Concentrations of Phenolic Acids Are Differently Genetically Determined in Leaves, Flowers, and Grain of Common Buckwheat (Fagopyrum esculentum Moench).

Common buckwheat (Fagopyrum esculentum Moench) is a valuable source of proteins, B vitamins, manganese, tryptophan, phytochemicals with an antioxidant effect, and the natural flavonoid rutin. Due to its composition, buckwheat supports the human immune system, regulates blood cholesterol, and is suitable for patients with diabetes or celiac disease. The study aimed to compare the allocation of selected phenolic acids (neochlorogenic acid, chlorogenic acid, trans-caffeic acid, trans-p-coumaric acid, trans-sinapic acid, trans-ferulic acid) and flavonoids (rutin, vitexin, quercetin, kaempferol) in the leaves, flowers, and grain of buckwheat cultivars of different origin. The content of individual phenolics was determined by the HPLC-DAD method. The results confirmed the determining role of cultivar on the relative content of chlorogenic acid, trans-caffeic acid, trans-sinapic acid, vitexin, and kaempferol in buckwheat plants. A significantly negative correlation among concentrations of phenolic acids in different common buckwheat plant parts shows that there are different mechanisms of genetic influences on the concentration of phenolic substances in common buckwheat flowers, leaves, and grain. These differences should be taken into account when breeding buckwheat for a high concentration of selected phenolic substances.

Antimicrobial and Antioxidant Properties of Four Lycopus Taxa and an Interaction Study of Their Major Compounds.

The compositions of leaf infusions of three genotypes of Lycopus europaeus L. with origins in central Europe, namely L. europaeus A (LeuA), L. europaeus B (LeuB), and L. europaeus C (LeuC), and one genotype of L. exaltatus (Lex), were examined by LC-MS-DAD (Liquid Chromatography Mass Spectrometry and Diode Array Detection) analysis. This revealed the presence of thirteen compounds belonging to the groups of phenolic acids and flavonoids, with a predominance of rosmarinic acid (RA) and luteolin-7-O-glucuronide (LGlr). The antimicrobial activity of leaf infusions was tested on the collection strains of Gram-positive and Gram-negative bacteria, and on the clinical Staphylococcus aureus strains. We detected higher activity against Gram-positive bacteria, of which the most susceptible strains were those of Staphylococcus aureus, including methicillin-resistant and poly-resistant strains. Furthermore, we examined the antioxidant activity of leaf infusions using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) methods, and on NIH/3T3 cell lines using dichlorodihydrofluorescein diacetate (DCFH-DA). We also studied the mutual interactions between selected infusions, namely RA and/or LGlr. In the mixtures of leaf infusion and RA or LGlr, we observed slight synergism and a high dose reduction index in most cases. This leads to the beneficial dose reduction at a given antioxidant effect level in mixtures compared to the doses of the parts used alone. Therefore, our study draws attention to further applications of the Lycopus leaves as a valuable alternative source of natural antioxidants and as a promising topical antibacterial agent for medicinal use.