Ladislav Kokoska

Determination of certain micro and macroelements in plant stimulants and their infusions

The quantitative analysis of Al, B, Cu, Fe, Mn, P and Zn by inductively coupled plasma optical emission spectrometry (ICP-OES) and Ca, K and Mg by atomic absorption spectrometry (AAS) has been carried out in both the raw material and infusions from 31 samples of traditional plant stimulants (tea and coffee) and mate, rooibos, honeybush and chamomile. The results were discussed with respect to differences to the beverage quality and their role in the human diet. The levels of elements not significantly differ between tea types (black, green, oolong, white), and between Arabica and Robusta coffee. In comparison with tea, coffee was found to be a poor source of elements with the exception of Ca and Fe. High levels of B, Ca, Cu, Mn, Mg and Zn were found in mate (mainly green type) and of B, Ca, Cu, Fe and P in chamomile, whereas the amounts of all elements in rooibos and honeybush infusions were low (except of Ca). Apart from tea, other stimulants appeared to not represent important sources of potentially harmful amounts of Al for the human diet.

In vitro anti-inflammatory activity of carvacrol: Inhibitory effect on COX-2 catalyzed prostaglandin E2 biosynthesisb

Possible anti-inflammatory effect of carvacrol was evaluated by in vitro cyclooxygenase-2 (COX-2) assay. Carvacrol inhibited production of prostaglandin E2 catalysed by COX-2 with an IC50 value of 0.8 μM what is practically the same concentration as the IC50 obtained for the standard inhibitors indomethacin and NS-398 with values of 0.7 μM and 0.8 μM, respectively. The COX-1 was inhibited approximately at the same rate (IC50 of 0.7 μM for carvacrol), which suggests non-selective inhibition of both enzyme isoforms. The results of the study demonstrate possible anti-inflammatory potential of this compound due to the inhibition of inducible COX-2 isoform.

Chemistry and pharmacology of Rhaponticum carthamoides: a review.

Rhaponticum carthamoides (Willd.) Iljin is a perennial herb, commonly known as a maral root or Russian leuzea, which has been used for centuries in eastern parts of Russia for its marked medicinal properties. This review based on 117 literary sources, with many of them being originally published in non-English languages (mainly in Russian), discusses the current knowledge of traditional uses, chemistry, biological effects and toxicity of this species. Several different classes of compounds were previously isolated from various parts of R. carthamoides of which the main groups are steroids, particularly ecdysteroids, and phenolics (flavonoids and phenolic acids) accompanied with polyacetylenes, sesquiterpene lactones, triterpenoid glycosides and terpenes (essential oil). A comprehensive account of the chemical constituents is given in this review (figures of 120 structures are shown). Various types of preparations, extracts and individual compounds derived from this species have been found to possess a broad spectrum of pharmacological effects on several organs such as the brain, blood, cardiovascular and nervous systems as well as on different biochemical processes and physiological functions including proteosynthesis, work capacity, reproduction, and sexual function. Moreover, the extracts and preparations from the plant, which are hopefully safe, exhibited various additional biological effects e.g. antioxidant, immunomodulatory, anticancerogenic, antimicrobial, antiparasitic and insect antifeedant or repellent activities. The results of data analysis on the chemical, pharmacological and toxicological characteristics of R. carthamoides support the view that this species has beneficial therapeutic properties and indicate its potential as an effective adaptogenic herbal remedy. Finally, some suggestions for further research on chemical and pharmacological properties are given in this review.

In vitro growth-inhibitory effect of plant-derived extracts and compounds against Paenibacillus larvae and their acute oral toxicity to adult honey bees.

In total, 26 natural compounds of various chemical classes (flavonoids, alkaloids, terpenoids) and 19 crude extracts from selected plants were tested in vitro for antibacterial activity against three strains of P. larvae, the causal agent of American Foulbrood Disease of honey bees (AFB) by the broth microdilution method. Among the individual substances, sanguinarine (MIC 4 microg/ml), followed by thymoquinone, capsaicin, trans-2-hexenal and nordihydroguaiaretic acid (MIC 4-32 microg/ml) possessed the strongest antibacterial effect. In case of extracts, common hop (Humulus lupulus L.) and myrtle (Myrtus communis L.) methanolic-dichloromethane extracts exhibited the highest growth-inhibitory effect with MICs ranging from 2 to 8 microg/ml. Acute oral toxicity of the most active natural products was determined on adult honey bees, showing them as non-toxic at concentrations as high as 100 microg peer bee. Our study leads to identification of highly potent natural products effective against AFB in vitro with very low MICs compared to those reported in literature, low toxicity to adult honey bees and commercial availability suggesting them as perspective, low cost and consumer-acceptable agents for control of AFB.

Comparison of chemical composition and antibacterial activity of Nigella sativa seed essential oils obtained by different extraction methods

Nigella sativa L. seed essential oils obtained by hydrodistillation (HD), dry steam distillation (SD), steam distillation of crude oils obtained by solvent extraction (SE-SD), and supercritical fluid extraction (SFE-SD) were tested for their antibacterial activities, using the broth microdilution method and subsequently analyzed by gas chromatography and gas chromatography-mass spectrometry. The results showed that the essential oils tested differed markedly in their chemical compositions and antimicrobial activities. The oils obtained by HD and SD were dominated by p-cymene, whereas the major constituent identified in both volatile fractions obtained by SD of extracted oils was thymoquinone (ranging between 0.36 and 0.38 g/ml, whereas in oils obtained by HD and SD, it constituted only 0.03 and 0.05 g/ml, respectively). Both oils distilled directly from seeds showed lower antimicrobial activity (MICs > or = 256 and 32 microg/ml for HD and SD, respectively) than those obtained by SE-SD and SFE-SD (MICs > or = 4 microg/ml). All oil samples were significantly more active against gram-positive than against gram-negative bacteria. Thymoquinone exhibited potent growth-inhibiting activity against gram-positive bacteria, with MICs ranging from 8 to 64 microg/ml.

In vitro synergistic effects of baicalin with oxytetracycline and tetracycline against Staphylococcus aureus

OBJECTIVES In this study we examined the in vitro synergistic effect of baicalin, the flavone constituent of Scutellaria spp., in combinations with oxytetracycline and tetracycline on the growth of Staphylococcus aureus. METHODS The MICs were determined by the broth microdilution method and the effect of combinations was evaluated according to the sum of fractional inhibitory concentration indices (FICIs). RESULTS Synergistic activity (FICI  ≤  0.5) was observed for combinations of baicalin with oxytetracycline or tetracycline against 4 of 10 strains tested, whereas the baicalin/oxytetracycline combination possessed the strongest synergistic effect (FICI = 0.418). CONCLUSIONS Baicalin acts synergistically with oxytetracycline and tetracycline, enhancing its antimicrobial activity against S. aureus, including methicillin- and tetracycline-resistant strains.

Aluminium and other elements in selected herbal tea plant species and their infusions

The determination of Al, B, Cu, Fe, Mn, Ni, P, Zn and Ca, K, Mg by inductively coupled plasma optical emission spectrometry (ICP-OES) and flame atomic absorption spectroscopy (FAAS), respectively, in digests and infusions of Hibiscus sabdariffa (petals), Rosa canina (receptacles), Ginkgo biloba (leaves), Cymbopogon citratus (leaves), Aloe vera (leaves) and Panax ginseng (roots) was carried out in this study. Particular attention has been given to Al and heavy metals for the identification of possible raw material contaminants, their transformation into the infusion and for predicting their eventual role in the human diet during daily consumption. Additionally, Ion Chromatography (IC) speciation of Al in the leachates was carried out. In dry herbs, hibiscus and ginkgo appeared to contain the greatest contents of Al, Fe, K, Mn, Ni, Zn and B, Mg, P, respectively. A. vera contained the highest amount of Ca and highest values of Cu and P were observed in ginseng. In infusions, the topmost concentrations of Al, B, Cu, Fe, P, K, Mn, Ni, Zn were detected in those prepared from hibiscus petals, Ca from aloe leaves and Mg from leaves of ginkgo. According to a possible daily consumption exceeding 1 L, hibiscus decoction was identified as potentially dietetically significant in the content of certain elements. It seems to be possibly one of the top contributors of B from food (up to 5.5±0.2 mg/L). The Mg contained in the infusion (up to 106±5 mg/L) may be a contributor in the attenuation of blood pressure. A high amount of accessible Mn (up to 17.4±1.1 mg/L) can probably have an adverse effect in humans. The total Al allowance (up to 1.2±0.1 mg/L) suggests that no more than 1 L of the hibiscus infusion should be consumed per day by sensitive individuals including pregnant women and should be completely excluded from the diet of children under 6 months of age and children with chronic renal failure.

Evaluation of Antimicrobial and Anti-Inflammatory Activities of Seed Extracts from Six Nigella Species

Seed extracts from six species of the genus Nigella (Family Ranunculaceae)-Nigella arvensis, Nigella damascena, Nigella hispanica, Nigella nigellastrum, Nigella orientalis, and Nigella sativa-obtained by successive extraction with n-hexane, chloroform, and methanol, were tested for their antimicrobial activity against 10 strains of pathogenic bacteria and yeast using the microdilution method as well as for anti-inflammatory properties by in vitro cyclooxygenase (COX)-1 and COX-2 assay. Chemical characterization of active extracts was carried out including free and fixed fatty acid analysis. Comparison of antimicrobial activity showed that N. arvensis chloroform extract was the most potent among all species tested, inhibiting Gram-positive bacterial and yeast strains with minimum inhibitory concentration (MIC) values ranging from 0.25 to 1 mg/mL. With the exception of selective inhibitory action of n-hexane extract of N. orientalis on growth of Bacteroides fragilis (MIC = 0.5 mg/mL), we observed no antimicrobial activity for other Nigella species. Anti-inflammatory screening revealed that N. sativa, N. orientalis, N. hispanica, N. arvensis n-hexane, and N. hispanica chloroform extracts had strong inhibitory activity (more than 80%) on COX-1 and N. orientalis, N. arvensis, and N. hispanica n-hexane extracts were most effective against COX-2, when the concentration of extracts was 100 microg/mL in both COX assays. In conclusion, N. arvensis, N. orientalis, and N. hispanica seeds, for the first time examined for antimicrobial and anti-inflammatory effects, revealed their significant activity in one or both assays.

Growth inhibitory effect of grape phenolics against wine spoilage yeasts and acetic acid bacteria

This paper investigates the in vitro antimicrobial potential of 15 grape phenolic compounds of various chemical classes (phenolic acids, stilbenes and flavonoids) using the broth microdilution method against yeasts and acetic acid bacteria frequently occurring in deteriorated wine. Pterostilbene (MICs=32-128 μg/mL), resveratrol (MICs=256-512 μg/mL) and luteolin (MICs=256-512 μg/mL) are among six active compounds that possessed the strongest inhibitory effects against all microorganisms tested. In the case of phenolic acids, myricetin, p-coumaric and ferulic acids exhibited selective antimicrobial activity (MICs=256-512 μg/mL), depending upon yeasts and bacteria tested. In comparison with potassium metabisulphite, all microorganisms tested were more susceptible to the phenolics. The results revealed the antibacterial and antiyeast effects against wine spoilage microorganisms of several highly potent phenolics naturally occurring in grapes. These findings also provide arguments for further investigation of stilbenes as prospective compounds reducing the need for the use of sulphites in winemaking.

Natural compound cudraflavone B shows promising anti-inflammatory properties in vitro.

Cudraflavone B (1) is a prenylated flavonoid found in large amounts in the roots of Morus alba, a plant used as a herbal remedy for its reputed anti-inflammatory properties. The present study shows that this compound causes a significant inhibition of inflammatory mediators in selected in vitro models. Thus, 1 was identified as a potent inhibitor of tumor necrosis factor α (TNFα) gene expression and secretion by blocking the translocation of nuclear factor κB (NF-κB) from the cytoplasm to the nucleus in macrophages derived from a THP-1 human monocyte cell line. The NF-κB activity reduction resulted in the inhibition of cyclooxygenase 2 (COX-2) gene expression. Compound 1 acts as a COX-2 and COX-1 inhibitor with higher selectivity toward COX-2 than indomethacin. Pretreatment of cells by 1 shifted the peak in an regulatory gene zinc-finger protein 36 (ZFP36) expression assay. This natural product has noticeable anti-inflammatory properties, suggesting that 1 potentially could be used for development as a nonsteroidal anti-inflammatory drug lead.