Herpesviruses (HV) are pathogens causing infections in humans and animals worldwide. Since it shares many common features with other HV, bovine HV type 1 (BoHV-1) was selected as a model to test the anti-herpesviral activity of medicinal plants.

Fifteen plants were chosen in this study for their medical, antibacterial and antiviral properties. The aim was to investigate ethanolic extracts from the selected medicinal plants for anti-BoHV-1 activity. The virucidal activities were evaluated by comparing the effect of noncytotoxic concentrations of extracts on BoHV-1 strain 1640 replication in Madin-Darby bovine kidney (MDBK) cells. Virucidal activity was determined by means of virus titration after exposure to the extracts. The extract of Desmodium canadense was found to be the most effective virucide – the 50% tissue culture infective dose (TCID50) after exposure was 3.75 log10 and the virus reduction factor was ≥5.0±0.25 log10. The extract of D. canadense was therefore chosen for further studies. Virus yield reduction assays showed that D. canadense extract had time-dependent and dose-dependent effects. It effectively reduced virus titre from 8.33 log10 to 4.67 log10 (p<0.01). The virucidal activity was also confirmed by real-time polymerase chain reaction (real-time PCR), where the number of threshold cycles (Ct) was inversely proportional to the virus titre in TCID50 The virucidal activity was also confirmed by real-time polymerase chain reaction (real-time PCR). This method showed that the number of threshold cycles (Ct) was inversely proportional to the virus titre (direct correlation with exposure time R=0.9321). The extract of D. canadense showed a high virus reduction capacity. In future, such active substances should be identified for the development of effective antivirals.

Despite many phytochemical and pharmacological investigations, to date, there are no reports concerning the antibabesial activity of extracts of A. millefolium against B. canis. This study was aimed at investigating the biological activities of A. millefolium against the Babesia canis parasite and to identify its chemical ingredients. The water (WE), ethanol (EE) and hexane/acetone (H/AE) extracts of plant aerial parts were screened for total phenolic content (TPC), total flavo- noid compound (TFC), DPPH free radical-scavenging activity and its antibabesial activity assay. In this study, imidocarb diproprionate was used as a positive control. The H/AE and EE extracts were analysed using gas chromatography–mass spectroscopy (GC–MS).

In the EE extract, the main compounds were 17.64% methyl octadec-9-ynoate, 16.68% stigmast-5-en-3-ol(3α,24S) and 15.17% hexadecanoic acid. In the H/AE extract, the main com- pounds were 34.55% 11-decyldocosane, 14.31% N-tetratetracontane, 8.22% β-caryophyllene, and 7.69% N-nonacosane. Extract of EE contained the highest content of phenolics followed by H/AE and WE. The concentration of flavonoids in EE, H/AE and WE extracts showed that TFC was higher in the EE samples followed by H/AE and WE. The antioxidant activities were highest for AA, followed by EE, WE and H/AE. The antibabesial assay showed that the WE, EE and H/AE extracts of A. millefolium were antagonistic to B. canis. At a 2 mg/mL concentration, it showed 58.7% (± 4.7%), 62.3% (± 5.5%) and 49.3% (± 5.1%) inhibitory rate in an antibabesial assay, respectively.

Considering these results, the present findings suggest that A. millefolium extracts may be a potential therapeutic agent and that additional studies including in vivo experiments are essential.

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).