Mefentrifluconazole (BAS 750F; trade name Revysol) is a novel potent azole derivative used as an agrochemical and broad-spectrum antifungal agent for controlling of diseases on cereals. It is a specific and orally bioavailable fungal CYP51 inhibitor with a Kd 0.5 nM, and shows less inhibitory effects against human aromatase with IC50 of0.92 μM.

Physicochemical Properties

Molecular Formula	C18H15CLF3N3O2
Molecular Weight	397.78
Exact Mass	397.08
Elemental Analysis	C, 54.35; H, 3.80; Cl, 8.91; F, 14.33; N, 10.56; O, 8.04
CAS #	1417782-03-6
PubChem CID	71230671
Appearance	Off-white to light yellow solid powder
LogP	4.65
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	7
Rotatable Bond Count	5
Heavy Atom Count	27
Complexity	491
Defined Atom Stereocenter Count	0
SMILES	ClC1C([H])=C([H])C(=C([H])C=1[H])OC1C([H])=C([H])C(=C(C(F)(F)F)C=1[H])C(C([H])([H])[H])(C([H])([H])N1C([H])=NC([H])=N1)O[H]
InChi Key	JERZEQUMJNCPRJ-UHFFFAOYSA-N
InChi Code	InChI=1S/C18H15ClF3N3O2/c1-17(26,9-25-11-23-10-24-25)15-7-6-14(8-16(15)18(20,21)22)27-13-4-2-12(19)3-5-13/h2-8,10-11,26H,9H2,1H3
Chemical Name	2-(4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl)-1-(1H-1,2,4-triazol-1-yl)propan-2-ol
Synonyms	Mefentrifluconazole; BAS 750 F; BAS 750F; 1417782-03-6; Revysol; 2-(4-(4-Chlorophenoxy)-2-(trifluoromethyl)phenyl)-1-(1H-1,2,4-triazol-1-yl)propan-2-ol; D9EYN9N7UI; Mefentrifluconazole [ISO]; 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol; 1H-1,2,4-Triazole-1-ethanol,alpha-(4-(4-chlorophenoxy)-2- (trifluoromethyl)phenyl)-alpha-methyl; BAS750F;
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

Targets	CYP51A(Kd=0.5 nM)
ln Vitro	In this study, the DMI fungicide mefentrifluconazole exhibited excellent inhibitory activity against the mycelial growth of S. rolfsii, with a mean EC50 value of 0.21 ± 0.11 mg L-1 and a range of 0.02 to 0.55 mg L-1 for 261 isolates collected from Hebei, Henan and Shandong provinces. Mefentrifluconazole significantly reduced the biomass of mycelia and affected the morphology of hyphae. Although sclerotia were more tolerant to mefentrifluconazole than mycelial growth, mefentrifluconazole greatly inhibited the formation and germination of sclerotia. In addition, sclerotia produced by mefentrifluconazole-treated mycelia were deficient in nutrients (e.g., protein, carbohydrate and lipid). These results indicated that mefentrifluconazole may reduce the population of S. rolfsii in the following year. In greenhouse experiments, mefentrifluconazole showed control efficacy and good persistence against peanut S. rolfsii. The preventative and curative activities of mefentrifluconazole at 200 mg L-1 against southern blight still reached 95.36% and 60.94%, respectively, after 9 days of application. No correlation was observed for the sensitivity of S. rolfsii to mefentrifluconazole and the tested DMI, quinone outside inhibitor and succinate dehydrogenase inhibitor fungicides. Conclusion: All data indicated that mefentrifluconazole could provide favorable control efficacy against S. rolfsii from peanuts and reduce the infection and population of S. rolfsii in the following year. © 2023 Society of Chemical Industry[2].
ln Vivo	Mefentrifluconazole is put through a rigorous toxicity testing regimen that includes numerous studies on reproductive toxicity. Studies on the long-term repeated dose toxicity and/or carcinogenicity in rats, mice, and dogs have been carried out. Systemic toxicity occurs at the highest dose level that has been studied in each species[1]. In the mefentrifluconazole acute and repeat dose toxicity studies. Rats receiving a single dose have an LD50 of greater than 2000 mg/kg bwt when administered orally, more than 5000 mg/kg bwt when applied topically, and more than 5.314 mg/L when inhaled as dust aerosol. Mefentrifluconazole is not a phototoxicant in vitro, nor is it irritating to the skin or eyes[1]. Mefentrifluconazole (oral administration; 2000 mg/kg bwt; single dose) reduces body weight gain and transient neurobehavioral effects only on the day of treatment (unsteady gait, decreased motor activity, decreased forelimb grip strength, and increased distance between the hind limbs in the landing foot-splay test) in the acute neurotoxicity study conducted in rats[1]. For all three of the species under investigation, the liver is the target organ in the repeated-dose toxicity studies. Higher doses in rats (oral diets; 383/334 mg/kg/bwt/d (4000 ppm)) and mice (C57BL/6JRj; 61 mg/kg bwt/d (300 ppm)) cause changes in clinical chemistry parameters, reduce food intake and body weight gain, and increase liver weight, which is accompanied by either liver cell necrosis or liver cell hypertrophy. Increases in liver weight are thought to be an adaptive response to treatment when they occur at low doses and are not linked to any histopathological changes[1].
Enzyme Assay	In vitro screening assays for candidate selection [1] The screening procedure used for candidate selection included computer modelling of binding to fungal CYP51 and human CYP19, glasshouse efficacy studies, in vitro binding experiments with Zymoseptoria tritici CYP51 (ZstCYP51), and in vitro aromatase inhibition assays using human recombinant CYP19 supersomes. The methodology of the CYP51 and CYP19 assays is briefly described below. [1] ZstCYP51was expressed in E. coli and the recombinant protein subsequently purified. Azole binding to the heme iron of ZstCYP51 was measured in the absence of reductase by difference spectroscopy as a “type II” spectrum characterized by a maximum at ∼430 nm and a minimum at ∼410 nm. Each binding experiment usually consisted of eight wavelength scans in the 400–450 nm range with rising concentration of azole, against a DMSO control. The delta absorption was plotted against the azole concentration and the binding constant Kd was determined by nonlinear regression. [1] The aromatase (CYP19) inhibition assay was conducted utilizing the recombinant human aromatase (Corning Supersomes Human CYP19 aromatase + reductase) and the fluorometric artificial substrate dibenzylfluorescein (DBF) (Sigma D-7191) as described by Stresser et al. (2000). Cofactors in this assay were 1.3 mM NADP+ , 0.4 mU Glucose-6-phosphat-dehydrogenase, 3.3 mM Glucose-6-phosphat and 3,3 mM MgCl2. Test compounds were dissolved in DMSO (final DMSO concentration 1%). Enzymatic reaction was started with enzyme/substrate mix (4 pmol/ml enzyme, 0.4 μM DBF) and incubated for 30 min at 37 °C. The reaction was stopped by addition of 75 μl 2 M NaOH and incubated for another 2 h at 37 °C. Measurement was conducted at 490 nm excitation wavelength, 530 nm emission wavelength and 515 nm cut-off. Dose response analyses were made using a log-logistic 4-parameter model. More recently, the above method was adapted for assessing the inhibition of rat aromatase utilizing recombinant rat aromatase (Corning Rat CYP19 + P450 Reductase SUPERSOMES™). [1] The results from the CYP in vitro assays were compared against marketed azole data (CYP19 and CYP51 data from in-house experiments and published toxicological information). As a conclusion from this screening exercise, a tentative threshold human aromatase inhibition IC50 value of 1 μM was defined for compound candidates for consideration of promotion to field testing and in vivo regulatory studies. Additionally, a quotient of target(CYP51) and off-target(CYP19) inhibition was calculated for candidate and market agrochemical azoles and used as selection criterion.
Animal Protocol	Rabbit [1] Four groups each of 27–33 nulliparous female New Zealand White rabbits (age range 10–15 weeks on receipt) were acclimatized for 5 days and then injected with 0.2 ml of a synthetic gonadotrophin releasing hormone (Receptal®). Approximately one hour later the females were inseminated with semen from stock male rabbits of the same source and strain. The day of insemination was designated gestation day (GD) 0. Bodyweights of females on GD 0 ranged between 2747 and 3819 g. Administration of mefentrifluconazole (MFZ) by oral gavage commenced on GD 6 and continued once daily until GD 28. Dose levels were 0, 5, 15 and 25 mg/kg bwt/day as a suspension in 1% w/v aqueous carboxymethylcellulose, at a dose volume of 10 ml/kg bwt. The high dose level in this study was set at half the lethal dose, as determined from the results of a preliminary study in non-pregnant female rabbits, in which severe toxicity was observed at 50 mg/kg bwt/day and two out of three animals at this dose were killed in extremis. At 150 mg/kg bwt/day and above all females died or were killed in extremis. [1] Throughout the study, clinical signs and food consumption were monitored daily and body weights were recorded at 2- to 3-day intervals. Prior to termination on GD 29 blood samples were taken from the marginal ear vein of each female for assessment of hematology and clinical chemistry parameters. On GD 29 all surviving females were killed by intravenous injection of pentobarbital (Narcoren® 2.0 ml per animal). The females were necropsied in random order, the uterus and ovaries were removed from each female and the intact uterus was weighed. All other gestational parameters were evaluated “blind” viz. numbers of corpora lutea, implantation sites, live and dead fetuses, early and late resorptions. Individual fetuses and placentae were weighed, and all fetuses were examined externally. Heads were removed from approximately half of the fetuses from each litter, fixed in Bouin's fluid and sectioned and examined, according to the method of Wilson (1965). The torsos and intact fetuses were examined internally, hearts and kidneys were sectioned and evaluated, and fetal sexes were recorded. Following examination, all fetuses and torsos were eviscerated, and the skeletons were processed using a modified method of Kimmel and Trammell (1981), prior to examination of ossified and cartilaginous structures. Rat [1] Nulliparous female Wistar rats (CRL:WI(Han)) were mated by the breeder. Mating was confirmed by vaginal plug/sperm-positive vaginal smear and the day of mating was designated GD 0. The mated females were shipped and received at the test facility on the same day. Body weight on GD 0 ranged between 144.2 and 185.7 g. On arrival, the females were randomly assigned to four groups of 25 females. Administration of mefentrifluconazole (MFZ) by oral gavage commenced on GD 6 and continued once daily until GD 19. Dose levels were 0, 50, 150 and 400 mg/kg bwt/day as a suspension in 1% w/v aqueous carboxymethylcellulose, at a dose volume of 10 ml/kg bwt. The high dose level was selected based upon the results from a 14-day dose range-finding study in non-pregnant rats, where oral administration of 250 and 500 mg/kg bwt/day gave rise to reductions in food consumption and body weight gain, and from a dose-range finding study in pregnant rats in which the NOAEL was found to be > 200 mg/kg bwt/day. On GD 20 the females were killed by cervical dislocation under isoflurane anesthesia. They were necropsied in random order; the uterus and ovaries were removed from each female and the intact uterus was weighed. All other gestational parameters were evaluated “blind”, viz. numbers of corpora lutea, implantation sites, live and dead fetuses, early and late resorptions. Any uterus or single uterine horn with no obvious implantation sites was stained using the Salewski technique (1964). Individual fetuses and placentae were weighed, and all fetuses were examined and sexed externally. Approximately half of the fetuses from each litter were fixed in Harrison's fluid and were subsequently examined according to the Barrow and Taylor method (1969). The remaining fetuses from each litter were eviscerated and processed using a modified method of Kimmel and Trammell (1981), prior to examination of ossified and cartilaginous skeletal structures. Two-generation reproduction toxicity study in rats [1] The study was conducted according to OECD TG 416 (2001). Wistar rats (Crl:WI(Han), aged 28 days ± 1 day on arrival were acclimatized for approximately 6 days and were then randomly assigned on a body weight basis to four groups of 25 males and 25 females per group to form the F0 generation. Males and females were derived from different litters and animals were housed individually except during pairing or during lactation, when the female and litter were housed together until weaning on postnatal day (PND). Environmental conditions were similar to those of the prenatal studies. In addition, nesting material was provided to pregnant females from late gestation. At commencement of treatment males were in the weight range 97.5–123.0 g and females 90.3–112.2 g. [1] mefentrifluconazole (MFZ) was administered via the diet at target dose levels of 0, 25, 75 and 200 mg/kg bwt/day. To achieve these target doses the concentration of mefentrifluconazole (MFZ) in the diet was adjusted weekly according to the animals’ group mean food intake, except during gestation when the females received the same dietary concentration as the last pre-mating week and during lactation when the concentration was reduced by 50% to allow for the increase in food intake. Food consumption and body weights were recorded weekly except during the mating periods. During lactation, food consumption was recorded for PND 1–4, 4–7, 7–14, and 14–22. The F0 and F1 animals were continuously exposed for a minimum of 75 days prior to mating until the study was terminated at weaning of the F1 or F2 litters.
Toxicity/Toxicokinetics	Mefentrifluconazole Fungicide Aves Bobwhite quail Colinus virginianus 22 Wk 14 D LD50 816 MGK Mefentrifluconazole Fungicide Aves Bobwhite quail Colinus virginianus ErlyLf 21 WK LOEL 531 PPM Mefentrifluconazole Fungicide Fishes Rainbow trout Oncorhynchus mykiss 1.7 g 96 hr LC50 536 PPB Mefentrifluconazole Fungicide Fishes Danio Danio rerio 0.3 g 96 hr LC50 823 PPB Mefentrifluconazole Fungicide Crustacea Water flea Daphnia pulex LifCyc 21 D LOEC 40.6 PPB
References	[1]. Innovative selection approach for a new antifungal agent mefentrifluconazole (Revysol®) and the impact upon its toxicity profile. Regul Toxicol Pharmacol. 2019 Aug;106:152-168. [2]. Bioactivity of the DMI fungicide mefentrifluconazole against Sclerotium rolfsii, the causal agent of peanut southern blight. Pest Manag Sci. 2023 Jun;79(6):2126-2134. d
Additional Infomation	2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1H-1,2,4-triazol-1-yl)propan-2-ol is an aromatic ether that is diphenyl ether substituted by a 2-hydroxy-1-(1H-1,2,4-triazol-1-yl)propan-2-yl group at position 1, trifluoromethyl group at position 2 and a chloro group at position 4. It is a member of monochlorobenzenes, a member of triazoles, a tertiary alcohol, an aromatic ether and a member of (trifluoromethyl)benzenes. Mefentrifluconazole (trade name: Revysol®) is an agrochemical active ingredient from the new sub-class of isopropanol-triazole fungicides, with high selective fungicide activity. A full program of toxicity testing conducted according to OECD guidelines has shown mefentrifluconazole (MFZ) to be non-genotoxic and non-carcinogenic. Repeated dose studies in rats, mice and dogs identified the liver as the main target organ. Prenatal developmental toxicity studies in rats and rabbits did not indicate treatment-related embryofetal toxicity or teratogenicity up to the highest dose levels tested. In a two-generation dietary study in rats, the high dose level resulted in reduced food consumption and body weight gain throughout the dosing-period. Mating performance and fertility, estrous cycles, gestation length and pre-and post-natal survival of offspring were essentially unaffected and there was no evidence of masculinization of female pups or feminization of male pups. The screening strategy that led to the selection of MFZ was aimed to identify candidates with both high fungicidal activity and minimal likelihood of adverse side effects thought to arise from aromatase inhibition. The success of the selection strategy has been illustrated for MFZ by the absence in toxicity studies of effects that would indicate an endocrine disrupting potential.[1] Background: Sclerotium rolfsii, the causal agent of peanut southern blight, has become increasingly prevalent and harmful in China, causing serious economic losses to the peanut industry. To effectively manage peanut southern blight, this study evaluated the bioactivity of the new-generation sterol demethylation inhibitor (DMI) fungicide mefentrifluconazole against peanut S. rolfsii. Results: In this study, the DMI fungicide mefentrifluconazole exhibited excellent inhibitory activity against the mycelial growth of S. rolfsii, with a mean EC50 value of 0.21 ± 0.11 mg L-1 and a range of 0.02 to 0.55 mg L-1 for 261 isolates collected from Hebei, Henan and Shandong provinces. Mefentrifluconazole significantly reduced the biomass of mycelia and affected the morphology of hyphae. Although sclerotia were more tolerant to mefentrifluconazole than mycelial growth, mefentrifluconazole greatly inhibited the formation and germination of sclerotia. In addition, sclerotia produced by mefentrifluconazole-treated mycelia were deficient in nutrients (e.g., protein, carbohydrate and lipid). These results indicated that mefentrifluconazole may reduce the population of S. rolfsii in the following year. In greenhouse experiments, mefentrifluconazole showed control efficacy and good persistence against peanut S. rolfsii. The preventative and curative activities of mefentrifluconazole at 200 mg L-1 against southern blight still reached 95.36% and 60.94%, respectively, after 9 days of application. No correlation was observed for the sensitivity of S. rolfsii to mefentrifluconazole and the tested DMI, quinone outside inhibitor and succinate dehydrogenase inhibitor fungicides. Conclusion: All data indicated that mefentrifluconazole could provide favorable control efficacy against S. rolfsii from peanuts and reduce the infection and population of S. rolfsii in the following year. © 2023 Society of Chemical Industry.[2]

Solubility Data

Solubility (In Vitro)

DMSO : ~100 mg/mL (~251.40 mM)

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 6.25 mg/mL (15.71 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 62.5 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 6.25 mg/mL (15.71 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 62.5 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. 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. Solubility in Formulation 3: ≥ 6.25 mg/mL (15.71 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 62.5 mg/mL clear DMSO stock solution to 900 μL corn oil and mix evenly.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.5140 mL	12.5698 mL	25.1395 mL
	5 mM	0.5028 mL	2.5140 mL	5.0279 mL
	10 mM	0.2514 mL	1.2570 mL	2.5140 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.