Svetlana Dokupilová

The antioxidant activity of Origanum vulgare L. and Mentha aquatica L. has been widely reported; however, interaction effects within and between different plant parts remain insufficiently characterized. This study aimed to evaluate the antioxidant behavior of methanolic extracts from leaves, flowers, and rhizomes of both species and to assess the nature of intraplant and interspecific interactions using combination analysis. Antioxidant activity was determined for individual extracts and their binary mixtures using DPPH and ABTS radical scavenging assays. Phytochemical analysis was performed by LC-MS/MS. In O. vulgare, all intraplant mixtures exhibited synergistic effects, suggesting complementary contributions of phenolic acids and flavonoids across plant organs. In contrast, M. aquatica showed more variable responses, with additive to antagonistic interactions, particularly in combinations involving rhizomes with lower phenolic content. Interspecific mixtures further demonstrated that interaction outcomes depended on the qualitative and quantitative composition of phytochemicals: leaf mixtures showed synergism, whereas flower and rhizomes mixtures tended toward antagonism. Comparable interaction trends were observed in both radical scavenging assays. These results indicate that antioxidant activity in plant mixtures is not simply additive but is strongly influenced by phytochemical composition and plant part, highlighting the importance of empirical testing when designing multicomponent plant-based antioxidant formulations.

Wounding triggers complex secondary metabolic pathways in plants, including benzylisoquinoline alkaloid (BIA) biosynthesis in opium poppy (Papaver somniferum L.). This study explores transcriptional and metabolic responses to wounding and methyl jasmonate (MeJA) treatment, focusing on BIA biosynthesis and regulatory mechanisms. Real-time expression analysis revealed significant up-regulation of transcripts in the (S)-reticuline and papaverine biosynthetic pathway, while the noscapine pathway was suppressed. The morphinan pathway also showed transcriptional activation, except in the case of codeinone reductase (COR), which remained unresponsive to both wounding and MeJA, suggesting a partially uncoupled mechanism. Metabolite profiling using HPLC-MS demonstrated a rapid accumulation of morphine post wounding, further supporting the hypothesis of independent regulatory control over COR. The role of phospholipase C (PLC) in modulating wound-induced BIA accumulation was investigated, revealing that PLC inhibition reduced morphine production and suppressed COR expression. These findings highlight the importance of phospholipid-dependent signalling in activating morphine biosynthesis, potentially at the expense of other BIAs. This study provides insights into plant stress responses and suggests strategies for enhancing BIA production through targeted interventions, offering potential applications in improving alkaloid yield.

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.

Thiopurines (TP) represent an important therapeutic tool for the treatment of inflammatory bowel diseases (IBD) in the current situation of rising incidence and health care costs. The results of multiple clinical studies aimed at finding correlations between levels of TP metabolites and response of IBD patients to the treatment are, however, often controversial due to variability in analytical and sample preparation procedures among these studies. In this work, therefore, an updated analytical and sample preparation procedure for therapeutic drug monitoring (TDM) of TP metabolites in blood samples obtained from patients with IBD was proposed to establish a unified protocol. An advanced analytical method based on ion-exchange liquid chromatography hyphenated with tandem mass spectrometry (IEC-ESI-MS/MS) was used for the determination of the profiles of 12 individual TP metabolites in the particular steps of sample preparation procedure including blood collection, red blood cells (RBC) isolation, lysis, and storage. Favorable performance parameters of the IEC-ESI-MS/MS method (LLOQs 1–10 nmol/L, accuracy 95–105%, intra-day and inter-day precision < 10%, selectivity demonstrated via no sample matrix interferences) and acceptable stability (peak area fluctuations < 15%) of clinical samples under the proposed sample preparation conditions {(i) EDTA anticoagulant tube for the blood collection; (ii) 4 °C and 4 h between the sample collection and RBC isolation; (iii) phosphate-buffered saline for RBC washing and re-suspendation; (iv) −20 °C for RBC lysis and short-term storage; (v) 50 mmol/L phosphate buffer, pH 7.4, 10 mmol/L DTT as a stabilizing medium for TPN in RBC lysates} demonstrated the suitability of such protocol for a well-defined and reliable routine use in studies on thiopurines TDM.