Combination Of Counter-current Chromatography Research Articles

Antimicrobial and antioxidant activities of flavonoids isolated from wood of sweet cherry tree (Prunus avium L.)

Sweet cherry (Prunus avium L.) is a tree widely cultivated in temperate regions for its tasty and healing fruits. Pruning works on the tree give each year considerable amounts of woody wastes that hardly have any utility. The aims of this work were to detect the most active antioxidants present in a cherry pruning wood sample, to isolate and characterize them, and study the antimicrobial and antibiofilm activities of components found in the wood ethyl acetate extract against a selection of foodborne microorganisms. The online HPLC–DPPH technique allowed the detection of two active antioxidant peaks that, after being isolated by a combination of countercurrent chromatography (FCPC) and conventional preparative techniques, and subsequent structural characterization by NMR, MS and polarimetry, resulted to be (‒)-catechin (1) and (‒)-taxifolin (4). Other components of the cherry wood extract were also isolated, among which compounds 1, 4, and (+)-dihydrowogonin (12) have never been reported in P. avium. A selection of the isolated flavonoids was submitted to antimicrobial and antibiofilm activity evaluations against strains from type culture collections, as well as on multi-resistant strains previously isolated in our laboratory. Those compounds with antimicrobial activity detected in preliminary screenings by standard agar diffusion tests ‒the flavan-3-ol 1, the flavanonols 4 and (+)-aromadendrin (5), the flavanone (+)-pinocembrin (15), and the flavone tectochrysin (17)‒ were subjected to the minimal inhibitory concentration (MIC) test, showing all of them MIC values of 100 μg/mL. Compound 4 also induced a significative inhibition on the formation of biofilms by Enterobacter sp. UJA37p at a concentration of 1 μg/mL and a significative disruption of preformed biofilm by this strain at 0.1 µg/mL. Similar results on biofilm disruption were observed with compound 17.

Isolation and characterization of secondary metabolites from Gaultheria tenuifolia berries.

Gaultheria berries (Ericaceae) are consumed as food or used in folk medicine throughout the world. In the present study, Gaultheria tenuifolia berries were studied to describe their polyphenol and iridoid composition, aroma volatiles, and cytoprotective effects. In total, 14 metabolites were isolated using a combination of countercurrent chromatography and Sephadex LH-20, namely, cyanidin-3-O-β-galactoside, cyanidin-3-O-β-arabinoside, 3-O-caffeoylquinic acid, 5-O-caffeoylshikimic acid, quercetin, quercetin-3-O-β-glucuronide, quercetin-3-O-β-rutinoside, quercetin-3-O-β-glucoside, quercetin-3-O-β-arabinoside, quercetin-3-O-β-rhamnoside, 6α-hydroxydihydromonotropein-10-trans-cinnamate, monotropein-10-trans-cinnamate, and an (epi)-catechin dimer and trimer. Other flavan-3-ols, proanthocyanidins, and iridoids were tentatively identified by spectroscopic and spectrometric means in the fruit extracts. The tentative volatile organic compound characterization pointed to methyl salicylate as responsible for the aroma of this species. The extracts showed significant cytoprotective effects in an oxidative stress model in human gastric epithelial cells. This is the first report on the isolation, characterization, and potential biological activity of secondary metabolites from G. tenuifolia berries and insights on its possible application as a functional food. PRACTICAL APPLICATION: Berries are desirable fruit species because of their phytochemical composition and pleasant taste. Gaultheria berries are special due to their high content of iridoids and the presence of salicylic acid derivatives. Aroma of native berries is relevant for the development of new products reflecting the local identity and use of fruits. The present work involves cooperation of academia and industry on the constituents of the native products. The results provided in this article could be useful for the introduction of this species in the food and nutraceutical industries.

New Possibility for REE Determination in Oil

A novel approach of rare earth elements (REE) determination in crude oil is suggested. Special application of countercurrent chromatography (CCC) is used as a sample pretreatment tool. An oil sample is continuously pumped through the rotating coil column (RCC) as a mobile phase, while an aqueous phase (nitric acid solution) is retained as a stationary phase. Two phases are kept well mixed and agitated, but there is no emulsion at the interface under the chosen conditions. Special features of CCC give an opportunity to vary the volume of oil samples to be analyzed from 10 mL to 1 L or more. Trace metals are preconcentrated into 10 mL of stationary phase (acidic solutions) pumped out of the column so that analysis can be easily determined with inductively coupled plasma mass spectrometry (ICP-MS) without additional sample preparation procedures. Optimal concentration of nitric acid in the stationary phase for preconcentration of REE from oil by CCC has been investigated. The combination of CCC with ICP-MS gives the possibility to develop a rapid, reliable, and accurate method of trace metal including rare earth elements (REE) determination in crude oils and oil products. Such method could be an alternative for unexpanded and expensive neutron-activation analysis (NAA).

Counter-current chromatography based analysis of synergy in an anti-tuberculosis ethnobotanical

The crude extract of an Alaskan ethnobotanical plant, Oplopanax horridus, was subjected to counter-current chromatography (CCC), and the selected active regions were evaluated for their synergistic effects with an in vitro model of anti-tubercular efficacy. CCC as a support-free high-resolution separation method was employed to preclude potential irreversible absorption to a solid stationary phase. The microplate Alamar blue assay and the isobole method were used to measure the biological activity and eliminate dose–response dependent errors, respectively. Using the combination of CCC, bioassay and isobole method, significant synergistic effects were observed. Among the entire polarity range, fractions with distribution constant between 0.44 and 0.81 showed the most synergistic enhancement with an increase in potency by 108% for the recombined fractions.