Secondary metabolite from Aspergillus flavus and Aspergillus parasiticus

Aflatoxins (AFs) are hepatogenic, teratogenic, imunosuppressive, and carcinogenic fungal metabolites found in feeds, nuts, wine-grapes, spices, and other grain crops. Humans are exposed to AFs via consumption of mycotoxin-contaminated foods. This study aimed to determine the prevalence of AF contamination in powdered red peppers sold in Sanliurfa. A total of 42 samples were randomly collected from retail shops, supermarkets, open bazaars, and apiaries and examined for the occurrence and levels of AFB1, AFB2, AFG1, and AFG2 toxins. AFs were determined by using an HPLC system after pre-separation utilizing immunoaffinity columns. AFs levels were below 2.5 μg/kg in 16 samples, between 2.5 and 10 μg/kg in 13 samples while 13 samples had AFs higher than the tolerable limit (10 μg/kg) according to the regulations of Turkish Food Codex and European Commission. The occurrence of AF fractions during powdered red pepper processing steps was also evaluated. According to the results obtained in this study, it was found that the highest AF accumulations in powdered red peppers start during perspiration and final drying of the products processed on soil contacted surfaces while there was no limit exceeding aflatoxin contamination in the samples produced on concrete surfaces [2].

Environmental occurrence of Aspergillus and other fungal spores are hazardous to humans and animals. They cause a broad spectrum of clinical complications. Contamination of aflatoxins in agri-food and feed due to A. flavus and A. parasiticus result in toxicity in humans and animals. Recent advances in aspergillus genomics and aflatoxin management practices are encouraging to tackle the challenges posed by important aspergillus species [1].

Aflatoxin analysis by HPLC [2]
Detection and quantification of AFB1, AFB2, AFG1, and AFG2 levels in the samples was carried out by HPLC equipped with an autosampler using a fluorescence detector. The HPLC equipment was a Shimadzu system with Shimadzu LC-20AD pump, Shimadzu SIL-20 ADHT autosampler, CTO-20AC column oven, Shimadzu RF-10AXL fluorescence detector (FLD) set at 360-nm excitation and 460-nm emission. An ODS3 column (ODS3 250 mm × 5 μm × 4.6 mm) was used. The mobile phase was distilled water/acetonitrile (90:10), and the flow rate was 1 ml/min; injection volume was 100 μl (AOAC, 999.07).

Absorption, Distribution and Excretion
Most of the aflatoxin administered to sheep appears to be destroyed in the body, only 8% of the amount given being recovered in the milk, urine and feces.
Analysis of 64 cord blood samples from pregnant women in Sierra Leone revealed the presence of ochratoxin A (OTA) and aflatoxins in 25% and 58% of samples, respectively. Of the eight maternal blood samples collected during delivery, one contained OTA and aflatoxins were detected in six. There was no relationship between mycotoxins in maternal and cord blood. The effect these toxins might have had on the birthweight of infants is discussed.
After a single oral administration of aflatoxin about 90% of the total amount eliminated by sheep is excreted during 48 hr after treatment. It cannot be detected in their milk after 6 days or in their urine or feces after 8 and 9 days respectively. Only 8.1% of a single oral dose of 1 mg/kg bw of mixed aflatoxin was recovered in an identifiable form in this species, the milk containing 0.1%, the urine 6.4% and the feces 1.6%.
Aflatoxin is excreted in the form of its metabolite aflatoxin M1 in the milk of lactating animals. In cattle given a single oral dose of aflatoxin, 85% of the total amount found in the milk and urine were detected in the first 48 hours after treatment. There was none in the milk after four days, nor in the urine or feces after six days. The total aflatoxin found in the milk was 0.39% of that ingested. ... Less than 0.6% of administered aflatoxin B1 was excreted in the milk. The amount of aflatoxin excreted in milk is unrelated to milk yield, and it disappears from the milk three to four days after the feeding of toxic meal is discontinued.
For more Absorption, Distribution and Excretion (Complete) data for AFLATOXINS (8 total), please visit the HSDB record page.
Aflatoxins B1 & G1 & their metabolites exist in systemic blood as protein conjugates. This conjugation is specific to plasma albumin & proceeds enzymatically by liver & kidney cells. The albumin-aflatoxin conjugate is permanent & conjugation is an irreversible one.
Three groups of four Large White sows were fed diets containing either 800 ppb purified aflatoxin B1 (group 1), 800 ppb purified aflatoxin G1 (group 2) or 400 ppb B1 and 400 ppb G1 (group 3) throughout gestation and lactation. A control group of four sows was fed a diet free of aflatoxins. Aflatoxins B1 and M1 were found in milk samples taken five and 25 days after parturition from the sows of group 1, aflatoxin G1 was present in the milk of the sows of group 2 and all three aflatoxins were present in samples from the sows of group 3. The concentration of aflatoxin in the milk was about 1000-fold lower than that in the feed, but increased over the 25 days after parturition.

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Metabolism / Metabolites
... Aflatoxins are metabolized by the liver to epoxides that have very short half-lives & act mainly on the liver.
Current research using both in vivo and in vitro studies has shown that the differences in response to aflatoxin in different animals can be attributed to their differential metabolism. The rates of metabolism and intermediate products formed are important factors in determining the type of toxic action of aflatoxin B1. According to these criteria, monkey and man are more susceptible to acute aflatoxicosis and relatively resistant to carcinogenic effects. On the other hand, animals, such as sheep and rat, are more susceptible to carcinogenic effects.
Aflatoxin B1 requires metabolic activation by the cytochrome p450 dependent mixed-function oxidase to be converted to the reactive 2,3-epoxide, the ultimate carcinogen. The aflatoxins, eg, aflatoxin B1, are genotoxic carcinogens and the reactive metabolites react with DNA. The major adduct formed with DNA in intracellular reactions is formed from the 2-position of aflatoxin B1 and the N-7 position of guanine in DNA. /B1/
CYP1A2, 2B6, 3A4, 3A5, 3A7 and GSTM1 are enzymes that mediate aflatoxin metabolism in humans. The overall contribution of these enzymes to aflatoxin-B1 metabolism in vivo will depend not only on their affinity but also on their expression level in human liver, where CYP3A4 is predominant. This enzyme mediates the formation of the exo-epoxide and aflatoxin Q1, while CYP1A2 can generate some exo-epoxide but also a high proportion of endo-epoxide and aflatoxin M1. In vitro evidence that both these enzymes are responsible for aflatoxin metabolism in humans has been substantiated by biomarker studies. Aflatoxins M1 and Q1, produced by CYP1A2 and 3A4, respectively, are present in the urine of individuals exposed to aflatoxin.
Aflatoxins are secondary metabolites produced by a group of strains, mainly Aspergillus and Penicillium species. These mycotoxins are bifurano-coumarin derivatives group with four major products B1, B2, G1 and G2 according to blue or green fluorescence emitted in ultraviolet light and according to chromatographic separation. After metabolism of aflatoxin B1 and B2 in the mammalian body, result two metabolites M1 and M2 as hydroxylated derivatives of the parent compound...
Yields aflatoxin B3 in rhizopus ... yields aflatoxin gm1 in rat. From table/
Aflatoxin B1, aflatoxin B2, & aflatoxin G1 admin iv to rats were rapidly metabolized to 7 groups of metabolites each, 6 of which were excreted in the bile. All 3 toxins were hydroxylated at the 2- & 4-positions. Bile from the rats that had received aflatoxin G1 contained glucuronide.
...The incubation of human liver microsomes with aflatoxin B1 /or/ aflatoxin G1 ...yielded genotoxic metabolites that induced umuC gene expression in Salmonella typhimurium (TA-1535/psK1002). The rank order of genotoxic potency was ...aflatoxin B1>aflatoxin G1. Microsomal activation of the ...aflatoxins was completely inhibited upon incubation with polyclonal antibodies against p450NF, and immunochemical determinations of p450NF /(nifedipine oxidase)/ in the liver microsomal preparations were correlated with the microsomal activation of ...aflatoxin G1 and aflatoxin B1. P450NF converted the ...aflatoxins to genotoxic metabolites in a reconstituted monooxygenase system containing the purified enzyme and an NADPH generating system. ...
Aflatoxins are metabolized in the liver by the cytochrome P-450-dependent polysubstrate mono-oxygenase system to less toxic metabolites. The main reactions in aflatoxin metabolism are hydroxylation, oxidation, and demethylation. (A2973)

Toxicity Summary
Aflatoxins produce singlet oxygen upon their exposure to UV (365-nm) light. Singlet oxygen in turn activates them to mutagens and DNA binding species. Aflatoxin metabolites can intercalate into DNA and alkylate the bases through their epoxide moiety, binding particularity to N7-guanine bases. In addition to randomly mutating DNA, this is thought to cause mutations in the p53 gene, an important gene in preventing cell cycle progression when there are DNA mutations, or signaling apoptosis. (L1877, A2859, A2972)

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Interactions
Aflatoxins B1, B2, G1 and G2 were administered in a low concentration (100 ppb of each aflatoxin [AN] in a mash offered to Baladi rabbits. An other group of rabbits were fed on the same contaminated mash in addition to 0.25% charcoal (CC). The two groups were compared to control animals fed on AN-free mash. Inclusion of AN in the diet decreased feed and water consumption, body weight and survival rate. Charcoal improved somewhat feed and water consumption and growth rate than AN-group. However, CC-group affected digestibility of organic matter more than AN-group. Relative weights of liver, kidneys, heart and adrenal glands were significantly higher in AN and CC groups than the control group. Blood hemoglobin content, packed cell volume percentage and sedimentation rate were lower in AN group. Although there were an increase in each of serum, calcium, inorganic phosphorus, cholesterol, phospholipids and glutamic-pyruvic transaminase in AN group, yet the serum nitrogen and glutamic-oxalacetic transaminase were reduced. Charcoal had alleviated AN-effects concerning N, GPT and phospholipids. Chemical analysis revealed elevation of water, ash and silica contents of liver and water content of muscles from AN-animals. On the other hand, fat content, GOT and vitamin A in the liver as well as muscles ash were reduced. Addition of CC to the diet reduced AN-effects on liver fat, ash and silica but resulted in a rise of the water content of liver and muscles and liver GPT activity. Charcoal also resulted in a sharp decrease in vitamin A content of the liver. Aflatoxin treatments (in AN and CC groups) reduced bone ash, silica and magnesium as well as bone volume. Charcoal administration increased Ca-content of bones. Aflatoxin feeding (in AN group) resulted in a high residual percentage of AN in muscles, serum, liver, heart and kidneys with relationships of 51 :24 : 3 :2 : 1, respectively. Only 1.42% of the fed AN was excreted in the feces. Charcoal usage had a good effect as it prevented AN to accumulate in the organs. Aflatoxin contaminated diets (in AN and CC groups) resulted in paralysis, disorder of fat deposition, discoloration and hemorrhages of some organs. Scanning electron microscopic examination revealed no ill effect on the surface structure of the small intestine due to either AN or AN + CC. Pathological examination showed that the main affected organs were liver, heart and spleen, ... . The changes include hepatic round cell infiltration, irregularities of lobular plats, focal necrosis and periportal fibrosis.
More subtle ... /effect/ of aflatoxin ingestion ... /is/ synergism or antagonism with various vitamins.
Mink were fed diets that contained 0, 34, or 102 ppb (ug/kg) aflatoxins with or without 0.5% hydrated sodium calcium aluminosilicate and/or 1.0% activated charcoal for 77 days. Consumption of the diet that contained 34 ppb aflatoxins was lethal to 20% of the mink, while 102 ppb dietary aflatoxins resulted in 100% mortality within 53 days. The addition of activated charcoal to the diet containing 102 ppb aflatoxins reduced mortality and increased survival time of the mink while the addition of hydrated sodium calcium aluminosilicate, alone or in combination with activated charcoal, prevented mortality. Histologic examination of livers and kidneys from the mink demonstrated liver lesions ranging from extremely severe in mink fed 102 ppb aflatoxin to mild to moderate in those that received 34 ppb aflatoxins. The addition of hydrated sodium calcium aluminosilicate and/or activated charcoal to the diets that contained 102 ppb aflatoxins reduced or essentially eliminated histopathologic lesions in the livers. No histopathologic alterations associated with the dietary treatments were observed in the kidneys.
The efficacy of detoxication by ammoniation of aflatoxin contaminated groundnut oil cakes was determined in long-term (18 month) feeding experiments with rats. The aflatoxin content of the cake was reduced very considerably by the pressurized application of ammonia, dropping from 1,000 to 140 ppb at a gas pressure of 2 bar and to 60 ppb at 3 bar. No reversion was noted during the experiment. The percentage of hepatic tumors obtained was very high for the untreated cakes, but fell sharply with medium treatment and was reduced to zero by the treatment at 3 bar. A satisfactory dose-effect relationship was shown between the residual aflatoxin content of the cakes and the observed incidence of tumors. The results show that ammonia treatment is a practical solution to the problem of the carcinogenic potency of contaminated oil cakes.
For more Interactions (Complete) data for AFLATOXINS (11 total), please visit the HSDB record page.

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Non-Human Toxicity Values
LD50 Monkey oral 1750 ug/kg
LD50 Monkey intramuscular 2020 mg/kg
LD50 Rat intraperitoneal 14,900 ug/kg.

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The Committee reaffirmed the conclusions of the forty-ninth meeting of JECFA that aflatoxins are among the most potent mutagenic and carcinogenic substances known, based on studies in test species and human epidemiological studies, and that hepatitis B virus (HBV) infection is a critical contributor to the potency of aflatoxins in inducing liver cancer. At the eighty-third meeting the Committee also evaluated co-exposure to aflatoxins and fumonisins. Fumonisins and aflatoxins are both frequent contaminants in cereals and cerealbased foods. Aflatoxins are common contaminants in groundnuts and tree nuts. Co-exposure to both mycotoxins is likely in areas where these foods are regularly consumed. Although evidence in laboratory animals from the previous and the present evaluations has suggested an additive or synergistic effect of fumonisin and aflatoxin co-exposure in the development of preneoplastic lesions or hepatocellular carcinoma, currently no data are available on such effects in humans. The Committee concluded that there are few data available to support co-exposure as a contributing factor in human disease. However, the interaction between AFB1, a compound with known genotoxic properties, and fumonisins, which have the potential to induce regenerative cell proliferation (particularly at exposures above the PMTDI), remains a concern. This is due to the fact that the incidences of chronic liver disease and stunting are high in the areas of the world where the exposures to both mycotoxins are high and the co-exposure has been confirmed with biomarkers.

[1]. Aflatoxins: Implications on Health. Indian J Clin Biochem. 2017 Jun;32(2):124-133.

[2]. Aflatoxins B1, B2, G1, and G2 contamination in ground red peppers commercialized in Sanliurfa, Turkey. Environ Monit Assess. 2015 Apr;187(4):184.

Aflatoxin G is a member of coumarins.
Aflatoxin G1 has been reported in Zea mays, Aspergillus flavus, and Aspergillus parasiticus with data available.
Aflatoxin is a group of mycotoxins, which are most commonly produced by Aspergillus flavus and A. parasiticus, and their toxic metabolites that are comprised of a fused coumarin-bis(dihydrofuran) ring structure, with potential acute and chronic toxic effects. Acute exposure to high levels of aflatoxins can cause liver damage. Chronic aflatoxin exposure results in an increased risk for liver cancer potentially caused by DNA intercalation and epoxide-mediated alkylation of nucleobases by aflatoxin metabolites, leading to increased levels of DNA damage, which may cause mutations.
Aflatoxin G is a mycotoxin produced by Aspergillus flavus and Aspergillus parasiticus

Aflatoxin G belongs to the family of Difurocoumarolactone Series. These are polycyclic aromatic compounds containing a delta-valerolactone ring fused to the coumarin moiety of the difurocoumarin skeleton. Difurocoumarolactones are a subgroup of the aflatoxins and related compounds.
See also: Aflatoxin G1 (annotation moved to).

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Mechanism of Action
It has been suggested that the most probable mode of action of aflatoxins involve an interaction with DNA and inhibition of the polymerases responsible for DNA and RNA syntheis.
... Covalent binding of aflatoxin 8,9-oxide to N-7 of guanine results in pairing of the adduct-bearing guanine with adenine rather than cytosine, leading to the formation of an incorrect codon and the insertion of an incorrect amino acid into the protein. Such events are involved in the aflatoxin-induced mutation of the ras proto-oncogene and the p53 tumor suppressor gene. /Aflatoxin 8,9-oxide/
...In the present study ...isoprenaline (ISO, 4x10-9), AFB(1) (3x10-6 and 6x10-5 M) and AFG(1) (3x10-6 and 6x10-6 M) contracted the isolated guinea pig atria, leaving the preparation hyperresponsive to ISO. These properties of AF are of interest as they could be responsible for certain cardiotoxic effects described in the literature.
G to T transversions in codon 249 of the p53 tumor-suppressor gene have been found in human liver tumors from geographic areas with high risk of aflatoxin exposure and in experimental animals.
Ability of aflatoxin B1, aflatoxin B2, & aflatoxin G1 to inhibit RNA polymerase activity & decr RNA content in rat hepatocyte nuclei was qualitatively similar to the carcinogenic & acute & subacute toxic actions of these compounds. Aflatoxin g1 induced a rapid macrosegregation of the fibrillar & granular portions of the hepatocyte nucleolus.
In vitro studies with human liver indicate that the major catalyst involved in the bioactivation of the hepato-carcinogen aflatoxin B1 to its genotoxic 2,3-epoxide derivative is cytochrome P-450NF, a previously characterized protein that also catalyzes the oxidation of nifedipine and other dihydropyridines, quinidine, macrolide antibiotics, various steroids, and other compounds. ...Cytochrome p-450NF or a closely related protein also appears to be the major catalyst involved in the activation of aflatoxin G1 and sterigmatocystin, the latter compound being more genotoxic than aflatoxin B1 in these systems. Several drugs and conditions are known to influence the levels and activity of cytochrome p-450NF in human liver, and the activity of the enzyme can be estimated by noninvasive assays. These findings provide a test system for the hypothesis that a specific human disease state (liver cancer) is linked to the level of oxidative metabolism in populations in which aflatoxin ingestion is high.
Aflatoxin B1, aflatoxin G1 & aflatoxin G2 inhibited incorporation of (14)carbon labeled orotic acid into the RNA of rat liver slices at toxin concentrations of 100 umole/3 mL. Respective percent inhibitions were approx 90, 40, & 20. Aflatoxin B1, 20 umole/3 mL, aflatoxin G1, 150 umole/3 mL, & aflatoxin G2, 230 umole/3 mL inhibited the incorporation of (14)carbon labeled dl-leucine into proteins of rat liver slices by 32%, 35%, & 38%, respectively.
Phagocytosis, intracellular killing of Candida albicans, and superoxide production by rat peritoneal macrophages exposed to aflatoxins B1, B2, G1, G2, B2a, and M1 at several times and concn were analyzed to evaluate the intensity of a depressive effect for each mycotoxin. All aflatoxins used at very low concn had a depressive effect on the functions of macrophages. The biggest impairment of phagocytosis, intracellular killing, and spontaneous superoxide production was observed in macrophages exposed to aflatoxins B1 and M1.
Among the toxic aflatoxins, aflatoxins B1 and G1 are the most biologically active, but other derivatives also exhibit carcinogenicity. Aflatoxin B1 requires metabolic activation by the cytochrome p450 dependent mixed-function oxidase to be converted to the reactive 2,3-epoxide, the ultimate carcinogen. The aflatoxins, eg, aflatoxin B1, are genotoxic carcinogens and the reactive metabolites react with DNA. The major adduct formed with DNA in intracellular reactions is formed from the 2-position of aflatoxin B1 and the N-7 position of guanine in DNA.

C17H12O7

328.27298

328.058

1165-39-5

Aflatoxin G1-13C17;1217444-07-9

14421

White to off-white solid powder

1.6±0.1 g/cm3

612.1±55.0 °C at 760 mmHg

244-246ºC

274.1±31.5 °C

0.0±1.8 mmHg at 25°C

1.680

-0.17

0

7

1

24

666

0

COC1=C2C3=C(C(=O)OCC3)C(=O)OC2=C4C5C=COC5OC4=C1

XWIYFDMXXLINPU-UHFFFAOYSA-N

InChI=1S/C17H12O7/c1-20-9-6-10-12(8-3-5-22-17(8)23-10)14-11(9)7-2-4-21-15(18)13(7)16(19)24-14/h3,5-6,8,17H,2,4H2,1H3

11-methoxy-6,8,16,20-tetraoxapentacyclo[10.8.0.02,9.03,7.013,18]icosa-1,4,9,11,13(18)-pentaene-17,19-dione

AFLATOXIN G1; Aflatoxin; 1165-39-5; 1402-68-2; AFLATOXINS; Aflatoxin G; Aflatoxin, crude; Aflatoxin G1-d3;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~10 mg/mL (~30.46 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)