Caffeic Acid Phosphanium Derivatives: Potential Selective Antitumor, Antimicrobial and Antiprotozoal Agents.

Caffeic acid (CA) is one of the most abundant natural compounds present in plants and has a broad spectrum of beneficial pharmacological activities. However, in some cases, synthetic derivation of original molecules can expand their scope. This study focuses on the synthesis of caffeic acid phosphanium derivatives with the ambition of increasing their biological activities. Four caffeic acid phosphanium salts (CAPs) were synthesized and tested for their cytotoxic, antibacterial, antifungal, and amoebicidal activity in vitro, with the aim of identifying the best area for their medicinal use. CAPs exhibited significantly stronger cytotoxic activity against tested cell lines (HeLa, HCT116, MDA-MB-231 MCF-7, A2058, PANC-1, Jurkat) in comparison to caffeic acid. Focusing on Jurkat cells (human leukemic T cell lymphoma), the IC50 value of CAPs ranged from 0.9 to 8.5 µM while IC50 of CA was >300 µM. Antimicrobial testing also confirmed significantly higher activity of CAPs against selected microbes in comparison to CA, especially for Gram-positive bacteria (MIC 13-57 µM) and the yeast Candida albicans (MIC 13-57 µM). The anti-Acanthamoeba activity was studied against two pathogenic Acanthamoeba strains. In the case of A. lugdunensis, all CAPs revealed a stronger inhibitory effect (EC50 74-3125 µM) than CA (>105 µM), while in A. quina strain, the higher inhibition was observed for three derivatives (EC50 44-291 µM). The newly synthesized quaternary phosphanium salts of caffeic acid exhibited selective antitumor action and appeared to be promising antimicrobial agents for topical application, as well as potential molecules for further research.

Proposed mechanisms of action of herbal drugs and their biologically active constituents in the treatment of coughs: an overview.

Various medicinal plants find their use in cough treatment, based on traditions and long-term experience. Pharmacological principles of their action, however, are much less known. Herbal drugs usually contain a mixture of potentially active compounds, which can manifest diverse effects. Expectorant or antitussive effects, which can be accompanied by others, such as anti-inflammatory or antibacterial, are probably the most important in the treatment of coughs. The aim of this review is to summarize the current state of knowledge of the effects of medicinal plants or their constituents on cough, based on reliable pharmacological studies. First, a comprehensive description of each effect is provided in order to explain the possible mechanism of action in detail. Next, the results related to individual plants and substances are summarized and critically discussed based on pharmacological in vivo and in vitro investigation.

Prenylated Flavonoids in Topical Infections and Wound Healing.

The review presents prenylated flavonoids as potential therapeutic agents for the treatment of topical skin infections and wounds, as they can restore the balance in the wound microenvironment. A thorough two-stage search of scientific papers published between 2000 and 2022 was conducted, with independent assessment of results by two reviewers. The main criteria were an MIC (minimum inhibitory concentration) of up to 32 µg/mL, a microdilution/macrodilution broth method according to CLSI (Clinical and Laboratory Standards Institute) or EUCAST (European Committee on Antimicrobial Susceptibility Testing), pathogens responsible for skin infections, and additional antioxidant, anti-inflammatory, and low cytotoxic effects. A total of 127 structurally diverse flavonoids showed promising antimicrobial activity against pathogens affecting wound healing, predominantly Staphylococcus aureus strains, but only artocarpin, diplacone, isobavachalcone, licochalcone A, sophoraflavanone G, and xanthohumol showed multiple activity, including antimicrobial, antioxidant, and anti-inflammatory along with low cytotoxicity important for wound healing. Although prenylated flavonoids appear to be promising in wound therapy of humans, and also animals, their activity was measured only in vitro and in vivo. Future studies are, therefore, needed to establish rational dosing according to MIC and MBC (minimum bactericidal concentration) values, test potential toxicity to human cells, measure healing kinetics, and consider formulation in smart drug release systems and/or delivery technologies to increase their bioavailability.

Treatment of Gastrointestinal Disorders-Plants and Potential Mechanisms of Action of Their Constituents.

The worldwide prevalence of gastrointestinal diseases is about 40%, with standard pharmacotherapy being long-lasting and economically challenging. Of the dozens of diseases listed by the Rome IV Foundation criteria, for five of them (heartburn, dyspepsia, nausea and vomiting disorder, constipation, and diarrhoea), treatment with herbals is an official alternative, legislatively supported by the European Medicines Agency (EMA). However, for most plants, the Directive does not require a description of the mechanisms of action, which should be related to the therapeutic effect of the European plant in question. This review article, therefore, summarizes the basic pharmacological knowledge of synthetic drugs used in selected functional gastrointestinal disorders (FGIDs) and correlates them with the constituents of medicinal plants. Therefore, the information presented here is intended as a starting point to support the claim that both empirical folk medicine and current and decades-old treatments with official herbal remedies have a rational basis in modern pharmacology.

Therapeutic Potential of Flavonoids and Tannins in Management of Oral Infectious Diseases-A Review.

Medicinal plants are rich sources of valuable molecules with various profitable biological effects, including antimicrobial activity. The advantages of herbal products are their effectiveness, relative safety based on research or extended traditional use, and accessibility without prescription. Extensive and irrational usage of antibiotics since their discovery in 1928 has led to the increasing expiration of their effectiveness due to antibacterial resistance. Now, medical research is facing a big and challenging mission to find effective and safe antimicrobial therapies to replace inactive drugs. Over the years, one of the research fields that remained the most available is the area of natural products: medicinal plants and their metabolites, which could serve as active substances to fight against microbes or be considered as models in drug design. This review presents selected flavonoids (such as apigenin, quercetin, kaempferol, kurarinone, and morin) and tannins (including oligomeric proanthocyanidins, gallotannins, ellagitannins, catechins, and epigallocatechin gallate), but also medicinal plants rich in these compounds as potential therapeutic agents in oral infectious diseases based on traditional usages such as Agrimonia eupatoria L., Hamamelis virginiana L., Matricaria chamomilla L., Vaccinium myrtillus L., Quercus robur L., Rosa gallica L., Rubus idaeus L., or Potentilla erecta (L.). Some of the presented compounds and extracts are already successfully used to maintain oral health, as the main or additive ingredient of toothpastes or mouthwashes. Others are promising for further research or future applications.

Antibacterial Activity of Medicinal Plants and Their Constituents in the Context of Skin and Wound Infections, Considering European Legislation and Folk Medicine-A Review.

Bacterial infections of skin and wounds may seriously decrease the quality of life and even cause death in some patients. One of the largest concerns in their treatment is the growing antimicrobial resistance of bacterial infectious agents and the spread of resistant strains not only in the hospitals but also in the community. This trend encourages researchers to seek for new effective and safe therapeutical agents. The pharmaceutical industry, focusing mainly on libraries of synthetic compounds as a drug discovery source, is often failing in the battle with bacteria. In contrast, many of the natural compounds, and/or the whole and complex plants extracts, are effective in this field, inactivating the resistant bacterial strains or decreasing their virulence. Natural products act comprehensively; many of them have not only antibacterial, but also anti-inflammatory effects and may support tissue regeneration and wound healing. The European legislative is in the field of natural products medicinal use formed by European Medicines Agency (EMA), based on the scientific work of its Committee on Herbal Medicinal Products (HMPC). HMPC establishes EU monographs covering the therapeutic uses and safe conditions for herbal substances and preparations, mostly based on folk medicine, but including data from scientific research. In this review, the medicinal plants and their active constituents recommended by EMA for skin disorders are discussed in terms of their antibacterial effect. The source of information about these plant products in the review is represented by research articles listed in scientific databases (Science Direct, PubMed, Scopus, Web of Science, etc.) published in recent years.

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.

Mentha Rhizomes as an Alternative Source of Natural Antioxidants.

Unlike its aerial parts, the underground parts of Mentha have so far been studied only marginally. By examining the polyphenolic fingerprint, the antioxidant efficacy and the mutual antioxidant behaviour of mixtures of mint rhizomes, our study presents a modest contribution to addressing this gap. Firstly, we examined the composition of the mint rhizomes: Mentha × piperita cv. 'Perpeta' (MPP), M. longifolia (ML), and M. × villosa cv. 'Snezna' (MVS). Our LC-MS-DAD analysis revealed the presence of ten compounds belonging to groups of phenolic acids and flavonoids, of which the rosmarinic acid (RA) and lithospermic were most strongly represented. Secondly, we evaluated the antioxidant activity of rhizome infusions by DPPH and ABTS and on NIH/3T3 cell lines by DCFH-DA. Thirdly, we determined, examined, and explained the mutual interactions of rhizome infusions mixtures. While most of the combinations acted additive, synergy was observed in ternary infusion mixtures. The synergic action was also detected in the combination of MPP rhizome infusion and RA in the DCFH-DA test. The combinations of mint rhizomes and rosmarinic acid displayed a high dose-reduction index. This leads to beneficial dose reduction at a given antioxidant effect level in mixtures, compared to the dose of the parts used alone. So far, the pharmaceutical and food industry has not used mint rhizomes in commercial products. Hence, our study draws attention to further applications of the Mentha rhizomes as a valuable alternative source of natural antioxidants.

Derivatization of Rosmarinic Acid Enhances its in vitro Antitumor, Antimicrobial and Antiprotozoal Properties.

On its own, rosmarinic acid possesses multiple biological activities such as anti-inflammatory, antimicrobial, cardioprotective and antitumor properties, and these are the consequence of its ROS scavenging and inhibitory effect on inflammation. In this study, two quaternary phosphonium salts of rosmarinic acid were prepared for the purpose of increasing its penetration into biological systems with the aim of improving its antimicrobial, antifungal, antiprotozoal and antitumor activity. The synthetized molecules, the triphenylphosphonium and tricyclohexylphosphonium salts of rosmarinic acid, exhibited significantly stronger inhibitory effects on the growth of HCT116 cells with IC50 values of 7.28 or 8.13 µM in comparison to the initial substance, rosmarinic acid (>300 µM). For the synthesized derivatives, we detected a greater than three-fold increase of activity against Acanthamoeba quina, and a greater than eight-fold increase of activity against A. lugdunensis in comparison to rosmarinic acid. Furthermore, we recorded significantly higher antimicrobial activity of the synthetized derivatives when compared to rosmarinic acid itself. Both synthetized quaternary phosphonium salts of rosmarinic acid appear to be promising antitumor and antimicrobial agents, as well as impressive molecules for further research.

[Phenolic compounds in leaves insertions of Mentha × villosa Huds. cv. Snezná]. / Fenolové látky v listových inzerciách Mentha × villosa Huds. cv. Snezná.

Lamiaceae plants mostly accumulate active ingredients in their leaves. The subfamily Nepetoideae, including the genus Mentha L., is characterized by the presence of essential oil and antioxidant phenolics, chiefly hydroxycinnamic acids with predominance of rosmarinic acid, and flavonoids. Mentha × piperita and M. spicata are the most broadly used mints in both medicine and industry, while M. x villosa is less known in our country. Herbal drugs in the form of leaves are usually analysed unpartitioned, while single leaves insertions have only been studied occasionally. Therefore, the aim of this work was the quantification of the active compounds content in the leaves pairs of Mentha × villosa Huds. cv. Snezná, using pharmacopoeial methods: total hydroxycinnamic derivatives expressed as rosmarinic acid (THD) and luteolin-type flavonoids. THD content ranged from 6.7% to 9.4% in the leaves pairs water extracts, and from 6.6% to 14.0% in methanol extracts. Flavonoids contents, expressed as luteolin-7-O-glucoside, ranged from 4.0% to 8.8% in water extracts, and from 4.0% to 10.5% in methanol extracts. Antioxidant activity (DPPH) expressed as SC50 ranged from 10.2 to 16.9 µg.ml-1 (drug dry weight) in water extracts, and from 10.7 to 21.6 µg.ml-1 in methanol extracts. The highest content of phenolic compounds as well as the highest antioxidant activity were found to be in the top sheet, while the lowest content of phenolic compounds and lowest antioxidant activity were detected in the leaves of the middle stem part.Key words: Mentha × villosa Huds cv. Snezná hydroxycinnamic derivatives rosmarinic acid luteolin-7-O-glucoside DPPH.