Crotaline (Monocrotaline) (Synonyms: Crotaline, MCT, NSC 28693)

Crotaline is an pyrrolizidine alkaloid extracted from the seeds of the Crotalaria spectabilis plant to induce pulmonary vascular syndrome in rats^[1]. crotaline a natural ligand exhibits dose-dependent cytotoxicity with potent antineoplastic activity. The in vitro cytotoxicity of crotaline is proved at IC50 24.966 μg/mL and genotoxicity at 2 X IC50 against HepG2 cells^[2].

In the absence of HepaRG hepatocytes, even at significantly high concentration (1200 μM) for 24 h treatment, Crotaline did not affect viability of HSECs, indicating no cytotoxicity. In contrast, after 24 h treatment in the two-layer transwell co-culture model with co-culture of HSECs and HepaRG hepatocytes, significant decrease in HSEC viability in a concentration-dependent manner was observed for Crotaline^[8].

Crotaline causes pulmonary vascular syndrome in rats, characterized by proliferative pulmonary vasculitis, pulmonary hypertension (PH), and cor pulmonale^[3].Changes in multiple pathways associated with PH development were observed by crotaline injection, including activated glycolysis, increased proliferation markers, disruption of carnitine homeostasis, increased inflammatory and fibrotic biomarkers, and decreased glutathione biosynthesis^[5].Using rats (14 days after exposure to crotaline), changes in multiple pathways associated with the development of PH, including activated glycolysis, increased markers of proliferation, disruptions in carnitine homeostasis, increased inflammatory and fibrosis biomarkers, and a reduction in glutathione biosynthesis^[4].PAH induced by Crotaline is a progressive disease with persistent inflammation. The inflammation in Crotaline -PAH model includes acute (the first 6 days after Crotaline injection) and chronic stages (after acute inflammation stage). Acute inflammation stage may be the time window of anti-inflammatory treatment in PAH induced by Crotaline ^[6,7].

References:
[1]: Gomez-Arroyo JG, Farkas L, et,al. The monocrotaline model of pulmonary hypertension in perspective. Am J Physiol Lung Cell Mol Physiol. 2012 Feb 15;302(4):L363-9. doi: 10.1152/ajplung.00212.2011. Epub 2011 Sep 30. PMID: 21964406.
[2]: Kusuma SS, Tanneeru K, et,al. Antineoplastic activity of monocrotaline against hepatocellular carcinoma. Anticancer Agents Med Chem. 2014;14(9):1237-48. doi: 10.2174/1871520614666140715085907. PMID: 25028149.
[3]: Wilson DW, Segall HJ, et,al. Mechanisms and pathology of monocrotaline pulmonary toxicity. Crit Rev Toxicol. 1992;22(5-6):307-25. doi: 10.3109/10408449209146311. PMID: 1489509.
[4]: Nogueira-Ferreira R, Vitorino R, et,al. Exploring the monocrotaline animal model for the study of pulmonary arterial hypertension: A network approach. Pulm Pharmacol Ther. 2015 Dec;35:8-16. doi: 10.1016/j.pupt.2015.09.007. Epub 2015 Sep 21. PMID: 26403584.
[5]: Rafikova O, Meadows ML, et,al. Metabolic Changes Precede the Development of Pulmonary Hypertension in the Monocrotaline Exposed Rat Lung. PLoS One. 2016 Mar 3;11(3):e0150480. doi: 10.1371/journal.pone.0150480. PMID: 26937637; PMCID: PMC4777490.
[6]: Tang C, Luo Y, et,al. Characteristics of inflammation process in monocrotaline-induced pulmonary arterial hypertension in rats. Biomed Pharmacother. 2021 Jan;133:111081. doi: 10.1016/j.biopha.2020.111081. Epub 2020 Dec 15. PMID: 33378977.
[7]: Nogueira-Ferreira R, Vitorino R, et,al. Exploring the monocrotaline animal model for the study of pulmonary arterial hypertension: A network approach. Pulm Pharmacol Ther. 2015 Dec;35:8-16. doi: 10.1016/j.pupt.2015.09.007. Epub 2015 Sep 21. PMID: 26403584.
[8]: Lu Y, Ma J, Lin G. Development of a two-layer transwell co-culture model for the in vitro investigation of pyrrolizidine alkaloid-induced hepatic sinusoidal damage. Food Chem Toxicol. 2019 Jul;129:391-398. doi: 10.1016/j.fct.2019.04.057. Epub 2019 May 2. PMID: 31054999.