Quantitative determination of total triterpenoids in exudates of Thymus species

Exudates consist mainly of lipophilic compounds accumulated on the surface of plant tissue. They are obtained by rapidly rinsed of the whole, not ground plant parts. Previously GC/MS analysis of exudates of Thymus species showed that triterpene acids are the main component of them. Triterpene acids are compounds with important biological and pharmacological activity, among them the antitumor is especially valuable. Simonyan et al., 1972, have described the rapid and easy method for the quantitative determination of triterpenoids. The method is based on the reaction of triterpenes with concentrated sulfuric acid whereupon (whereby) they are oxidized and form colored products that can be measured spectrophotometrically in the 310 nm region. Spectrophotometric analysis of exudates of eight Thymus species was applied to assess quickly and easily the content of triterpenoids. The plant material was collected from their natural localities. Four of the studied species are members of the section Hyphodromi (Thymus atticus, T. perinicus, T. striatus, and T. zygioides) and the other four species belong to section Serpyllum (T. longedentatus, T. longicaulis, T. pulegioides, and T. sibthorpii). One of the studied species is a local endemic with distribution in Pirin Mts only (T. perinicus), one is a Balkan endemic (T. longedentatus) and two of them are sub-endemics (T. atticus, T. sibthorpii). Exudates were obtained from dry, not ground plant material by washing with acetone to dissolve the exudate material. Total triterpenoids were determined by sulfuric acid following the principles cited above. The triterpenoid content was expressed as percent (%) in exudate in equivavalent of oleanolic acid. The highest content of triterpenoids was found in T. perinicus, T. pulegioides, T. striatus, T. atticus, T. longicaulis exudates. The established high levels of triterpenoids in the exudates define them as promising fractions for the study of antitumor and antimicrobial activities.  

Reference

Simonyan, A.V., Shinkarenko, A.L., Oganesyan E.T. 1972. Quantitative determination of triterpenoids in plants of the genus Thymus. Chemistry of Natural Compounds, 8 (3), 290–291. DOI: 10.1007/bf00563731

Acknowledgment. This work was supported by the National Science Fund, Ministry of Education and Science, Bulgaria, Project DN 16/3.