Norbert Kúsz

Bioactivity-Guided Investigation of the Anti-Inflammatory Activity of Hippophae rhamnoides Fruits

According to modern ethnobotanical records, the fruit of Hippophae rhamnoides is effective in the treatment of different allergic symptoms. In order to obtain pharmacological evidence for this observation, the fruit was investigated for anti-inflammatory activity using in vivo animal models. Aqueous and 70% MeOH extracts were tested in 48/80-induced rat paw edema assay after oral administration, and it was found that the 70% MeOH extract (500 mg/kg) reduced significantly edema volume (0.660 ± 0.082 mL vs. control 0.935 ± 0.041 mL). Extracts of different parts of the fruit (pulp, peel, seed) were investigated in the same assay, and the peel extract was shown to exhibit maximum edema-reducing effect (0.470 ± 0.124 mL vs. control 0.920 ± 0.111 mL). This extract was used to elucidate the mode of action. Different inflammation inducers (serotonin, histamine, dextran, bradykinin, and carrageenan) were applied in the rat paw model, but the extract inhibited only the compound 48/80 elicited inflammation. The active extract was then fractionated by solvent-solvent partitioning and chromatographic methods with the guidance of the 48/80-induced anti-inflammatory assay, and the main compounds responsible for the activity were identified as ursolic acid and oleanolic acid. Our data suggest that the activity is most probably based on a membrane stabilizing effect caused by the inhibition of degranulation of mast cells. Moreover, previously unknown 2,5-bis-aryl-3,4-dimethyltetrahydrofuran lignans, nectandrin B, fragransin A2, and saucernetindiol were isolated and identified from H. rhamnoides for the first time.

Synthesis and SAR Study of Anticancer Protoflavone Derivatives: Investigation of Cytotoxicity and Interaction with ABCB1 and ABCG2 Multidrug Efflux Transporters

There is a constant need for new therapies against multidrug‐resistant (MDR) cancer. Natural compounds are a promising source of novel anticancer agents. We recently showed that protoflavones display activity in MDR cancer cell lines that overexpress the P‐glycoprotein (P‐gp) drug efflux pump. In this study, 52 protoflavones, including 22 new derivatives, were synthesized and tested against a panel of drug‐sensitive parental cells and their MDR derivatives obtained by transfection with the human ABCB1 or ABCG2 genes, or by adaptation to chemotherapeutics. With the exception of protoapigenone, identified as a weak ABCG2 substrate, all protoflavones bypass resistance conferred by these two transporters. The majority of the compounds were found to exhibit mild to strong (up to 13‐fold) selectivity against the MCF‐7Dox and KB‐V1 cell lines, but not to transfected MDR cells engineered to overexpress the MDR transporters. Our results suggest that protoflavones can overcome MDR cancer by evading P‐gp‐mediated efflux.

Abietane diterpenoids from Sideritis montana L. and their antiproliferative activity

The present study aimed at the phytochemical and pharmacological investigation of Sideritis montana L. (Lamiaceae). Two new abietane diterpenes [sideritins A (1) and B (2)] were isolated from the methanol extract of the plant. Six known compounds [pomiferin E (3), 9α,13α-epi-dioxyabiet-8(14)-en-18-ol (4), paulownin (5), 6-methoxysakuranetin (6), 3-oxo-α-ionol (7) and 4-allyl-2,6-dimethoxyphenol glucoside (8)] were also obtained from the plant. The structures were determined by means of HREIMS and NMR experiments. The antiproliferative effect of the isolated compounds was investigated on human cancer cell lines (HeLa, SiHa and C33A) at 10 and 30μM concentrations, using the MTT assay. The results demonstrated that pomiferin E (3) and 6-methoxysakuranetin (6) displayed considerable activity [inhibition (%)±SEM: 46.93±2.35 on HeLa (pomiferin E), and 51.52±2.45 on C33A (6-methoxysakuranetin)] at 30μM concentration.

First phytochemical investigation of secondary metabolites of Euphorbia davidii Subils. and antiproliferative activity of its extracts.

The present work is the first phytochemical investigation of Euphorbia davidii Subils. After multistep separation process, three flavonoid glycosides were obtained from the ethyl acetate soluble fraction of the methanol extract of the whole plant. The structures of the isolated compounds were determined as kaempferol 3-O-rhamnoside, myricetin 3-O-rhamnoside, and quercetin 3-O-rhamnoside. Aqueous and organic extracts of the plant were screened in vitro for antiproliferative activity against HeLa (cervix epithelial adenocarcinoma), A431 (skin epidermoid carcinoma), A2780 (ovarian carcinoma) and MCF7 (breast epithelial adenocarcinoma) cells, using the MTT assay. n-Hexane and chloroform extracts demonstrated moderately dose-dependent cell growth inhibitory activity against all four cell lines.

Bioactive Segetane, Ingenane, and Jatrophane Diterpenes from Euphorbia taurinensis

A novel segetane (1: ) and jatrophane diterpene (2: ), together with five known diterpenoids possessing segetane (3: ), jatrophane (4: ), and ingenane skeletons (5 - 7: ), were isolated from the methanol extract of Euphorbia taurinensis All. The structure elucidation of the compounds was performed by means of extensive spectroscopic analysis, including HRESIMS and 1D (1H, J-modulated spin-echo carbon experiment) and 2D (HSQC, HMBC, COSY, NOESY) NMR experiments. The multidrug resistance reversing and cytotoxic effects of five diterpenes (1, 4:  - 7: ) were studied on the L5178 mouse lymphoma cell line using rhodamine 123 accumulation and the MTT cell viability assay. Segetane and jatrophane diterpenes had no cytotoxic activity on the sensitive parent and multidrug resistance cells, while ingenane diterpenes showed a cytotoxic effect on both cell lines. Ingenanes 6: and 7: and segetane 1: demonstrated the remarkable multidrug resistance modulating effect at 20 µM.

Phenanthrenes from Juncus Compressus Jacq. with Promising Antiproliferative and Anti-HSV-2 Activities

Juncaceae species are rich sources of phenanthrenes. The present study has focused on the isolation and structure determination of biologically active components from Juncus compressus. Eleven compounds (nine phenanthrenes and two flavonoids) have been isolated from the plant by the combination of different chromatographic methods. Two compounds (compressins A (Compound 1) and B (Compound 2)) are novel natural products, while seven phenanthrenes (effusol (Compound 3), effususol (Compound 4), juncusol (Compound 5), 2-hydroxy-1-methyl-4-oxymethylene-5-vinyl-9,10-dihydrophenanthrene (Compound 6), 7-hydroxy-1-methyl-2-methoxy-5-vinyl-9,10-dihydrophenanthrene (Compound 7), effususin A (Compound 8), and dehydroeffusol (Compound 9)), and two flavonoids (apigenin (Compound 10) and luteolin (Compound 11) were isolated for the first time from the plant. Compressin B (Compound 2) is a dimeric phenanthrene, in which two juncusol monomers (Compound 5) are connecting through their C-3 atoms. The structure elucidation of the isolated compounds was carried out using 1D, 2D NMR spectroscopic methods and HR-MS measurements. In vitro investigation of the antiproliferative effect of the phenanthrenes on two cervical (HeLa and SiHa) and an ovarian human tumor cell line (A2780) revealed that compounds have remarkable antiproliferative activity, mainly on the HeLa cell line. Moreover, juncusol (Compound 5) proved to possess significant antiviral activity against the herpes simplex 2 virus (HSV-2).

New iridoids from the roots of Valeriana dioscoridis Sm.

Four new iridoids (1-4), together with three known iridoids (5-7), one known flavonoid glycoside, three phenolic acids and one phytosterol were isolated from the roots of Valeriana dioscoridis. Their structures were elucidated by means of NMR spectroscopy and mass spectrometry. This is the first report on the phytochemical composition of the non-volatile constituents of V. dioscoridis and the occurrence of a bis-iridoid glycoside in the genus Valeriana. The antiproliferative effects of the iridoids (1-7) were evaluated against three human cancer cell lines of gynacological origin (HeLa, A2780 and T47D) at 10, 30 and 60 μM concentrations, using the MTT assay and they elicited modest antiproliferative activity when compared to the reference agent, cisplatin.

Two New neo -clerodane Diterpenes from Scutellaria galericulata

Two new neo-clerodane derivatives, scutegalerins F and G, have been isolated from the acetone extract of the aerial parts of Scutellaria galericulata. The structures of the compounds were established by spectroscopic means and by comparison with the literature data of closely relative compounds.

Three New Iridoid Glycosides from the Aerial Parts of Asperula involucrata

Three new iridoid glycosides, named involucratosides A – C (1 – 3), were isolated from the H2O subextract of crude MeOH extract prepared from the aerial parts of Asperula involucrata along with a known iridoid glycoside (adoxoside), three flavone glycosides (apigenin 7‐O‐β‐glucopyranoside, luteolin 7‐O‐β‐glucopyranoside, apigenin 7‐O‐rutinoside) as well as two phenolic acid derivatives (chlorogenic acid and ferulic acid 4‐O‐β‐glucopyranoside). Their chemical structures were established by UV, IR, 1D‐ (1H, 13C and JMOD) and 2D‐ (COSY, HSQC, HMBC and NOESY) NMR experiments and HR‐ESI‐MS. In addition, the crude extract, subextracts and isolates were evaluated for their xanthine oxidase inhibitory and antioxidant activities in in vitro tests. This is the first report on the chemical composition and bioactivities of A. involucrata.