Metabolic Activation of Myristicin and Its Role in Cellular Toxicity.

Myristicin is widely distributed in spices and medicinal plants. The aim of this study was to explore the role of metabolic activation of myristicin in its potential toxicity through a metabolomic approach. The myristicin- N-acetylcysteine adduct was identified by comparing the metabolic maps of myristicin and 1'-hydroxymyristicin. The supplement of N-acetylcysteine could protect against the cytotoxicity of myristicin and 1'-hydroxymyristicin in primary mouse hepatocytes. When the depletion of intracellular N-acetylcysteine was pretreated with diethyl maleate in hepatocytes, the cytotoxicity induced by myristicin and 1'-hydroxymyristicin was deteriorated. It suggested that the N-acetylcysteine adduct resulting from myristicin bioactivation was closely associated with myristicin toxicity. Screening of human recombinant cytochrome P450s (CYPs) and treatment with CYP inhibitors revealed that CYP1A1 was mainly involved in the formation of 1'-hydroxymyristicin. Collectively, this study provided a global view of myristicin metabolism and identified the N-acetylcysteine adduct resulting from myristicin bioactivation, which could be used for understanding the mechanism of myristicin toxicity.

Cytotoxicity of piperamides towards Aedes aegypti (Diptera: Culicidae).

The effectiveness of the amides piplartine and piperlonguminine isolated from Piper species for controlling L3 and L4 of Aedes aegypti (L.) was assessed through bioassays at concentrations ranging from 1 to 300 g/l ml. Piplartine reduced the mosquito development period and caused larval mortality only at concentrations > 100 microg/ml, whereas piperlonguminine resulted in an extended period of mosquito development (10 microg/ml) and caused 100% larval mortality (30 microg/ml) within 24 h. The toxicity and cytotoxic effects of piperlonguminine on epithelial cells of the digestive system of Ae. aegypti were viewed using transmission electron microscopy, which indicated vacuolization of cytoplasm, mitochondrial swelling and leaking of nuclear material. Piperlonguminine was the more effective amide, showing toxic activity with LD50 of approximately 12 microg/ml against the larvae of Ae. aegypti.

The natural compounds piperovatine and piperlonguminine induce autophagic cell death on Trypanosoma cruzi.

The currently available treatments for Chagas disease show limited therapeutic potential and are associated with serious side effects. Our group has been attempting to find alternative drugs isolated from natural products as a potential source of pharmacological agents against Trypanosoma cruzi. Here, we demonstrate the antitrypanosomal activity of the amides piperovatine and piperlonguminine isolated from Piper ovatum against epimastigotes and intracellular amastigotes. We also investigated the mechanisms of action of these compounds on extracellular amastigote and epimastigote forms of T. cruzi. These amides showed low toxicity to LLCMK(2) mammalian cells. By using transmission and scanning electron microscopy, we observed that the compounds caused severe alterations in T. cruzi. These alterations were mainly located in plasma membrane and mitochondria. Furthermore, the study of treated parasites labeled with Rh123, PI and MDC corroborate with our TEM data. These mitochondrial dysfunctions induced by the amides might trigger biochemical alterations that lead to cell death. Altogether, our data evidence a possible autophagic process.

Accumulation of lignans by in vitro cultures of three Linum species.

Justicidin B, an arylnaphthalene lignan, has strong cytotoxicity on chronic myeloid and chronic lymphoid leukemia cell lines. The first report of the production of justicidin B in a Linum species concerned in vitro culture of Linum austriacum. Therefore, culture characterization and presence of arylnaphthalene-type lignans in calli and plantlets of Linum tenuifolium from section Linastrum, Linum bienne, and Linum glaucum from section Linum were studied. Seed germination of L. tenuifolium in the light and darkness was significantly higher (p < 0.05) than of L. bienne in the light and L. glaucum in the darkness. L. tenuifolium seedling length in the darkness was significantly higher (p < 0.01) than under light conditions. There were no significant differences in the calli and shoot biomass weight, number and length of shoots in three species over one month, while the shoot diameter of L. bienne was significantly different (p < 0.05) from that of L. glaucum. Justicidin B was detected in L. glaucum callus and plantlet cultures by HPLC/MS/UV-DAD and HPLC coupled with a photodiode array detector. This finding is important from pharmaceutical point of view and shows the chemosystematic relation between L. glaucum and L. austriacum and this method will be a powerful tool for detecting natural products in interested and endangered medicinal plants.

Toxicological efficacy of some indigenous dill compounds against the flesh fly, Parasarcophaga dux Thomson.

The effect of the LC50 of the three isolated compounds (apiol, myristicin and d-carvone) from dill, Anethum graveolus on growth and reproduction of Parasarcophaga dux showed that three compounds especially apiol caused significant reduction in the percentage of adults emergence and females fecundity. The temperature toxicity relation shape of the three compounds and five insect growth regulations (methoprene, hydroprene, teflubenzuron, chlorfluazuron and Precocene I) alone or in combination against P. dux was studied and discussed.

Synthesis and anticonvulsant activity of some new dioxolane derivatives.

In this study, ten 2-acetylnaphthalene derivatives with a dioxolane structure were synthesized and screened for their anticonvulsant activities. Dioxolane derivatives were prepared by the reaction with appropriate ethanone, glycol and p-toluensulphonic acid. The structures of the compounds were elucidated by IR, 1H-NMR and elemental analysis. Anticonvulsant activities of the compounds were determined by maximal electroshock seizure (MES) test and subcutaneous metrazol (ScMet.) test. The rotarod toxicity test was used for the assessment of neurological deficits. According to the activity studies compound 6 was found neurotoxic, compounds, 1, 4, 5, 7-9 were found protective against MES and 7-10 were found protective against ScMet. Compounds 2 and 3 were found inactive.

The Kidney Invasion Test: an assay allowing macroscopic quantification of malignant invasion in vivo. Comparison between the microtubule inhibitor tubulozole and the podophyllotoxin congener etoposide (VP-16-213).

When MO4 tumor fragments were implanted under the renal capsule of syngeneic or allogeneic mice, invasion of the renal parenchyma was observed. Inhibition of invasion by the microtubule inhibitor tubulozole could be macroscopically quantified and compared with the invasion permissive drug etoposide (VP-16-213). These results have been histologically confirmed, and the use of this assay in vivo for the rapid macroscopical screening of compounds with potential anti-invasive properties is discussed.

Carcinogenicity tests of certain environmental and industrial chemicals.

Fourteen chemicals of varied uses were tested for carcinogenicity by oral administration in male and female Charles River CD rats. Under the conditions of the tests, propane sultone, propylene imine, and ethylenethiourea, in addition to the positive control N-2-fluorenylacetamide, were carcinogenic. Avadex, bis(2-chloroethyl) ether, the potassium salt of bis(2-hydroxyethyl) dithiocarbamic acid, ethylene carbonate, and semicarbazide hydrochloride were not carcinogenic under the test conditions. Dithiooxamide, glycerol alpha-monochlorohydrin, and thiosemicarbazide gave somewhat ambiguous results, though administered at high enough dose levels to be toxic. An inadequate number of animals survived treatments with sodium azide, sodium bisulfide, and vinylene carbonate, or the animals may not have received sufficiently high doses of the test chemicals to provide maximum test sensitivity. However, there were no indications that these three chemicals were carcinogenic under the test conditions.

Preliminary screening of anticholinergic effect of new 1,3-dioxolane and 1,3,-dioxane derivatives.

Some of the 28 investigated new derivatives show distinct anticholinergic activity. The greatest activity, that of 2-cyclohexyl-2-phenyl-5-piperidinodioxane-1,3 was greater than of the atropine sulfate.