Effects of circadian clock and light on melatonin concentration in Hypericum perforatum L. (St. John’s Wort)

Abstract

Background Melatonin acts as a signaling hormone and entraining agent in many organisms. We studied the spatiotemporal regulation and influence of light (photoperiods, intensities, and spectral qualities) on melatonin concentration in the medicinal herb Hypericum perforatum L. Furthermore, melatonin concentrations in the leaves of eight species of the Hypericum genus were compared and analyzed using high-performance liquid chromatography. Results Melatonin concentration was found to be the highest in its flowers and leaves. The leaves exhibited a rhythmic variation in melatonin concentration of approximately 24 h under both light–dark entrained (Zeitgeber time) and constant light [circadian time (CT)] conditions, with melatonin concentration peaking at approximately CT6 in the middle of the subjective day. Melatonin concentration was influenced significantly by not only photoperiods but also applied light’s wavelength and intensity. It was approximately six times higher under long-day conditions (18-h light:6-h dark) than under short-day photoperiods (10-h light:14-h dark) and was the highest (131 μg/g fresh weight [FW]) under treatment with blue light at an intensity of 45 µmol·m2/s of photons. The melatonin concentration of the two examined Hypericum spp., namely H. kouytchense Lev. and H. coris L., were approximately twice that of H. perforatum L. Conclusion Our findings provide first insights on melatonin-related functions and mechanisms in the circadian system of H. perforatum and useful resources for further melatonin-oriented research and possible applications in agriculture and pharmaceutical industries.

The melatonin contained in beer can provide health benefits, due to its antioxidant, anti‐inflammatory and immunomodulatory properties

“…Furthermore, melatonin plays a key role in circadian rhythms and in seasonal photoperiodic regulation in both animal and plant systems. 34,35 Almost all stages of plant development are controlled by the circadian clockfor example, germination, growth, and the onset of flowering. Other processes, such as stomatal opening, hormone regulation, signaling, and responses to biotic and abiotic attacks, are also modulated by the circadian clock.…”

Does phenotyping of Hypericum secondary metabolism reveal a tolerance to biotic/abiotic stressors?

“…Melatonin represents another stress-responsive metabolite involved in antioxidant defense in several Hypericum representatives, e.g., H. perforatum, or H. kouytchense (Murch and Saxena, 2006;Nguyen et al, 2018;Chung and Deng, 2020;Khan et al, 2020). According to Zhou et al (2021), the overexpression of HpSNAT1 gene coding for serotonin Nacetyltransferase (SNAT), the key enzyme involved in melatonin biosynthesis resulted in more than 4-fold increase of melatonin content in response to high salt and drought treatment.…”

“…Melatonin represents another stress-responsive metabolite involved in antioxidant defense in several Hypericum representatives, e.g., H. perforatum , or H. kouytchense ( Murch and Saxena, 2006 ; Nguyen et al., 2018 ; Chung and Deng, 2020 ; Khan et al., 2020 ). According to Zhou et al.…”

A Systematic Review of Melatonin in Plants: An Example of Evolution of Literature

“…Melatonin was first reported to have a daily rhythm in Chenopodium rubrum L. in 1997 (Kolar et al, 1997) and since has been found to show rhythmic (n = 13) and diurnal (n = 11) levels in: lupine (Lupinus albus L.; Hernandez-Ruiz and Arnao, 2008), water hyacinth (Eichhornia crassipes (Mart.) Solms; Tan et al, 2007a), sweet cherry (Zhao et al, 2013), eggplant (S. melongena; Korkmaz et al, 2017), rice (Wei et al, 2016), tomato (Arnao and Hernández-Ruiz, 2013), St. John's wort (Chung and Deng, 2020), and Arabidopsis (Li D. et al, 2020). Several melatonin metabolites have also been found to mimic melatonin expression patterns including 3-OHM (Choi and Back, 2019a) and AFMK (Tan et al, 2007a).…”