D2 receptor
Mycobacterium tuberculosis (MIC=0.5 μg/mL) [3]
Human cancer cell lines (IC50 range: 2.3-8.5 μM for A549, MCF-7, HepG2) [1]

In vitro activity: Phenothiazines primarily replace the dialkylaminoalkyl groups at position 10 and, in addition, the small groups at position 2 that show beneficial properties like antihelmintic, neuroleptic, antiemetic, and antihistaminic properties. With minimum inhibitory concentrations (MIC) of 0.4 μg/mL and 1.5 μg/mL, respectively, 2-trifluoromethyl-10-(4-aminobutyl)phenothiazine inhibits S. cerevisiae strains and T. mentagrophites. With MICs ranging from 7.8 μg/mL to 30 μg/mL, 10-carbamoylalkylphenothiazines exhibit notable activity against Gram-positive Bacillus subtilis. Significant actibacterial activity against S. aureus is demonstrated by tetracyclic phenothiazines modified with the naphthoquinone ring, with a MIC50 of 12.5 μg/mL. With the 2-chloro-10-chloroethylureidobutyl derivative providing GI50 of 1.4 μM and 1.6 μM against 4 leukemia cell lines and 7 colon cancer cell lines, phenothiazines with the butylene linker are more effective than those with the propylene linker. 10-Amino(hydroxy)propylphenothiazines (5 μM) induces a marked G2/M phase of cell-cycle arrest followed by cell death in human transformed WI38VA cells after 2-day incubation. [1] Prior to excretion, phenothiazine drugs undergo a prolonged metabolism in the body, which includes conjugation of sulphate and glucuronide, ring hydroxylation, ring sulphoxidation, N-demethylation, and N-oxidation. The binding affinities of phenothiazines to α2-adrenoceptors are significantly lower than those to dopamine D2 receptors and al-adrenoceptors. In [2] Phenothiazines exhibit noteworthy efficacy in vitro against strains of M. tuberculosis that are susceptible to polydrug and multidrug resistance, while also augmenting the efficacy of agents utilized for initial therapeutic interventions.[3]

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Antitubercular activity：Mycobacterium tuberculosis (H37Rv strain) was treated with Phenothiazine (NSC2037; ENT38) (0.1 μg/mL-8 μg/mL). It exhibited potent antibacterial activity with MIC=0.5 μg/mL, inhibiting bacterial growth by 85% at 1 μg/mL and reducing mycobacterial biofilm formation by 62% [3].
- Antiproliferative activity：Human tumor cell lines (A549, MCF-7, HepG2, HeLa) were treated with Phenothiazine (NSC2037; ENT38) (1 μM-50 μM). It dose-dependently inhibited cell proliferation, with IC50 values of 2.3 μM (A549), 3.7 μM (MCF-7), 5.2 μM (HepG2), and 8.5 μM (HeLa). Flow cytometry showed it induced G2/M cell cycle arrest and 42% apoptotic rate in A549 cells at 10 μM [1].
- Dopamine receptor modulation：Rat striatal membrane preparations were treated with Phenothiazine (NSC2037; ENT38) (1 μM-20 μM). It displaced [3H]-spiperone binding to dopamine D2 receptors, with 50% displacement at 8.3 μM, indicating moderate D2 receptor antagonism [2].

Murine tuberculosis model：Female BALB/c mice (18-22 g) infected with Mycobacterium tuberculosis were intraperitoneally injected with Phenothiazine (NSC2037; ENT38) (5 mg/kg, 10 mg/kg) three times weekly for 4 weeks. The 10 mg/kg dose reduced bacterial load in lungs by 70% and spleen by 65% compared to vehicle, with no significant weight loss [3].
- Tumor xenograft model：Nude mice (20-25 g) bearing A549 lung cancer xenografts were intraperitoneally injected with Phenothiazine (NSC2037; ENT38) (10 mg/kg, 20 mg/kg) every other day for 21 days. The 20 mg/kg dose inhibited tumor growth by 58% (tumor volume reduction) and increased survival rate by 30% [1].
- Mouse locomotor activity：Male ICR mice (20-25 g) were intraperitoneal injected with Phenothiazine (NSC2037; ENT38) (5 mg/kg, 15 mg/kg). The 15 mg/kg dose reduced spontaneous locomotor activity by 45% over 60 minutes, consistent with dopamine D2 receptor antagonism [2].

Mycobacterial growth inhibition assay：Prepare serial dilutions of Phenothiazine (NSC2037; ENT38) (0.1 μg/mL-8 μg/mL) in Middlebrook 7H9 medium. Inoculate with Mycobacterium tuberculosis (10⁶ CFU/mL) and incubate at 37°C for 7 days. Measure bacterial growth via absorbance at 600 nm and determine MIC as the lowest inhibitory concentration [3].
- Dopamine D2 receptor binding assay：Prepare rat striatal membrane fractions, incubate with [3H]-spiperone (0.5 nM) and Phenothiazine (NSC2037; ENT38) (1 μM-20 μM) at 25°C for 60 minutes. Separate bound/free ligand via vacuum filtration, measure radioactivity, and calculate displacement efficiency [2].

Tumor cell proliferation assay：Seed human tumor cells (A549, MCF-7, etc.) in 96-well plates and incubate for 24 hours. Treat with Phenothiazine (NSC2037; ENT38) (1 μM-50 μM) for 72 hours. Assess proliferation via MTT assay; analyze cell cycle and apoptosis via flow cytometry (Annexin V/PI staining) [1].
- Mycobacterial biofilm assay：Grow Mycobacterium tuberculosis biofilms in 24-well plates for 5 days. Treat with Phenothiazine (NSC2037; ENT38) (0.5 μg/mL-2 μg/mL) for 48 hours. Stain biofilms with crystal violet, elute, and measure absorbance at 570 nm to quantify biofilm reduction [3].

Tuberculosis infection model：Female BALB/c mice (18-22 g) were intravenously infected with Mycobacterium tuberculosis (10⁵ CFU/mouse). Seven days post-infection, Phenothiazine (NSC2037; ENT38) was dissolved in 0.5% carboxymethylcellulose sodium and administered via intraperitoneal injection (5 mg/kg, 10 mg/kg) three times weekly for 4 weeks. Euthanize mice to quantify bacterial load in lungs and spleen [3].
- Tumor xenograft model：Nude mice (20-25 g) were subcutaneously implanted with A549 cells (10⁷ cells/mouse). When tumors reached 100 mm³, Phenothiazine (NSC2037; ENT38) (10 mg/kg, 20 mg/kg) was administered intraperitoneally every other day for 21 days. Measure tumor volume twice weekly; record survival rate [1].
- Locomotor activity assay：Male ICR mice (20-25 g) were acclimated to activity chambers for 30 minutes. Phenothiazine (NSC2037; ENT38) was dissolved in physiological saline and administered via intraperitoneal injection (5 mg/kg, 15 mg/kg). Record locomotor activity (total distance traveled) for 60 minutes post-administration [2].

Absorption, Distribution and Excretion
Due to its low solubility, the rate of absorption in the gastrointestinal tract depends on particle size. The particulate form of the drug is rapidly absorbed. Approximately 30-50% of the oral dose passes through the digestive tract unchanged. Some phenothiazines are converted to lysate derivatives in the intestine… These derivatives are absorbed into the portal venous system… These derivatives are excreted in the urine, causing the urine to turn red upon exposure to air. They are also found in bile and the milk of mammals. In sheep, after oral administration of phenothiazines or their derivatives, 80% is excreted in the urine and feces; the fate of the remaining 20% is unknown. Absorption via the skin. Phenothiazines are readily absorbed from the digestive tract; free drug and red oxidation products appear in the urine. Metabolisms/Metabolites Some phenothiazines are converted to sol derivatives in the intestine, primarily phenothiazine sulfate… In dogs, 3-hydroxyphenothiazines are formed. /Excerpt from Table/
The anthelmintic phenothiazines are oxidized to sulfoxides by enzymes in the segments of tapeworms (Moniezia expansa) and in the cytosol of intestinal epithelial cells of swine ascaris suum. These enzymes can also reduce sulfoxides to thioethers in the absence of oxygen.
Rats, mice, and gerbils primarily excrete phenothiazines in conjugated form. Rats, mice, and gerbils produce nitrosylphenothiazines sulfate as their main metabolite, relying more heavily on the C-oxidation pathway, while hamsters excrete large amounts of phenothiazines N-glucuronide.

Interactions
Previous rinsing with carbon tetrachloride may also increase its toxicity. Antioxidants, such as phenothiazines, inhibited the mutagenicity of benzo[a]pyrene and some of its derivatives on Salmonella typhimurium TA98 strain; this inhibition was concentration-dependent. Non-human toxicity values The oral LD50 in rats was 5000 mg/kg. Acute toxicity: The intraperitoneal LD50 in rats was 120 mg/kg, and the intraperitoneal LD50 in mice was 95 mg/kg [2]. Chronic toxicity: After 4 weeks of intraperitoneal administration of phenothiazines (NSC2037; ENT38) (20 mg/kg/day) to rats, mild sedation and reduced food intake (10%) were observed, without significant hepatotoxicity, nephrotoxicity, or hematological abnormalities [2].
- Tumor model toxicity: Nude mice treated with a dose of 20 mg/kg experienced transient weight loss (5-8%), but recovered within 3 days; no other obvious toxic reactions were observed [1].

[1]. Eur J Med Chem . 2011 Aug;46(8):3179-89.

[2]. Eur J Pharmacol . 1986 Jun 24;125(3):373-81.

[3]. J Antimicrob Chemother . 2001 May;47(5):505-11.

Phenothiazines are a light green to steel-blue powder that turns greenish-brown under sunlight. (NTP, 1992)
10H-Phenothiazines are the 10H-tautomers of phenothiazines. They are plant metabolites with free radical scavenging and ferroptosis-inhibiting effects. They are tautomers of 4aH-phenothiazines, 1H-phenothiazines, and 3H-phenothiazines.
Phenothiazines (PTZs) are organothiazide compounds.
Phenothiazines have been reported in Mimosa pudica, and relevant data exist.
Phenothiazines are a class of drugs with antiemetic, antipsychotic, antihistamine, and anticholinergic activities. Phenothiazines antagonize dopamine D2 receptors in the chemoreceptor trigger zone (CTZ) of the brain, potentially preventing chemotherapy-induced vomiting. Furthermore, these drugs have peripheral or central antagonistic effects on α-adrenergic receptors, serotonergic receptors, histamine receptors, and muscarinic receptors. (NCI)
See also: Promethazine (with subclasses); Chlorpromazine (with subclasses); Trifluoperazine (with subclasses)...See more...

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Therapeutic Uses>
Macrolactone antibiotics; anti-animal agents
Formerly used in human medicine as an anthelmintic and urinary tract disinfectant.
Drug (Veterinary): ...used in veterinary medicine to treat pinworm, nematode, and roundworm infections. It was also previously used as a urinary tract disinfectant...
Drug (Veterinary): It remains effective in treating helminthiasis in sheep and other livestock.
For more complete data on the therapeutic uses of phenothiazines (8 in total), please visit the HSDB record page.

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Drug Warnings>
Veterinarians: ...animals...died after receiving...therapeutic doses, while other animals survived after receiving several times the dose. ...Toxicity differences...Adequate diet, especially its protein content, is an important factor. Dehydration is another cause of mortality, with lambs exhibiting the highest mortality rates under drought conditions. Sensitivity to toxicity is considered to be highest in horses, followed by dogs and pigs, while ruminants and birds appear to be resistant. Toxicity is more common in cattle than in sheep and goats. Young and debilitated animals are more prone to digestive disturbances that promote absorption. The use of this drug in debilitated animals, especially those that are anemic or emaciated, is strictly prohibited. Phenothiazines should not be used to treat animals known to have constipation, as retention in the digestive tract and resulting overabsorption are likely to lead to toxicity. Phenothiazines are contraindicated during pregnancy, except in the last month of gestation. Phenothiazines (NSC2037; ENT38) are a multipharmacological drug with anti-tuberculosis, anti-proliferative, and dopamine D2 receptor antagonistic activities [1,2,3].
- Mechanism of action: Inhibits the growth and biofilm formation of Mycobacterium tuberculosis; induces G2/M phase arrest and apoptosis in tumor cells; regulates central dopamine signaling through D2 receptor antagonism [1,2,3].
- Experimental indications: Has potential for treating tuberculosis (preclinical studies) and cancer (experimental models); has been used as an antipsychotic drug (based on D2 receptor antagonism) [2,3].
- Safety: Well tolerated in preclinical models with only mild sedation; no serious organ toxicity was observed at therapeutic doses [2].

C12H9NS

199.27

199.045

C, 72.33; H, 4.55; N, 7.03; S, 16.09

92-84-2

Phenothiazine-d8; 1219803-41-4

7108

Off-white to light green solid powder

1.2±0.1 g/cm3

371.0±12.0 °C at 760 mmHg

184 °C

178.2±19.6 °C

0.0±0.8 mmHg at 25°C

1.675

4.15

1

2

0

14

187

0

S1C2C(=CC=CC=2)NC2C1=CC=CC=2

WJFKNYWRSNBZNX-UHFFFAOYSA-N

InChI=1S/C12H9NS/c1-3-7-11-9(5-1)13-10-6-2-4-8-12(10)14-11/h1-8,13H

10H-phenothiazine

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)

Solubility in Formulation 1: ≥ 2.5 mg/mL (12.55 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 25.0 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.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (12.55 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 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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