Natural product/phenolic alkaloid; anti-protozoal; anticancer; antiviral; Zika virus (ZIKV); Ebola virus (EBOV)

The natural extracted agent emetine reportedly has anticancer effects. This study aimed to explore the possible role of emetine in cisplatin resistance. We used cell viability, Western blot, and Wnt reporter assays to show that emetine suppresses proliferation, β-catenin expression, and Wnt/β-catenin signaling in non-small cell lung cancer (NSCLC). The synergism of emetine and cisplatin was assessed by constructing isobolograms and calculating combination index (CI) values using the Chou-Talalay method. Emetine effectively synergized with cisplatin to suppress the proliferation of cancer cells. Furthermore, nuclear β-catenin and cancer stem cell-related markers were upregulated in the cisplatin-resistant subpopulation of CL1-0 cells. Emetine enhanced the anticancer efficacy of cisplatin and synergized with cisplatin in the cisplatin-resistant subpopulation of CL1-0 cells. Taken together, these data suggest that emetine could suppress the growth of NSCLC cells through the Wnt/β-catenin pathway and contribute to a synergistic effect in combination with cisplatin[1].

---

In this study, we show that emetine, an anti-protozoal agent, potently inhibits ZIKV and EBOV infection with a low nanomolar half maximal inhibitory concentration (IC50) in vitro[2].

This study tested the protective efficacy of Emetine in an EBOV mouse model. Six to eight week-old, female BALB/c mice (n = 6 per group) were injected IP with 1000-times the mean lethal dose for 50% (LD50) of mouse-adapted Ebola virus (MA-EBOV). Before infection with MA-EBOV, mice were then treated either with emetine (1 mg/kg/day), cephaeline (5 mg/kg/day) or VC (in the control group) starting 3 h before viral innoculation via IP. After IP administration of MA-EBOV, mice continued treatment with emetine, cephaeline, or VC IP for 7 more days. The animals were monitored daily for survival. As expected, all of the control animals uniformly succumbed to EBOV infection with a mean time to death of 8.33 ± 1.03 d.p.i. In contrast, for 67%, or four out of six mice, survival was achieved in both treated groups (Fig. 4c and Supplementary Figure S5e-f). Similar to the effects of emetine and cephaeline treatment in ZIKV infection, the drugs effectively suppressed EBOV infection in vivo.[2]

In vitro RNA polymerase assays[2]
An RNA polymerase assay kit was purchased from Profoldin. RNA synthesis assays were performed in 10 µL of reactions following the manufacturer’s instructions. After 23 ng of purified Zika NS5 was added into 384-well small-volume plate in 3 µL, serial dilutions of emetine were added into the wells in 3 µL. The mixtures were pre-incubated for 30 mins at room temperature. A master mix containing single-stranded polyribonucleotide, 10 µM of NTP mix, 20 mM Tris–HCl, pH 8.0, 1 mM DTT, and 8 mM MgCl2 was added into each well in 4 µL. The reactions were incubated at 37 °C for 1 h and then stopped by adding the fluorescence dye in 10 µL. The fluorescence intensities (Ex = 485 ± 5, Em = 535 ± 10 nm) were measured using a Tecan plate reader.

The inhibition assay was performed as described previously. In brief, Vero E6 cells were pre-treated with emetine or cephaeline (0–2.0 µM) or DMEM alone for 1 h at 37 °C, and infected with a MOI = 0.1 of GFP-expressing EBOV in the presence of emetine, cephaeline or DMEM alone for 1 h at 37 °C. Cells were then further incubated for 72 h in the presence of Emetine, Cephaeline or DMEM. At 72 h, the green fluorescent protein signal was quantified on a Biotek Synergy HTX plate reader. Infection was determined by comparing fluorescence readings of emetine or cephaeline-treated infected cells to DMEM-treated controls. The EC50 and EC90 values were calculated using a four-parameter logistic regression in Prism 5[2].

Evaluating the protective efficacy of emetine and cephaeline against MA-EBOV in mice[2]
Six to eight week-old BALB/C mice, female, were randomly assigned into groups (6 per group). All the mice were challenged with a dose of 1000 times the lethal dose (LD50) MA- EBOV via IP. Treatments with either emetine (1 mg/kg/day) or cephaeline (5 mg/kg/day) or PBS (same volume) for the control group were initiated at 3 h prior to challenge and continued for up to 6 d.p.i. All animals were monitored for signs of disease and weight change for 14 days post challenge, and survival for additional 14 days.

Absorption, Distribution and Excretion
Emetine is absorbed via the parenteral administration site and excreted slowly. Although the drug is detectable in urine 20-40 minutes after injection, it remains detectable in urine for 40-60 days after discontinuation. …The highest concentration of this alkaloid is found in the liver… Significant amounts of this alkaloid are also present in the lungs, kidneys, and spleen. …Emetine tends to accumulate in muscle organs… Metabolism/Metabolites Aminoacylation of Emetine Emetine is metabolized slowly in the liver, and its metabolites are detectable in urine for 40-60 days…

Interactions
In isolated rat gastric fundus smooth muscle, pretreatment with 5–15 μg emetine for 10 minutes antagonized prostaglandin E2-induced contractile enhancement. Maximum inhibitory effects were obtained with 10 and 15 μg emetine.

[1]. Emetine Synergizes with Cisplatin to Enhance Anti-Cancer Efficacy against Lung Cancer Cells. Int J Mol Sci. 2019 Nov 25;20(23):5914.
[2]. Emetine inhibits Zika and Ebola virus infections through two molecular mechanisms: inhibiting viral replication and decreasing viral entry. Cell Discov. 2018 Jun 5;4:31.

Emetine is a pyridoisoquinoline compound composed of an emetan molecule with methoxy groups substituted at positions 6', 7', 10, and 11. It is an antimicrobial drug and emetic. It inhibits the replication of SARS-CoV-2, Zika virus, and Ebola virus, and possesses antimalarial, antitumor, and anti-amoebic activities. Emetine can be used as an antimicrobial drug, plant metabolite, antiviral drug, emetic, protein synthesis inhibitor, antimalarial drug, antitumor drug, autophagy inhibitor, anti-infective drug, expectorant, anticoronavirus drug, and anti-amoebic drug. It is a pyridoisoquinoline compound and also an isoquinoline alkaloid. Functionally, it is related to cephalosporin compounds. It is the conjugate base of emetine (2+). It is derived from the hydride of emetan.
Emidin has been reported to be found in sage (Alangium salviifolium), ivy (Hedera helix), and other organisms with relevant data.
Emidin hydrochloride is a chloride of a white crystalline bitter alkaloid isolated from the roots of the plant Psychotria ipecacuanha and other plants with antiemetic and anthelmintic properties. Emidin inhibits protein synthesis in eukaryotic cells (but not prokaryotic cells) by irreversibly blocking the movement of ribosomes along the mRNA chain and inhibits DNA replication in the early S phase of the cell cycle. (NCI04)
The main alkaloid of Psychotria ipecacuanha, extracted from the roots of Uragoga (or Cephaelis) ipecacuanha or U. acuminata, both belonging to the Rubiaceae family. It is used as an amoeboid in various preparations and can cause severe heart, liver, or kidney damage, as well as severe diarrhea and vomiting. Emidin inhibits protein synthesis in eukaryotic cells but not in prokaryotic cells.

---

Mechanism of Action
Emidin inhibits protein synthesis in animal cells by suppressing the translocation of peptidyl-tRNA from the ribosome receptor site to the donor site.Emidin…inhibits protein synthesis in eukaryotes but not in prokaryotes.
Emidin is a direct myotoxin that inhibits protein synthesis, disrupts mitochondrial oxidative phosphorylation, and leads to skeletal muscle and cardiomyopathy.
Emidin causes nuclear degeneration and cytoplasmic reticulation in amoeba cells; it is believed to eradicate the parasite by interfering with trophozoite proliferation.

---

Therapeutic Uses
Amoeboid; antinematode; protein synthesis inhibitor
... /IT/ Used to treat acute amoebic dysentery, amoebic hepatitis, and amoebic abscesses in the liver and other organs. …Ineffective against cysts.

In amoebic hepatitis, the total dosage of emetine is greater than that used to treat amoebiasis… Rest for one week, while taking oral diiodohydroxyquinoline or glibenclamide (Milibis) or other similar medications.
Emetine is effective in treating severe amoebic diarrhea and acute amoebic dysentery, i.e., when trophozoites are found in the stool.
For more complete data on the therapeutic uses of emetine (10 in total), please visit the HSDB record page.
Drug Warnings
Patients…should remain seated and be under close medical supervision (including ECG monitoring).
Diarrhea caused by emetine may be misdiagnosed as an exacerbation of amoebic dysentery; the two can be differentiated by the fact that diarrhea caused by emetine usually precedes the symptom improvement period.
Precordial pain caused by emetine may be similar to pain caused by coronary artery thrombosis and requires differential diagnosis. Tachycardia usually precedes ECG abnormalities. Imetin should be discontinued immediately if any of the following occur:
If neuromuscular symptoms, significant gastrointestinal reactions, or significant weakness occur, discontinue use immediately.
For more complete data on drug warnings for imetin (17 in total), please visit the HSDB record page.

C29H40N2O4

480.65

516.275

C, 72.47; H, 8.39; N, 5.83; O, 13.31

483-18-1

316-42-7 (HCl);483-18-1;2228-39-9 (2HCl);7083-71-8 (HCl hydrate); 316-42-7 (2HCl); 14198-59-5 (HCl)

10219

WHITE AMORPHOUS POWDER

1.17g/cm3

600.3ºC at 760mmHg

89-96ºC

316.9ºC

ipecac root

6.012

1

6

7

35

679

4

COC1C=C2C([C@@H](C[C@@H]3[C@@H](CC)CN4[C@H](C5=CC(OC)=C(OC)C=C5CC4)C3)NCC2)=CC=1OC

AUVVAXYIELKVAI-CKBKHPSWSA-N

InChI=1S/C29H40N2O4/c1-6-18-17-31-10-8-20-14-27(33-3)29(35-5)16-23(20)25(31)12-21(18)11-24-22-15-28(34-4)26(32-2)13-19(22)7-9-30-24/h13-16,18,21,24-25,30H,6-12,17H2,1-5H3/t18-,21-,24+,25-/m0/s1

(2S,3R,11bS)-2-[[(1R)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolin-1-yl]methyl]-3-ethyl-9,10-dimethoxy-2,3,4,6,7,11b-hexahydro-1H-benzo[a]quinolizine

EMETINE; 483-18-1; Emetin; Cephaeline methyl ether; Methyl cephaeline; 6',7',10,11-Tetramethoxyemetan; (-)-Emetine; Cephaline-O-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)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

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.

---

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).

View More

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)

---

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).

View More

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

---

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.

---

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