The free-living Acanthamoeba sp. causes various diseases. Treatment of them is very difficult and not always effective because of encystation, making it highly resistant to antiamoebic drugs. Gram-positive bacteria Staphylococcus aureus, Gram-negative bacteria Escherichia coli, and an yeast Candida albicans also exhibit outstanding resistance to antimicrobial substances. The search for new natural amoebicidal and antimicrobial agents of plant origin is still of current interest. The aim of the study was to investigate the amoebicidal activity of the extracts obtained from tissue culture and a field-grown plant of Chaenomeles japonica against pathogenic trophozoites of Acanthamoeba spp. and antimicrobial effect against S. aureus, E. coli, and C. albicans. The extracts of C. japonica had an inhibitory effect on the proliferation of Acanthamoeba trophozoites as compared to the non-treated control. Among the crude extracts tested, the extract of leaves, from both shoot culture and the field-grown plant had remarkable amoebicidal action against the trophozoites but also antibacterial activity against Gram-positive bacteria Staphylococcus aureus. The extract from leaves from shoot culture, already on the second and third days of treatment, showed an antiamoebicidal effect at a concentration of 1 mg mL-1 (inhibition of trophozoites 87.5% and 91.8%, respectively). In addition to leaves from shoot culture (a conc. 5 mg mL-1, 2nd day inhibition of trophozoites 85.7% and 3rd day 97.2%), leaves from a field-grown plant (a conc. 5 mg mL-1, 2nd day 91.0% and 3rd day 94.4%) and callus (a conc. 5 mg mL-1, 2nd day 90.0% and 3rd day – 95.4%) also exhibited a good antiamoebicidal activity. Out of the four extracts, the extracts from leaves from both shoot culture and a field-grown plant were reported to be the most active against Gram-positive S. aureus, which was determined by the values of MIC = 5.0 mg mL-1 and MIC = 2.5 mg mL-1, respectively. The inhibitory potential depends on the yield and composition of mainly bioactive compounds: pentacyclic terpenoids (mainly betulinic, ursolic, and oleanolic acids) and polyphenols (mainly chlorogenic acid and its isomers, epicatechin, dimeric, and trimeric proanthocyanidins, quercetin and kaempferol derivatives).

Abstract An efficient micropropagation protocol for production of genetically uniform clones of Eryngium campestre L. was developed. To determine the effect of nutritional and hormonal factors on shoot and root development and bioactive compounds production, three variants of media differing in the content of macro- and micronutrients, as well as plant growth regulators of various types and concentrations were tested. The highest regeneration (100%), with over 13 shoots per explant, was induced on Murashige and Skoog (MS) medium with 1.0 mg l−1 benzyladenine (BA) and 0.1 mg l−1 indole-3-acetic acid (IAA). The in vitro derived shoots multiplied through axillary bud formation were rooted and transferred to an experimental plot with 78% frequency of survival. Flow cytometry showed no variation in nuclear DNA between the seedlings and micropropagated plants. Preliminary thin layer chromatography (TLC) analysis indicated that phenolic acids, saponins, flavonoids and acetylenes were present in plant biomass. Ultra high performance liquid chromatography (UHPLC) analysis revealed that shoots and roots from in vitro derived plants and root cultures maintained the ability to produce rosmarinic acid (RA), rosmarinic acid hexoside (RA-HEX) and chlorogenic acid (CGA). The highest phenolic acid content was detected in roots of in vitro regenerated plants. The extract from those roots expressed the highest inhibitory effect against bacteria Staphylococcus aureus, as well as dermatophytes Trichophyton mentagrophytes and T. rubrum.