Influence of Abiotic Stress Factors on the Antioxidant Properties and Polyphenols Profile Composition of Green Barley (Hordeum vulgare L.)

Abstract

The influence of stress factors on the plant can, on the one hand, lead to worse functioning of the plant and loss of its crop, but on the other, it can have a positive effect on the metabolism of compounds with documented biological activity. In this study, the effect of light and drought intensity on photosynthetic activity and physiological status of two barley varieties, as well as the antimicrobial, antioxidant properties and profile of polyphenolic compounds of green barley were analysed. It was shown that under the conditions of water shortage, the KWS Olof variety showed a smaller decrease in CO₂ assimilation and transpiration and higher values of these parameters at both light intensities. Only in the KWS Olof variety increased stress as a result of increased light intensity. It has also been shown that both the intensity of radiation and drought-related stress have a significant impact on the profile of polyphenolic compounds from green barley, without a simple relationship between the impact of stress factors on the content of polyphenols. Changes in the profile of polyphenolic compounds augmented the antioxidant and antimicrobial activity of the material. This, in turn, proposes the possibility of reducing the applied doses of herbal material thanks to a greater content of active substances in extracts obtained from the plants used to produce medicinal preparations.

Keywords: antimicrobial activity; antioxidant activity; barley grass; drought; flavonoids; phenolic acids; solar radiation.

Figure 1

PCA, chemical profile of green barley samples determined by LC-MS. (A)—score plot (O—KWS Olof, N—Nokia, C—control, D—drought, L—PAR = 400, H—PAR = 800), (B)—loading plot (compounds—monoisotopic neutral mass_retention time: 1—522.24 Da_9.3 min, 2—372.11 Da_11.1 min, 3—400.17 Da_11.6 min, 4—304.1 Da_12 min, 5—550.3 Da_9.7 min, 6—386.12 Da_10.7 min, 7—416.17 Da_10.8 min, 8—498.23 Da_10.9 min, 9—584.23 Da_11.6 min, 10—238.08 Da_12.3 min, 11—468.22 Da_12.8 min, 12—482.24 Da_13.7 min, 13—482.24 Da_14 min, 14—524.25 Da_14.2 min, 15—568.24 Da_14.1 min, 16—524.25 Da_14.5 min, 17—568.24 Da_14.5 min, 18—414.13 Da_15.6 min).