Effect of estragole over the RN4220 Staphylococcus aureus strain and its toxicity in Drosophila melanogaster.

Among the bacterial resistance mechanisms, efflux pumps are responsible for expelling xenobiotics, including bacterial cell antibiotics. Given this problem, studies are investigating new alternatives for inhibiting bacterial growth or enhancing the antibiotic activity of drugs already on the market. With this in mind, this study aimed to evaluate the antibacterial activity of Estragole against the RN4220 Staphylococcus aureus strain, which carries the MsrA efflux pump, as well as Estragole's toxicity in the Drosophila melanogaster arthropod model. The broth microdilution method was used to perform the Minimum Inhibitory Concentration (MIC) tests. Estragole was used at a Sub-Inhibitory Concentration (MIC/8) in association with erythromycin and ethidium bromide to assess its combined effect. As for Estragole's toxicity evaluation over D. melanogaster, the fumigation bioassay and negative geotaxis methods were used. The results were expressed as an average of sextuplicate replicates. A Two-way ANOVA followed by Bonferroni's post hoc test was used. The present study demonstrated that Estragole did not show a direct antibacterial activity over the RN4220 S. aureus strain, since it obtained a MIC ≥1024 µg/mL. The association of estragole with erythromycin demonstrated a potentiation of the antibiotic effect, reducing the MIC from 512 to 256 µg/mL. On the other hand, when estragole was associated with ethidium bromide (EtBr), an antagonism was observed, increasing the MIC of EtBr from 32 to 50.7968 µg/mL, demonstrating that estragole did not inhibited directly the MsrA efflux pump mechanism. We conclude that estragole has no relevant direct effect over bacterial growth, however, when associated with erythromycin, this reduced its MIC, potentiating the effect of the antibiotic.

Dehydrodieugenol B derivatives as antiparasitic agents: Synthesis and biological activity against Trypanosoma cruzi.

Chagas disease is a neglected protozoan disease that affects more than eight million people in developing countries. Due to the limited number and toxicity profiles of therapies in current use, new drugs are urgently needed. In previous studies, we reported the isolation of two related antitrypanosomal neolignans from Nectandra leucantha (Lauraceae). In this work, a semi-synthetic library of twenty-three neolignan derivatives was prepared to explore synthetically accessible structure activity relationships (SAR) against Trypanosoma cruzi. Five compounds demonstrated activity against trypomastigotes (IC50 values from 8 to 64 µM) and eight showed activity against intracellular amastigotes (IC50 values from 7 to 16 µM). Eighteen derivatives demonstrated no mammalian cytotoxicity up to 200 µM. The phenolic acetate derivative of natural dehydrodieugenol B was effective against both parasite forms and eliminated 100% of amastigotes inside macrophages. This compound caused rapid and intense depolarization of the mitochondrial membrane potential, with decreased levels of intracellular reactive oxygen species being observed. Fluorescence assays demonstrated that this derivative affected neither the permeability nor the electric potential of the parasitic plasma membrane, an effect also corroborated by scanning electron microscopy studies. Structure-activity relationship studies (SARs) demonstrated that the presence of at least one allyl side chain on the biaryl ether core was important for antitrypanosomal activity, and that the free phenol is not essential. This set of neolignan derivatives represents a promising starting point for future Chagas disease drug discovery studies.

In vitro susceptibility of Microsporum spp. and mammalian cells to Eugenia caryophyllus essential oil, eugenol and semisynthetic derivatives.

BACKGROUND: Microsporum spp. are keratinophilic dermatophytes that mainly invade the stratum corneum of the skin and hair causing clinical symptoms associated with tinea. Its treatment has several limitations, and the search for new active molecules is necessary. OBJECTIVE: To evaluate the antifungal and cytotoxic potential of Eugenia caryophyllus essential oil (EO), eugenol, isoeugenol and methylisoeugenol against Microsporum canis, M. gypseum and Vero cells. METHODS: The EO was extracted by conventional heating-assisted hydrodistillation, the eugenol obtained commercially and the derivatives through Williamson synthesis. Minimal inhibitory concentration (MICs), minimum fungicidal concentration, inhibition of radial mycelial growth and germination inhibition were used to evaluate the antifungal activity. In addition, a colorimetric test was conducted to evaluate cytotoxic activity. RESULTS: MIC and MFC values for all compounds were 62.5-500 µg/mL for both of the species of Microsporum evaluated. Also, concentrations of 300 µg/mL of the compounds inhibited 100% of M. canis mycelium. The inhibition of germination was observed after 6 hours of treatment (11.86 ± 3.46-85.31 ± 0%). No cytotoxicity was observed in Vero cells (CC50  > 105 µg/mL), whereas terbinafine showed CC50 31.00 ± 0.61 µg/mL. CONCLUSIONS: Our study indicates an interesting bioactivity of isoeugenol and methylisoeugenol against M. canis, M. gypseum and mammalian cells.

Developmental toxicity evaluation of Pimenta pseudocaryophyllus (Gomes) Landrum, (E)-methyl isoeugenol chemotype, in Wistar rats.

BACKGROUND: Pimenta pseudocaryophyllus (Gomes) Landrum (Myrtaceae) has been traditionally used in Brazilian folk medicine. Studies have established the botanical characterization, phytochemistry profile, and pharmacological potential of this species, including antibiotic, anxiolytic, antidepressant, antioxidant, antinociceptive, and anti-inflammatory properties. Despite its widespread use, no previous study has been conducted regarding its toxicological profile, especially during pregnancy. Thus, this study investigated the developmental toxicity of the dry leaf extract of the P. pseudocaryophyllus, (E)-methyl isoeugenol chemotype, in rats. METHODS: First, the dry leaf extract was prepared by a spray-drying technique. Then, pregnant Wistar rats were orally treated with dry extract at doses of 0, 2000, 2500, or 3000 mg/kg from gestational day 6 through 15 (organogenesis period). On gestational day 21, the rats underwent cesarean sections and the reproductive outcomes and biochemistry parameters related to hepatic and renal markers were evaluated. Additionally, the fetuses were examined for external and skeletal variations and malformations. RESULTS: The spray-drying technique preserved the phytocomplex components and showed a satisfactory yield. No relevant differences were seen in the food consumption, reproductive performances, and hepatic and renal biochemical parameters between groups. However, there was a decrease in body weight gain of the dams during the organogenesis period and an increase of minor skeletal variations in the offspring (increased fetal incidences only of delayed ossification of the metacarpals, metatarsals, phalanges, sternebra, and rudimentary ribs) treated with the dry extract. CONCLUSION: The extract of P. pseudocaryophyllus, (E)-methyl isoeugenol chemotype, showed low maternal toxicity and induced minor skeletal variations in the offspring. Birth Defects Research 109:1292-1300, 2017. © 2017 Wiley Periodicals, Inc.

Anti-Toxoplasma Activity of Estragole and Thymol in Murine Models of Congenital and Noncongenital Toxoplasmosis.

Toxoplasmosis is caused by Toxoplasma gondii , an obligatory intracellular protozoan. Normally benign, T. gondii infections can cause devastating disease in immunosuppressed patients and through congenital infection of newborn babies. Few prophylactic and therapeutic drugs are available to treat these infections. The goal of the present study was to assess the anti-Toxoplasma effects in a congenital and noncongenital model of toxoplasmosis (using ME49 strain), besides assessing immunological changes, in vitro cytotoxicity, and in vivo acute toxicity of commercial estragole and thymol. The congenital experimental model was used with intermediate stages of maternal infection. The serum levels of immunoglobulin (Ig)M, IgG, interleukin (IL)-10, IL-12, and interferon-gamma (IFN-γ) were quantified from infected and treated C57Bl/6 mice. Estragole and thymol respectively exhibited low to moderate in vivo toxicity and cytotoxicity. Animals treated with estragole showed high IFN-γ and strong type 1 helper T cell response. Both compounds were active against T. gondii ME49 strain. Furthermore, orally administered estragole in infected pregnant mice improved the weight of offspring compared with untreated controls. Subcutaneous administration of both compounds also increased the weight of mouse offspring born to infected mothers, compared with untreated controls. Estragole and thymol display important anti-Toxoplasma activity. Further studies are needed to elucidate the mechanism of action of these compounds.

Insecticidal activity against Aedes aegypti larvae of some medicinal South American plants.

The insecticidal activity of 11 extracts from nine South American medicinal plants has been studied using the Aedes aegypti larvicidal assay. Eight of the 11 plant extracts studied showed toxicity against the A. aegypti larvae (LC(50)<500 microg/ml). The dichloromethane extracts of Abuta grandifolia and Minthostachys setosa demonstrated high larvicidal activity, the most active being the dichloromethane extract of A. grandifolia, with an LC(50)=2.6 microg/ml (LC(100)= 8.1 microg/ml), indicating an activity 2-fold higher than beta-asarone, a natural botanical insecticide used as a positive control (LC(100)=16 microg/ml). On the other hand, the dichloromethane extract of M. setosa was quite potent against A. aegypti larvae showing an LC(50)=9.2 microg/ml (LC(100)=25.2 microg/ml). The results obtained suggest that the extracts of A. grandifolia and M. setosa are promising as larvicides against A. aegypti larvae and could be useful in the search for new larvicidal natural compounds.

Dominant lethal study of alpha-asarone in male mice.

Alpha-asarone is a hypolipidaemic agent obtained from Guatteria gaumeri, a medical plant used in Mexico to treat hypercholesteraemia and cholelithiasis. alpha-Asarone has been shown to be hepatocarcinogenic and mutagenic in a human lymphocyte assay, a murine bone marrow cell assay and in an unscheduled DNA synthesis assay. In this study, alpha-asarone was tested for dominant lethal effects in male CF1 mice. The drug was given orally at doses of 0, 10 and 30 mg/kg per day for 5 days. Males were mated weekly with eight consecutive batches of naive, nulliparous female mice. Repeated matings revealed no perceptible effect of alpha-asarone on the incidence of pregnancy. Examination of surgically exposed uteri and ovaries of pregnant females on day 13-15 of gestation revealed an increased incidence of post-implantation loss. Semen examination of a separate group of mice showed a decreased concentration and motility of spermatozoa. These results suggest a dominant lethal mutation as well as direct alpha-asarone toxicity to spermatozoa by in treated mice.

[Pharmacology and toxicology of Guatteria gaumeri and alpha-asarone]. / Farmacología y toxicología de Guatteria gaumeri y alfa-asarona.

Guatteria gaumeri Greenman (Annonacease) has been used as bark infusion in the traditional mexican medicine for the treatment of hypercholesterolemia and cholelithiasis. The main component is alpha-asarone which has been isolated by different extraction procedures and subsequently synthetized, as well as 16 analogs, derivatives of 4-propenyl-1,2-dimethoxybenzenes 5-substituted. After daily dosing per os of 80 mg/kg of alpha-asarone and the amino and metoxi analogs for seven days to hypercholesterolemic male rats, cholesterol decreased 57.3, 37.5 and 46.9% and triglycerides diminished 42.5, 67.6 and 17.2% respectively. Some of the other analogs showed also important hypolipidemic activity. Similarly alpha-asarone decreased 80.6% the weight of gallstones in hamsters. Studies using adult rat hepatocytes suggest that at least part of the hypolipidemic effect of alpha-asarone could be due to a decrease in the secretion of lipids. Alpha-asarone did not produce any toxic effect after oral administration to rats of 10 or 50 mg/kg for 28 days, or genotoxicity by the dominant lethal test. However long-term exposure of cultivated hepatocytes to micromolar concentrations produced morphologic and ultrastructural alterations, triacylglycerol accumulation and inhibition of protein synthesis and secretion. At the same time both the Ames and sister-chromatid exchange tests showed genotoxic effect. No teratogenicity was observed in pregnant rats during organogenesis but in mice slight fetal toxicity was manifested by hydrocephaly, skeletal defects and fetal weight retardation. There are no data on the possible exposure levels in humans consuming the bark extract, but the toxic effects of alpha-asarone in animals suggest caution in the use of this plant.(ABSTRACT TRUNCATED AT 250 WORDS)

[Teratogenic action of alpha-asarone in the mouse]. / Action tératogène de l'alpha-asarone chez la souris.

The embryotoxicity and teratogenicity of alpha-asarone were investigated in mice. The drug was dissolved in corn oil, and administered daily, by gavage, on days 6 to 15 of gestation, at 0 (controls), 5, 15, 30 and 60 mg/kg. Fetuses were removed on day 18 by caesarean section and examined using routine teratological methods. A significant maternal toxicity was observed in dams given 60 mg/kg, as indicated by a reduced weight gain. An embryolethality was observed in 15, 30 and 60 mg/kg treated groups. In addition, the highest dose induced fetal malformations, mainly represented by hydrocephaly, extra-ribs, clubfeet and cleft lips.

Sister-chromatid exchange induction produced by in vivo and in vitro exposure to alpha-asarone.

The effect of alpha-asarone, a chemical with hypocholesterolemic properties extracted from Guatteria gaumeri, on SCE induction was studied both in human lymphocytes in vitro and in murine bone marrow cells in vivo. A slight but consistent increase in SCE was observed in both biological systems.