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Abstract: This study describes the in vitro metabolism, by the gastrointestinal tract, together with the biological activity of the herbal tea obtained from Plectranthus barbatus leaves. The results showed that there was no appreciable degradation and that the activity was kept constant after gastric juice digestion. In the presence of pancreatic juice, degradations varied from negligible, in the case of flavonoid glucuronides, to almost complete, in the case of the abietane diterpenoid. The digested decoction contained only 50% of its initial biological activity, after pancreatic digestion. The action of Caco-2 cells on the extract revealed that neither rosmarinic acid, the main compound of the extract, nor the other components present in minute quantities were metabolised by the intact cells. Rosmarinic acid could be found inside Caco-2 cells although in trace amount. Glucoronidase from Escherichia coli, a gut bacterium, was able to hydrolyse the flavonoid derivatives, thus the aglycones were formed and permeate the Caco-2 cells. [Copyright &y& Elsevier]

Abstract: Plectranthus barbatus, known as “falso boldo” in Brazil, is used in herbal tea or cooked as a vegetable. Infusions and decoctions of leaves from P. barbatus were analysed for their inhibition of acetylcholinesterase and their antioxidant activity. The decoction showed high inhibition activity (31% inhibition with 0.5mg of extract/ml) and also high antioxidant activity (IC50 =45.8±0.5μg of dry extract/ml in the DPPH test; IC50 =69.8±3.1μg of dry extract/ml in the β-carotene–linoleic acid test). Rosmarinic acid, scutellarein 4′-methyl ether 7-O-glucuronide and (16S)-coleon E were the main constituents identified. These compounds have antiacetylcholinesterase activity. Rosmarinic acid and the scutellarein derivative have IC50 =440μg/ml and 1mg/ml, respectively. One milligram per millilitre of (16S)-coleon E showed 61% inhibition of the enzyme. Other Plectranthus species, P. ecklonii, P. fructicosus, P. lanuginosus and P. verticillatus, were also analysed and the results obtained correlated with the content in rosmarinic acid. [Copyright &y& Elsevier]

Abstract: A novel water soluble organometallic compound, [RuCp(mTPPMSNa)(2,2′-bipy)][CF3SO3] (TM85, where Cp=η5-cyclopentadienyl, mTPPMS=diphenylphosphane-benzene-3-sulfonate and 2,2′-bipy=2,2′-bipyridine) is presented herein. Studies of interactions with relevant proteins were performed to understand the behavior and mode of action of this complex in the biological environment. Electrochemical and fluorescence studies showed that TM85 strongly binds to albumin. Studies carried out to study the formation of TM85 which adducts with ubiquitin and cytochrome c were performed by electrospray ionization mass spectrometry (ESI-MS). Antitumor activity was evaluated against a variety of human cancer cell lines, namely A2780, A2780cisR, MCF7, MDAMB231, HT29, PC3 and V79 non-tumorigenic cells and compared with the reference drug cisplatin. TM85 cytotoxic effect was reduced in the presence of endocytosis modulators at low temperatures, suggesting an energy-dependent mechanism consistent with endocytosis. Ultrastructural analysis by transmission electron microscopy (TEM) revealed that TM85 targets the endomembranar system disrupting the Golgi and also affects the mitochondria. Disruption of plasma membrane observed by flow cytometry could lead to cellular damage and cell death. On the whole, the biological activity evaluated herein combined with the water solubility property suggests that complex TM85 could be a promising anticancer agent. [Copyright &y& Elsevier]

Abstract: Anticancer activity of the new [Ru(η5-C5H5)(PPh3)(Me2bpy)][CF3SO3] (Me2bpy = 4,4′-dimethyl-2,2′-bipyridine) complex was evaluated in vitro against several human cancer cell lines, namely A2780, A2780CisR, HT29, MCF7, MDAMB231 and PC3. Remarkably, the IC50 values, placed in the nanomolar and sub-micromolar range, largely exceeded the activity of cisplatin. Binding to human serum albumin, either HSA (human serum albumin) or HSAfaf (fatty acid-free human serum albumin) does not affect the complex activity. Fluorescence studies revealed that the present ruthenium complex strongly quench the intrinsic fluorescence of albumin. Cell death by the [Ru(η5-C5H5)(PPh3)(Me2bpy)][CF3SO3] complex was reduced in the presence of endocytosis modulators and at low temperature, suggesting an energy-dependent mechanism consistent with endocytosis. On the whole, the biological activity evaluated herein suggests that the complex could be a promising anticancer agent. [Copyright &y& Elsevier]

Abstract: A new family of “RuCp” (Cp=η5-C5H5) derivatives with bidentate N,O and N,N′-heteroaromatic ligands revealed outstanding cytotoxic properties against several human cell lines namely, A2780, A2780CisR, HT29, MCF7, MDAMB231, and PC3. IC50 values were much lower than those found for cisplatin. Crystal structure of compound 4 was determined by X-ray diffraction studies. Density functional theory (DFT) calculations performed for compound 1 showed electronic flow from the ruthenium center to the coordinated bidentate ligand, in agreement with the electrochemical studies and the existence of a metal-to-ligand charge-transfer (MLCT) band evidenced by spectroscopic data. [Copyright &y& Elsevier]