Agnieszka Grzegorczyk

Bioactivity-guided isolation of antimicrobial coumarins from Heracleum mantegazzianum Sommier & Levier (Apiaceae) fruits by high-performance counter-current chromatography

An efficient strategy, based on bioassay-guided fractionation, high-performance liquid chromatography (HPLC), and high-performance counter-current chromatography (HPCCC), was established to purify and evaluate the bioactive compounds from the dichloromethane extract of the fruits of Heracleum mantegazzianum Sommier & Levier (Apiaceae). The quaternary solvent system n-heptane-ethyl acetate-methanol-water (6:5:6:5 v/v) was used in the reversed phase mode. Using this method, in a single run, seven fractions were isolated, among them three were the pure furanocoumarins: pimpinellin, imperatorin, and phellopterin. In order to purify xanthotoxin a more polar system (1:1:1:1 v/v) was further applied. The antimicrobial activity of extract, chromatographic fractions, and single compounds were in the range of MIC = 0.03-1 mg mL(-1). Xanthotoxin may have priority as a compound of further interest based on its antimicrobial activity. For the first time, an extensive antimicrobial study was performed for pimpinellin and phellopterin.

Biological evaluation and molecular modelling study of thiosemicarbazide derivatives as bacterial type IIA topoisomerases inhibitors.

Abstract In the present article, we describe the inhibitory potency of nine thiosemicarbazide derivatives against bacterial type IIA topoisomerases, their antibacterial profile and molecular modelling evaluation. We found that one of the tested compounds, compound 7, significantly inhibits activity of Staphylococcus aureus DNA gyrase with an IC50 below 15 μM. Besides, this compound displays antibacterial activity on reference Staphylococuss spp. and Enterococcus faecalis strains as well as clinical S. aureus isolates at non-cytotoxic concentrations in mammalian cells with MIC values ranging from 16 to 32 μg/mL thereby indicating, in some cases, equipotent or even more effective action than standard drugs such as vancomycin, ampicillin and nitrofurantoin. The computational studies showed that both molecular geometry and the electron density distribution have a great impact on antibacterial activity of thiosemicarbazide derivatives.

Nasopharyngeal vs. adenoid cultures in children undergoing adenoidectomy: prevalence of bacterial pathogens, their interactions and risk factors

Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus colonization of the adenoids and nasopharynx in 103 preschool children who underwent adenoidectomy for recurrent upper respiratory tract infections was examined. Bacterial interactions and risk factors for bacterial colonization of the nasopharynx and adenoids, separately, were analysed statistically. The prevalence of simultaneous isolation from both anatomical sites was 45·6% for S. pneumoniae, 29·1% for H. influenzae, 15·5% for M. catarrhalis and 18·4% for S. aureus. Three pathogens were significantly more frequent together from adenoid samples; nasopharyngeal swabs more often yielded a single organism, but without statistical significance. M. catarrhalis and S. aureus significantly more frequently co-existed with S. pneumoniae and H. influenzae than with each other and a positive association of S. pneumoniae and H. influenzae in adenoid samples was evident. Several differences between risk factors for nasopharyngeal and adenoid colonization by the individual pathogens were observed. We conclude that the adenoids and nasopharynx appear to differ substantially in colonization by pathogenic microbes but occurrence of H. influenzae and S. pneumoniae in the nasopharynx could be predictive of upper respiratory tract infections.

Genotyping of Staphylococcus aureus strains isolated from healthy persistent carriers

The paper presents results on the relatedness of Staphylococcus aureus strains colonizing the upper respiratory tract isolated from healthy persistent carriers. Genotyping was carried out using two methods—multiple-locus variable-number tandem-repeat fingerprinting (MLVF) and pulsed-field gel electrophoresis (PFGE). By comparison of the results obtained by both methods, good correlations between MLVF and PFGE genotyping of strains isolated from the asymptomatic carriers were observed. Further studies are needed to evaluate methods useful for genotyping of S. aureus strains circulating in the community.

Liquid chromatographic techniques in betacyanin isomers separation from Gomphrena globosa L. flowers for the determination of their antimicrobial activities

HighlightsFirst isolation of pure betacyanin isomers from Gomphrena globosa L.Study on separation of naturally coexisting acylated gomphrenin isomers.First determination of antimicrobial activity of pure betacyanins/isomers.Acylation of betacyanins increases antimicrobial properties. ABSTRACT High‐speed counter‐current chromatography (HSCCC) combined with HPLC were established to purify, for the first time, betacyanin isomers from Gomphrena globosa L. flowers. The mixture of tert‐butyl methyl ether – butanol – methanol ‐ water TBME‐BuOH‐MeOH‐H2O (1.0% heptafluorobutyric acid HFBA) 2:2:1:5 (v/v/v/v) in reversed phase mode was used for preliminary purification of gomphrenin derivatives. Then, semiprep‐HPLC was used to obtained ten pure betacyanins: gomphrenins II and III with their cis‐isomers as well as sinapoyl‐gomphrenin I and its corresponding diastereomers. This is the first study on separation of naturally coexisting acylated gomphrenin isomers. The isolated compounds showed a broad antimicrobial spectrum (in the range of 0.19–1.5 mg mL−1) by inhibiting the growth of all of food‐borne pathogens tested. The antimicrobial activity of acylated betacyanins was higher than that of non‐acylated gomphrenin I/isogomphrenin I. Therefore, the acylation with phenolic acids increases the activity of betacyanins against fungi and bacteria, suggesting a synergetic effect of the acylated moieties and the pigment chromophoric system on the activity, which was evaluated for the first time.

A Search for Dual Action HIV-1 Reverse Transcriptase, Bacterial RNA Polymerase Inhibitors

Using molecular modeling approach, potential antibacterial agents with triazole core were proposed. A moderate to weak level of antibacterial activity in most of the compounds have been observed, with best minimal inhibitory concentration (MIC) value of 0.003 mg/mL, as shown by the 15 against S. epidermidis. Studied compounds were also submitted to the antifungal assay. The best antifungal activity was detected for 16 with MIC at 0.125 and 0.25 mg/mL against C. albicans and C. parapsilosis, respectively.

Antimicrobial activity of petroleum ether and methanolic extracts from fruits of Seseli devenyense Simonk. and the herb of Peucedanum luxurians Tamam.

Abstract Plants of the Apiaceae family usually contain coumarins. These are used worldwide in traditional medicine, as well as in modern therapeutics. The aim of our study was to determine the antimicrobial activity of four extracts (methanolic and petroleum ether extracts) obtained from two Apiaceae species: Seseli devenyense (fruits) and Peucedanum luxurians (herb). The activity of the investigated extracts was tested against 7 strains of Gram+ bacteria, and 7 strains of Gram-, as well as three of yeast. The results of this show that the best activity of such extracts (specifically, by way of petroleum ether) was seen as being against Staphylococcus aureus strains.