Crocodiles and alligators: Antiamoebic and antitumor compounds of crocodiles.

Crocodiles exist in unsanitary environments, feed on rotten meat, are often exposed to heavy metals such as arsenic, cadmium, cobalt, chromium, mercury, nickel, lead, selenium, tolerate high levels of radiation, and are amid the very few species to survive the catastrophic Cretaceous-Tertiary extinction event, nonetheless they can live for up to a 100 years. Moreover, as they live in unhygienic conditions, they regularly come across pathogens. Logically, we postulate that crocodiles possess mechanisms to defend themselves from noxious agents as well as protecting themselves from pathogens. To test this hypothesis, various organ lysates and serum of Crocodylus palustris were prepared. Amoebicidal assays were performed using Acanthamoeba castellanii belonging to the T4 genotype. Cytotoxicity assays were performed using Prostate cancer cells culture by measuring lactate dehydrogenase release as a marker for cell death. Growth inhibition assays were performed to determine the growth inhibitory effects of various organ lysates. Serum and heart lysates of Crocodylus palustris exhibited powerful anti-tumor activity exhibiting more than 70% Prostate cancer cell death (P < 0.05). Additionally, lysates from gall bladder and bile also showed significant host cell cytotoxicity, however intestine, lungs and brain showed partial cytotoxicity. Both sera and heart lysates of Crocodylus palustris abolished Prostate cells growth. Moreover, serum completely abolished A. castellanii viability. For the first time, these findings showed that the organ lysates of Crocodylus palustris exhibit potent anti-amoebic and anti-tumor activity. The discovery of antimicrobial and antitumor activity in crocodile will stimulate research in finding therapeutic molecules from unusual sources, and has potential for the development of novel antitumor/antimicrobial compound(s) that may also overcome drug resistance. Nevertheless, rigorous research in the next few years will be necessary to realize these expectations.