Synthesis and cytotoxic activity evaluation of 2,3-thiazolidin-4-one derivatives on human breast cancer cell lines

It is well known that resveratrol (RSV) displayed cancer-preventing and anticancer properties but its clinical application is limited because of a low bioavailability and a rapid clearance from the circulation. Aim of this work was to synthesize pharmacologically active resveratrol analogs with an enhanced structural rigidity and bioavailability. In particular, we have synthesized a library of 2,3-thiazolidin-4-one derivatives in which a thiazolidinone nucleus connects two aromatic rings. Some of these compounds showed strong inhibitory effects on breast cancer cell growth. Our results indicate that some of thiazolidin-based resveratrol derivatives may become a new potent alternative tool for the treatment of human breast cancer.     

Fetal and Newborn Calf Thymus as a Source of Chromatin Proteins: Purification of HMG-1 and HMG-2

The high mobility group (HMG) non-histone chromosomal proteins were first isolated from calf thymus' but were later found in numerous organs of many vertebrates.' The proteins can be extracted from calf thymus 1 with 0.35 M NaCl and they are quite soluble in 2% trichloroacetic acid. We have shown that members of the HMG-1 family (i.e., HMG-1, HMG-2, and HMG-E) exhibit a preferential affinity for single-stranded DNA at roughly physiological ionic trength. Members of this family have other intriguing properties (see references 6 and 7 for recent reviews), including the ability to assemble nucleosomes in vitroe8 The architecture of the proteins strongly suggests that they are designed to interact simultaneously with histones and with DNA through physically distinct domains^{6, 9}.     

Purification and partial biochemical characterization of polyphenol oxidase from mamey (Pouteria sapota)

While a long shelf life for fruit products is highly desired, enzymatic browning is the main cause of quality loss in fruits and is therefore a main problem for the food industry. In this study polyphenol oxidase (PPO), the main enzyme responsible for browning was isolated from mamey fruit (Pouteria sapota) and characterized biochemically. Two isoenzymes (PPO 1 and PPO 2) were obtained upon ammonium sulfate precipitation and hydrophobic and ion exchange chromatography; PPO 1 was purified up to 6.6-fold with 0.28% yield, while PPO 2 could not be characterized as enzyme activity was completely lost after 24 h of storage. PPO 1 molecular weight was estimated to be 16.1 and 18 kDa by gel filtration and SDS-PAGE, respectively, indicating that the native state of the PPO 1 is a monomer. The optimum pH for PPO 1 activity was 7. The PPO 1 was determined to be maximum thermally stable up to 35 °C. Kinetic constants for PPO 1 were K_m = 44 mM and K_m = 1.3 mM using catechol and pyrogallol as substrate, respectively. The best substrates for PPO 1 were pyrogallol, 4-methylcatechol and catechol, while ascorbic acid and sodium metabisulfite were the most effective inhibitors.     

Fabrication of polyphenol biosensor based on laccase immobilized on copper nanoparticles/chitosan/multiwalled carbon nanotubes/polyaniline-modified gold electrode

A high-performance amperometric polyphenol biosensor was developed, based on covalent immobilization of Ganoderma sp. laccase onto copper nanoparticles (CuNP's)/chitosan (CHIT)/carboxylated multiwalled carbon nanotube (cMWCNT)/polyaniline (PANI)-modified gold (Au) electrode. The CuNP's and cMWCNT had a synergistic electrocatalytic effect in the matrix of CHIT. The biosensor showed optimum response at pH 6.0 (0.1 M acetate buffer) and 35 °C, when operated at 50 mV s⁻¹. The biosensor exhibited excellent sensitivity (the detection limit was down to 0.156 μM for guaiacol), fast response time (less than 4 s) and wide linear range (from 1 to 500 μM). Analytical recovery of added guaiacol was 96.40-98.46%. Within batch and between batch coefficients of variation were <2.6% and <5.3%, respectively. The enzyme electrode was used 300 times over a period of 7 months, when stored at 4 °C.     

Oxidative stress augments the secretion of atrial natriuretic peptide in isolated rat atria

Reactive oxygen species (ROS) play a role in cardiovascular diseases such as hypertension and heart failure. The objective of the present study was to investigate the role of endogenous ROS in atrial hemodynamics and ANP secretion in isolated perfused beating rat atria. Pyrogallol (a generator of superoxide anion, 0.1, 1 mM) or hydrogen peroxide (0.1, 1, 10, 30 mM) was perfused into atria paced at 1.2 Hz. Pyrogallol and hydrogen peroxide stimulated ANP secretion and concentration in a dose-dependent manner and dramatically decreased atrial contractility and translocation of extracellular fluid. The stimulatory effect of pyrogallol and hydrogen peroxide on ANP secretion was attenuated by the pretreatment with ascorbic acid (an antioxidant; 1 mM) and cariporide (an inhibitor of the Na⁺/H⁺ exchanger; 1 μM) but negative inotropic effect was not changed. U120 (a MAPK^erk pathway inhibitor; 10 μM) attenuated the stimulatory effect of hydrogen peroxide on ANP secretion. However, U120 augmented negative inotropic effect and stimulatory effect of ANP concentration induced by pyrogallol. Antioxidant such as N-acetyl cystein, gallate, propyl gallate, or ellagic acid did not cause any significant changes in atrial parameters. These results suggest that intracellular - formed ROS stimulates ANP secretion partly through activation of MAPK^erk pathway and Na⁺/H⁺ exchanger.     

加工型马铃薯品种多酚氧化酶活性的变化规律

为探寻加工型马铃薯多酚氧化跨活性的变化规律,本研究对5个加工型马铃薯品种多酚氧化酶(PPO)活性进行了测定。结果表明：植株生长期间,各组织器官PPO活性发生看规律性变化。叶片PP0活性表现出低—高—低的波动,并于现蕾至决茎膨大期达到高峰[31．12(0．01△OD/／min];块茎PP0活性呈现高—低—高—低的趋势;花药PPO活性交化趋势与叶片相同,并在墨花期达到高峰[129．80(0．01△OD／min]。此外,在同一发育阶段,不同组织器官PPO活性也不同,花药＞匍匐茎＞花蕾、花瓣＞叶片和块茎。进一步检剩结果表明,即使是同一块茎不同部位的PPO活性也呈现较大差分,其中决茎外皮PP0活性最高,髓最低。贮藏待播的决茎芽PPO活性明显高于块茎本身。本项结果对今后利用生物工程技术抑制PPO活性,有效改良加工型马铃薯品种县有重要意义。     

Antioxidant and Neuroprotective Activities of Mogami-benibana (Safflower,Carthamus tinctorius Linne)

Free radical scavenging activity of the extracts of petals (bud, early stage, full blooming and ending stage), leaf, stem, root and seeds of Mogami-benibana (safflower, Carthamus tinctorius Linne), the contents of the major active components of carthamin and polyphenols, and neuroprotective effect of the petal extracts and carthamin in the brain of mice and rats were examined. Water extracts of Mogami-benibana petals scavenged superoxide, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and singlet oxygen. The scavenging activities of the extract of safflower petals with various colors showed the order of orange, yellow and white from high to low. This order is consistent with the contents of carthamin, which is a pigment of orange color and is found highest in orange petals and lowest in white petals. There was also a relationship between DPPH radical scavenging activity and carthamin content in the petal extracts of safflower. The neuroprotective effects were examined in cellular and animal models. Mogami-benibana petal extract inhibited glutamate-induced C6 glia cell death, significantly decreased the formation of malondialdehyde in mouse cerebrum, and inhibited the increase in thiobarbituric acid reactive substances and 8-hydroxy-2′-deoxyguanosine (8-OHdG) in the cerebral cortex of rats subjected to an injection of FeCl₃ solution into the sensory motor cortex. Carthamin showed similar effects in inhibiting 8-OHdG by the petal extract in rats. These results suggest that the petal extract of Mogami-benibana has free radical scavenging activity and neuroprotective effect and carthamin is one of the major active components. Special Issue Article in Honor of Dr. Akitane Mori.     

Identification of Predominant Phytochemical Compounds and Cytotoxic Activity of Wild Olive Leaves (Olea europaea L. ssp. sylvestris) Harvested in South Portugal

This study has been aimed at providing a qualitative and quantitative evaluation of selected phytochemicals such as phenolic acids, flavonoids, oleuropein, fatty acids profile, and volatile oil compounds, present in wild olive leaves harvested in Portugal, as well as at determining their antioxidant and cytotoxic potential against human melanoma HTB‐140 and WM793, prostate cancer DU‐145 and PC‐3, hepatocellular carcinoma Hep G2 cell lines, as well as normal human skin fibroblasts BJ and prostate epithelial cells PNT2. Gallic, protocatechuic, p‐hydroxybenzoic, vanillic acids, apigenin 7‐O‐glucoside, luteolin 7‐O‐glucoside, and rutin were identified in olive leaves. The amount of oleuropein was equal to 22.64 g/kg dry weight. (E)‐Anethole (32.35%), fenchone (11.89%), and (Z)‐3‐nonen‐1‐ol (8%) were found to be the main constituents of the oil volatile fraction, whereas palmitic, oleic, and alpha‐linolenic acid were determined to be dominating fatty acids. Olive leaves methanol extract was observed to exerted a significant, selective cytotoxic effect on DU‐145 and PC‐3 cell lines. Except the essential oil composition, evaluated wild olive leaves, with regard to their quantitative and qualitative composition, do not substantially differ from the leaves of other cultivars grown for industrial purposes and they reveal considerable antioxidant and cytotoxic properties. Thus, the wild species may prove to be suitable for use in traditional medicine as cancer chemoprevention.     

Allelopathic agents from aquatic ecosystems: potential biopesticides models

Allelopathy is usually regarded as a terrestrial science and little attention has been paid to the allelochemicals involved in the interactions between aquatic autotrophs. Also, chemicals involved in the interaction between algae (macro or microscopic) and their environment are not often acknowledged as allelopathic. Allelopathy is a key factor for explaining microalgae assemblages, community structure and the dynamics of the populations within the ecosystem. Herein we present an overview of what is known in this field, describing the chemicals yet identified and which kind of interactions are they involved in.     

Comparison of enzymically glucuronidated flavonoids with flavonoid aglycones in an in vitro cellular model of oxidative stress protection

This study modeled, in vitro, the potential effect of conjugative (phase II) metabolism on the cytoprotective capacity of fruit flavonoids against oxidative stress. Flavonoid aglycones were compared with their corresponding isomeric mixtures of glucuronides for their ability to enhance the survival of cultured human Jurkat T and neuroblastoma cells stressed with hydrogen peroxide. Various polyphenolic compounds were tested as substrates in vitro for an ovine liver glucuronyl transferase preparation. Flavonoids and their glycoside derivatives were found to be good substrates, whereas phenolic acids were either poor or nonsubstrates. Five common flavonoids were glucuronidated to prepare mixtures for bioassay testing. Glucuronidation generally weakened the cytoprotective capacities of flavonoids (in the presence of H₂O₂), but some compounds were weakened much more than others. The concentration that halved cell death was well below 0.5 μM for most flavonoids tested, but glucuronidation increased median effective concentration values to a range of 1–16 μM. This compares with the generally accepted physiological range (0.1–10 μM) for circulating dietary polyphenolics detected in the body. Therefore, some flavonoids may retain a reduced cytoprotective capacity in vitro, after glucuronidation, whereas others may be effectively inactivated.