Response of selected antioxidants and pigments in tissues of Rosa hybrida and Fuchsia hybrida to supplemental UV‐A exposure

Abstract

The effect of supplemental UV‐A (320–400 nm) radiation on tissue absorption at 355 nm, levels of various antioxidants (ascorbate, glutathione, carotenoids and flavonoids) and of antioxidant scavenging capacity were investigated with leaves and petals of Rosa hybrida, cv. Honesty and with leaves, petals and sepals of Fuchsia hybrida, cv. Dollarprinzessin. Supplemental UV‐A did not result in visible changes in plant morphology of either species. In leaves it induced small increases in levels of chlorophylls a and b, the carotenoids antheraxanthin, lutein and β‐carotene, and high increases in the flavonols quercetin and kaempferol. Petals hardly responded, while the coloured sepals of fuchsia showed an increase in quercetin derivatives. HPLC of unhydrolysed flavonoids showed that individual quercetin derivatives in leaves of both species and kaempferol derivatives in rose leaves increased 2‐fold. Some kaempferol derivatives in fuchsia leaves were more than 2‐fold enhanced or were newly induced by supplemental UV‐A. Increases in l‐ascorbic acid levels in fuchsia leaves, and decreases in rose leaves as result of supplemental UV‐A were observed, but differences appeared statistically not significant, while l‐ascorbate levels remained unchanged in the other tissues investigated. Anthocyanins and reduced glutathione levels were unaffected in all tissues. The combined UV‐A induced increases in concentrations of these antioxidant species, did not lead to significant increases in antioxidant capacity of tissues, measured as Trolox equivalents in 50%‐ethanol extracts. Light absorption at 355 nm of leaf extracts was significantly increased upon UV‐A exposure. Our results indicate that the major protection towards UV‐A exposure, in particular in the leaves, will originate from absorption of irradiation, and not from scavenging reactive oxygen species.

Impact of strawberries on human health: insight into marginally discussed bioactive compounds for the Mediterranean diet

“…The folate levels that we observed are in keeping with values reported previously (Table 1), though we used the microbiological assay as analytical method (17) ; also, water content ranged similarly from 87 % to 94 %. Interestingly, higher variation in the folate content was observed among the genotypes analysed, with the selections showing the highest folate contents with respect to all the cultivars studied.…”

UV-spectra dependence of seedling injury and photosynthetic pigment change in Cucumis sativus and Glycine max

“…Previous studies found that this accumulation of ␤-carotene may act as a protective mechanism for photosynthesis in high UV-A/blue/white light conditions, suggesting that ␤-carotene protects against damage by screening the light-harvesting complexes through absorption of blue/UV wavelengths (Jahnke, 1999;Helsper et al, 2003). On the other hand, ␤-carotene concentration was decreased by B-UVB, which could be due to the damage of photosynthetic membrane by higher photo dose (Carletti et al, 2003).…”

The Content of Biologically Active Compounds in Some Fruits from Natural State

“…Carotenoids were determined by the method described by Helsper et al (2003) with some modifications (author's modification 2011). In short, the examined freeze-dried fruits sample was weighed and put into the plastic test tube, having added 0.1% BHT in hexane, magnesium carbonate; the samples were incubated in an ultrasonic bath.…”