Antioxidant and cytotoxic activities of Hypericum sp. on brine shrimps and human cancer cell lines.

Ten different samples of five Hypericum sp. were tested on brine shrimps, human colon carcinoma and human hepatoma cell lines for their cytotoxic activities. H. triquetrifolium Turra. (Rafina) showed the highest activity (LC50 = 22 mg/mL) on brine shrimps, while the extracts of the other nine samples showed significant to moderate activities (LC50 from 37 to 107 mg/mL). H. empetrifolium Wild. (Parnon) showed the highest activity in human colon carcinoma and human hepatoma cell lines, with LC50 values 29 and 25.1 mg/mL, respectively, while the LC50 values of the other samples were more than 45 mg/mL. It is very interesting to observe that most Hypericum samples showed good antioxidant activity in vitro.

Verbalactone, a new macrocyclic dimer lactone from the roots of Verbascum undulatum with antibacterial activity.

A novel macrocyclic dimer lactone, named verbalactone, was isolated from the roots of Verbascum undulatum and exhibited interesting antibacterial activity. It is the first time that 1,7-dioxacyclododecane is reported as the ring system of a natural product. The structure and the absolute stereochemistry of the new compound were determined by spectral methods and chemical correlation.

Samioside, a new phenylethanoid glycoside with free-radical scavenging and antimicrobial activities from Phlomis samia.

A new phenylethanoid glycoside, samioside, was isolated from the aerial parts of Phlomis samia and identified as 1-O-3,4-(dihydroxyphenyl)ethyl beta-D-apiofuranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->3)-4-O-caffeoyl-beta-D-glucopyranoside (1). In addition, one known phenylethanoid glycoside and three known flavonoids were identified as acteoside (2), apigenin, chrysoeriol, and ermanin, respectively. The structure of 1 was elucidated on the basis of its spectroscopic data. Samioside (1) demonstrated scavenging properties toward the DPPH radical and antimicrobial activity against Gram-positive and -negative bacteria.

New semisynthetic antimicrobial labdane-type diterpenoids derived from the resin "ladano" of Cistus creticus.

The antimicrobial activity of fifteen semisynthetic labdane-type diterpenes derived from the two major natural compounds 3 and 4 of the resin "ladano" of Cistus creticus is reported. The chloroethyl carbamidic esters 15 and 20 showed the strongest antimicrobial activity against Gram(+), Gram(-) bacteria and pathogenic fungi.

Composition and antimicrobial activity of the essential oil of Salvia ringens.

The essential oils of Salvia ringens (samples A and B), were analyzed by means of GC and GC/MS. From the seventy-five identified constituents representing 99.82 and 99.86% of the oils, 1,8-cineole and alpha-pinene were the major components. Furthermore, sample B exhibited a very interesting antimicrobial profile after it was tested against six gram (+/-) bacteria and three pathogenic fungi.

Three new dihydroisocoumarins from the Greek endemic species Scorzonera cretica.

Extracts of the Greek endemic species Scorzonera cretica afforded three new compounds, the dihydroisocoumarin scorzocreticin (1) and its glycosides, scorzocreticoside I (2) and scorzocreticoside II (3), as well as 11 known compounds. The structures of the isolated compounds were elucidated on the basis of spectral data and chemical methods. The absolute configurations of 1-3 were established using circular dichroism.

Essential oil of Phlomis lanata growing in Greece: chemical composition and antimicrobial activity.

The essential oil obtained from the aerial parts of Phlomis lanata has been analyzed by GC/MS. 48 compounds representing 96.85% of the oil were identified; alpha-pinene, limonene and trans-caryophyllene were found as its main components. The essential all showed a moderate in vitro activity against six Gram (+/-) bacteria and a stronger one against the three tested pathogenic fungi.

New prostaglandins from the chemically defended soft coral Plexaura nina.

Three new prostaglandins were isolated as minor constituents of the organic extract from the Caribbean soft coral Plexaura nina. The structures of the new natural products were established by means of spectral data analysis, including 2D NMR experiments. The unpalatability of the lipid extract of the coral and the defensive role of the major prostaglandin metabolites were determined by laboratory and field fish-feeding assays.

Evaluation of the antiviral activity of kaempferol and its glycosides against human cytomegalovirus.

The antiviral activity of seven flavonoids, belonging to the kaempferol series, was evaluated against human cytomegalovirus (HCMV) by a rapid method of detection of the immediate-early (IE) antigen, induced by the virus in infected cells. Flavonoids bearing acyl substituents were found to be the most active compounds.

Cytotoxicity against human leukemic cell lines, and the activity on the expression of resistance genes of flavonoids from Platanus orientalis.

The cytotoxic activity of three flavonoids, belonging to the kaempherol series, was evaluated against 15 human leukemic cell lines. Flavonoids bearing acyl substituants, 2 and 3, were found to be the most active compounds. A further compound, 1, was examined for its ability to modulate the expression of MDR-1 and GST-pi resistance genes and compounds 2 and 3 for their effect on the uptake of [3H]-thymidine as a marker of DNA synthesis.

Antibacterial and cytotoxic natural and synthesized hydroquinones from sponge Ircinia spinosula.

In order to check the structure-activity relationship and find more potent derivatives of the natural products 1 and 2 obtained from sponge Ircinia spinosula, a series of oxidation, hydrogenation, acetylation and methylation derivatives was prepared. All compounds (natural and synthetic ones) were screened for their cytotoxic and antibacterial activities. The biological studies showed a wide range of antibacterial activity even though only 2 and 2d showed a moderate cytotoxicity against the clone C98. The oxidation of the hydroquinone to quinone and the hydrogenation of the side-chain increased the antibacterial effect of the molecules.

Analysis of labdane-type diterpenes from Cistus creticus (subsp. creticus and subsp. eriocephalus), by GC and GC-MS.

The qualitative and quantitative analysis of labdane-type diterpenes of the hexane extracts and of the essential oils of the leaves, fruits and resin "Ladano", of Cistus creticus subsp. creticus and Cistus creticus subsp. eriocephalus, have been carried out by GC and GC-MS analysis using two capillary chromatographic columns, i.e., HP-5MS and CP-Wax. The methanolic extract of the fruits of C. creticus subsp. creticus was examined and seven labdane diterpenes were isolated and identified by spectroscopic methods. Data on the investigation of labdane diterpenes by GC and GC-MS is limited and most of them have never been analysed by this method. The results obtained by this analysis could be useful for identifying them in crude plant extracts. Manoyl oxides were studied further for the percentage content of their isomers. The hexane extracts of the two subspecies as well as the manoyl oxide isomers isolated from the methanolic extract of the fruits of C. creticus subsp. creticus, were tested for their antimicrobial activity against Gram-positive and Gram-negative bacteria. Global numerical differences of these C. creticus subspecies, based on labdane diterpenes content in the hexane extracts as well as in the essential oils, were established by statistical methods. Phenotypic differences are discussed.

Volatile constituents of bracts and leaves of wild and cultivated Origanum dictamnus.

The chemical composition of the volatile constituents from bracts and leaves of wild and hydroponically cultivated ORIGANUM DICTOMNUS were analysed by GC and GC-MS. Three different levels of nitrogen (100,150, 200 mg/l), were used in the nutrient solution for the cultivation, using the Nutrient Film Technique (N.F.T). Carvacrol was the predominant compound in all cases. The essential oils were investigated for their antimicrobial activity against STAPHYLOCOCCUS AUREUS, STAPHYLOCOCCUS EPIDERMIDIS, STAPHYLOCOCCUS HOMINIS, ESCHEIRICHIA COLI, and PSEUDOMONOS AERUGINOSA.

Cytotoxic coumarins from the aerial parts of Tordylium apulum and their effects on a non-small-cell bronchial carcinoma line.

Seven coumarins were isolated from the aerial parts of Tordylium apulum; their structures were established by spectroscopic means. All compounds were tested in vitro for their cytotoxicity against two cell line systems. The antiproliferative effects for three of them were studied at the level of the cell cycle in asynchronous cells of the NSCLC-N6 line with a flow cytometry apparatus.

Cytotoxic coumarins from the aerial parts of Tordylium apulum and their effects on a non-small-cell bronchial carcinoma cell line.

Seven coumarins were isolated from the aerial parts of Tordylium apulum; their structures were established by spectroscopic means. All compounds were tested in vitro for their cytotoxicity against two cell line systems. The antiproliferative effects for three of them were studied at the level of the cell cycle in asynchronous cells of the NSCLC-N6 line with a flow cytometry apparatus.

Polyphenolic constituents from the leaves of two Cynara species growing in Greece.

The chemical analyses of two Cynara species: C. humilis and C.cornigera revealed various combinations of flavones, flavonols, flavanones, coumarins, phenolic acids, and an aurone. All the identified constituents are reported for the first time from the two species, while the presence of the aurone is reported for the second time in the genus.

Cytotoxic and antibacterial labdane-type diterpenes from the aerial parts of Cistus incanus subsp. creticus.

Seven labdane-type diterpenoids were isolated from the leaves of Cistus incanus subsp. creticus; their structures were established by spectroscopic means. All compounds were tested in vitro for their cytotoxicity against three cell line systems: KB, P-388; and NSCLC-N6. Their antibacterial and antifungal activities were tested against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosae, Enterobacter cloacae, Escherichia coli, Klebsiella pneumonia, Torulopsis glabrata, Saccharomyces cerevisiae, and Candida albicans as well.

Bioactive compounds from the buds of Platanus orientalis and isolation of a new kaempferol glycoside.

A new compound kaempferol 3-O-alpha-L-(2"-E-p-coumaroyl)-rhamnopyranoside, as well as the known flavonoids, kaempferol 3-O-beta-D-(6"-E-p-coumaroyl)-glucopyranoside, kaempferol 3-O-alpha-L-(2",3"-di-E-p-coumaroyl)-rhamnopyranoside, and caffeic acid were obtained from the methanolic extract of Platanus orientalis L. buds. All the compounds were isolated by column chromatography and identified using 1H-NMR, 2D-1H-NMR (COSY), 1H-13C-NMR, and CIDMS techniques. Cytotoxic and antimicrobial studies were carried out in vitro against human cell lines and against Gram-positive and Gram-negative organisms.