Search

Compounds of plant origin are considered promising alternative approaches in the development of medicines for the prevention and treatment of cancer. The large diversity of herbal species still requires careful exploration as a source for new anticancer compounds. The goal of the study was to screen different herbal extracts traditionally used in Armenian folk medicine for their cytotoxic effect against some cancer cell lines, and to find the prospective plant species among them. The cytotoxicity of the plant ethanol extracts was evaluated with MTT test against HeLa (human cervical carcinoma) and A549 (human lung adenocarcinoma) cells. Antioxidant properties were assessed with DPPH free radical scavenging assay. Five of the tested ten herbal extracts exhibited significant growth-inhibiting activity on HeLa cells. Moreover, Alchemilla smirnovii and Hypericum alpestre extracts also showed potent cytotoxicity on human lung adenocarcinoma cells. These two plants possessed high antiradical activity as well. Their DPPH stoichiometric values were 0.4234 and 0.14437 respectively, meaning that 1 µg of plant extract brought the reduction of DPPH equal to the respective stoichiometric values in µg. Thus, A. smirnovii and H. alpestre extracts expressed themselves as potent cytotoxic and antioxidant agents and could have promising anticancer potential. Further evaluation of their in vivo anticancer properties has much interest.

The present article includes data on the possible selective cytotoxic effect of extract of Ribes nigrum L. growing at high Armenian landscape. For this purpose, different non-cancer (microglial BV-2 wild type (Wt), acyl-CoA oxidase 1 (ACOX1) deficient (Acox1−/−) and cancer (human colon adenocarcinoma HT29 and human breast cancer MCF7) cell lines were applied. R. nigrum leaf ethanol extract showed a growth inhibition effect towards HT29 and MCF7 cells started from 6 h of treatment at the concentration of 0.5 mg/mL DW. The lowest concentration (0.125 mg/mL DW) of the investigated extract expressed cytotoxicity after 72 hours following cancer cell treatment. In contrast to the cancer cells, in the case of the tested non-cancer cells, cytotoxic effect was not observed at the applied concentrations. The extract sub-cytotoxic concentration, in this case, was reported to be the 1 mg/mL DW. Further investigations are needed to confirm the selective cytotoxicity and possible action mechanisms of the leaf extract of R. nigrum.

Silver nanoparticles (Ag NPs) represent one of the most widely employed metal-based engineered nanomaterials with a broad range of applications in different areas of science. Plant extracts (PEs) serve as green reducing and coating agents and can be exploited for the generation of Ag NPs. In this study, the phytochemical composition of ethanolic extract of black currant (Ribes nigrum) leaves was determined. The main components of extract include quercetin rutinoside, quercetin hexoside, quercetin glucuronide, quercetin malonylglucoside and quercitrin. The extract was subsequently employed for the green synthesis of Ag NPs. Consequently, R. nigrum leaf extract and Ag NPs were evaluated for potential antibacterial activities against Gram-negative bacteria (Escherichia coli ATCC 25922 and kanamycin-resistant E. coli pARG-25 strains). Intriguingly, the plant extract did not show any antibacterial effect, whilst Ag NPs demonstrated significant activity against tested bacteria. Biogenic Ag NPs affect the ATPase activity and energy-dependent H+-fluxes in both strains of E. coli, even in the presence of N,N’-dicyclohexylcarbodiimide (DCCD). Thus, the antibacterial activity of the investigated Ag NPs can be explained by their impact on the membrane-associated properties of bacteria.

Polyphenols are a group of plant secondary metabolites characterized with the presence of multiples of phenol structural units. Tannins are plant-originated phenolic substances, which play an important role in plant defense system as well as have found applications in medicine, industry, and other fields of human activity. Despite these, the mechanisms of bioavailability of these substances are poorly studied and even there are very few amounts of sources gathering recent studies concerning this issue. So the main purpose of this review is to focus on the known peculiarities and possible ways of the bioavailability of these oligomeric substances. Due to the ability of tannins to bind proteins and other macromolecules, they are responsible for astringency or bitterness of red wines and also for the anti-nutritional effects, which can be reduced by the action of tannase. In nutriceutical industry, tannins are used as natural preservers and antioxidants. They have also a wide range of medicinal application as anti-hemorrhagic and hemostatic, anti-malarial and antitumor, antimicrobial, antioxidant, anti-tyrosinase, anthelmintic, antiviral, and anti-inflammatory activities among others. It is suggested that absorption of tannins is correlated with their polymerization degree and the activity of these components depends on their absorption in the gut, metabolism and, therefore, the bioavailability. Despite numerous promising applications, there are still plenty of open spaces to fully understand determinants of the bioavailability of tannins and other oligomeric polyphenols pivotal for the expression of their biological activity.

Herbal medicine requires searching for new sources with antimicrobial activity. Alkanna sp. (Boraginaceae) is widely used in medicine due to detoxification and antibacterial effects. The aim of this study was to obtain Alkanna orientalis (L.) Boiss. plant callus extracts, to investigate antimicrobial activity of extracts against bacteria and yeast and to reveal responsible mechanisms. Callus tissue cultures have been obtained using different nutrient media. Antimicrobial activity and minimal inhibitory concentrations (MIC) were determined by the methods of extract diffusion in agar and dilution using different test-microorganisms. Quantity and quality of naphthoquinones were determined using spectrophotometric and high performance liquid chromatographic analyses. H+/K+ exchange by whole cells was assayed using selective electrodes, ATPase activity and SH-groups number of membrane vesicles—by spectrophotometric methods. It was revealed that callus extracts containing naphthoquinones (0.19 ± 0.01 %) possessed bacteriostatic activity against gram-positive bacteria including pathogenic ones (MIC were 125–750 μg/mL−1), and bactericidal activity against lactic acid bacteria (Lactobacillus acidophilus, L. rhamnosus) (MIC was 250 μg/mL). MIC against Enterococcus hirae was 250 μg/mL of callus extract or 31.25 μg/mL of shikonin. It depended on the medium content, cultivation duration and the activity remained for 10–11 years. Moreover, intact root extracts inhibited H+/K+ exchange of E. hirae but callus extracts had a stronger effect. The inhibitor, N,N′-dicyclohexylcarbodiimide (DCCD)-sensitive H+/K+ exchange was changed; ATPase activity and SH-groups number were lowered by two and more fold under the influence of the extracts. Alkanet root and callus tissues extracts were concluded to have a high antimicrobial activity. So, they might directly affect the FOF1-ATPase which in turn regulates the bacterial growth. These results are useful for further investigation of alkanet extracts composition and their application as an alternative antimicrobial agent in pharmaceutical and food industry as well as in medicine.