Preparing of the antiviral and antibacterial medicinal plants is a promising task of native pharmacy. In this regard, it is interesting to study species of the genus penny, namely Hedysarum caucasicum M.Bieb., Hedysarum grandiflorum Pall., Hedysarum daghestanicum Rupr. ex. Boiss., the regions of distribution, chemical composition and known pharmacological properties will allow to justify directions of their rational use, as well as creation of new phytopreparations of antiviral action on the basis of medicinal raw materials. During the complex pharmacognostic studies of three species of Hedysarum L. we have developed the method for isolation and quantitative determination of the sum of xanthones in terms of mangiferin by UV spectrophotometry. The technique takes into account the basic physical and chemical properties of xanthones, is characterized by reproducibility, high accuracy, simplicity of implementation, allows to carry out both screening evaluation of various raw objects containing mangiferin derivatives, as well as standardization of the prepared medicinal plant raw material of the penny. The developed methods are tested on the aerian organs of Hedysarum L. species, collected and dried taking into account the rules and requirements of drug raw material procurement. As a result, Hedysarum caucasicum M.Bieb herb (0.624%) was found to be the highest quantitative amount of xanthone sum in terms of mangiferin. The obtained results show the prospect of further research of the aerian part of the Hedysarum caucasicum M.Bieb. as an additional source of mangiferin. The method of quantitative determination of xanthone sum in the list for mangiferin in the above-ground part of Hedysarum caucasicum M.Bieb; Based on the obtained data, it has been found that the proposed technique is highly sensitive, reproducible and usable.