Thiolytic screening method for exploring condensed tannin variation in a unique sainfoin germplasm bank

Stringano, E., Hayot, C., Smith, L., Theodoridou, K., Aufrere, J., Brown, R., Hayes, W. ORCID: https://orcid.org/0000-0003-0047-2991, Cramer, R. ORCID: https://orcid.org/0000-0002-8037-2511 and Mueller-Harvey, I. (2010) Thiolytic screening method for exploring condensed tannin variation in a unique sainfoin germplasm bank. Planta Medica, 76 (12). 0_3. ISSN 1439-0221 doi: 10.1055/s-0030-1264189

Abstract/Summary

This EU funded 'HealthyHay'project stablished a sainfoin (Onobrychis vicifolia) germplasm bank at NIAB, Cambridge, with 306 accessions from around the world. A screening method was developed to characterise tannins by thiolytic degradation [1] directly in green plants for the first time. the method was validated by separate analysis of unextractable, extractable and purified tannins using thiolysis, HPLC-GPC and MALDI-TOF MS. Most tannins (58 to 73% of the total) could be recovered after Toyopearl HW50 fractionation with water, aqueous methanol and acetone. the greatest losses during purification occurred amongst larger molecular weight tannins with mean degree of polymerisation (mDP) > 18. The composition of water-,aqueous methanol- and acetone-soluble tannins differed considerably in their mDP and trans/cis ratios, but not in their prodelphinidin/orocyanidin (PD/PC) ratios.