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  • Author: P. Mucaji x
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Contribution to the TLC separation of ursolic and oleanolic acid mixture

The aim of the study was to develop a rapid, simple, effective and reproducible TLC method for separation of a naturally occurring mixture of ursolic and oleanolic acids. Because of the similarity of chemical structures, in situ derivatisation by iodine was necessary to separate these triterpenic acids. Separation was achieved on silica gel plates. After derivatisation, a chromatographic plate was developed with the mobile phase consisting of light petrol, ethyl acetate and acetone (8.2:1.8:0.1, v/v/v) following visualisation by spraying with sulphuric acid in diethylether (25%, v/v) and heating to 120°C for 5 min. The method used enabled chromatographical differentiation of ursolic and oleanolic acid mixtures in all tested mutual ratios.

Abstract

Resveratrol and caffeic acid belong to plant polyphenols and are known for their antioxidant effects. The aim of our research was to study their impact on Maillard reaction. This one occurs when the reducing saccharides react with amino groups of biomolecules including proteins, alter their protein conformation and transform to the variety of advanced glycation end products (AGEs). AGEs exhibit browning and generate fluorescence. There exist expectations that this oxidative protein glycosylation could be prevented by antioxidants. In this study, we incubated bovine serum albumin (BSA) with glucose for 7 days at 37°C and measured characteristic fluorescence and UV absorbance of the formed AGEs. Surprisingly, resveratrol and caffeic acid enhanced transformation of BSA to glycation products, which was confirmed either when cupric Cu(II) or ferric Fe(III) ions in nanomolar concentration were added to the system as pro-oxidant agent.

Abstract

Our recent study is focussed on the investigation of the influence of biotic (Botrytis cinerea, methyl jasmonate) and abiotic (cadmium and cobalt chloride) elicitors on Melissa officinalis L. (lemon balm) suspension cultures production properties. The plant material was treated with different concentrations of methyl jasmonate (10 and 100 μmol.l−1), with a phytopathogenic fungus hydrolyzate (Botrytis cinerea, 1 and 2 ml with glucose equivalent 24 μg.ml−1), cadmium and cobalt (II) chloride (both at concentrations 100 μmol.l−1 and 1 μmol.l−1). Elicited suspension cultures were harvested after 24, 48 and 72 h of elicitor treatment. The elicitation effect was evaluated based on hydroxycinnamic acid derivatives content expressed as rosmarinic acid in dose- and time-dependent manners. The Botrytis cinerea hydrolyzate exhibited the best effect on Melissa officinalis L. suspension cultures production properties among biotic elicitors (glucose equivalent 24 mg.ml−1, 1 ml, after 72 h of treatment). The hydroxycinnamic acid derivatives content increased in triplicate compared to non-elicited samples. Methyl jasmonate affected the suspension cultures production properties moderately at concentration 10 μmol.l−1. Chlorides salts of cobalt and cadmium stimulated phenolic compounds production effectively at concentrations 100 μmol.l−1. The presence of cobalt and cadmium ions in suspension cultures growth media increased the hydroxycinnamic acid derivatives content twofold and quadruple, respectively.

The present study evaluates antihyperglycemic activity of fractionated Pycnogenol® and its ability to improve endothelial dysfunction in diabetic animals. The aim of this study was to isolate from Pycnogenol® mixture its active compounds and compare their efficacy on observed parameters. Pycnogenol® mixture was fractioned by re-extracting with petroleum ether, chloroform, ethyl acetate and butanol, subsequently. Pycnogenol® mixture and fractions (butanolic, water, ethyl acetate) were administered during 6 weeks to diabetic rats. Blood glucose levels were assessed from the arterio-venous blood at the beginning of experiment and at the end of experiment. Endothelial dysfunction was evaluated as the contractile responses to phenylephrine and acetylcholine. The amount of collagen I and III was assessed from thoracic aorta after picrosirius red staining. For the confirmation of the changes on molecular level, we determinated endothelial NO synthase (eNOS) and heat shock protein 90 (Hsp90) expression from left ventricle. Overall, the result suggest, that fractions are not so effective on observed parameters as Pycnogenol® mixture itself, indicating synergistic effect of the plant constituents.

Abstract

Peppermint belongs to one of most popular medicinal plants in pharmacy as well as in the food industry.

Aim: For the conventional usage, the aerial part, especially leaves, is used. This investigation was aimed at the determination of phenolic compound in peppermint rhizomes infusion and the comparison with the phenolics in leaves infusions.

Methods: For the separation and identification of the phenolic compounds, the Sykam HPLC-DAD connected with Microsaic 4500MiD®, a single quadrupole mass spectrometer, was used.

Results: Three compounds in rhizomes and eight compounds in leaves were identified and quantified. In rhizomes, rosmarinic acid was determined as the main secondary metabolite, but its content was three times lower than that in leaves. Infusion of peppermint leaves was richer in flavonoids content with eriocitrin as a major phenolic compound.

Conclusion: Rhizomes of peppermint may also be used as a potential source of rosmarinic acid and caffeic acid derivatives.