Effect of salicylic acid on phenolic compounds, antioxidant and antihyperglycemic activity of plants grown in a temperate climate.

Background: The family, one of the most important herbaceous and shrub plant families, includes a wide variety of plants with biological and medicinal uses. This study aimed to conduct a comparative analysis of phenolic compounds content and biological activity of extracts from eight species of e plants, cultivated in a temperate climate, and to study the effect of the foliar salicylic acid application on these parameters.

Methods: plants (, , , , , , , ) cultivated on field experimental sites. Plants were sprayed with salicylic acid at a concentration of 1 mM. The untreated with salicylic acid plants were used as control.

Results: The highest contents of hydroxycinnamic acids and flavonoids in control plants were observed in (6.4 ± 0.6 mg g-1 and 6.5 ± 0.4 mg g-1 respectively). The highest content of phenolic compounds was found in (13.8 ± 0.7 mg g-1). Among the control plants, , and were characterized by the highest antioxidant activity. All the studied extracts had the ability to inhibit α-amylase and α-glucosidase. Significant positive correlations were revealed between the antioxidant activity and the contents of hydroxycinnamic acids, total phenolic compounds, and flavonoids. A high degree of correlation was found between the α-amylase inhibitory activity and the content of hydroxycinnamic acids ( = 0.72, ≤ 0.05), as well as between the α-glucosidase inhibitory activity and the content of flavonoids ( = 0.83, ≤ 0.05) and hydroxycinnamic acids ( = 0.81, ≤ 0.05). The foliar treatment with salicylic acid led to an increase in the contents of hydroxycinnamic acids (in 6 species), flavonoids (in 2 species), total phenolic compounds (in 7 species), antioxidant activity (in 5 species), as well as in α-amylase (in 4 species) and α-glucosidase (in 5 species) inhibitory activity compared to the control plants. was the most susceptible to foliar treatment with salicylic acid. In this plant species, a significant increase in all studied biochemical parameters was noted.

Conclusions: The results obtained on the stimulating effects of salicylic acid can be used to increase the nutritional and pharmacological value of plants of the family cultivated in temperate climates.