Juncaceae Species as Promising Sources of Phenanthrenes: Antiproliferative Compounds from Juncus maritimus Lam.

Juncaceae family represents an abundant source of phenanthrenes. In continuation of our work aiming at the isolation of biologically active compounds from Juncaceae species, Juncus maritimus Lam. was subjected to phytochemical and pharmacological investigations. The isolation process was carried out by using combined extraction and chromatographic methods. The structures of the obtained chemical compounds were elucidated by spectroscopic analysis, including HRESIMS, 1D (1H, 13C-JMOD), and 2D (1H-1H-COSY, HSQC, HMBC, NOESY) NMR spectra. Four new [maritins A-D (1-4)] and seven known phenanthrenes (5-11) were isolated from the plant, of which two (4 and 11) are phenanthrene dimers composed of effusol monomers. Maritin C (3) has an unusual 4,5-ethanophenanthrene skeleton most likely produced by biosynthetic incorporation of a vinyl group into a cyclohexadiene ring. Compounds 1-11 were tested for their antiproliferative activity on seven human tumor cell lines (HeLa, HTM-26, T-47D, A2780, A2780cis, MCF-7, KCR) and one normal cell line (MRC-5) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The dimeric phenanthrenes showed strong antiproliferative activity against T-47D cells with IC50 values of 9.1 and 6.2 µM, respectively.

Gerardiins A-L and Structurally Related Phenanthrenes from the Halophyte Plant Juncus gerardii and Their Cytotoxicity against Triple-Negative Breast Cancer Cells.

Species in the Juncaceae accumulate different types of secondary metabolites, among them phenanthrenes and 9,10-dihydrophenanthrenes in substantial amounts. These compounds have chemotaxonomic significance and also possess interesting pharmacological activities. The present study has focused on the isolation, structure determination, and pharmacological investigation of phenanthrenes from Juncus gerardii. Twenty-six compounds, including 23 phenanthrenes, have been isolated from a methanol extract of this plant. Twelve compounds, the phenanthrenes gerardiins A-L (1-12), were obtained as new natural products. Eleven phenanthrenes [effusol (13), dehydroeffusol (14), effususin A (15), compressin A, 7-hydroxy-2-methoxy-1-methyl-5-vinyl-9,10-dihydrophenanthrene, juncusol, 2-hydroxy-7-hydroxymethyl-1-methyl-5-vinyl-9,10-dihydrophenanthrene, 2,7-dihydroxy-5-formyl-1-methyl-9,10-dihydrophenanthrene, effususol A, 2,7-dihydroxy-5-hydroxymethyl-1-methyl-9,10-dihydrophenanthrene, and jinflexin C], 1-O-p-coumaroyl-3-O-feruloyl-glycerol, and the flavones apigenin and luteolin were isolated for the first time from this plant. The cytotoxicity of the 23 isolated phenanthrenes in both mouse (4T1) and human (MDA-MB-231) triple-negative breast cancer cells and in a nontumor (D3, human cerebral microvascular endothelial) cell line was tested using an MTT viability assay. The results obtained showed that the dimeric compounds gerardiins I (9), J (10), K (11), and L (12), derived biogenetically from effusol and dehydroeffusol, were cytotoxic to both tumor and nontumor cell lines, while the monomeric compounds exerted no or very low cytotoxicity. Impedance measurements were consistent with the results of the MTT assays performed.

Unique Phenanthrenes from Juncus ensifolius and Their Antiproliferative and Synergistic Effects with the Conventional Anticancer Agent Doxorubicin against Human Cancer Cell Lines.

Phenanthrenes are the main special metabolites of Juncaceae species from phytochemical, pharmacological, and chemotaxonomical points of view. The present study focused on the isolation, structure determination, and pharmacological investigation of phenanthrenes from Juncus ensifolius. Nineteen compounds, including 17 phenanthrenes, were identified from the methanol extract of the plant. Thirteen compounds, namely, ensifolins A−M (1−13), were obtained for the first time from natural sources. Four phenanthrenes [2-hydroxy-1,7-dimethyl-5-vinyl-9,10-dihydrophenanthrene (14), juncuenin B (15), juncatrin B (16), and sylvaticin A (17)], 4-hydroxybenzaldehyde (18) and luteolin (19) were isolated for the first time from J. ensifolius. Ensifolins A (1) and B (2) are structurally unique phenanthrenes, considering that they are flavonoid- (1) or benzaldehyde-adducts (2). The antiproliferative activity of all isolated compounds against HeLa, COLO 205, and COLO 320 cancer cells and a non-tumor (MRC-5) cell line was tested using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) viability assay. The luteolin-substituted phenanthrene ensifolin A (1) proved to be the most active against all three cancer cell lines (IC50 values 3.9−12.7 µM) and showed good selectivity (SI = 4.95) in the case of COLO 205. The best selectivity was recorded for ensifolins D (4, SI > 5.15, HeLa), H (8, SI > 8.13, HeLa), and 17 (SI > 9.43, HeLa). The synergistic activity of the compounds with doxorubicin was also tested on HeLa cells, and ensifolins E (5) and H (8) exhibited very strong synergism (CI < 0.1). In conclusion, these phenanthrenes are worthy of further investigation.

Concentration-dependent effects of effusol and juncusol from Juncus compressus on seedling development of Arabidopsis thaliana.

Juncus species are valuable sources of phenanthrene compounds that have been used in traditional Chinese medicine for thousands of years. Effusol and juncusol are the most investigated compounds reported to have antimicrobial and anticancer effects; however, to date, their effects on higher plants have not been investigated. In this study, we examined the effects of effusol and juncusol on the growth and other biochemical parameters of the dicot model plant Arabidopsis thaliana in a concentration-dependent manner with a focus on polyamine metabolism. Phenanthrene induced toxic effects on plant growth and development, while effusol and juncusol induced higher biomass and maintained antioxidant defence mechanisms associated with reduced polyamine degradation. Taken together, our results suggest that these compounds could be good candidates for new biopesticide or biostimulant plant growth regulators in the future.

Antibacterial screening of Rumex species native to the Carpathian Basin and bioactivity-guided isolation of compounds from Rumex aquaticus.

Plants belonging to the genus Rumex (family Polygonaceae) are used worldwide in traditional medicine for the treatment of various diseases caused by different microorganisms (e.g. bacteria-related dermatologic conditions, dysentery and enteritis). The present study focused on the antibacterial screening of Rumex species native to the Carpathian Basin, and isolation of compounds from one of the most efficient species, Rumex aquaticus. The antibacterial effects of n-hexane, chloroform and aqueous fractions of methanol extracts prepared from different parts of 14 Rumex species (R. acetosella, R. acetosa, R. alpinus, R. aquaticus, R. conglomeratus, R. crispus, R. hydrolapathum, R. obtusifolius subsp. obtusifolius, R. obtusifolius subsp. subalpinus, R. patientia, R. pulcher, R. scutatus, R. stenophyllus and R. thyrsiflorus) were investigated against Staphylococcus epidermidis, S. aureus, MRSA, Bacillus subtilis, Moraxella catarrhalis, Streptococcus pyogenes, S. pneumoniae, S. agalactiae, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae using the disc diffusion method. Mainly the n-hexane and chloroform extracts prepared from the roots of the plants displayed high antibacterial activity (inhibition zones>15mm) against one or more bacterial strains. The highly active extracts of the aerial part and root of R. aquaticus were subjected to a multistep separation procedure. 19 Compounds, among them naphthalenes (musizin, and its glucoside, torachrysone-glucoside, 2-methoxystypandrone), anthraquinones (emodin, chrysophanol, physcion, citreorosein, chrysophanol-8-O-glucoside), flavonoids (quercetin, quercetin-3,3'-dimethylether, isokaempferide, quercetin 3-O-arabinoside, quercetin 3-O-galactoside, catechin), stilbenes (resveratrol, piceid), and 1-stearoylglycerol were isolated from the plant. The antibacterial activities of isolated compounds were determined, and it was observed that especially naphthalenes exerted remarkable antibacterial effects against several bacterial strains.