Toxicological evaluation of harmful substances by in situ enzymatic and biological detection in high-performance thin-layer chromatography

The efficiency of a chromatographic analysis method is determined by the selectivity of the chromatographic separation and the specificity of the detection method. In the case of high-performance thin-layer chromatography (HPTLC) the separated components can be detected and quantified directly on the chromatogram by physical and chemical methods. By coupling high-performance thin-layer chromatography with biological or biochemical inhibition tests it was possible to detect toxicologically active substances in situ. A linear relationship was shown between the signal of the inhibition of cholinesterase and the concentration of the inhibitor using a constant enzyme concentration and a constant incubation time. The graph of the inhibition of the luminescence of Photobacterium vibrio fisheri in relation to the concentration of pentachlorophenol (range 20–80 ng) is nearly linear. Measurements were done by using a densitometer or a videodensitometric scanner.     

Sesquiterpenoids from Ligularia virgaurea spp. oligocephala

Four novel eremophilane-type sesquiterpene lactones, 6β,10α-dihydroxy-1-oxoeremophila-7(11),8(9)-dien-12,8-olide (1), 6β-acetyl-2-oxoeremophila-1(10),7(11), 8(9)-trien-12,8-olide (2), 6β,8β-diacetyl-2-oxoeremophila-1(10),7(11)-dien-12,8-olide (3), dimeric eremophilane ligulolide B (5), and known sesquiterpenoid, 6β,8α-diacetyleremophila-1(10),7(11)-dien-12,8-olide (4), were isolated from an extract of the whole plant of Ligularia virgaurea spp. oligocephala. The structure of 1 was confirmed by NMR spectra and single crystal X-ray crystallography investigation, as well as 2, 3, and 5 were elucidated by spectroscopic methods including 1D and 2D NMR spectra. A discussion of biogenesis of 5 was described. Cytotoxicities of compound 1 were measured in vitro against selected cancer cells human promyelocytic leukemia (HL-60), human ovarian (HO-8910) and human lung epithehial (A-549).     

Active Flavonoids from Colubrina greggii var. greggii S. Watson against Clinical Isolates of Candida spp.

Candida albicans is the most commonly implicated agent in invasive human fungal infections. The disease could be presented as minimal symptomatic candidemia or can be fulminant sepsis. Candidemia is associated with a high rate of mortality and high healthcare and hospitalization costs. The surveillance programs have reported the distribution of other Candida species reflecting the trends and antifungal susceptibilities. Previous studies have demonstrated that C. glabrata more frequently presents fluconazole-resistant strains. Extracts from Mexican plants have been reported with activity against pulmonary mycosis, among them Colubrina greggii. In the present study, extracts from the aerial parts (leaves, flowers, and fruits) of this plant were evaluated against clinical isolates of several species of Candida (C. albicans, C. glabrata, C. parapsilosis, C. krusei, and C. tropicalis) by the broth microdilution assay. Through bioassay-guided fractionation, three antifungal glycosylated flavonoids were isolated and characterized. The isolated compounds showed antifungal activity only against C. glabrata resistant to fluconazole, and were non-toxic toward brine shrimp lethality bioassay and in vitro Vero cell line assay. The ethyl acetate and butanol extracts, as well as the fractions containing the mixture of flavonoids, were more active against Candida spp.     

Biocatalytic racemization of α-hydroxycarboxylic acids using a stereo-complementary pair of α-hydroxycarboxylic acid dehydrogenases

Biocatalytic racemization of aliphatic, (aryl)aliphatic and aromatic α-hydroxycarboxylic acids was achieved via a reversible oxidation-reduction sequence using a pair of stereo-complementary Prelog- and anti-Prelog d- and l-α-hydroxyisocaproate dehydrogenases from Lactobacillus confusus DSM 20196 and Lactobacillus paracasei DSM 20008, resp., overexpressed in Escherichia coli. The mild reaction conditions ensured essential ‘clean’ isomerization, undesired ‘over-oxidation’ of the substrate forming the α-ketoacid could be suppressed by exclusion of O₂ and adjustment of the NAD⁺/NADH-ratio.     

Seasonal trend of Anisakidae infestation in South Mediterranean bluefish

Abstract

A total of 1104 fish samples from markets of Sicily were analysed for the detection and species identification of Anisakidae nematodes. The preliminary analysis of the fish samples showed the presence of 2459 larvae. All the fish species revealed different prevalence of infestation, with a maximum of 100% for Lepidopus caudatus and a minimum of 4.5% in Sardina pilchardus. The 80% of the larvae examined by PCR-RFLP analysis belonged to Anisakis pegreffii species. The seasonal infestation trend of Anisakis was evaluated in all the fish sample examined. The results of the seasonal infestation trend showed a marked connection with the ecological aspects of the fish species examined. As far as we know, this work report for the first time important ecological aspects of Lepidopus caudatus specimens of South Mediterranean. This work could be useful to plan a seasonal fishing strategy aimed at reducing the health risks related to Anisakis.     

Comparison of classical and ultrasound-assisted extractions of steroids and triterpenoids from three Chresta spp

A comparative study of classical and ultrasound-assisted extractions of steroids and triterpenoids from stem, leaves and flowers of Chresta exsucca, C. scapigera and C. sphaerocephala is described. The direct analysis of crude apolar and medium-polar extracts has been conducted by high-resolution gas chromatography followed by co-injections of the crude extract with certified standards on capillary columns of different polarities. The use of ultrasound decreased significantly the total time of treatment and in addition, this extraction method was more effective for the steroids and most of the triterpenes.     

Trichoderma versus Fusarium—Inhibition of Pathogen Growth and Mycotoxin Biosynthesis

This study evaluated the ability of selected strains of Trichoderma viride, T. viridescens, and T. atroviride to inhibit mycelium growth and the biosynthesis of mycotoxins deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEN), α-(α-ZOL) and β-zearalenol (β-ZOL) by selected strains of Fusarium culmorum and F. cerealis. For this purpose, an in vitro experiment was carried out on solid substrates (PDA and rice). After 5 days of co-culture, it was found that all Trichoderma strains used in the experiment significantly inhibited the growth of Fusarium mycelium. Qualitative assessment of pathogen–antagonist interactions showed that Trichoderma colonized 75% to 100% of the medium surface (depending on the species and strain of the antagonist and the pathogen) and was also able to grow over the mycelium of the pathogen and sporulate. The rate of inhibition of Fusarium mycelium growth by Trichoderma ranged from approximately 24% to 66%. When Fusarium and Trichoderma were co-cultured on rice, Trichoderma strains were found to inhibit DON biosynthesis by about 73% to 98%, NIV by about 87% to 100%, and ZEN by about 12% to 100%, depending on the pathogen and antagonist strain. A glycosylated form of DON was detected in the co-culture of F. culmorum and Trichoderma, whereas it was absent in cultures of the pathogen alone, thus suggesting that Trichoderma is able to glycosylate DON. The results also suggest that a strain of T. viride is able to convert ZEN into its hydroxylated derivative, β-ZOL.     

In Vitro Activity of Essential Oils Distilled from Colombian Plants against Candida auris and Other Candida Species with Different Antifungal Susceptibility Profiles

Multi-drug resistant species such as Candida auris are a global health threat. This scenario has highlighted the need to search for antifungal alternatives. Essential oils (EOs), or some of their major compounds, could be a source of new antifungal molecules. The aim of this study was to evaluate the in vitro activity of EOs and some terpenes against C. auris and other Candida spp. The eleven EOs evaluated were obtained by hydro-distillation from different Colombian plants and the terpenes were purchased. EO chemical compositions were obtained by gas chromatography/mass spectrometry (GC/MS). Antifungal activity was evaluated following the CLSI standard M27, 4th Edition. Cytotoxicity was tested on the HaCaT cell line and fungal growth kinetics were tested by time–kill assays. Candida spp. showed different susceptibility to antifungals and the activity of EOs and terpenes was strain-dependent. The Lippia origanoides (thymol + p-cymene) chemotype EO, thymol, carvacrol, and limonene were the most active, mainly against drug-resistant strains. The most active EOs and terpenes were also slightly cytotoxic on the HaCaT cells. The findings of this study suggest that some EOs and commercial terpenes can be a source for the development of new anti-Candida products and aid the identification of new antifungal targets or action mechanisms.     

Quantitative Determination of Aucubin in Seven Plantago Species Using HPLC,HPTLC, and LC-ESI-MS Methods

A reversed-phase high-performance liquid chromatographic (HPLC) method was developed and validated for the determination of aucubin in Plantago lanceolata. The analyses were carried out on Zorbax SB-C₁₈ column with an aqueous phosphoric acid and acetonitrile gradient. The correlation coefficient of calibration curve showed good linearity (r > 0.9995), with average recoveries between 96.7 and 104.5%. The developed method was applied for quantification in P. atrata, P. bellardii, P. coronopus, P. holosteum, P. reniformis, and P. schwarzenbergiana. The aucubin content in plant extracts was compared by HPLC, HPTLC, and LC-ESI-MS techniques and no significant differences between the conducted methods were observed.     

Identification and quantification of gossypol in cotton by using packed micro-tips columns in combination with HPLC

Self-packed micro-tip columns containing a C₁₈-bonded silica stationary phase, based on the same principles as solid-phase extraction methods, were used to obtain gossypol and related sesquiterpenoid aldehyde-enriched fractions. The enriched metabolite fractions were then analyzed by optimized high-performance liquid chromatography (HPLC) with a C₁₈ column (4.6 mm×25 cm) eluted with the binary mobile phase acetonitrile–0.1% aqueous TFA solution (80:20). This method has proven to be highly reproducible. The precision and accuracy, as %RSD and %RME values, were determined to be less than 15% for the method. The minimum detection limit of gossypol was determined to be 10 ng (absolute gossypol). Absolute recovery was greater than 94% with a standard deviation of ±3.68%. This is a simple, fast, and cost-effective method for isolation, identification, and quantification of gossypol and related secondary metabolites. Comparative analysis of gossypol content was performed on different parts of the cotton plant (seeds, stems and leaves) of two different cultivars of Gossypium hirsutum L. (Acala_1517–70 and OR₁₉). The results indicate that the OR₁₉ cv naturally contains higher gossypol levels than the Acala cv. It was also found that treatment of leaves with a Verticillium dahliae-derived elicitor induced production of deoxyhemigossypol rather than gossypol.