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Eleven compounds were isolated from the aerial blooming parts of Hypericum trichocaulon Boiss. & Heldr., a narrow endemic plant of the island of Crete (Greece). These compounds comprise one previously undescribed prenylated phloroglycinol derivative (adhyperfoliatin), together with ten known compounds, procyanidin A2, hyperixanthone A, (E)-chlorogenic acid, trans-phytol, five flavonoids, i.e. I3,II8-biapigenin, quercitrin, hyperoside, rutin, myricitrin and one fatty acid. The structures of the isolated compounds were established by means of 1D and 2D NMR, as well as MS spectral analyses. Phloroglucinol derivatives are recognized as chemophenetic markers for the genus Hypericum, and the isolation of adhyperfoliatin contributes to the characterization of the section Drosocarpium Spach, where the under-investigation taxon belongs. Moreover, the investigation of the methanol extract led to the isolation of myricitrin in high amounts, a specialized metabolite which also serves as a marker for this section. © 2021 Elsevier Ltd

The genus Crepis L. (Asteraceae) comprises more than 200 currently recognized species. Several studies have been conducted on non-volatile phytochemicals of Crepis spp., featuring mainly sesquiterpene lactones and phenolic derivatives. Nevertheless, no report has been made on assessing the volatile constituents of the genus. Therefore, the present study is the first report to the chemical composition of the volatile constituents of two odoriferous Crepis spp., namely C. foetida L. and C. rubra L. Flowers and stems with leaves volatiles were analysed separately by gas chromatography coupled with mass spectrometry. In total, 37 volatile compounds were detected. Salicylaldehyde, carvacrol and aliphatic hydrocarbons are the main components of both C. foetida fractions, however C. rubra flowers are characterized by the abundance of β-sitosterol and eicosanoic acid, while the stems-leaves volatiles revealed to be more complex with hydrocarbons as main constituents. In addition, we investigated the salicylaldehyde rich volatile fraction for its in vitro activity on TNF-α induced ICAM-1 expression. © 2021

In the pursuit of highly active specialized metabolites from endemic plants, Centaurea papposa (Coss.) Greuter, an endemic plant in Algeria and Tunisia, was investigated and afforded eleven sesquiterpene lactones (1-11). Cytotoxic evaluation of these compounds using the in vitro MTT assay on three human cancerous cell lines (HeLa, SK-MEL-28 and HepG2), revealed that isolates 4, 8 and 9 (IC50 ≤ 10 μM) could be potential anti-cancer drugs for cervical cancer according to the National Cancer Institute. Further evaluation of the in vitro anti-inflammatory activity showed that compounds 1 and 4 inhibited the TNF-α induced ICAM-1 expression in HMEC-1 endothelial cells at a maximum of 21% and 2% of the control (IC50 values 21.9 and 5.7 μM, respectively). The Michael reactions of the α-methylene-γ-lactone ring seem to be responsible for the strong activity, while no toxicity was observed in the HMEC-1 cells in all the range of tested concentrations (6.25-50.0 µM). © 2021 Informa UK Limited, trading as Taylor & Francis Group.

Euphorbia deflexa, an endemic spurge from Greece, was investigated for the occurrence of its diterpene constituents. Through continuous monitoring by 1H NMR, 22 diterpenoids were isolated, including 16 previously undescribed compounds (euphodeflexins A-P), which belong to the jatrophane, ingenane, segetane, and pepluane diterpene types. Their chemical structures were elucidated through a combination of HRESIMS, NMR spectroscopy, and X-ray data. The isolated diterpenoids were tested against a panel of human cancer cell lines, as well as against two bacterial strains. Compounds 1, 13, and 17 were active against the HeLa cell line with IC50 values 9.9, 9.8, and 5.8 μM, respectively. ©

Thirteen prenylated acylphloroglucinols (1 - 13), including 2 previously undescribed compounds (1) and (2), were isolated from Hypericum jovis. Their structures were elucidated by high-field NMR spectroscopy. The isolated prenylated acylphloroglucinols were evaluated for their anti-inflammatory effects in vitro through the reduction of the intercellular adhesion molecule 1 expression induced by TNF- α in the human microvascular endothelial cells 1 cell line. Compounds 3, 5, 6, 8, and 12 significantly reduced intercellular adhesion molecule 1 expression in a concentration-dependent manner with IC 50values of 16.9, 34.4, 4.0, 3.2, and 7.7 μM, respectively. In addition, compound 12 showed notable inhibitory activity on the formation of cyclooxygenase-1- and 12-lipoxygenase-derived inflammatory mediators in an ex vivo cyclooxygenase-lipoxygenase assay. Eleven further constituents were isolated (14 - 24), including the rare quercetin 3-O-(2-O-acetyl)-arabinofuranoside (18). © 2021 Royal Society of Chemistry. All rights reserved.

In the search for bioactive compounds from natural sources against cancer and inflammation, Calea jamaicensis (L.) L., a plant endemic to Panama, was investigated. Using multiple chromatographic steps, seventeen sesquiterpene lactones together with nine chromene derivatives were isolated from the non-polar extract of the plant. Among them, fourteen sesquiterpene lactones and three chromanes are described herein for the first time. Structure elucidation was achieved by extensive spectroscopic analysis and comparison with reported data. The isolated sesquiterpene lactones were tested against HeLa, SK-MEL-28 and HePG2 cancerous cell lines for their cytotoxic effects, as well as in the ICAM-1 assay for their anti-inflammatory potential. This study revealed strong cytotoxic agents on the one hand and strong inhibitors on the other. The compounds inhibited the TNF-α induced ICAM-1 expression on the endothelial HMEC-1 cells in a dose-dependent manner and with no toxicity observed on this non-cancerous cell line. In addition to the well-known cytotoxic activities of sesquiterpene lactones, further exploration may offer a novel therapeutic approach to cope with inflammatory diseases and the genus Calea may serve as a biobank for the isolation of potential phytopharmaceuticals, which could be utilized as leads in drug discovery and therapy. © 2021 Elsevier Inc.

Thirteen compounds were isolated from the aerial parts of Hypericum kelleri BALD., growing as an endemic on the island of Crete (Greece). These compounds comprise four previously unknown prenylated xanthones 1,2-dihydro-3,8-dihydroxy-6-methoxy-1,1,5-tri(3-methylbut-2-enyl)xanthen-2,9-dione (kellerine A), 1,2-dihydro-3,6,8-trihydroxy-1,1,5-tri(3-methylbut-2-enyl)xanthen-2,9-dione (kellerine B), 1,2-dihydro-3,8-dihydroxy-6-methoxy-1,1-bi(3-methylbut-2-enyl)xanthen-2,9-dione (6-methylpatulone), (R/S)-1,3,5-trihydroxy-2-(3-methyl-2-buten-1-yl)-4-[2-(3-methylbut-2-enyl)-3-methylbut-3-enyl]-6-methoxy-9H-xanthen-9-one ((2″R/S)-kellerine C) and the hitherto undescribed depsidone (R/S)-1,3,6-trihydroxy-5-methoxy-2-(3-methyl-2-buten-1-yl)-4-[2-(3-methylbut-2-enyl)-3-methylbut-3-enyl]-11Η-dibenzo[b,e] [1,4]dioxepin-9-one ((2″R/S)-creticine). As known compounds, brevipsidone D, 4-geranyl-2-(2′-isobutyryl)-phloroglucinol, 4-geranyl-2-(2′-methylbutyryl)-phloroglucinol, I3, II8-biapigenin, quercetin, avicularin, pseudohypericin and neochlorogenic acid have been isolated. The structures were elucidated on the basis of their 1D, 2D NMR, CD and MS data. The study confirms the typical occurrence of xanthones in Hypericum section Oligostema (BOISS.) STEF., and is also the first report on the simultaneous isolation of acylphloroglucinols in this section. Furthermore the first evidence of depsidones in the genus Hypericum L. is reported. Cytotoxicity was investigated in HeLa cells for prenylated xanthones and the depsidones. Both triprenylated 1,2-dihydroxanthones (kellerine A and B) showed significant in vitro cytotoxicity with IC50 values of 2.5 ± 0.1 (kellerine A) and 5.9 ± 0.9 (kellerine B) μM, whereas other compounds were less cytotoxic (IC50 > 20 μM). © 2017