Protein-binding affinity of various condensed tannin molecular weights from tropical leaf peel

Abstract

The phenolic compound, condensed tannin (CT), from plant-based foods has suggested to have a beneficial function in the biological system of the animal kingdom. However, there is a lack of information for a comprehensive understanding of their molecular weight (MW) and protein-binding affinity (PBA) evaluated in tropical plants as commonly used feedstuff. Therefore, we evaluated concentration, MW, and PBA of CT from selected tropical leaf peel. The four plant materials harvested, extracted, and purified as experimental groups were cassava (CV) leaves (Manihot esculenta Crantz.), Leucaena (LN) leaves (Leucaena leucocephala Lam. de Wit), Siamese neem (SN) leaves (Azadirachta indica A. Juss. var. siamensis Valeton), and mangosteen (MS) peels (Garcinia mangostana Linn.). A commercial quebracho tannin (QB) was used to compare simultaneously. MW was determined using the gel permeation chromatography and PBA was subsequently measured by assaying purified experimental groups in protein precipitation. We found that the ranges of CT and MW in selected plant materials were 1.2%-14.4% on a dry matter basis and 2.9-3.6 Da, respectively. The PBA was ranked in the ascending order as follows: MS peels < LN leaves < CV leaves < SN leaves. Of note, the SN leaves were higher than QB. Our results indicated that a higher concentration of MW of CT resulted in a greater PBA. In conclusion, SN leaves could be a promised tropical plant as a PBA modifier on the system biology of animal nutrition.