Gastrodin attenuates perfluorooctanoic acid-induced liver injury by regulating gut microbiota composition in mice.

Perfluorooctanoic acid (PFOA) can accumulate in the livers of humans and animals via the food chain, resulting into liver injury, which is closely related to intestinal flora dysbiosis. Gastrodin has been reported to have hepatoprotective effect. However, whether gastrodin can alleviate PFOA-induced liver injury via modulating gut microbiota remains unclear. Herein, a PFOA-induced liver injury model was established by gavage of PFOA (5 mg/kg body weight) in 2% Tween 80 solution once daily for 6 weeks in mice, and then gastrodin in saline (20 mg/kg body weight) was used once daily for 8 weeks to treat liver damage. The biochemical indexes associated with liver function, oxidative stress, and inflammatory factors were examined. Hematoxylin-eosin staining was used to determine the liver histopathological changes. Besides, 16S rRNA sequencing was used to analyze the difference of gut microbiota between the model and treatment groups. The results showed that gastrodin significantly improved the oxidative stress caused by PFOA. Intestinal flora analysis showed that gastrodin treatment significantly increased the relative abundance of probiotics, such as Lactobacillus, Bifidobacterium, and Bacteroides, while the harmful bacteria, including Desulfovibrio were decreased. Gastrodin treatment also significantly increased the level of short-chain fatty acids (SCFAs), such as butyric acid and isobutyric acid. Spearman correlation analysis showed that the composition changes of gut microbiota and SCFAs increase were both beneficial to alleviate the liver injury caused by PFOA. To sum up, gastrodin can effectively alleviate PFOA-induced liver injury through regulating gut microbiota composition.

Enzymatic decolorization of melanin by lignin peroxidase from Phanerochaete chrysosporium.

Skin darkening results as a consequence of the accumulation of skin pigment melanin. To combat this, the amplitude of skin lightening agents are commercially available, most of which inhibit melanin synthesis. Decolorization of melanin is an alternative method of skin lightening. In this study, we show that lignin peroxidase (LiP), an extracellular enzyme purified from Phanerochaete chrysosporium NK-1 isolated from a forest soil can effectively degrade and decolorize melanin in vitro. Decolorization conditions including pH, temperature, incubation time, enzyme concentration, and mediator addition were investigated to optimize the reaction conditions. The results indicate that pH 3, 40 °C, 15 IU/ml, and 10 h incubation were the optimal conditions for the decolorization of the melanin. The use of the mediator, veratryl alcohol was also found effective to enhance the efficacy of the melanin decolonization, with up to 92% decolorization. The scanning electron microscopy results showed void spaces on the treated melanin granules as compared to the untreated sample, indicating the degradation of melanin. Changes in the fingerprint region of the melanin were observed. Between wavenumbers 1500-500 cm-1, for example, the presence of new peaks in the treated melanin at 1513, 1464, and 1139 cm-1 CH2, CH3 bend and C-O-C stretch represented structural changes. A new peak at 2144 cm-1 (alkynyl C≡C stretch) was also detected in the decolorized melanin. The cytotoxicity study has shown that the treated melanin and LiP have low cytotoxic effects; however, the mediator of veratryl alcohol could result in high mortality which suggests that its use should be meticulously tested in formulating health and skincare products. The findings of the study suggest that LiP produced by Phanerochaete chrysosporium has the potential to be used in the medical and cosmetic industries, particularly for the development of biobased cosmetic whitening agents.

Tissue-Adhesive Paint of Silk Microparticles for Articular Surface Cartilage Regeneration.

Current biomaterials and tissue engineering techniques have shown a promising efficacy on full-thickness articular cartilage defect repair in clinical practice. However, due to the difficulty of implanting biomaterials or tissue engineering constructs into a partial-thickness cartilage defect, it remains a challenge to provide a satisfactory cure in joint surface regeneration in the early and middle stages of osteoarthritis. In this study, we focused on a ready-to-use tissue-adhesive joint surface paint (JS-Paint) capable of promoting and enhancing articular surface cartilage regeneration. The JS-Paint is mainly composed of N-(2-aminoethyl)-4-(4-(hydroxymethyl)-2-methoxy-5-nitrosophenoxy) butanamide (NB)-coated silk fibroin microparticles and possess optimal cell adhesion, migration, and proliferation properties. NB-modified silk fibroin microparticles can directly adhere to the cartilage and form a smooth layer on the surface via the photogenerated aldehyde group of NB reacting with the -NH2 groups of the cartilage tissue. JS-Paint treatment showed a significant promotion of cartilage regeneration and restored the smooth joint surface at 6 weeks postsurgery in a rabbit model of a partial-thickness cartilage defect. These findings revealed that silk fibroin can be utilized to bring about a tissue-adhesive paint. Thus, the JS-Paint strategy has some great potential to enhance joint surface regeneration and revolutionize future therapeutics of early and middle stages of osteoarthritis joint ailments.

RIFM fragrance ingredient safety assessment, p-isopropylbenzyl alcohol, CAS Registry Number 536-60-7.

The existing information supports the use of this material as described in this safety assessment. p-Isopropylbenzyl alcohol was evaluated for genotoxicity, repeated dose toxicity, developmental and reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from the read-across analog benzyl alcohol (CAS # 100-51-6) show that p-isopropylbenzyl alcohol is not expected to be genotoxic. Data from the read-across analog benzyl alcohol (CAS # 100-51-6) provide a calculated MOE >100 for the repeated dose, developmental, and local respiratory toxicity endpoints. The reproductive toxicity endpoint was evaluated using the TTC for a Cramer Class I material, and the exposure is below the TTC (0.03 mg/kg/day). Data from read-across analog benzyl alcohol (CAS # 100-51-6) provided p-isopropylbenzyl alcohol a NESIL of 5900 µg/cm2 for the skin sensitization endpoint. The phototoxicity and photoallergenicity endpoints were evaluated based on UV spectra; p-isopropylbenzyl alcohol is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; p-isopropylbenzyl alcohol was found not to be a PBT as per the IFRA Environmental Standards, and its risk quotients, based on its current volume of use in Europe and North America (i.e., PEC/PNEC) are <1.

Toxicological Assessment of Intermediates in Natural Attenuation of p-Xylene to Marine Microalgae.

The toxic effects of p-xylene, 4-methylbenzyl alcohol, p-methyl benzaldehyde, and p-toluic acid on two marine microalgae (Phaeodactylum tricornutum Bohlin, and Skeletonema costatum) were investigated. p-Xylene was the most toxic to Pha. tricornutum with a 96 h EC50 value of 6.76 mg L-1. Based on the 96 h EC50 values for two microalgae, the toxicity of the four chemicals, in descending order, was: p-xylene, p-methyl benzaldehyde, 4-methylbenzyl alcohol, then p-toluic acid. The results showed that the toxicity of the transformed products of p-xylene was lower than that of p-xylene.

Acute and 28-day sub-acute intravenous toxicity studies of 1'-S-1'-acetoxychavicol acetate in rats.

1'-S-1'-acetoxychavicol acetate (ACA) has been previously reported to reduce tumor volume in nude mice, at an effective dose of 1.56 mg/kg body weight. However, the detailed toxicological profile for ACA has not yet been performed. Herein, we investigated the toxicity of intravenous administration of ACA in male and female Sprague-Dawley rats, both acutely (with single doses of 2.00, 4.00 and 6.66 mg/kg body weight, for 14 days), and sub-acutely (with weekly injections of 0.66, 1.33, and 2.22 mg/kg, for 28 days). In both toxicity studies, treatment with ACA did not affect behavior, food/water intake or body weight, nor did it induce any changes in clinically relevant hematological and biochemical parameters or mortality, suggesting that the LD50 of ACA was higher than 6.66 mg/kg body weight, regardless of sex. Sub-acutely, there was however, mild focal inflammation of kidneys and lobular hepatitis, but these were not associated with significant functional adverse effects. Therefore, the no-observed-adverse-effect level (NOAEL) for intravenous administration of ACA in the present 28-day sub-acute study was 2.22 mg/kg body weight, in both male and female rats. These findings provide useful information regarding the safety of ACA use in a healthy, non-tumor-bearing rat model.

Discovery of (2-aminophenyl)methanol as a new molecular chaperone that rescues the localization of P123S mutant pendrin stably expressed in HEK293 cells.

Pendred syndrome is the most common form of syndromic deafness. It is associated with a mutation in the SLC26A4 gene that encodes pendrin, which is thought to maintain the ion concentration of endolymph in the inner ear most likely by acting as a chloride/bicarbonate transporter. Mutations in the SLC26A4 gene are responsible for sensorineural hearing loss. In this study, we established a stable HEK293 cell line expressing P123S mutant pendrin and developed screening methods for compounds that show pharmacological chaperone activity by image analysis using CellInsight™. Morphological analysis of stained cells in each well of 96-well plates yielded six compounds in the compound library. Furthermore, fluorescence intensity analysis of the intracellular localization of P123S mutant pendrin in HEK293 cells using FLUOVIEW™ and cytotoxicity experiments revealed that (2-aminophenyl)methanol 8 is the most promising molecular chaperone to rescue P123S mutant pendrin: the plasma membrane (M)/cytoplasm (C) ratios are 1.5 and 0.9 at the concentrations of 0.3 and 0.1mM, respectively, and a sustained effect was observed 12h after removal of the compound from the cell medium. Because the M/C ratio of salicylate, which was previously discovered as a molecular chaperone of P123S mutant pendrin, was approximately 1 at 10mM concentration and a sustained effect was not observed even at 6h, (2-aminophenyl)methanol 8 was 100 times more potent and exhibited a longer sustained effect than salicylate. These findings suggest that (2-aminophenyl)methanol 8 is an attractive candidate for therapeutic agent for Pendred syndrome patients.

Use of genetically manipulated Salmonella typhimurium strains to evaluate the role of human sulfotransferases in the bioactivation of nitro- and aminotoluenes.

Various nitro- and aminotoluenes demonstrated carcinogenic activity in rodent studies, but were inactive or weakly active in conventional in vitro mutagenicity assays. Standard in vitro tests do not take into account activation by certain classes of enzymes. This is true in particular for sulfotransferases (SULTs). These enzymes may convert aromatic hydroxylamines and benzylic alcohols, two major classes of phase-I metabolites of nitro- and aminotoluenes, to reactive esters. Here it is shown that expression of certain human SULTs in Salmonella typhimurium TA1538 or TA100 strongly enhanced the mutagenicity of various nitrotoluenes and nitro- and amino-substituted benzyl alcohols. Human SULT1A1, SULT1A2, and SULT1C2 showed the strongest activation. The observation that some nitrotoluenes as well as some aminobenzyl alcohols were activated by SULTs in the absence of cytochromes P450 implies that mutagenic sulfuric esters were formed at both the exocyclic nitrogen and the benzylic carbon, respectively. Nitroreductase deficiency (using strain YG7131 instead of TA1538 for SULT1A1 expression) did not affect the SULT-dependent mutagenicity of 1-hydroxymethylpyrene (containing no nitro group), moderately enhanced that of 2-amino-4-nitrobenzyl alcohol, and drastically attenuated the effects of nitrobenzyl alcohols without other substituents. The last finding suggests that either activation occurred at the hydroxylamino group formed by nitroreductase or the nitro group (having a strong -M effect) had to be reduced to an electron-donating substituent to enhance the reactivity of the benzylic sulfuric esters. The results pointed to an important role of SULTs in the genotoxicity of nitrotoluenes and alkylated anilines. Activation occurs at nitrogen functions as well as benzylic positions.

Comparative evaluation of gastroulcerogenic potential of nitrogen isoforms of salicyl alcohol and aspirin in rats: biochemical and histological study.

The aim of the current study was to explore in vivo any relative gastroulcerogenic prospective propensity of newly synthesized nitrogen containing derivatives of salicyl alcohol; compound (I) [1-(2-hydroxybenzyl)piperidinium chloride], compound (II) [4-carbamoyl-1-(2-hydroxybenzyl)piperidinium chloride] and aspirin in albino rats. The experimental groups received the following oral treatments daily for 6 days: group I saline control; group II, standard (aspirin) treatment group [150 mg/kg of body weight]; group III, test (compound I) treatment group [100, 150 mg/kg]; group IV, test (compound II) treatment group [100, 150 mg/kg]. The results showed that in the case of the aspirin treated group and compound (I) [150 mg/kg], there was a significant increase in gastric volume, free acidity, total acidity, ulcer score and a decrease in gastric pH. Furthermore, histopathological examination of gastric mucosa of these treated groups revealed detectable morphological changes. Utilizing the same protocol, synthetic compound (I) [100 mg/kg] and (II) [100, 150 mg/kg] exhibited no statistically significant ulcerogenic or cytotoxic properties. A cyclooxygenase (COX) selectivity test indicated the preferential inhibition of COX-I and COX-II enzymes by compounds (I) and (II). This study therefore indicates that these synthetic compounds may possess reduced ulcerogenic potential and could be a functional substitute to aspirin.

Synthetically modified bioisosteres of salicyl alcohol and their gastroulcerogenic assessment versus aspirin: biochemical and histological correlates.

The present study was conducted to synthesize nitrogen containing derivatives of salicyl alcohol and to investigate in vivo their ulcerogenic potential in comparison with aspirin in rats. The compounds [4-(2-hydroxybenzyl) morpholin-4-iumchloride (I)] and [1,4-bis(2-hydroxybenzyl) piperazine-1,4-diium chloride (II)] were synthesized and their chemical structures were characterized using spectral data. In our previous study (Ali et al., Afr J Pharm Pharmacol 7:585-596, 2013), both compounds showed anti-inflammatory, antinociceptive, and antipyretic properties in standard animal models and a greater binding affinity for cyclooxygenase-2 versus cyclooxygenase-1 in molecular docking and dynamics analysis. For in vivo studies, animals were randomly divided into four groups. The synthetic compounds (both at 100 or 150 mg/kg), aspirin (150 mg/kg), or saline vehicle was administered orally, once daily for 6 days and then tested for ulcerogenic activity. At the end of the procedure, gastric juice and tissues were collected and subjected to biochemical and histological analyses. The results of the study revealed that in the case of the aspirin-treated group, there was a significant increase in gastric juice volume, free acidity, total acidity, and ulcer score and a decrease in gastric pH. Moreover, histological examination of the gastric mucosa of the aspirin-treated group indicated morphological changes while neither of the synthetic compounds showed any significant ulcerogenic or cytotoxic properties. The results of the present study suggest that both compounds are free from ulcerogenic side effects and may represent a better alternative to aspirin.

Near-infrared light-triggered micelles for fast controlled drug release in deep tissue.

In this manuscript, a near-infrared (NIR) light-breakable amphiphilic block copolymer N-succinyl-N'-4-(2-nitrobenzyloxy)-succinyl-chitosan micelles (SNSC), containing light-sensitive triggering group 2-nitrobenzyl alcohol on the hydrophobic block, was developed. The UV-Vis absorption spectra, Fourier Transform Infrared (FTIR) spectra, and (1)H nuclear magnetic resonance ((1)H NMR) spectra were characterized to confirm the successful synthesis of the micelles. Two-photon photolysis of SNSC micelles was displayed by transmission electron microscopy (TEM). By encapsulating a NIR dye cypate (Ex/Em: 780/808 nm) into the hydrophobic core of the micelles, the dissociation of the micelles under NIR illumination was greatly accelerated, enabling a controlled fast release of co-loaded hydrophobic species in the micelles. In vivo distribution and acute toxicity of the NIR light-sensitive micelles were also investigated to verify the low cytotoxicity of the micelles. Results indicate that this system provides an efficient method to surmount the drawback of UV or visible light-responsive polymeric systems for controlled drug release in deep tissues.

Toxicological effects of a mixture used in weight loss products: p-synephrine associated with ephedrine, salicin, and caffeine.

p-Synephrine is an adrenergic amine found in Citrus aurantium L. fruits and has been used for weight loss in dietary supplements. There are commercial products containing this substance associated to caffeine, salicin, and ephedrine. The aim of this study was to evaluate the acute toxicity of this mixture in mice of both sexes. The significative results observed after acute oral administration to male and female mice of 300, 350, and 400 mg/kg total of p-synephrine, ephedrine, salicin, plus caffeine in a 10:4:6:80 w/w ratio included a reduction in locomotor activity and ptosis in all treated groups for both sexes. Seizures were also observed in male (400 mg/kg) and female groups (350 and 400 mg/kg). Gasping and tearing were observed in males. Salivation (400 mg/kg), agitation (350 and 400 mg/kg), and piloerection (all treated groups) were significantly observed only in females. Deaths occurred in males at 350 and 400 mg/kg treated groups and the necropsy showed cardiopulmonary hemorrhage. A reduction in locomotor activity was confirmed through the spontaneous locomotor activity test, in which the number of crossings considerably decreased (P < .01) in all treated groups. The rotarod test showed a decrease in motor coordination at 400 mg/kg. Body temperature decreased significantly (P < .01) in all treated groups compared to controls. The results suggested clear signs of toxicity of p-synephrine, ephedrine, salicin, and caffeine association; this toxicity augments the attentiveness on commercial products containing this mixture, given the expressive number of adverse events related to its utilization.

Fragrance material review on α-methylbenzyl alcohol.

A toxicologic and dermatologic review of α-methylbenzyl alcohol when used as a fragrance ingredient is presented. α-Methylbenzyl alcohol is a member of the fragrance structural group Aryl Alkyl Alcohols and is a secondary alcohol. The AAAs are a structurally diverse class of fragrance ingredients that includes primary, secondary, and tertiary alkyl alcohols covalently bonded to an aryl (Ar) group, which may be either a substituted or unsubstituted benzene ring. The common structural element for the AAA fragrance ingredients is an alcohol group -C-(R1)(R2)OH and generically the AAA fragrances can be represented as an Ar-C-(R1)(R2)OH or Ar-Alkyl-C-(R1)(R2)OH group. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for α-methylbenzyl alcohol were evaluated then summarized and includes physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, skin sensitization, toxicokinetics, repeated dose, genotoxicity, and carcinogenicity data. A safety assessment of the entire Aryl Alkyl Alcohols will be published simultaneously with this document; please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all Aryl Alkyl Alcohols in fragrances.

Formulation and evaluation of in situ gelling systems for intranasal administration of gastrodin.

Gastrodin is the major bioactive constituent of the traditional Chinese drug "Tianma." It is used in the treatment of some nervous system diseases and can be transported to the brain via intranasal administration. In the current paper, the development of a novel ion-activated in situ gelling system for the nasal delivery of gastrodin is discussed. An in situ perfusion model was used to determine the absorption-rate constant of gastrodin through rat nasal mucosa. The optimal formulation was determined by measuring the critical cation concentration, anti-dilution capacity, gel expansion coefficient, water-holding capacity, and adhesive capacity. The best formulation consisted of 10% gastrodin, 0.5% deacetylated gellan gum as the gelatinizer, and 0.03% ethylparaben as the preservative. The rheological properties of gastrodin nasal in situ gels were also investigated. The viscosity and elasticity sharply increased at temperatures below 25°C. When physiological concentrations of cations were added into the preparation, the mixture gelled into a semi-solid. The results of an accelerated stability test show that gastrodin nasal in situ gels can be stable for more than 2 years. Mucociliary toxicity was evaluated using the in situ toad palate model and the rat nasal mucociliary method; both models demonstrated no measurable ciliotoxicity. Pharmacodynamic studies suggest that similar acesodyne and sedative effects were induced following intranasal administration of 50 mg/kg gastrodin nasal in situ gels or oral administration of 100 mg/kg gastrodin solution. The in situ gel preparation is a safe and effective nasal delivery system for gastrodin.

Predicting mixture toxicity of seven phenolic compounds with similar and dissimilar action mechanisms to Vibrio qinghaiensis sp.nov.Q67.

The predictions of mixture toxicity for chemicals are commonly based on two models: concentration addition (CA) and independent action (IA). Whether the CA and IA can predict mixture toxicity of phenolic compounds with similar and dissimilar action mechanisms was studied. The mixture toxicity was predicted on the basis of the concentration-response data of individual compounds. Test mixtures at different concentration ratios and concentration levels were designed using two methods. The results showed that the Weibull function fit well with the concentration-response data of all the components and their mixtures, with all relative coefficients (Rs) greater than 0.99 and root mean squared errors (RMSEs) less than 0.04. The predicted values from CA and IA models conformed to observed values of the mixtures. Therefore, it can be concluded that both CA and IA can predict reliable results for the mixture toxicity of the phenolic compounds with similar and dissimilar action mechanisms.

Perturbation of rat heart plasma membrane fluidity due to metabolites of permethrin insecticide.

Due to increased global use, acute and chronic exposures to pyrethroid insecticides in humans are of clinical concern. Pyrethroids have a primary mode of action that involves interference with the sodium and calcium channels in excitable cells, which may include cardiac myocytes. Here, we investigated the possible cardiac toxicity of permethrin metabolites (METP), 3-phenoxy-benzyl alcohol (3PBA), 3-phenoxy-benzaldehyde (3PBALD), and 3-phenoxybenzoic acid (3PBACID). Plasma membrane fluidity, polarity, lipid, and protein oxidation were studied in isolated rat heart cells. Laurdan was chosen as probe to detect the lateral mobility and polarity of its environment and thus water penetration into the hydrophobic part of the bilayer, while 1,6-diphenyl-1,3,5-hexatriene permits to measure changes in fluidity in the inner part of the bilayer. Results show that METP can change membrane fluidity at different depths of the bilayer according to their partition coefficient. Consequently, 3PBA, at all concentration used, decreases membrane fluidity and polarity in the hydrophilic-hydrophobic region of the bilayer, and similar effect was observed with 20 µM 3PBALD or 10 or 20 µM 3 PBACID. Membrane dynamics in the hydrophobic core resulted decreased by 3PBALD, while it was increased by 20 µM 3PBACID. All METP increase protein and lipid oxidation, and the peroxidative lipid damage decreases with the type of METP produced during the transformation pathway from parent compound to 3PBACID. Consequently, 3PBA induced the highest lipid peroxidation, while 3PBACID was the stronger inducer of protein damage.

[Experimental studies on toxic effects of Tiangou Jiangya capsule].

OBJECTIVE: To study the acute and chronic toxicity of Tiangou Jiangya capsule. METHOD: Tiangou Jiangya capsule was intragastrically administered to mice twice a day. The appearance, behavior, mental status, respiratory changes of mice and the number of poisoned and dead mice in each group were noted daily for 14 consecutive days. The amount of weight and feed of survived mice were recorded every day. The mice were divided into four groups: the treatment groups (minimum, middle, maximum dose of Tiangou Jiangya capsule) and the control group. After continuously orally administrated for 6 months, the rats' behavior, weight gain, food consumption, indications for hematology, blood biochemistry, urine analysis, electrocardiogram, systematic autopsy and histopathology were observed. The above physiological indexes were inspected again 1 month after cease of administration. RESULT: The oral acute toxicity study of Tiangou Jiangya capsule in mice revealed that the maximum dose is 534.86 g x kg(-1), which was 534.86 times the recommended human maximum dose in clinical practice. Compared with normal control group, no significant differences were observed in rats' behaviors, food-intake, electrocardiogram and relative examination indexes among the treatment groups. There was no difference of hematology, biochemistry test, urine and histopathology. CONCLUSION: The minimum dosage of Tiangou Jiangya capsule is relatively safe. It caused weight loss by administrated with the middle and maximum dose for 6 months, which should be paid attention in clinical studies.

The pyrethroid metabolites 3-phenoxybenzoic acid and 3-phenoxybenzyl alcohol do not exhibit estrogenic activity in the MCF-7 human breast carcinoma cell line or Sprague-Dawley rats.

Synthetic pyrethroids are one of the most frequently and widely used class of insecticides, primarily because they have a higher insect to mammalian toxicity ratio than organochlorines or organophosphates. The basic structure of pyrethroids can be characterized as an acid joined to an alcohol by an ester bond. Pyrethroid degradation occurs through either oxidation at one or more sites located in the alcohol or acid moieties or hydrolysis at the central ester bond, the latter reaction being important for mammalian metabolism of most pyrethroids. The primary alcohol liberated from the ester cleavage is hydroxylated to 3-phenoxybenzyl alcohol, which for most pyrethroids is then oxidized to 3-phenoxybenzoic acid. These products may then be conjugated with amino acids, sulfates, sugars, or sugar acids. In vitro studies have suggested that some of the pyrethroids may have estrogenic activity. Interestingly, the chemical structure of specific pyrethroid metabolites indicates that they may be more likely to interact with the estrogen receptor than the parent compounds. Two of the pyrethroid metabolites, 3-phenoxybenzoic acid (3PBA) and 3-phenoxybenzyl alcohol (3PBalc) have been reported to have endocrine activity using a yeast based assay. 3PBAlc exhibited estrogenic activity with reported EC(50)s of 6.67 x 10(-6) and 2 x 10(-5) while 3PBAcid exhibited anti-estrogenic activity with a calculated IC(50) of 6.5 x 10(-5). To determine if the metabolites were able to cause the same effects in a mammalian system, the estrogen-dependent cell line, MCF-7, was utilized. Cells were treated with 1.0, 10.0 or 100.0 microM concentrations of each metabolite and cytotoxicity was assessed. The two lowest concentrations of both metabolites did not induce cell death and even appeared to increase proliferation over that of the control cells. However, when cellular proliferation was measured using a Coulter counter neither metabolite stimulated proliferation (1.0 nM, 10.0 nM, or 10.0 microM) or induced an estrogen receptor alpha/ERE-controlled luciferase reporter in the MCF-7 cells. Following the in vitro screenings, the metabolites were then evaluated for estrogenic activity in vivo using the uterotrophic assay in Sprague-Dawley rats. Animals were orally gavaged (10.0, 5.0, and 1.0 mg/kg) once daily for 3 days. Neither metabolite had any effect on uterine wet weight, body weight, or organ weight. Lastly, in order to determine if either metabolite was able to alter the onset of puberty, immature female rats were orally gavaged (10.0, 5.0, and 1.0 mg/kg) once a day with the metabolites beginning 1 day post-weaning until the onset of puberty as evidenced by vaginal opening (VO). Again, neither metabolite had any effect on the onset of VO.