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In this study several investigations and tests were performed to determine the antioxidant activity and the acetylcholinesterase and tyrosinase inhibitory potential of and aqueous extracts (10% mass) and ethanolic extracts (10% mass and 70% ethanol), respectively. Moreover, for each type of the prepared extracts of and of the content in the biologically active compounds - polyphenols, flavones and proanthocyanidins was determined. The antioxidant activity was assessed using two methods, namely the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and reducing power assay. The analyzed plant extracts showed a high acetylcholinesterase and tyrosinase inhibitory activity in the range of 72.24-94.24% (at the highest used dose - 3 mg/mL), 66.96% and 94.03% (at 3 mg/mL), respectively correlated with a high DPPH radical inhibition - 70.29-84.9% (at 3 mg/mL). These medicinal plants could provide a potential natural source of bioactive compounds and could be beneficial to the human health, especially in the neurodegenerative disorders and as sources of natural antioxidants in food industry.

This study evaluated the biological activities of Eryngium planum and of Cnicus benedictus extracts enriched in polyphenols obtained by nanofiltration. The HPLC-MS analysis showed that E. planum contains mainly flavonoids, especially rutin, while in C. benedictus extracts show the high concentration of the phenolic acids, principally the chlorogenic acid and sinapic acid. Herein, there is the first report of ursolic acid, genistin, and isorhamnetin in E. planum and C. benedictus. C. benedictus polyphenolic-rich extract showed high scavenging activity (IC50=0.0081 mg/mL) comparable to that of standard compound (ascorbic acid) and a higher reducing power (IC50= 0.082 mg/mL), with IC50 having a significantly lower value than IC50 for ascorbic acid. Both extracts were nontoxic to NCTC cell line. Among the investigated herbs, E. planum polyphenolic-rich extract showed the highest inhibitory activities with the IC50 value of 31.3 μg/mL for lipoxygenase and 24.6 μg/mL for hyaluronidase. Both polyphenolic-rich extracts had a higher inhibitory effect on α-amylase and α-glucosidase than that of the acarbose. The synergistic effect of ursolic acid, rutin, chlorogenic acid, rosmarinic acid, genistin, and daidzein identified in polyphenolic-rich extracts could be mainly responsible for the pharmacological potentials of the studied extracts used in managing inflammation and diabetes.

This study was meant to determine the inhibitory activity of tannins and flavonoid compounds from Geranium robertianum, Helleborus purpurascens and Hyssopus officinale plant polyphenol rich extracts against urease and a-chymotrypsin. The G. robertianum, H. purpurascens and H. officinale extracts were purified and concentrated by microfiltration and ultrafiltration. Phenolic compounds including flavonoids and tannins have been linked to many pharmacological activities. Thus, the polyphenolic content of the extracts was assessed by UV-Vis spectroscopy and HPLC. The concentrated extracts enriched in polyphenolic compounds (flavonoids, tannins and phenolic acids) showed a significant inhibition against urease from jack bean (over 90%), whereas in case of the a-chymotrypsin, they proved to have an inhibition below 54%. The results of this support the use of G. robertianum, H. purpurascens and H. officinale polyphenolic extracts as potential sources of urease inhibitors. Among the three plant extracts tested, H. officinale polyphenolic extracts exhibited a high inhibitory activity (92.67%) against urease and low inhibition (19.6%) against a-chymotrypsin and could be considered as possible remedy in ulcer treatment.

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The paper reports the successful application of membranes processes to obtain the good quality extracts with compounds of high antioxidative activity and therapeutic value. This study provided investigations on the phenolic compounds from two plant species used in Romanian ethno-medicine and evaluated the antioxidant and cytotoxic activities. Three extracts prepared from Geranium robertianum and Symphytum officinale were concentrated by microfiltration and ultrafiltration. The levels of phenolic compounds and flavonoids were determined by UV-Vis spectroscopy and HPLC. The freeradical scavenging activity of concentrated extracts was determined by DPPH method. The preliminary tests of cytotoxic activity for the concentrated extracts have been carried out on human epidermoid laryngeal carcinoma cell line (Hep-2p) and normal monkey kidneys cells (RM). The results showed that all concentrated extracts had a very low cytotoxicity against healthy cells, but a significant cytotoxic effect on Hep-2p tumor cells. The concentrated extracts have a high antioxidant activity (% DPPH inhibition > 80%)

This study was focused on the phytochemical composition and biological activities of Anchusa officinalis and Melilotus officinalis polyphenolic-rich extracts obtained by nanofiltration. The high-performance liquid chromatography–mass spectrometry analysis showed that chlorogenic acid and rosmarinic acid were the main phenolic acids in both extracts. The main flavonoid compound from A. officinalis extracts is luteolin, whereas rutin and isoquercitrin are the main flavonoids in M. officinalis. M. officinalis polyphenolic-rich extract had the highest α-amylase (from hog pancreas) inhibitory activity (IC50 = 1.30 ± 0.06 μg/mL) and α-glucosidase (from Saccharomyces cerevisiae) inhibitory activity (IC50 = 92.18 ± 1.92 μg/mL). However, both extracts presented a significant α-glucosidase inhibitory activity. Furthermore, the hyaluronidase inhibition of polyphenolic-rich extracts also proved to be stronger (IC50 = 11.8 ± 0.1 μg/mL for M. officinalis and 36.5 ± 0.2 μg/mL for A. officinalis), but there was moderate or low lipoxygenase inhibition. The studies on the fibroblast cell line demonstrated that both A. officinalis and M. officinalis polyphenolic-rich extracts possess the cytotoxic effect at a concentration higher than 500 μg/mL. The experimental data suggest that both extracts are promising candidates for the development of natural antidiabetic and anti-inflammatory food supplements.

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