Cytotoxic effects of 2-arylbenzofuran phytoestrogens on human cancer cells: modulation by adrenal and gonadal steroids

Although 2-arylbenzofuran phytoalexins are known for decades, their anticancer activity has not been studied systematically. We have previously reported on the isolation and the estrogen receptor (ER) modulation properties of three new 2-arylbenzofurans from Onobrychis ebenoides, ebenfuran I [2-(2,4-dihydroxyphenyl)-5-hydroxy-6-methoxy-benzofuran], ebenfuran II [2-(2,4-dihydroxyphenyl)-3-formyl-4-hydroxy-6-methoxy-benzofuran] and ebenfuran III [2-(2,4-dihydroxyphenyl)-3-formyl-4-hydroxy-6-methoxy-5-(3-methyl-buten-2-yl)-benzofuran]. We now show that, while I and II could stimulate the proliferation of MCF-7 cells, III was inhibitory in a proliferation-dependent manner. III inhibited the growth of all human cancer cells examined, regardless of ER or multidrug resistance status. Estradiol rendered MCF-7 cells more sensitive to III, and this coincided with the ability of the hormone at concentrations ≥0.1 nM to bind to the ER of the cells and stimulate their proliferation in the presence of III. Cell proliferation stimulating concentrations of I and II also enhanced the effect of III on MCF-7 cells. However, dehydroepiandrosterone and dihydrotestosterone were ineffective in this respect. III-treated MCF-7 cells exhibited G1 phase arrest followed by detachment-induced cell death and/or apoptosis in the adherent fraction, pronounced induction of Bax and suppression of estradiol induction of Bcl-2. Our data indicate that the largely unexplored pool of benzofuran phytoalexins includes entities potentially suitable for chemoprevention and treatment of human cancer.     

Inhibition of ozone-induced SP-A oxidation by plant polyphenols

Surfactant protein-A (SP-A) is the best studied and most abundant of the protein components of lung surfactant and plays an important role in host defense of the lung. It has been shown that ozone-induced oxidation of SP-A protein changes its functional and biochemical properties. In the present study, eight plant polyphenols (three flavonoids, three hydroxycinnamic acids, and two hydroxybenzoic acids) known as strong antioxidants, were tested for their ability to inhibit ozone-induced SP-A oxidation as a mechanism for chemoprevention against lung damage. SP-A isolated from alveolar proteinosis patients was exposed to ozone (1 ppm) for 4 h. The flavonoids protected SP-A from oxidation in a dose dependent manner. ( - )-Epicatechin was the most potent flavonoid and exhibited inhibition of ozone-induced formation of carbonyls by 35% at a concentration as low as 5 μM. Hydroxybenzoic acids inhibited SP-A oxidation in a dose-dependent manner although they were less potent than flavonoids. On the other hand, hydroxycinnamic acids exhibited a different inhibitory pattern. Inhibition was observed only at medium concentrations. The results indicate that inhibition of SP-A oxidation by plant polyphenols may be a mechanism accounting for the protective activity of natural antioxidants against the effects of ozone exposure on lungs.     

Thermal, dynamic and structural properties of drug AT1 antagonist olmesartan in lipid bilayers

It is proposed that AT1 antagonists (ARBs) exert their biological action by inserting into the lipid membrane and then diffuse to the active site of AT1 receptor. Thus, lipid bilayers are expected to be actively involved and play a critical role in drug action. For this reason, the thermal, dynamic and structural effects of olmesartan alone and together with cholesterol were studied using differential scanning calorimetry (DSC), 13C magic-angle spinning (MAS) nuclear magnetic resonance (NMR), cross-polarization (CP) MAS NMR, and Raman spectroscopy as well as small- and wide angle X-ray scattering (SAXS and WAXS) on dipalmitoyl-phosphatidylcholine (DPPC) multilamellar vesicles. 13C CP/MAS spectra provided direct evidence for the incorporation of olmesartan and cholesterol in lipid bilayers. Raman and X-ray data revealed how both molecules modify the bilayer's properties. Olmesartan locates itself at the head-group region and upper segment of the lipid bilayers as 13C CP/MAS spectra show that its presence causes significant chemical shift changes mainly in the A ring of the steroidal part of cholesterol. The influence of olmesartan on DPPC/cholesterol bilayers is less pronounced. Although, olmesartan and cholesterol are residing at the same region of the lipid bilayers, due to their different sizes, display distinct impacts on the bilayer's properties. Cholesterol broadens significantly the main transition, abolishes the pre-transition, and decreases the membrane fluidity above the main transition. Olmesartan is the only so far studied ARB that increases the gauche:trans ratio in the liquid crystalline phase. These significant differences of olmesartan may in part explain its distinct pharmacological profile.     

Development and Validation of a Combined Methodology for Assessing the Total Quality Control of Herbal Medicinal Products – Application to Oleuropein Preparations

Oleuropein (OE) is a secoiridoid glycoside, which occurs mostly in the Oleaceae family presenting several pharmacological properties, including antioxidant, cardio-protective, anti-atherogenic effects etc. Based on these findings OE is commercially available, as Herbal Medicinal Product (HMP), claimed for its antioxidant effects. As there are general provisions of the medicine regulating bodies e.g. European Medicines Agency, the quality of the HMP’s must always be demonstrated. Therefore, a novel LC-MS methodology was developed and validated for the simultaneous quantification of OE and its main degradation product, hydroxytyrosol (HT), for the relevant OE claimed HMP’s. The internal standard (IS) methodology was employed and separation of OE, HT and IS was achieved on a C18 Fused Core column with 3.1 min overall run time employing the SIM method for the analytical signal acquisition. The method was validated according to the International Conference on Harmonisation requirements and the results show adequate linearity (r² > 0.99) over a wide concentration range [0.1–15 μg/mL (n=12)] and a LLOQ value of 0.1 μg/mL, for both OE and HT. Furthermore, as it would be beneficial to control the quality taking into account all the substances of the OE claimed HMP’s; a metabolomics-like approach has been developed and applied for the total quality control of the different preparations employing UHPLC-HRMS-multivariate analysis (MVA). Four OE-claimed commercial HMP’s have been randomly selected and MVA similarity-based measurements were performed. The results showed that the examined samples could also be differentiated as evidenced according to their scores plot. Batch to batch reproducibility between the samples of the same brand has also been determined and found to be acceptable. Overall, the developed combined methodology has been found to be an efficient tool for the monitoring of the HMP’s total quality. Only one OE HMP has been found to be consistent to its label claim.     

Design and synthesis of novel amino-substituted xanthenones and benzo[b]xanthenones: evaluation of their antiproliferative activity and their ability to overcome multidrug resistance toward MES-SA/D x 5 cells

A number of new xanthenone and benzo[b]xanthenone amino derivatives and their pyrazole-fused counterparts have been designed and synthesized possessing structural analogy to the potent anticancer agent 9-methoxypyrazoloacridine. The synthesis of the compounds proceeds through nucleophilic substitution of 1-chloro-4-nitroxanthenone or the corresponding benzo[b]xanthenone by the appropriately substituted amine or hydrazine, reduction of the nitro group, and conversion into the suitable dialkylaminoacetamides. This method cannot be applied for synthesis of the pyrazole-fused benzo[b]xanthenones, consequently a different, simple, and high-yielding synthetic procedure was developed for the preparation of the target molecules. In vitro cytotoxic potencies of the new derivatives toward the murine leukemia L1210 cell line, human colorectal adenocarcinoma (HT-29), and human uterine sarcoma (MES-SA and its 100-fold resistant to doxorubicin variant MES-SA/D x 5) cell lines are described and compared to those of reference drugs. The compounds exhibited significant cytotoxic activity against the tested cell lines and in addition they retain activity against the multidrug resistant MES-SA/D x 5 subline, showing resistant factors close to 1. A number of derivatives were found to possess DNA binding capacity, according to a standard ethidium bromide displacement assay. The majority of the studied compounds induce a G2/M arrest, although among them some G1 or S blockers have also been identified.     

Paeonicluside,a new salicylic glycoside from the Greek endemic species Paeonia clusii

A new glycoside of salicylic aldehyde, paeonicluside, was isolated from the roots of the Greek endemic species Paeonia clusii subsp. clusii and identified as alpha-L-arabinopyranosyl-(1-->6)-O-beta-D-glucopyranoside of salicylic aldehyde (1). In addition, one characteristic monoterpene and two monoterpene glycosides were identified as paeoniflorigenone, paeoniflorin and benzoyl paeoniflorin, respectively. The structure of 1 was elucidated on the basis of its spectroscopic data and chemical correlation. It is the first time that a derivative of salicylic aldehyde is isolated from the well-studied Paeonia genus.     

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.     

Design and synthesis of some new pyranoxanthenone aminoderivatives with cytotoxic activity

The synthesis, DNA binding and in vitro cytotoxicity of a series of novel pyranoxanthones, analogues of the acridone alcaloid acronycine, are described. The new compounds proved to bind weakly to DNA. On the contrary, they exhibited interesting cytotoxic activity against murine leukemia L1210 cell line, as well as against some human solid tumor cell lines.     

2,2-Dimethyl-2H-anthra[2,3-b]pyran-6,11-diones: a new class of cytotoxic compounds

The synthesis and cytotoxic activity of some new 2,2-dimethyl-2H-anthra[2,3-b]pyran-6,11-diones is described. Certain compounds possess interesting activity against murine leukemia L-1210 cells. Relationships between the biological activity and the pyrano-ring conformations are discussed.