Soyasaponins

Pharmacology

See Also

• Saponins?
• Sialic acid and sialyltransferase dysfunction in breast cancer
• [Sialic acid]?
• Glycosyltransferase?
• Thomsen-Friedenreich (T-Tn) antigen

Description

Soyasaponins are bioactive compounds found in many legumes. Results from in vitro fermentation suggested that colonic microflora readily hydrolyzed the soyasaponins to [Aglycone? aglycones].

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Discussion

Soyasaponins appear to be significant inhibitors of sialyltransferase, which may indicate a significant role in cancer chemotherapeutics and prevention.

These observations suggest that the soyasaponins may be an important dietary chemopreventive agent against colon cancer, after alteration by microflora.(1)

Soyasaponins appear to be hepatoprotective. (2, 3 )

• Glycine max (soybean)
• Pisium sativa (pea)
• Medicago hispida 4(Alfalfa variant)
• Trofolium 5 (red clover)

Although soyasaponins are bioactive, there is evidence of rather limited intestinal absorption. (6) However, since they are typically found in lectin-containing legumes, and [Lectins, induced changes in intestinal permeability? lectins induce increased gut permeability], it could be conjectures that soyasaponin isolates may not be as easily assimilated as instead when present in the intact whole food.

Abstracts

Soyasaponin I, a potent and specific sialyltransferase inhibitor

Biochem Biophys Res Commun. 2001 Jun 8;284(2):466-9. Wu CY, Hsu CC, Chen ST, Tsai YC. Institute of Biochemistry, National Yang-Ming University, Taipei, Taiwan.

• A growing number of reports demonstrate that hypersialylation, which is observed in certain pathological processes, such as oncogenic transformation, tumor metastasis, and invasion, is associated with enhanced sialyltransferase (ST) activity. There is therefore a need for the development of ST inhibitors to modulate ST activity and thus alleviate the disease processes caused by STs. In the present study, soyasaponin I had been discovered to be a potent and specific ST inhibitor by screening strategy from 7500 samples including microbial extracts and natural products. Kinetic analysis shows that it is a CMP-Neu5Ac competitive inhibitor with for ST3Gal I with an inhibition constant (K(i)) of 2.1 microM. In addition, it is only active against ST, but not against the other tested glycosyltransferases and glycosidases. Our study is the first report to discover ST inhibitor by screening method and also to provide the new chemical structure information that should be useful in the development of other novel ST inhibitors

Human fecal metabolism of soyasaponin I

J Agric Food Chem. 2004 May 5;52(9):2689-96. Hu J, Zheng YL, Hyde W, Hendrich S, Murphy PA.

Department of Food Science and Human Nutrition, and College of Veterinary Medicine, Iowa State University, 2312 Food Science Building, Ames, Iowa 50011, USA.

• The metabolism of soyasaponin I by human fecal microorganisms was investigated. Fresh feces were collected from 15 healthy women and incubated anaerobically with 10 mmol soyasaponin I/g feces at 37 degrees C for 48 h. The disappearance of soyasaponin I in this in vitro fermentation system displayed apparent first-order rate loss kinetics. Two distinct soyasaponin I degradation phenotypes were observed among the subjects: rapid soyasaponin degraders with a rate constant k = 0.24 +/- 0.04 h(-)(1) and slow degraders with a k = 0.07 +/- 0.02 h(-)(1). There were no significant differences in the body mass index, fecal moisture, gut transit time, and soy consumption frequency between the two soyasaponin degradation phenotypes. Two primary gut microbial metabolites of soyasaponin I were identified as soyasaponin III by NMR and electrospray ionized mass spectroscopy. Soyasaponin III appeared within the first 24 h and disappeared by 48 h. Soyasapogenol B seemed to be the final metabolic product during the 48 h anaerobic incubation. These results indicate that dietary soyasaponins can be metabolized by human gut microorganisms. The sugar moieties of soyasaponins seem to be hydrolyzed sequentially to yield smaller and more hydrophobic metabolites.

Soyasaponin-I-modified invasive behavior of cancer by changing cell surface sialic acids

Gynecol Oncol. 2005 Feb;96(2):415-22. Hsu CC, Lin TW, Chang WW, Wu CY, Lo WH, Wang PH, Tsai YC. Institute of Biochemistry, National Yang-Ming University, Taipei, Taiwan.

• OBJECTIVE: Sialylation involving tumor formation and invasive behavior goes along with altered sialyltransferase (ST) activity. A potent ST inhibitor, soyasaponin I (SsaI), was discovered to selectively inhibit the cellular alpha2,3-sialyltranserase activity. In this study, we further test the effects of SsaI on modifying the metastatic and invasive behaviors of cancer cell lines. METHODS: Nonmetastatic breast cancer cell line, MCF-7, and highly metastatic breast cancer cell line, MDA-MB-231, were used to investigate the effects of SsaI on tumor cells. RESULTS: SsaI did not affect cell growth cycle and also failed to inhibit cell growth in this study (the concentration of SsaI < or=100 muM). SsaI was as predicted to successfully inhibit cellular alpha2,3-ST activity and depressed the dose-dependent tumor cell surface alpha2,3-sialic acid expression. In addition, different concentrations of SsaI did stimulate MCF-7 cell adhesion to collagen type I linearly and significantly enhanced cell adhesion to the Matrigel-matrix. Furthermore, SsaI significantly decreased MDA-MB-231 cell migration. Reverse transcriptase polymerase chain reaction for evaluating mRNA expression of ST3Gal I, III and IV showed that SsaI also down-regulated the expression of ST3Gal IV but did not affect the other two. CONCLUSIONS: The results showed that SsaI was implicated in the invasive behavior of tumor cells, suggesting that altered alpha2,3-sialylation pathway played a crucial role in the adhesion and tumor metastases. SsaI is a good candidate for studying the biological roles of ST, and might provide a new preventive strategy in tumor metastasis.

Soyasaponin I decreases the expression of alpha2,3-linked sialic acid on the cell surface and suppresses the metastatic potential of B16F10 melanoma cells

Biochem Biophys Res Commun. 2006 Mar 10;341(2):614-9. Epub 2006 Jan 13. Chang WW, Yu CY, Lin TW, Wang PH, Tsai YC.

Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan, ROC.

• The transfer of sialic acids to the non-reducing terminal positions on sugar chains of glycoconjugates is catalyzed by sialyltransferases (STs). Increased sialylation is correlated with oncogenic transformation and metastatic potential. ST inhibitors may be potentially valuable as anti-cancer and anti-metastatic agents. In this study, we evaluated the effects of soyasaponin I (Ssa I), a known inhibitor of STs, on tumor metastasis through studying a highly metastatic cancer cell line B16F10. Ssa I specifically inhibited the expression of alpha2,3-linked sialic acids without affecting other glycans on the B16F10 cell surface. We also found that Ssa I decreased the migratory ability of cells, enhanced cell adhesion to extracellular matrix proteins. Finally, a pulmonary metastasis assay demonstrated that alteration of glycosylation in this way significantly reduced the ability of tumor cells to distribute to the lungs of mice. Collectively, these findings suggested that alpha2,3-linked sialic acids may play an important role in metastasis potential of B16F10 cells.

References