Distinct UV-A or UV-B irradiation induces protochlorophyllide photoreduction and bleaching in dark-grown pea (Pisum sativum L.) epicotyls

Possible lessons of a model experiment: To what extent can UV activate the production of leaf phenolics in indoor plant cultivation?

Tobacco (Nicotiana tabacum L.) plants were grown outdoors (N°46.07, E°18.18) under either natural or UV-deprived sunlight for 25 days in the summer. High PAR resulted in high polyphenol content, which was selectively affected by solar UV-A and UV-B irradiation. Solar UV-A irradiation increased anthocyanins, but not flavonoids, in the epidermis, and this additional protection resulted in higher photochemical yields and lower NPQ. The simultaneous presence of UV-B overrode the effects of UV-A, increased epidermal flavonoids, and decreased anthocyanins. Leaves grown in full sunlight had the same photochemical yields of NPQ as those grown under a UV-excluding filter. A combination of these effects can falsely dismiss the effects of UV-B on outdoor photosynthesis. Phenolic acid content, corresponding to approximately 80% of phenolic compounds, did not depend on solar UV, and total flavonoids increased under full solar UV irradiation, but not under UV-A only. The polyphenol content in outdoor leaves also served as a reference point for an indoor experiment, which showed that even a short, 4-day exposure of low PAR grown plants to UV from an artificial source increased the amount of some, although not all, components close to or even above outdoor levels. In indoor leaves, a selective increase in quercetin glycosides (to 62-85% of outdoor levels) supports both enzymatic and non-enzymatic antioxidant functions, and the increase in crypto- and neochlorogenic acids (to 76% and 117% of outdoor levels, respectively) suggests a redistribution among biosynthesis pathways. These results demonstrate the potential and efficiency of cultivation systems without sunlight.

Chlorophyllides: Preparation, Purification, and Application

Chlorophyllides can be found in photosynthetic organisms. Generally, chlorophyllides have a-, b-, c-, d-, and f-type derivatives, and all chlorophyllides have a tetrapyrrole structure with a Mg ion at the center and a fifth isocyclic pentanone. Chlorophyllide a can be synthesized from protochlorophyllide a, divinyl chlorophyllide a, or chlorophyll. In addition, chlorophyllide a can be transformed into chlorophyllide b, chlorophyllide d, or chlorophyllide f. Chlorophyllide c can be synthesized from protochlorophyllide a or divinyl protochlorophyllide a. Chlorophyllides have been extensively used in food, medicine, and pharmaceutical applications. Furthermore, chlorophyllides exhibit many biological activities, such as anti-growth, antimicrobial, antiviral, antipathogenic, and antiproliferative activity. The photosensitivity of chlorophyllides that is applied in mercury electrodes and sensors were discussed. This article is the first detailed review dedicated specifically to chlorophyllides. Thus, this review aims to describe the definition of chlorophyllides, biosynthetic routes of chlorophyllides, purification of chlorophyllides, and applications of chlorophyllides.