Tag Archives: polyphenols

Biological profiles of Q. cerris, Q. dalechampii, and Q. robur bark extracts: A characterization study

DOI: 10.2478/amma-2024-0003

Objective: The main objective of the present study was to characterize the extracts obtained from the bark of three oak species in order to assess their use in potential cosmetic products.
Methods: The extracts were obtained from the oak barks (periderm and rhytidome) using ultrasound-assisted extraction. The total polyphenolic content was assessed afterward, using the Folin–Ciocâlteu method, while the antioxidant capacity was determined using methods based on the neutralization of the 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radicals. To assess the tyrosinase inhibitory effect, a protocol using L–DOPA as the substrate of the enzyme was employed.
Results: The extracts presented high levels of polyphenolic compounds, with Q. cerris having the highest content. Because of the high concentration of the extracts in polyphenolic compounds, they revealed a great reducing capacity against both DPPH and ABTS radicals, but unfortunately the tyrosinase inhibitory activity of the tested extracts was very weak compared to the positive control.
Conclusions: The extracts may have beneficial effects when used in cosmetic products because of the antioxidant effects, but more studies must be conducted for the determination of the main phytochemical compounds comprised in the extracts and their correlation to the biological effects.

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Phenolic Content from Medicinal Plants and their Products Used in Veterinary Medicine

DOI: 10.2478/amma-2018-0013

Objective: The aim of the study was to determine the content of polyphenols and flavonoids from sixteen selected medicinal plants from the spontaneous Romanian flora and fifteen tinctures obtained with propylene glycol.
Methods: The polyphenols were determined by the Folin-Ciocalteu method while the flavonoids by using a colorimetric method from the 10th edition of the Romanian Pharmacopoeia. The antioxidant activities of the most common nine medicinal plants and fifteen tinctures were determined by DPPH and ABTS methods.
Results: The results highlighted that the phenolic compounds and flavonoids have contributed to their antioxidant activities and the medicinal plants and tinctures included in the study are rich sources of natural antioxidants.
Conclusions: There are a wide variety of extraction methods for the determination of phenolics and flavonoids. The study confirms a correlation between phenolic and flavonoid contents obtained by using the DPPH and ABTS tests.

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Researches Upon Indigenous Herbal Products for Therapeutic Valorification in Metabolic Diseases.Note I. Polyphenols’ Analysis of Rubi idaei folium

Introduction: Raspberry leaves (Rubi idaei folium) are a source of flavonoids, gallic tannins, phenolcarboxylic acids, sterols, vitamin C and oligoelements (selenium, vanadium). The leaves are not mentioned by the scientific literature for their possible use in metabolic diseases (diabetes, dyslipidaemia, hyperuricaemia), but among their compounds, polyphenols, sterols and vitamin C might be responsible for these properties. The aim of the study was to determine the optimum time for harvesting the leaves, in order to obtain pharmacological active extracts, with the highest content of flavonoids, phenolcarboxylic acids and tannins.
Material and methods: Qualitative (specific chemical reactions and thin layer chromatography, TLC) and quantitative (spectrophotometric methods and high liquid chromatography, HPLC) analyses upon leaves, harvested at different stages of development (before and after blossom, at fruits’ ripening and at the end of vegetative state) were applied.
Results: Flavonoids, tannins and phenolcarboxylic acids were present in all vegetative states; rutin, hyperoside and chlorogenic acid were identified using TLC. The greatest amount of total polyphenols (16.0317 g% tannic acid), tannins (11.4376 g% tannic acid), flavonoids (2.6347 g% hyperoside) and phenolcarboxylic acids (2.4011 g% chlorogenic acid) were found in young leaves. Using HPLC, gallic, chlorogenic, caffeic, p-coumaric and ferulic acids, tannin, rutin, quercetin and catechin were identified in young leaves; rutin (0.0540 g%) and p-coumaric acid (0.03174 g%) were also quantified.
Conclusions: The highest content of flavonoids, phenolcarboxylic acids and tannins were found in leaves, harvested before blossom. The tannins content were higher, compared with scientific literature.

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