In vitro antileukemic, antioxidant and prooxidant activities of Antoksyd S (C/E/XXI): a comparison with baicalin and baicalein.

There is increasing interest concerning the use of natural antioxidants as low toxic antileukemic compounds. Antoksyd S (C/E/XXI), is a novel herbal drug derived in Poland from the powdered roots of Scutellaria baicalensis, and the biological activities of its major components (baicalin and baicalein) were compared on the human leukemia cell line HL-60. On MTT assay, Antoksyd S (C/E/XXI) showed an obvious cytotoxic effect on HL-60 cells, which was compared with those caused by cisplatin and doxorubicin under the same experimental conditions. A comparative assay of the antioxidative and prooxidative capacity of Antoksyd S (C/E/XXI) was also undertaken using two different reactive species: superoxide (O2-) and a transition metal (Cu2+). Antoksyd S (C/E/XXI) has low toxicity, acting as a modifier of HL-60 cells proliferation and as an antioxidant, which could act prooxidatively in the presence of transition metal ions. Taken together, it seems reasonable to suggest that Antoksyd S (C/E/XXI) as compared to baicalin and baicalein, or to the cytostatics cisplatin and doxorubicin, might be an especially good candidate for the future development of new therapeutic techniques, alone or in "combination treatment regimens", to enhance leukemia cell killing.

Cytotoxicity, cytoprotection and neurotoxicity of novel deprenyl-related propargylamines, stable nitroxide free radicals, in vitro and in vivo.

Since novel synthesized deprenyl-related derivatives of nitroxides, named "JSAKs", have been shown to possess antioxidative properties, their cytotoxicity on neuronal-like PC-12 cells line was examined. The antiproliferative effect of two selected JSAKs was examined and expressed as IC10, IC50 and IC90, and compared with those of the parent nitroxide (Nx-640), model nitroxide TEMPO and deprenyl. There were substantial differences in the dose-dependence of all the observed antiproliferative and cytotoxic effects. Compared to anticancer drugs and apoptosis inducers with topoisomerase inhibitor properties (etoposide and camptothecin), novel compounds displayed cytotoxicity at considerably higher concentrations. The dose-dependent anti-apoptotic potency of JSAKs and Nx-640 was also investigated and compared to TEMPO and deprenyl effects. The observed structure-dependent correlation was very encouraging and prompted us to screen and to compare the in vivo time-dependent effects of JSAKs, Nx-640 and deprenyl administration on the rat intact nigrostriatal neurocytes. TH-immunochemistry was applied as the test method and marker for the changes in the state of the rat catecholaminergic system, also giving evidence that low-toxic and cell-permeable JSAKs can cross the blood-brain barrier, which is the mandatory prerequisite for the therapeutic application of antioxidants and drugs to the brain. Taken together, it can be concluded with great certainty that novel deprenyl-related JSAKs might be especially good candidates for further anticancer investigations in vitro and in vivo and future pharmacological applications.

Antioxidant properties of newly synthesized N-propargylamine derivatives of nitroxyl: a comparison with deprenyl.

In our search for novel, low-toxic, cell-penetrable and neuroprotective antioxidants, we have designed a number of novel N-propargylamine derivatives of nitroxyl, named "JSAKs". The reactivity and antioxidative potency of two selected JSAKs and their parent nitroxyl against reactive oxygen species (ROS) were examined in vitro, in a cell-free gamma-radiolysis and in model Fenton-type reaction systems and compared with those of deprenyl, the investigated member of adjunct therapies in clinical neurology. The efficiency of JSAKs to suppress the oxidative degradation of a model target (deoxyribose), deprenyl and dopamine, caused by hydroxyl radical (*OH) was also investigated. The data demonstrated that the novel compounds, JSAKs, can act as promising antioxidants and protectors of targets against ROS toxicity, thus, providing a sound chemical basis for further comparative investigations of their activity in vivo. The findings were discussed from a mechanistic point of view as well as in terms of the structure-dependent, comprehensive properties of JSAKs as dual-function compounds: antioxidants and anti-apoptotic propargylamines. The novel class of N-propargylamine nitroxyls, JSAKs, may have potential implications for the experimental therapies of Parkinson's disease, where ROS mediate deleterious effects, because these compounds have an ability to either block or reduce the progression of neurotoxic cascade of brain damage.

Synthesis and antioxidant activity evaluation of novel antiparkinsonian agents, aminoadamantane derivatives of nitroxyl free radical.

Two new analogues of the antiparkinsonian drug 1-aminoadamantane: 4-(1-adamantylamino)-2,2,6,6-tetramethylpiperidine-1-oxyl and 4-(1-adamantylammonio)-1-hydroxy-2,2,6,6-tetramethylpiperidinium dihydrochloride have been synthesized. Their antioxidant activity towards reactive oxygen species (ROS: (z.rad;)OH and O(2)(z.rad;-)) have been evaluated in three test systems. The compound with nitroxide substituent displays higher anti-oxidative capacity than those containing hydroxylamine. The in vivo study of ROS-involving 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-rat model of induced parkinsonism was undertaken to ascertain the neuroprotective ability of the novel synthesized compounds-antioxidants. The data clearly shows that the nitroxide free radical moiety of the molecule is necessary for their neuroprotective action on dopaminergic neurons under the applied conditions of deep oxidative stress caused by the neurotoxin (MPTP). The new synthesized analogues may find application in treatment of parkinsonian syndromes, either to block or to reduce the ROS-mediated neuronal damage and death.

Anticancer, antiradical and antioxidative actions of novel Antoksyd S and its major components, baicalin and baicalein.

Here we show for the first time that the novel designed drug, Antoksyd S and its polyphenolic flavones (baicalin and baicalein), act as cell proliferation modifiers of mouse leukemia cells (L1210). The cytotoxicity of Antoksyd S and baicalein in vitro was expressed as ED50 and compared with those of the cytostatics doxorubicin, cisplatin and DACA, under the same experimental conditions. Cell viability was determined by modified tetrazolium dye assay, using as a model cells with neoblastic phenotype (L1210). The antiradical activity of Antoksyd S and baicalin were investigated using the DPPH test in order to obtain their antioxidant characteristics. Structure- and concentration-dependent one electron bioactivations (peroxidative oxidation) of Antoksyd S and baicalin were performed in the absence or in the presence of GSH or SOD. It appears that Antoksyd S is a low toxic novel drug which could be effective in providing concentration-dependent antioxidative activity, acting as a cell proliferation modifier and, probably, as an apoptosis inducer in vitro, though this remains to be explored. These findings are discussed from a mechanistic standpoint as well as in terms of potential pharmacological applications under acute oxidative stress and apoptotic events. This work provides the basis for further investigations of Antoksyd S action in vitro and in vivo, since the presented results are indicative of its intracellular metabolic activation, which can only be partially associated with its observed action towards model cancer cells (mouse leukemia L1210).