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Quantitative analysis of polyphenols in eighteen Hypericum taxa

Background and Purpose: Phenolics are one of the most ubiquitous groups of plant secondary metabolites, which play an important role in plant stress tolerance, growth, reproduction, resistance to pathogens, pigmentation and etc. In this study we have analysed the content of polyphenols in the aerial parts of eighteen cultivated Hypericum taxa, collected over two consecutive seasons. No peer-reviewed literature could be found regarding determination of the quantities of polyphenols present in the majority of the analyzed taxa of the native or cultivated samples. Quantitative analysis of phenolic compounds was therefore investigated. Materials and Methods: The content of phenolic compounds (total polyphenols, non-tannin polyphenols and tannins) in the aerial parts of eighteen Hypericum taxa collected over two consecutive seasons was determined by spectrophotometric methods. Results: The quantity of the total polyphenols of investigated taxa (Table 1), ranged from 3.96 to 16.88%. The highest content of total polyphenols was found in the samples of H. kouytchense (16.88%) collected in 2011 and H. hookerianum (14.75%) collected in 2012, while the samples of H. richeri subsp. grisebachii contained the lowest amount of total polyphenols (4.55 and 3.96%). The average content of tannins in the majority of investigated samples was found to be two times higher than the content of nontannin polyphenols, but in the rest of the samples, the most often ratio of tannins to nontannin polyphenols was 1:1. Conclusion: The variable content of polyphenols examined here, probably reflects the plant adaptation to seasonal changes in its environment. The occurrence of these metabolites in the taxa explored, hopefully will contribute to future understanding of their pharmacological properties and activity.

Hypericum; total polyphenols; nontannin polyphenols; tannins; spectrophotometry; quantitative analysis

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