The content, profile and biological activity of tannins in some tanniniferous plants

Abstract

The present study was carried out on the quantification, chromatographic profiling and biological activity assessments of selected tanniniferous forages viz. leaves of oak/ban (Quercus leucotrichophora), robinia (Robinia pseudoacacia), khirk (Celtisaustralis), kachnar (Bauhinia variegata), siris (Albizia lebbeck), pakar (Ficus infectoria), tremal (Ficus roxburghii) and buince (Salix alba), and leaves and fruits of bhera (Terminalia bellerica) and harad (Terminalia chebula). The total tannin content was found high in harad and bhera fruits & leaves. Kachnar, robinia and pakar leaves were rich source of condensed tannins. However, hydrolysable tannins were the predominant component of the total tannin phenols of oak, harad and bhera leaves. The extraction of tannins was followed by TLC fingerprinting. TLC fingerprint analysis of selected plants showed remarkable difference in the overall complexity and the polarity of the tannins. Prospections were also carried out on the protein precipitating capacity and free radical scavenging activity of these tannins. The antioxidant activity of the plant samples was done using 1,1-Diphenyl-2-picryl-hydrazyl spray. The protein precipitation capacity and antioxidant activity – the major indicators of biological activity of tannins, suggested that a fine balance has to be struck between the beneficial and deleterious effects of these tannins by maintaining a control over their concentration vis-à-vis their intake by the animals.