Plasmodium
Inhibition of the Ras-Raf1-ERK1/2 protein kinase cascade in T cells.

Rat C6 glioma cell growth is inhibited by artemeether (0-200 μg/mL, 24-72 h) in a dose- and time-dependent manner[2].
Artemether (0-10 μM, 72 h) suppresses the expression of genes related to osteoclast formation (osteoclast precursor cells, BMMs) caused by RANKL (TRAP, NFATc1, V-ATPase-d2, CTSK, DC-STAMP, MMP-9)[2].
Artemether (48 or 96 h) inhibits the proliferation of BALB/c splenocytes induced by ConA or alloantigen (IC50: 6.3 and 3.5 μM)[4].
In BALB/c splenocytes, artemeether (0-50 μM, 16–36 h) suppresses IL-2 and IFN-γ production[4].
Artemether (0-50 μM, 72 h) inhibits cell cycle progression through G1/S transition, as well as ConA-induced splenocyte, CD4+T, and CD8+ T-cell divisions[4].

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Artemether suppressed concanavalin A (ConA)-induced splenocyte proliferation with an IC50 of 6.3 ± 1.9 μM, and alloantigen-induced proliferation with an IC50 of 3.5 ± 0.6 μM. It also dose-dependently inhibited ConA-induced production of IL-2 and IFN-γ in splenocytes.
Artemether inhibited T-cell division (CFSE assay) and arrested cell cycle progression at the G0/G1 phase in a dose-dependent manner. It also reduced the expression of cyclin D3 and CDK6, and suppressed the degradation of p27^kip in anti-CD3-stimulated T cells.
Artemether inhibited anti-CD3-induced phosphorylation of Raf1 and activation of Ras in primary T cells, and suppressed ERK1/2 phosphorylation in both ovalbumin-stimulated T cells from immunized mice and anti-CD3-stimulated primary T cells. [4]

In SD rats containing C6 glioma cells, artemeether (0-66 mg/kg, p.o.) inhibits tumor growth and angiogenesis[2].
Mice treated with esters (10 mg/kg, i.p., for 8 days) are shielded from LPS-induced osteolytic bone loss[3].
In the DNFB-induced DTH model in BALB/c mice, artemeether (50 and 100 mg/kg, p.o.) inhibits T-cell-mediated immune responses (ear swelling)[4].

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Oral administration of Artemether (50 and 100 mg/kg) dose-dependently suppressed ear swelling in the DNFB-induced delayed-type hypersensitivity (DTH) reaction in BALB/c mice.
In ovalbumin-immunized BALB/c mice, oral Artemether (100 mg/kg daily for 7 days) significantly suppressed ovalbumin-specific T-cell proliferation and cytokine (IL-2 and IFN-γ) production in ex vivo recall assays. [4]

Cell Line: ConA-stimulated T lymphocytes
Concentration: 1, 10 and 50 μM
Incubation Time: 72 h
Result: Arrested 47, 56 and 91% (at 1, 10 and 50 μM) of the cells at G0/G1 phases, respectively.

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Proliferation assay: Splenocytes (4×10⁵ cells/well) were cultured with ConA (5 μg/mL) or irradiated allogeneic splenocytes in 96-well plates for 48 or 96 h. Proliferation was measured by [³H]thymidine incorporation during the last 8 or 24 h of culture. Artemether was added at the initiation of culture.
Cytokine measurement: Splenocytes (4×10⁶ cells/mL) were cultured with ConA (2 μg/mL) for 16, 24, or 36 h. IL-2 and IFN-γ levels in supernatants were measured by ELISA.
CFSE division assay: Splenocytes were labeled with CFSE (2.5 μM), stimulated with ConA (5 μg/mL) for 72 h in the presence or absence of Artemether, and analyzed by flow cytometry for CD4⁺ and CD8⁺ T-cell division.
Cell cycle analysis: T cells from lymph nodes were stimulated with ConA for 16 h, fixed, stained with propidium iodide (PI), and analyzed by flow cytometry for DNA content.
Western blotting for cell cycle and signaling proteins: Purified T cells were activated with anti-CD3 mAb (5 μg/mL) for 10 min (signaling) or 24 h (cell cycle proteins). Whole-cell lysates were subjected to SDS-PAGE and immunoblotted for phospho-ERK, total ERK, phospho-Raf1, total Raf1, cyclin D3, CDK6, and p27^kip.
Ras activation assay: T cells were stimulated with anti-CD3 mAb for 5 min. Active Ras-GTP was affinity-purified using Raf1-RBD-GST beads and detected by Western blotting with anti-Ras antibody. [4]

Animal Model: LPS (5 mg/kg) treated mice[3]
Dosage: 10 mg/kg
Administration: i.p., 8 days
Result: prevented the loss of osteolytic bone and the decrease in bone volume caused by LPS.
reduced osteoclast surface/bone surface (Oc.S/BS), increased bone volume/total volume (BV/TV), and number of TRAP-positive cells.

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DTH model: BALB/c mice were sensitized with 0.5% DNFB on the hind feet on days 0 and 1. On day 9, they were challenged with DNFB on the right ear. Vehicle, Artemether (5, 50, 100 mg/kg, p.o.), or cyclosporin A (CsA, 2 mg/kg, i.p.) was administered once daily from day 8 to day 10. Ear swelling (thickness and weight) was measured 72 h post-challenge.
Ovalbumin immunization model: BALB/c mice were immunized subcutaneously with ovalbumin (100 μg/mouse) in CFA on day 1. Artemether (100 mg/kg, p.o.) or vehicle was administered once daily for 7 days. On day 7, T cells from draining lymph nodes were isolated and co-cultured with irradiated antigen-presenting cells (APCs) from naïve mice in the presence of ovalbumin for proliferation and cytokine assays. [4]

Absorption, Distribution and Excretion
Food can increase absorption. The administered drug or dihydroartemisinin was barely detectable in urine. /Dihydroartemisinin/ Pharmacokinetic studies following intramuscular injection showed that peak plasma concentrations of artemisinin (AM) occurred 2 to 4 hours after administration, elimination was slow, and there was a tendency for accumulation with repeated administration. Only low concentrations of the major metabolite, dihydroartemisinin (DHA), were detected. AM concentrations in cerebrospinal fluid (CSF) were less than 10% of plasma concentrations. AM concentrations were significantly lower after oral administration than after intramuscular administration. DHA concentrations were higher on day 1 but almost zero on day 7, indicating rapid inactivation in dogs. Two hours after the eighth oral administration, neither artemisinin (AM) nor dihydroartemisinin (DHA) was detected in CSF, which may explain the absence of neurotoxicity after oral administration of artemisinin in dogs. This study investigated the pharmacokinetics of artemisinin and its major plasma metabolite dihydroartemisinin in patients with severe falciparum malaria. The study included 6 patients with severe falciparum malaria and acute renal failure (ARF) and 11 patients without ARF. All patients received artemisinin intramuscularly as a loading dose of 160 mg, followed by 80 mg daily for 6 days (total dose 640 mg). Both patients with and without ARF showed good initial response to treatment; parasite clearance time and defervescence time were 66 (30–164) hours and 76 (36–140) hours, respectively (median (range)). No relapse of parasitemia was observed in peripheral blood smears within 7 days of treatment initiation in all patients. The time to regain consciousness in comatose patients was 51.6 (22–144) hours. Artemisinin was detectable in plasma 1 hour after administration of 160 mg and, in most cases, decreased to undetectable levels within 24 hours. Compared with patients who did not develop acute renal failure (ARF), patients who developed ARF had significantly higher Cmax (2.38 (1.89 to 3.95) vs 1.56 (1.05 to 3.38) ng/mL/mg dose), significantly lower Vz/F (5.45 (3.2 to 6.9) vs 8.6 (4.2 to 12.3) L/kg), and significantly lower CL/F (7.4 (5.4 to 13.8) vs 19.1 (8.5 to 25.1) mL/min/kg). Furthermore, the half-life (t1/2z) was significantly prolonged in patients with ARF (7.0 (5.5 to 10.0) hours vs 5.7 (4.2 to 6.6) hours). The pharmacokinetics of dihydroartemisinin were similar in both groups. ARF significantly altered the pharmacokinetics of artemether administered intramuscularly. These changes may be attributed to increased absorption/bioavailability, decreased systemic clearance, or altered plasma protein binding.
Oral administration of dihydroartemisinin results in rapid absorption, reaching peak plasma concentration approximately 2.5 hours later. Rectal administration results in slightly slower absorption, reaching peak plasma concentration approximately 4 hours later. Plasma protein binding is approximately 55%. The half-life of elimination via intestinal and hepatic glucuronidation is approximately 45 minutes. Dihydroartemisinin
For more complete data on the absorption, distribution, and excretion of artemethers (6 in total), please visit the HSDB record page.

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Metabolism/Metabolites
Artemether is rapidly metabolized to its active metabolite, dihydroartemisinin.
Artemether…is converted to dihydroartemisinin…The antimalarial activity of artemisinin compounds primarily derives from dihydroartemisinin…
Oral administration of artemisinin to rats results in rapid and complete absorption. However, even at doses up to 300 mg/kg, plasma concentrations are extremely low. The liver is the primary site of inactivation. Significant and sustained plasma concentrations were detected after intramuscular injection of artemisinin. Following intravenous injection, artemisinin crosses the blood-brain barrier and the blood-placental barrier. Regardless of the route of administration, little unmetabolized artemisinin was detected in urine or feces within 48 hours. Metabolites identified after human administration include deoxyartemisinin, deoxydihydroartemisinin, and 9,10-dihydroxydeoxyartemisinin. /Artemisinin/

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Biological Half-Life
Artemether: 1.6 ± 0.7 and 2.2 ± 1.9 hours; Dihydroartemisinin: 1.6 ± 0.6 and 2.2 ± 1.5 hours
Artemether…is converted to dihydroartemisinin…which disappears rapidly from plasma with a half-life of approximately 45 minutes.

Protein Binding
In vitro experiments showed that both artemisinin and artemether were highly bound to human serum proteins (95.4% and 99.7%, respectively). Dihydroartemisinin also bound to human serum proteins (47% to 76%). Interactions This study aimed to assess the effect of grapefruit juice on the time-dependent decrease in artemisinin bioavailability. In a randomized, two-stage crossover study, eight healthy male subjects took 100 mg of artemisinin orally once daily, administered with either 350 mL of water or 350 mL of double-concentration fresh frozen grapefruit juice for five days. Seventeen blood samples were collected within eight hours on days 1 and 5. On day 5 after the last dose, the peak plasma concentration (Cmax) and mean area under the concentration-time curve (AUC) of artemisinin were approximately one-third of those on day 1, and the elimination half-life remained unchanged after co-administration with drinking water (Cmax: P = 0.006; AUC: P = 0.005) and grapefruit juice (Cmax and AUC: P < 0.001). Grapefruit juice doubled the Cmax (P = 0.021) and AUC (P < 0.001) on both day 1 (P = 0.021) and day 5 (Cmax: P = 0.05; AUC: P = 0.004). The active metabolite dihydroartemisinin doubled the Cmax (P = 0.006) and AUC (P = 0.001) after administration of grapefruit juice, but no time-dependent changes were observed in pharmacokinetic parameters. Grapefruit juice significantly improved the oral bioavailability of artemisinin but did not prevent its bioavailability from decreasing over time. This suggests that CYP3A4 in the intestinal wall is one of the metabolic enzymes of artemisinin but does not appear to be involved in its self-induction process. There are concerns that the use of antipyretics, associated with delayed parasite clearance, might weaken the host's defenses against malaria. However, this appears to be due to delayed cell adhesion, which may be beneficial. Therefore, there is no reason to discontinue antipyretics in malaria treatment. …Acetaminophen and ibuprofen are the preferred antipyretics. The cytotoxicity of artemisinin to spleen cells was assessed using the MTT assay. After 48 hours of culture, the CC50 (concentration at which cell viability decreased by 50%) was 350 ± 39 μM; after 96 hours of culture, the CC50 was 80 ± 0.4 μM. In in vivo experiments, no death or disease symptoms were observed in mice treated with artemisinin at doses up to 100 mg/kg (oral LD₅₀ = 977 mg/kg). At the tested dose, artemisinin had no effect on body weight, spleen weight, spleen cell count, or T cell count in mice. [4]

[1]. Recent investigations of artemether, a novel agent for the prevention of schistosomiasis japonica, mansoni and haematobia. Acta Trop, 2002. 82(2): p. 175-81.

[2]. Inhibitive effect of artemether on tumor growth and angiogenesis in the rat C6 orthotopic brain gliomas model. Integr Cancer Ther, 2009. 8(1): p. 88-92.

[3]. Artemether attenuates LPS-induced inflammatory bone loss by inhibiting osteoclastogenesis and bone resorption via suppression of MAPK signaling pathway. Cell Death Dis. 2018 May 1;9(5):498.

[4]. Investigation of the immunosuppressive activity of artemether on T-cell activation and proliferation. Br J Pharmacol. 2007 Mar;150(5):652-61.

Artemether is a derivative of artemisinin, formed by converting the lactone in artemisinin into the corresponding lactone methyl ether. It is used in combination with artemether as an antimalarial drug to treat multidrug-resistant Plasmodium falciparum malaria. It is a sesquiterpene compound, cyclic acetal, organic peroxide, artemisinin derivative, and semi-synthetic derivative. Artemether is an antimalarial drug used to treat acute unidentified malaria. Its combination with artemether enhances efficacy. This combination therapy is effective against the erythrocyte stage of Plasmodium. It can be used to treat infections caused by Plasmodium falciparum and unidentified Plasmodium species, including malaria in chloroquine-resistant areas.
An artemisinin derivative used to treat malaria.

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Drug Indications
Artemether and fluorenol combination therapy is indicated for the treatment of acute unidentified malaria caused by Plasmodium falciparum, including malaria in chloroquine-resistant areas. It can also be used to treat unidentified unidentified Plasmodium species. Suitable for adults and children weighing over 5 kg.
FDA Label

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Mechanism of Action
Interacts with iron protoporphyrin IX (“heme”) or ferrous ions in the food vacuoles of acidic parasites, thereby generating cytotoxic free radicals. The generally accepted mechanism of action for peroxide-based antimalarial drugs is that the peroxide-containing drug interacts with heme (a byproduct of hemoglobin degradation, derived from the proteolysis of hemoglobin). This interaction is thought to lead to the formation of a series of potentially toxic oxygen and carbon-centered free radicals.
Artemisinin (AM) is an antimalarial drug derived from artemisinin, which is extracted from the herb Artemisia annua L. Its antiparasitic action is that of a schizonticide, and its mechanism of action is through rapid absorption by parasite-infected red blood cells and interaction with components of hemoglobin degradation, thereby forming free radicals. Clinical studies have shown that it has a high cure rate.
Based on the known properties of pharmaceutically active peroxides, two theories regarding the antimalarial mechanism of action of artemisinin-based antimalarial drugs have been proposed. The first theory posits that artemisinin must come into contact with reduced heme (ferrous heme, Fe(II)PPIX) or non-heme ferrous iron (exogenous iron) to be activated, leading to the cleavage of peroxides to generate oxygen-centered free radicals (alkoxy radicals). These radicals are then thought to be converted into carbon-centered free radicals via the transfer of neighboring hydrogen atoms from the periphery of the peroxide molecule. These carbon-centered free radicals are believed to be capable of alkylating sensitive but not yet fully understood biomolecules in parasites. The second theory suggests that intact artemisinin binds to a binding site on an important protein in the parasite. This binding leads to the conversion of the peroxide into hydroperoxides or similar open peroxides, which, based on the known properties of such compounds, generate one or more reactive chemical entities, such as oxidants, oxygen transfer agents, or oxygen-centered free radicals. This is closely related to the binding process. In this way, artemisinin may act as an (irreversible) inhibitor. Iron may or may not be involved in the activation process. No specific biological target supporting this theory has yet been found in parasites, but membrane-bound proteins may be involved.

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Therapeutic Use
MeSH Keywords: Antimalarial drugs, Antifungal drugs, Antibiotics, Anticoccidial drugs, Antischistosomiasis drugs
Therapeutic Category: Antimalarial Drugs
To address the threat of resistance to monotherapy in Plasmodium falciparum and to improve treatment efficacy, the World Health Organization currently recommends the use of combination antimalarial drugs for the treatment of falciparum malaria. The currently recommended artemisinin-based combination therapy (ACTs) is artemether-fluorene.
Artemether-fluorene: Combination tablets are currently available… The recommended course of treatment is 6 doses, twice daily for 3 consecutive days. The advantage of this combination therapy is that fluorene is not currently a monotherapy and has never been used alone to treat malaria. Recent evidence suggests that the efficacy and safety of this combination therapy are similar in children weighing less than 10 kg to older children; therefore, artemether-fluorene is currently recommended for patients weighing 5 kg. Co-administration with fat can enhance the absorption of fluorene. Low blood drug concentrations leading to treatment failure may be due to insufficient fat intake. Therefore, patients and caregivers must be informed that this antimalarial combination therapy (ACT) should be taken with milk or fatty foods, especially on the second and third days of treatment.
For more complete data on the therapeutic uses of artemether (11 in total), please visit the HSDB record page.

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Drug Warnings
There have been reports of transient first-degree atrioventricular block, dose-related reversible decreases in reticulocyte and neutrophil counts, and transient increases in serum aspartate aminotransferase activity after taking this drug…Some studies have found that volunteers taking this drug experience transient drug-induced fever…/Artemisinin-based drugs/
Due to the potential for long-term toxicity caused by high doses of artemisinin-based drugs in experimental animals, including neurotoxicity, QT interval prolongation, bone marrow suppression, and fetal reabsorption, there is a possibility of long-term toxicity. Artemisinin-based drugs exist in the human body. Some patients cannot tolerate oral treatment and require 1-2 days of parenteral or rectal administration until they can reliably swallow and retain the oral medication. Although these patients may not develop severe symptoms, they should receive the same antimalarial drug dosage regimen as patients with severe malaria. Some patients may not develop severe symptoms but have very high parasitemia on blood smears. The risk of high parasitemia varies depending on the patient's age and the intensity of transmission. Therefore, the threshold and definition of high parasitemia also vary. Patients with high parasitemia have an increased risk of treatment failure and development of severe malaria, and therefore an increased risk of death. These patients can be treated with oral antimalarial combination therapies (ACTs) recommended for the treatment of uncomplicated malaria. However, close monitoring is required to ensure drug effectiveness and the absence of severe symptoms, and a longer course of treatment may be necessary to ensure a cure. For more complete data on drug warnings for artemether (18 in total), please visit the HSDB records page.

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Pharmacodynamics
In vivo, artemether is metabolized into the active metabolite dihydroartemisinin. This drug combats the erythrocyte stage of Plasmodium falciparum by inhibiting nucleic acid and protein synthesis. Artemether can enhance efficacy when used in combination with artemether. Artemether has a rapid onset of action and is rapidly eliminated from the body. It is believed that artemether rapidly relieves symptoms by reducing the number of Plasmodium. Lumefentin has a longer half-life and is believed to be able to eliminate residual parasites.

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Artemisinin is a semi-synthetic derivative of artemisinin and is mainly used as an antimalarial drug. This study revealed its potent immunosuppressive activity, which directly inhibits T cell activation and proliferation by inhibiting the Ras-Raf1-ERK1/2 signaling pathway. [4]

C16H26O5

298.3746

298.178

C, 64.41; H, 8.78; O, 26.81

71963-77-4

Artemether-d3;93787-85-0

68911

Crystals

1.2±0.1 g/cm3

357.5±42.0 °C at 760 mmHg

86-89ºC

140.5±27.8 °C

0.0±0.8 mmHg at 25°C

1.518

3.07

0

5

1

21

429

8

O1C23[C@]4([H])O[C@@]([H])([C@]([H])(C([H])([H])[H])[C@]2([H])C([H])([H])C([H])([H])[C@@]([H])(C([H])([H])[H])C3([H])C([H])([H])C([H])([H])C(C([H])([H])[H])(O1)O4)OC([H])([H])[H]

SXYIRMFQILZOAM-HVNFFKDJSA-N

InChI=1S/C16H26O5/c1-9-5-6-12-10(2)13(17-4)18-14-16(12)11(9)7-8-15(3,19-14)20-21-16/h9-14H,5-8H2,1-4H3/t9-,10-,11+,12+,13+,14-,15-,16-/m1/s1

(3R,5aS,6R,8aS,9R,10S,12R,12aR)-decahydro-10-methoxy-3,6,9-trimethyl-3,12-epoxy-12H-pyrano[4,3-j]-1,2-benzodioxepin

Dihydroqinghaosu methyl ether; Dihydroartemisinin methyl ether; SM224; SM-224; Artemos; Artenam; Artesaph; Artesian; Dihydroartemisinin Methyl Ether; Falcidol; Gvither; Larither; Malartem; SM 224; β-Artemether; β-Dihydroartemisinin Methyl Ether

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 : 60~100 mg/mL ( 201.09~335.15 mM )
Ethanol : ~60 mg/mL
H2O : ~0.1 mg/mL (~0.34 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (8.38 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 (8.38 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 25.0 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.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (8.38 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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Solubility in Formulation 4: 3% DMSO + 97% Corn oil: 6mg/ml (20.11mM)

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