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Several flavonoids have been recognized as nutraceuticals, and myricetin is a good example. Myricetin is commonly found in plants and their antimicrobial and antioxidant activities is well demonstrated. One of its beneficial biological effects is the neuroprotective activity, showing preclinical activities on Alzheimer, Parkinson, and Huntington diseases, and even in amyotrophic lateral sclerosis. Also, myricetin has revealed other biological activities, among them as antidiabetic, anticancer, immunomodulatory, cardiovascular, analgesic and antihypertensive. However, few clinical trials have been performed using myricetin as nutraceutical. Thus, this review provides new insights on myricetin preclinical pharmacological activities, and role in selected clinical trials.

Main Conclusion: Environmentally induced variation and the genotypic differences in flavonoid and phenolic content in lettuce can be reliably detected using the appropriate parameters derived from the records of rapid non-invasive fluorescence technique. The chlorophyll fluorescence excitation ratio method was designed as a rapid and non-invasive tool to estimate the content of UV-absorbing phenolic compounds in plants. Using this technique, we have assessed the dynamics of accumulation of flavonoids related to developmental changes and environmental effects. Moreover, we have tested appropriateness of the method to identify the genotypic differences and fluctuations in total phenolics and flavonoid content in lettuce. Six green and two red genotypes of lettuce (Lactuca sativa L.) grown in pots were exposed to two different environments for 50 days: direct sunlight (UV-exposed) and greenhouse conditions (low UV). The indices based on the measurements of chlorophyll fluorescence after red, green and UV excitation indicated increase of the content of UV-absorbing compounds and anthocyanins in the epidermis of lettuce leaves. In similar, the biochemical analyses performed at the end of the experiment confirmed significantly higher total phenolic and flavonoid content in lettuce plants exposed to direct sun compared to greenhouse conditions and in red compared to green genotypes. As the correlation between the standard fluorescence indices and the biochemical records was negatively influenced by the presence of red genotypes, we proposed the use of a new parameter named Modified Flavonoid Index (MFI) taking into an account both absorbance changes due to flavonol and anthocyanin content, for which the correlation with flavonoid and phenolic content was relatively good. Thus, our results confirmed that the fluorescence excitation ratio method is useful for identifying the major differences in phenolic and flavonoid content in lettuce plants and it can be used for high-throughput pre-screening and phenotyping of leafy vegetables in research and breeding applications towards improvement of vegetable health effects.

Background: The aim of our research work was to quantify total flavonoid contents in the leaves of 13 plant species family Asteraceae, 8 representatives of family Lamiaceae and 9 plant species belonging to family Rosaceae, using the multiplex fluorimetric sensor. Fluorescence was measured using optical fluorescence apparatus Multiplex(R) 3 (Force-A, France) for non-destructive flavonoids estimation. The content of total flavonoids was estimated by FLAV index (expressed in relative units), that is deduced from flavonoids UV absorbing properties., Results: Among observed plant species, the highest amount of total flavonoids has been found in leaves of Helianthus multiflorus (1.65 RU) and Echinops ritro (1.27 RU), Rudbeckia fulgida (1.13 RU) belonging to the family Asteraceae. Lowest flavonoid content has been observed in the leaves of marigold (Calendula officinalis) (0.14 RU) also belonging to family Asteraceae. The highest content of flavonoids among experimental plants of family Rosaceae has been estimated in the leaves of Rosa canina (1.18 RU) and among plant species of family Lamiaceae in the leaves of Coleus blumei (0.90 RU)., Conclusions: This research work was done as pre-screening of flavonoids content in the leaves of plant species belonging to family Asteraceae, Lamiaceae and Rosaceae. Results indicated that statistically significant differences (P > 0.05) in flavonoids content were observed not only between families, but also among individual plant species within one family.

Hyperspectral analysis represents a powerful technique for diagnostics of morphological and chemical information from aboveground parts of the plants, but the real potential of the method in pre-screening of phenolics in leaves is still insufficiently explored. In this study, assessment of the sensitivity and reliability of non-invasive methods of various phenolic compounds, also analyzed by HPLC in chicory plants (Cichorium intybus L.) exposed to various color light pretreatments was done. The hyperspectral records in visible and near infrared (VNIR) spectra were recorded using a handheld spectrometer and relationships between the specific hyperspectral parameters and the contents of tested phenolic compounds in chicory leaves were analyzed. Moreover, the correlations between the hyperspectral parameters and related parameters derived from the multispectral fluorescence records were assessed to compare the sensitivity of both techniques. The results indicated a relatively high correlation of anthocyanin-related parameters (ARI, mARI, mACI indices) with the content of some of tested phenolic compounds (quercetin-3-gluconuride, isorhamnetine-3-gluconuride, etc.), as well as with fluorescence ANTH index. Similar trends were observed in flavonoid parameter based on the near infra-red spectral bands (700, 760 nm), which expressed a high correlation with chlorogenic acid. On the other hand, the most frequently used flavonoid (FLAVI) indices based on UV-to-blue band reflectance showed very weak correlations with phenolic compounds, as well as with fluorescence FLAV index. The detailed analysis of the correlation between reflectance and fluorescence flavonoid parameters has shown that the parameters based on spectral reflectance are sensitive to increase of UV-absorbing compounds from low to moderate values, but, unlike the fluorescence parameter, they are not useful to recognize a further increase from middle to high or very high contents. Thus, our results outlined the possibilities, but also the limits of the use of hyperspectral analysis for rapid screening phenolic content, providing a practical evidence towards more efficient production of bioactive compounds for pharmaceutical or nutraceutical use. • Spectral reflectance is sensitive to recognize of UV-absorbing compounds from low to moderate values. • High correlation of anthocyanin-related parameters (ARI, mARI, mACI indices) with the tested phenolics. • High correlation of flavonoid spectral reflectance indices with a chlorogenic acid content. • The reflectance-based FLAVI index showed very weak correlation with phenolic compounds. • The results outlined the possibilities, but also the limits of the use of hyperspectral analysis. [ABSTRACT FROM AUTHOR]

• Color shade pretreatment influenced the composition of phenolics in later growth stages of chicory. • Red light pretreatment led to an increase in quercetin derivatives in leaves. • Isorhamnetin and feruloyl malate were accumulated in plants exposed to orange light. • Blue light preferentially triggered production of isorhamnetin-3-glucoside. • Light environment in early growth stages induced long-term photoacclimation. Manipulation of spectral composition has been found to be an efficient way to influence the growth and quality of plant production in protected or controlled environments. The aim of this study was to compare the short- and long-term effects of early pretreatment with different color shades on the composition of phenolic compounds and photosynthetic pigments in Cichorium leaves. The analyses conducted immediately after color shade pretreatments at ˜40 μmol m−²s−1 (blue, red orange, white) indicated lower values of chlorophyll, anthocyanin and flavonoid indices, as well as of the majority of flavonoids, compared to those in the same plants subsequently grown for 4 weeks under higher white light with an intensity of ˜320 μmol m−²s−1. However, we observed significant differences in the contents of phenolics and pigments depending on previous color shade pretreatment in plants grown for 4 weeks in the same environment and in leaves grown during this period. The most significant effect was observed in plants pretreated with orange light, in which levels of isorhamnetin, its derivatives and feruloyl malate were increased, and kaempferol-3-(6"-acetyl)-glucoside levels were significantly decreased. Blue light pretreatment led to lower values of chlorogenic acid, caftaric acid and isorhamnetin-3-(6"-acetyl)-glucoside but a higher content of isorhamnetin-3-glucoside. Red light led to an increase in quercetin derivatives. Compared to plants grown under constant conditions, low light in the early growth phases led to the upregulation of feruloyl malate, caffeoyl malate and kaempferol derivatives. Nondestructive measurements enabled the identification of significant effects of light pretreatment on the chlorophyll contents, as well as the accumulation of flavonoids and anthocyanins in the epidermal leaf layer. The induction of specific metabolites influenced by the acclimation of plants to colored light environments may emphasize the environment‐induced biochemical responses associated with the remarkable plasticity of phenylpropanoid metabolism. [ABSTRACT FROM AUTHOR]

Environmental conditions influence the content and metabolic profile of phenolic compounds in vegetables. The present study focused on distinguishing between the effects of ultraviolet (UV) radiation and temperature on lettuce plants with green or red leaf color when grown in either a greenhouse or outdoors. A combination of the non-destructive, fluorescence-based method with spectrophotometric and HPLC analyses enabled us to assess the effects of environment, cultivar, and plant-leaf color on concentrations of flavonoids, anthocyanins, and phenolic compounds. The accumulation of total phenolics, flavonoids, anthocyanins, and phenolic acids (benzoic acid derivatives and cinnamic acid derivatives) increased in direct sunlight (high UV radiation, moderate temperature) conditions outdoors as compared to the greenhouse conditions (low UV radiation, high temperature). The comparison of the effects of UV radiation and temperature (indoor-outdoor effect) indicated that the level of UV radiation plays a dominant role in the accumulation of flavonoids, anthocyanins, and methoxycinnamic acid; while temperature predominantly influences the accumulation of phenolic acids (rosmarinic, p-anisic, vanillic acid. Although, the leaf color (green vs. red) was strongly related to the content of majority of studied phytochemicals, environmental conditions affected their concentrations in both color types similarly. The concentrations of compounds estimated with the non-invasive, fluorescence excitation ratio method were highly consistent with those obtained by standard analytical approaches. Our results show that this fast, non-invasive method can be effectively used for determining concentrations of flavonoids and phenolic acids in lettuce plants. [ABSTRACT FROM AUTHOR]

Bioactive phenolic compounds are powerful antioxidants in traditionally used medicinal and industrial crop plants and have attracted increased interest in the last years in their application and role in non-destructive methodology for pre-screening analysis of some stress factors. In this study the qualitative target was linked with future possible applications of received data for improving non-destructive methodology as well as for improving existing knowledge regarding antioxidant content in some plant species. Comparative analysis of total phenolics, flavonoid contents, phenolic acid composition, and antioxidant activity in known east central Europe medicinal and industrial crop plants of 26 species of families Asteraceae , Rosaceae and Lamiaceae was done. Among the investigated leaf extracts the highest total phenolic, total flavonoid contents and antioxidant activity have been seen for Stachys byzantine L. ( Lamiaceae ), Calendula officinalis L. ( Asteraceae ) and for Potentilla recta L. ( Rosaceae ). The highest syringic acid content has been found in the leaf extracts of plant family Asteraceae – in the range from 0.782 to 5.078 mg g −1 DW. The representative’s family Rosaceae has a higher content of p-anisic acid in the range 0.334–3.442 mg g −1 DW compared to the leaf extracts of families Lamiaceae and Asteraceae . The comparative study showed significant differences of content of phenolic acids in the leaf extracts of different representative’s families Rosaceae , Asteraceae and Lamiaceae . We suggest that the presence of some phenolic acids can be used as a possible marker for family botanical specifications of representative families Asteraceae and Rosaceae . It was supposed that some pharmacological effects can be connected with the analyzed data. [ABSTRACT FROM AUTHOR]

Epilobium species are generally known as "Yakı Otu" in Turkey, which mens "plaster herb" in English. Young shoots of Epilobium angustifolium L., Epilobium stevenii Boiss., and Epilobium hirsutum L. are consumed as salad or meal. These species have been used as a poultice for the treatment of mouth wounds in traditional medicine. An ointment prepared from leaves is used for skin disorders in children. We aimed to evaluate the ethnopharmacological use of Epilobium angustifolium, E. stevenii, and E. hirsutum by using in vivo and in vitro experimental models, and to identify the active wound-healer compound(s) and to explain the probable mechanism of the wound-healing activity. Evaluation of wound healing effects of plant extracts was performed in rats and mice by linear incision and circular excision wound models. Determination of total phenolic constituents and antioxidant capacities, which are known to promote the wound healing process, were carried out through Folin-Ciocalteau method and 2,2 Diphenyl 1 picrylhydrazyl (DPPH) scavenging assay as well as determination of total antioxidant status (TAS) and total oxidant status (TOS) on the treated tissues. The active ethyl acetate (EtOAc) sub-extract of E. angustifolium was fractionated by different chromatographic separation techniques. The structures of isolated compounds were elucidated via detailed analyzes (NMR and LC/MS). In addition, in vitro collagenase, hyaluronidase, and elastase enzymes inhibitory activity tests were performed on the isolated compounds to discover the activation pathways of the samples. Among the methanol (MeOH) extracts, E. angustifolium had the highest wound healing activity. Among the sub-extracts, EtOAc showed the highest wound healing activity. Thus, EtOAc sub-extract was subjected to chromatography to isolate the active compounds. Five known flavonoids namely hyperoside (quercetin-3- O -β-D-galactoside) (1), kaempferol (2), kaempferol-3- O -α-L-rhamno pyranoside (3), quercetin-3- O -α-L-rhamno pyranoside (4), and quercetin-3- O -α-L-arabino pyranoside (5) were isolated from the EtOAc sub-extract of E. angustifolium. In vitro tests showed that hyperoside could be the compound responsible for the wound-healing activity by its significant anti-hyaluronidase, anti-collagenase, and antioxidant activities. The EtOAc sub-extract of the aerial part of Epilobium angustifolium displayed remarkable wound-healing activity with anti-hyaluronidase, anti-collagenase, and antioxidant activities. Hyperoside was detected as the primary active compound of the aerial parts. According to the results, we suggest that EtOAc sub-extract of E. angustifolium and hyperoside may be a potent nominee to be used for the improvement of a wound-healing agent. Image 1 [ABSTRACT FROM AUTHOR]