Natural Ingredients of Transdermal Drug Delivery Systems as Permeation Enhancers of Active Substances through the Stratum Corneum.

In recent years, significant progress has been made in transdermal drug delivery systems, but there is still a search for enhancers that can improve the absorption of active substances through the stratum corneum. Although permeation enhancers have been described in the scientific literature, the use of naturally occurring substances in this role is still of particular interest, because they can offer a high level of safety of use, with a low risk of skin irritation, and high efficiency. In addition, these ingredients are biodegradable, easily available, and widely accepted by consumers due to the growing trust in natural compounds. This article provides information on the role of naturally derived compounds in transdermal drug delivery systems that help them penetrate the skin. The work focuses on the components found in the stratum corneum such as sterols, ceramides, oleic acid, and urea. Penetration enhancers found in nature, mainly in plants, such as terpenes, polysaccharides, and fatty acids have also been described. The mechanism of action of permeation enhancers in the stratum corneum is discussed, and information on the methods of assessing their penetration efficiency is provided. Our review mainly covers original papers from 2017 to 2022, supplemented with review papers, and then older publications used to supplement or verify the data. The use of natural penetration enhancers has been shown to increase the transport of active ingredients through the stratum corneum and can compete with synthetic counterparts.

Metabolic Study of Cucumber Seeds and Seedlings in the Light of the New, Controversial Trend of Preventive Use of Systemic Fungicides.

Cucumber is one of the most commonly produced vegetable crops. The greatest economic losses in the yields of these crops have resulted from fungal infections-powdery mildew and downy mildew. The action of fungicides not only affects the fungi, but can also lead to metabolic disorders in plants. However, some fungicides have been reported to have positive physiological effects. Our research focused on the action of two commercially available fungicides, Scorpion 325 SC and Magnicur Finito 687,5 SC, on plant metabolism. Two approaches were used to check the effect of the fungicides at the early stage of plant development when metabolic changes occur most dynamically: spraying on the leaves of cucumber seedlings and presowing seed treatment. The application of the fungicide formulation as a presowing seed treatment caused perturbations in the phytase activity, leading to disorders in the energetic status of the germinating seeds. In addition, the tested preparations changed the morphology of the germinating seeds, limiting the growth of the stem. Furthermore, the application of the tested fungicides on seedlings also showed a disruption in the energetic status and in the antioxidative system. Therefore, the use of pesticides as agents causes a "green effect" and requires a much deeper understanding of plant metabolism.

Mentha piperita: Essential Oil and Extracts, Their Biological Activities, and Perspectives on the Development of New Medicinal and Cosmetic Products.

This review aims to analyze Mentha piperita L. as a potential raw material for the development of new health-promoting products (nutraceuticals, cosmetics, and pharmaceutical products). A lot of scientific publications were retrieved from the Scopus, PubMed, and Google Scholar databases which enable the study and generalization of the extraction procedures, key biologically active compounds of essential oil and extracts, biological properties, and therapeutic potential of M. piperita, along with perspectives on the development of its dosage forms, including combinations of synthetic active substances and herbal preparations of M. piperita. The results of this review indicate that M. piperita is a source rich in phytoconstituents of different chemical nature and can be regarded as a source of active substances to enhance health and to develop medicinal products for complementary therapy of various conditions, especially those related with oxidant stress, inflammation, and moderate infections. Essential oil has a broad spectrum of activities. Depending on the test and concentration, this essential oil has both anti- and prooxidant properties. Gram-positive bacteria are more sensitive to the essential oil of M. piperita than Gram-negative ones. This review also considered some facets of the standardization of essential oil and extracts of M. piperita. Among the identified phenolics of extracts were caffeic acid, rosmarinic acid, eriocitrin, luteolin derivates (luteolin-7-O-rutinoside, luteolin-7-O-glucoronide), and hesperidin. The concentration of these phenolics depends on the solvent used. This review also considered the relationships between the chemical component and biological activity. The results showed that the essential oil and extracts reduced inflammation in vitro by inhibiting the production of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), and in vivo by reducing the paw edema induced using carrageenan injection in rats. Therefore, herbal preparations of M. piperita are promising medicinal and cosmetic preparations for their usage in skincare and oral cavity care products with antimicrobial, anti-inflammatory, and wound-healing properties. This plant can also be regarded as a platform for the development of antibacterial preparations and combined anti-inflammatory and cardioprotective medicinal products (synthetic active substances plus herbal preparations). This review could be considered for the justification of the composition of some medicinal products during their pharmaceutical development for writing a registration dossier in the format of Common Technical Document.

Synthesis, structure, properties and antimicrobial activity of para trifluoromethyl phenylboronic derivatives.

The [2-formyl-4-(trifluoromethyl)phenyl]boronic acid as well as its benzoxaborole and bis(benzoxaborole) derivatives were obtained and their properties studied. The 2-formyl compound displays an unusual structure in the crystalline state, with a significant twist of the boronic group, whereas in DMSO solution it tautomerizes with formation of a cyclic isomer. All the studied compounds exhibit relatively high acidity as well as a reasonable antimicrobial activity. Docking studies showed interactions of all the investigated compounds with the binding pocket of Candida albicans LeuRS. High activity against Bacillus cereus was determined for the 2-formyl compound as well as for the novel bis(benzoxaborole), whereas the studied benzoxaborole shows high antifungal action with MIC values equal to 7.8and 3.9 µg/mL against C. albicans and A. niger respectively. None of the studied compounds exhibits reasonable activity against E. coli.

Influence of monoterpenoids on the growth of freshwater cyanobacteria.

Cyanobacteria are characterized by a very high tolerance to environmental factors. They are found in salt water, fresh water, thermal springs, and Antarctic waters. The wide spectrum of habitats suitable for those microorganisms is related to their particularly effective metabolism; resistance to extreme environmental conditions; and the need for only limited environmental resources such as water, carbon dioxide, simple inorganic salts, and light. These metabolic characteristics have led to cyanobacterial blooms and the production of cyanotoxins, justifying research into effective ways to counteract the excessive proliferation of these microorganisms. A new and interesting idea for the immediate reduction of cyanobacterial abundance is to use natural substances with broad-spectrum biological activity to restore phytoplankton diversity. This study describes the effects of selected monoterpenoid derivatives on the development of cyanobacterial cultures. In the course of the study, some compounds ((±)-citronellal, (+)-α-pinene) showed the ability to inhibit the colonization of the tested photosynthetic bacteria, while others (eugenol, eucalyptol) stimulated the growth of these microorganisms. By analyzing the results of these experiments, information was obtained on the mutual relations of cyanobacteria and the tested monoterpenes, which are present in the aquatic environment. KEY POINTS: • Monoterpenoids significantly inhibit the growth of single cyanobacterial strains. • Monoterpenoids can inhibit the growth of cyanobacterial consortia. • Natural substances can control the growth of freshwater cyanobacteria.

Phosphonates as Unique Components of Plant Seeds-A Promising Approach to Use Phosphorus Profiles in Plant Chemotaxonomy.

Phosphorus is one of the most important elements essential for all living beings. Plants accumulate and store phosphorous in various forms that have diverse physiological and biochemical functions. In this study, we determine and then examine the phosphorus profiles of seeds of plants belonging to different taxa based on extractable inorganic phosphates and organic forms of phosphorus. We paid particular attention to the presence of natural phosphonates in the tested materials. The inorganic phosphates were determined colorimetrically, whereas phosphorus profiles were created by using 31P NMR spectroscopy. Our study on phosphorus profiles revealed that the obtainedsets of data vary significantly among the representatives of different taxa and were somehow specific for families of plants. It should be emphasised that the measurements obtained using 31P NMR spectroscopy undoubtedly confirmed-for the first time-the presence of phosphonates among the natural components of plant seeds. Hence, the classification of plants considering the phosphorus profiles, including the presence of phosphonates, may be a new additional chemotaxonomic feature.

Synthesis and Influence of 3-Amino Benzoxaboroles Structure on Their Activity against Candida albicans.

Benzoxaboroles emerged recently as molecules of high medicinal potential with Kerydin® (Tavaborole) and Eucrisa® (Crisaborole) currently in clinical practice as antifungal and anti-inflammatory drugs, respectively. Over a dozen of 3-amino benzoxaboroles, including Tavaborole's derivatives, have been synthetized and characterized in terms of their activity against Candida albicans as a model pathogenic fungus. The studied compounds broaden considerably the structural diversity of reported benzoxaboroles, enabling determination of the influence of the introduction of a heterocyclic amine, a fluorine substituent as well as the formyl group on antifungal activity of those compounds. The determined zones of the growth inhibition of examined microorganism indicate high diffusion of majority of the studied compounds within the applied media as well as their reasonable activity. The Minimum Inhibitory Concentration (MIC) values show that the introduction of an amine substituent in position "3" of the benzoxaborole heterocyclic ring results in a considerable drop in activity in comparison with Tavaborole (AN2690) as well as unsubstituted benzoxaborole (AN2679). In all studied cases the presence of a fluorine substituent at position para to the boron atom results in lower MIC values (higher activity). Interestingly, introduction of a fluorine substituent in the more distant piperazine phenyl ring does not influence MIC values. As determined by X-ray studies, introduction of a formyl group in proximity of the boron atom results in a considerable change of the boronic group geometry. The presence of a formyl group next to the benzoxaborole unit is also detrimental for activity against Candida albicans.

5-Trifluoromethyl-2-formylphenylboronic Acid.

2-Formylphenylboronic acids display many interesting features, not only from synthetic but also from an application as well as structural points of view. 5-Trifluoromethyl-2-formyl phenylboronic acid has been synthesized and characterized in terms of its structure and properties. The presence of an electron-withdrawing substituent results in a considerable rise in the acidity in comparison with its analogues. In some solutions, the title compound isomerizes with formation of the corresponding 3hydroxybenzoxaborole. Taking into account the probable mechanism of antifungal action of benzoxaboroles, which blocks the cytoplasmic leucyl-tRNA synthetase (LeuRS) of the microorganism, docking studies with the active site of the enzymes have been carried out. It showed possible binding of the cyclic isomer into the binding pocket of Candida albicans LeuRS, similar to that of the recently approved benzoxaborole antifungal drug (AN2690, Tavaborole, Kerydin). In case of Escherichia coli LeuRS, the opened isomer displays a much higher inhibition constant in comparison with the cyclic one. The antimicrobial activity of the title compound was also investigated in vitro, showing moderate action against Candida albicans. The compound reveals higher activity against Aspergillus niger as well as bacteria such as Escherichia coli and Bacillus cereus. In case of Bacillus cereus, the determined Minimum Inhibitory Concentration (MIC) value is lower than that of AN2690 (Tavaborole). The results confirm potential of 2-formylphenylboronic acids as antibacterial agents and give a hint of their possible mechanism of action.

Antifungal activity and tautomeric cyclization equilibria of formylphenylboronic acids.

2-Formylphenylboronic acid and four isomeric fluoro-2-formylphenylboronic acids have been found active against a series of fungal strains: Aspergillus, Fusarium, Penicillium and Candida. The level of antifungal activity was evaluated by agar diffusion tests as well as the determination of minimum inhibitory concentrations (MICs) by serial dilution method. Among the tested compounds, 4-fluoro-2-formylphenylboronic acid - an analogue of the known antifungal drug Tavaborole (AN2690) - proved to be the most potent antifungal agent. The tautomeric equilibrium leading to the formation of 3-hydroxybenzoxaboroles as well as the position of the fluorine substituent were revealed to play a crucial role in the observed activity.

Metabolic relation of cyanobacteria to aromatic compounds.

Cyanobacteria, also known as blue-green (micro)algae, are able to sustain many types of chemical stress because of metabolic adaptations that allow them to survive and successfully compete in a variety of ecosystems, including polluted ones. As photoautotrophic bacteria, these microorganisms synthesize aromatic amino acids, which are precursors for a large variety of substances that contain aromatic ring(s) and that are naturally formed in the cells of these organisms. Hence, the transformation of aromatic secondary metabolites by cyanobacteria is the result of the possession of a suitable "enzymatic apparatus" to carry out the biosynthesis of these compounds according to cellular requirements. Another crucial aspect that should be evaluated using varied criteria is the response of cyanobacteria to the presence of extracellular aromatic compounds. Some aspects of the relationship between aromatic compounds and cyanobacteria such as the biosynthesis of aromatic compounds, the influence of aromatic compounds on these organisms and the fate of aromatic substances inside microalgal cells are presented in this paper. The search for this information has suggested that there is a lack of knowledge about the regulation of the biosynthesis of aromatic substances and about the transport of these compounds into cyanobacterial cells. These aspects are of pivotal importance with regard to the biotransformation of aromatic compounds and understanding them may be the goals of future research.

Biocatalytic hydrogenation of the C=C bond in the enone unit of hydroxylated chalcones-process arising from cyanobacterial adaptations.

To verify the hypothesis that cyanobacteria naturally biosynthesising polyphenolic compounds possess an active enzymatic system that enables them to transform these substances, such an ability of the biocatalytic systems of whole cells of these biota was assessed for the first time. One halophilic strain and seven freshwater strains of cyanobacteria representing four of the five taxonomic orders of Cyanophyta were examined to determine the following: (i) whether they contain polyphenols, including flavonoids; (ii) the resistance of their cultures when suppressed by the presence of exogenous hydroxychalcones-precursors of flavonoid biosynthesis and (iii) whether these photoautotrophs can transform hydroxylated chalcones. All examined strains were found to contain polyphenols and flavonoids, and the growth of their cultures was inhibited in the presence of 2'-hydroxychalcone, 2″-hydroxychalcone and 4″-hydroxychalcone. We also confirmed that the examined cyanobacteria transformed hydroxychalcones via hydrogenative bio-reduction and formed the corresponding hydroxydihydro derivatives with yields above 90% whenever the substrates were bioavailable for such a conversion. Moreover, we observed that the routes and efficiency of biohydrogenation (and hydroxylation) of chalcones were dependent on the location of the hydroxyl substituent. The final products obtained as the results of biotransformations were extracted from the media and identified by mass spectrometry (LC-MS/MS) and nuclear magnetic resonance (1H NMR, 13C NMR, COSY, HSQC). Based on those results, we believe that the very efficient biohydrogenation of hydroxychalcones, which may easy be scaled up for biotechnological purposes, reflects the natural activity of the cyanobacterial defence system, because hydroxydihydrochalcones were less active inhibitors of the growth of cyanobacterial cultures than the corresponding substrates.

Biodegradation of the aminopolyphosphonate DTPMP by the cyanobacterium Anabaena variabilis proceeds via a C-P lyase-independent pathway.

Cyanobacteria, the only prokaryotes capable of oxygenic photosynthesis, play a major role in carbon, nitrogen and phosphorus global cycling. Under conditions of increased P availability and nutrient loading, some cyanobacteria are capable of blooming, rapidly multiplying and possibly altering the ecological structure of the ecosystem. Because of their ability of using non-conventional P sources, these microalgae can be used for bioremediation purposes. Under this perspective, the metabolization of the polyphosphonate diethylenetriaminepenta(methylenephosphonic) acid (DTPMP) by the strain CCALA 007 of Anabaena variabilis was investigated using 31 P NMR analysis. Results showed a quantitative breakdown of DTPMP by cell-free extracts from cyanobacterial cells grown in the absence of any phosphonate. The identification of intermediates and products allowed us to propose a unique and new biodegradation pathway in which the formation of (N-acetylaminomethyl)phosphonic acid represents a key step. This hypothesis was strengthened by the results obtained by incubating cell-free extracts with pathway intermediates. When Anabaena cultures were grown in the presence of the phosphonate, or phosphorus-starved before the extraction, significantly higher biodegradation rates were found.

Highly effective, regiospecific reduction of chalcone by cyanobacteria leads to the formation of dihydrochalcone: two steps towards natural sweetness.

BACKGROUND: Chalcones are the biogenetic precursors of all known flavonoids, which play an essential role in various metabolic processes in photosynthesizing organisms. The use of whole cyanobacteria cells in a two-step, light-catalysed regioselective bio-reduction of chalcone, leading to the formation of the corresponding dihydrochalcone, is reported. The prokaryotic microalgae cyanobacteria are known to produce phenolic compounds, including flavonoids, as natural components of cells. It seems logical that organisms producing such compounds possess a suitable "enzymatic apparatus" to carry out their biotransformation. Therefore, determination of the ability of whole cells of selected cyanobacteria to carry out biocatalytic transformations of chalcone, the biogenetic precursor of all known flavonoids, was the aim of our study. RESULTS: Chalcone was found to be converted to dihydrochalcone by all examined cyanobacterial strains; however, the effectiveness of this process depends on the strain with biotransformation yields ranging from 3% to >99%. The most effective biocatalysts are Anabaena laxa, Aphanizomenon klebahnii, Nodularia moravica, Synechocystis aquatilis (>99% yield) and Merismopedia glauca (92% yield). The strains Anabaena sp. and Chroococcus minutus transformed chalcone in more than one way, forming a few products; however, dihydrochalcone was the dominant product. The course of biotransformation shed light on the pathway of chalcone conversion, indicating that the process proceeds through the intermediate cis-chalcone. The scaled-up process, conducted on a preparative scale and by using a mini-pilot photobioreactor, fully confirmed the high effectiveness of this bioconversion. Moreover, in the case of the mini-pilot photobioreactor batch cultures, the optimization of culturing conditions allowed the shortening of the process conducted by A. klebahnii by 50% (from 8 to 4 days), maintaining its >99% yield. CONCLUSIONS: This is the first report related to the use of whole cells of halophilic and freshwater cyanobacteria strains in a two-step, light-catalysed regioselective bio-reduction of chalcone, leading to the formation of the corresponding dihydrochalcone. The total bioconversion of chalcone in analytical, preparative, and mini-pilot scales of this process creates the possibility of its use in the food industry for the production of natural sweeteners.

Phytoplankton communities of polar regions--Diversity depending on environmental conditions and chemical anthropopressure.

The polar regions (Arctic and Antarctic) constitute up to 14% of the biosphere and offer some of the coldest and most arid Earth's environments. Nevertheless several oxygenic phototrophs including some higher plants, mosses, lichens, various algal groups and cyanobacteria, survive that harsh climate and create the base of the trophic relationships in fragile ecosystems of polar environments. Ecosystems in polar regions are characterized by low primary productivity and slow growth rates, therefore they are more vulnerable to disturbance, than those in temperate regions. From this reason, chemical contaminants influencing the growth of photoautotrophic producers might induce serious disorders in the integrity of polar ecosystems. However, for a long time these areas were believed to be free of chemical contamination, and relatively protected from widespread anthropogenic pressure, due their remoteness and extreme climate conditions. Nowadays, there is a growing amount of data that prove that xenobiotics are transported thousands of kilometers by the air and ocean currents and then they are deposed in colder regions and accumulate in many environments, including the habitats of marine and freshwater cyanobacteria. Cyanobacteria (blue green algae), as a natural part of phytoplankton assemblages, are globally distributed, but in high polar ecosystems they represent the dominant primary producers. These microorganisms are continuously exposed to various concentration levels of the compounds that are present in their habitats and act as nourishment or the factors influencing the growth and development of cyanobacteria in other way. The most common group of contaminants in Arctic and Antarctic are persistent organic pollutants (POPs), characterized by durability and resistance to degradation. It is important to determine their concentrations in all phytoplankton species cells and in their environment to get to know the possibility of contaminants to transfer to higher trophic levels, considering however that some strains of microalgae are capable of metabolizing xenobiotics, make them less toxic or even remove them from the environment.

The influence of fluorine position on the properties of fluorobenzoxaboroles.

5-Fluoro-2,1-benzoxaborol-1(3H)-ol, a potent antifungal drug also known as Tavaborole or AN2690, has been compared with its three isomers in terms of its activity against several fungi as well as pKa and multinuclear NMR characterization. The molecular and crystal structure of 6-fluoro-2,1-benzoxaborol-1(3H)-ol was determined and compared with that of AN2690.

The overproduction of 2,4-DTBP accompanying to the lack of available form of phosphorus during the biodegradative utilization of aminophosphonates by Aspergillus terreus.

Although information about the ability of some filamentous fungi to biodegrade organophosphonates is available, the knowledge about accompanying changes in fungal metabolism is very limited. The aim of our study was to determine the utilization of the chosen, structurally diverse aminophosphonates by Aspergillus terreus (Thom), in the context of the behaviour of this fungus while growing in unfavourable conditions, namely the lack of easily available phosphates. We found that all the studied compounds were utilized by fungus as nutritive sources of phosphorus, however, their effect on the production of fungal biomass depended on their structure. We also observed an interesting change in the metabolism of A. terreus; namely the overproduction of 2,4-di-tert-butylphenol (2,4-DTBP), which is known to possess fungistatic activity. In the case of our study, the biosynthesis of this compound was induced by phosphorus starvation, caused either by the lack of that element in the medium, or the poor degradation of phosphonate.

Determination of phosphorus compounds in plant tissues: from colourimetry to advanced instrumental analytical chemistry.

Although the spectrum of effective methods and techniques that allow determination of inorganic or total phosphorus is impressive, more precise analysis of these substances in plant tissues is not a routine or trivial task. The complexity of chemical composition of plant tissues treated as the analytical matrices is thought to be the main cause why there is no one answer, how appropriate phosphorus compounds may be determined qualitatively and quantitatively. Even if more advanced spectrophotometric measurements and classical variants of absorption (FAAS) or emission (ICP-AES/ ICP-OES) spectrometry techniques are used, it is necessary at first to isolate various forms of phosphorus from the matrix, and then to mineralize them prior the determination. Significant progress in such a kind of analytical efforts was brought by implementation of combined methods e.g. ETV-ICP-AES or HR-ETAAS, does allow the isolation of the phosphorus analyte and its detection during a kind of "one step" analytical procedure, directly in plant tissues. Similar benefits, regarding sensitivity of determinations, are obtained when XRF, SIMS or nanoSIMS-more expensive techniques of imaging the presence of phosphorus in biological matrices have been used. Nowadays, obviously being aware of higher limit of detection, nuclear magnetic resonance spectroscopy, especially the 31P NMR technique, is thought to be the most universal analytical tool allowing to determine various chemical forms of plant phosphorus qualitatively and quantitatively, at the same time. Although 31P NMR provides valuable information about the phosphorus profile of plants, it should be emphasized that each analytical issue related to the determination of phosphorus compounds in plant tissues and organs, requires an individual approach to defined problem.

The toxicity of Roundup® 360 SL formulation and its main constituents: glyphosate and isopropylamine towards non-target water photoautotrophs.

The toxicity of commercial formulation of Roundup® 360 SL, widely used, nonselective herbicide and its main constituents, glyphosate (PMG), equimolar (1:1) isopropylamine salt of glyphosate (GIPA) and isopropylamine (IPA) was examined towards eight aquatic microphotoautotrophs; seven cyanobacterial strains representing either saline or freshwater communities, and common eukaryotic algae Chlorella vulgaris Beijerinck. Autotrophs were cultured 21 days in their appropriate standard media supplemented with various amounts of Roundup®, glyphosate, GIPA and IPA. The determination of the growth of examined photoautotrophs was performed by time-course measurements of total chlorophyll content in experimental cultures. The growth rates related to corresponding concentrations of chemicals, the EC(50) values and generation doubling time were determined in order to present the toxicity Roundup® 360 SL formulation and its main constituents. Market available formulation of Roundup® was found to possess toxicity significantly higher than this, attributed to its main constituents; however both these compounds, isopropylamine and glyphosate, also inhibited the growth of examined strains in a dose-dependent manner. Notably, the interpretation of toxicity of the examined substances was found to be significantly dependent on the method of EC(50) calculation. The choice of molar or weight concentration of substances tested separately and in specific formulation was found to be essential in this matter. Due to these findings the EC(50) values were calculated based either on molar or on weight concentrations. Considering Roundup® 360 SL formulation, these values ranged from 10(-3) up to 10(-1) mM and they were one order of magnitude lower than those found for isopropylamine. Quite surprisingly the minimum EC(50) values found for glyphosate did not reach micromolar concentrations, whereas most of the EC(50) values revealed to IPA did not exceed this range. Notably, in all the cases except for Synechocystis aquatilis Sauvageau, isopropylamine alone was indicated as more toxic than glyphosate.

Possible fungistatic implications of betulin presence in betulaceae plants and their hymenochaetaceae parasitic fungi.

Betulin and its derivatives (especially betulinic acid) are known to possess very interesting prospects for their application in medicine, cosmetics and as bioactive agents in pharmaceutical industry. Usually betulin is obtained by extraction from the outer layer of a birch bark. In this work we describe a simple method of betulin isolation from bark of various species of Betulaceae trees and parasitic Hymenochaetaceae fungi associated with these trees. The composition of the extracts was studied by GC-MS, whereas the structures of the isolated compounds were confirmed by FTIR and 1H NMR. Additionally, the significant fungistatic activity of betulin towards some filamentous fungi was determined. This activity was found to be strongly dependent on the formulation of this triterpene. A betulin-trimyristin emulsion, in which nutmeg fat acts as emulsifier and lipophilic carrier, inhibited the fungal growth even in micromolar concentrations--its EC50 values were established in the range of 15 up to 50 microM depending on the sensitivity of the fungal strain. Considering the lack of fungistatic effect of betulin applied alone, the application of ultrasonic emulsification with the natural plant fat trimyristin appeared to be a new method of antifungal bioassay of water-insoluble substances, such as betulin.

Boronic Acids of Pharmaceutical Importance Affect the Growth and Photosynthetic Apparatus of Cyanobacteria in a Dose-Dependent Manner.

The dynamic increase in the commercial application of antimicrobial derivatives of boronic acids, and potential impact of their presence in aquatic systems, supports the necessity to study the toxicity of these substances towards microorganisms of crucial meaning in the environment. One example of the mentioned derivatives is tavaborole (5-fluoro-substituted benzoxaborole), a pharmaceutical agent with antifungal activity. Cyanobacteria were used as model organisms, which are photoautotrophic prokaryotes, as representative aquatic bacteria and photoautotrophs associated with the plant kingdom. To the best of our knowledge, we investigated this issue for the first time. In order to recognize the under-stress response of those microorganisms, the concentration of photopigments-a key factor in the activity of photosynthetic apparatus-was measured spectrophotometrically. We found that the 3-piperazine bis(benzoxaborole) significantly suppressed the growth of halophilic and freshwater cyanobacteria, at a concentration 3.0 mM and 0.3 mM, respectively. Our results also showed that the tested substances at micromolar concentrations stimulated the growth of cyanobacteria, particularly in the freshwater strain Chroococcidiopsis thermalis. The tested substances acted with various strengths, depending on their structure and concentration; nevertheless, they had a greater influence on the synthesis of phycobiliproteins (e.g., lowered their concentration) than on the formation of chlorophyll and carotenoids.