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The objective of this study was to present a comparative analysis of the antimicrobial activity of methanolic leaf extracts from seven Juniperus L. species, together with a tentative analysis of their total flavonoid and o-dihydroxyphenolic acids content. The chemical analyses were performed by colorimetric methods and the antimicrobial activity was assessed via broth microdilution. The studied extracts showed total content of o-dihydroxyphenols in the range of 26 to 34 µg of caffeic acid equivalent/mg DE and total flavonoid content of 13 to 24 µg of quercetin equivalent/mg DE. The sensitivity of Gram-positive bacteria to the studied extracts differed significantly with the following order of activity: J. sabina var. balkanensis > J. communis ‘Laxa’ > J. formosana > J. pinchotii > J. ashei > J. excelsa ≈ J. sibirica. Weak activity was observed for all extracts against Gram-negative bacteria and Candida strains. The analysis of the MBC/MIC ratio showed that the extracts exhibited bactericidal effect against Gram-negative bacteria (MBC/MIC≤4), while bactericidal or bacteriostatic action (MBC/MIC>4) was determined towards Gram-positive bacteria. Moreover, these extracts showed fungicidal (MFC/MIC≤4) or fungistatic effect (MFC/MIC>4). Best antibacterial activity was registered for the J. sabina var. balkanensis leaf extract. The multivariate data analyses were carried out by SIMCA 16 (v16.0.2) software. The hierarchical cluster analysis and principal component analysis, based on phytochemical and antimicrobial data, classified the studied juniper species into four groups: 1. J. ashei; 2. J. excelsa, J. sibirica; 3. J. sabina var. balkanensis, J. communis Laxa, J. formosana; 4. J. pinchotii.

Podophyllotoxin (PPT) is used in the industrial production of efficient anticancer, antiviral and other drugs. Sinopodophyllum hexandrum or Podophyllum peltatum are natural sources of PPT, but at present they are considered as endangered species. Their PPT content is variable, depending on the growing conditions. Searching for new sources of PPT, some representatives of the genus Juniperus were found to exhibit efficient PPT biosynthesis. However, PPT is highly toxic and poorly soluble in water compound, which limits its clinical applications. In this connection, amphiphilic polymer micelles are considered to be suitable PPT carriers, aimed at increase in water solubility and decrease in toxicity. The present research deals with the evaluation of MPEG–polycarbonate block copolymer micelles loaded with PPT or juniper extracts. The active component-loaded polymer nanocarriers were characterized by dynamic and electrophoretic light scattering, as well as by transmission electron microscopy. The active component loading efficiency and loading capacity were also determined. Highly efficient antiproliferative activity of the loaded micelles was determined in a panel of cancer cell lines. The obtained amphiphilic nanocarriers, loaded with PPT-containing bioactive components, have application in future in vivo preclinical trials of their pharmacokinetics and pharmacodynamics as potential therapeutical agents in the prospective nanomedicine. [ABSTRACT FROM AUTHOR]

Juniper representatives are natural sources of plenty of bioactive metabolites and have been used since ancient times as folk remedies against tapeworms, warts, cancer, etc. The antiproliferative activities of junipers are attributed to podophyllotoxin (PPT), which is a precursor for the synthesis of efficient anticancer drugs. However, the natural sources of PPT, Sinopodophyllum hexandrum (Royle) T. S. Ying and Podophyllum peltatum L., are already endangered species because of their intensive industrial exploitation. Therefore, identification of other sources of PPT is necessary. This study is a broad comparative investigation of junipers, for which original sources have been accessed from different continents of the world. The present research is aimed at the identification of species, producing PPT and other lignans at concentrations that are sufficient for the high antiproliferative activity of the corresponding extracts. Cytotoxic juniper leaf extracts demonstrated a broad spectrum of activity on a panel of cancer cell lines. The antiproliferative properties of junipers were attributed to the combined activity of great diversity of lignans (podophyllotoxin, deoxypodophyllotoxin, β-peltatin, yatein, matairesinol, anhydropodorhizol, etc.), detected by UHPLC-HRMS and LC-ESI-MS/MS in the corresponding extracts. Several species of the genus Juniperus L. were outlined as perspective sources of drug precursors with potential pharmaceutical applications. [ABSTRACT FROM AUTHOR]