3β,15α-dihydroxyspirost-5-ene 15-O-α-L-rhamnopyranoside (4), named jasminoside A, was isolated from the methanolic extract of S. jasminoides.

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.