Monday Micro – sloths a source of new drugs?!

By Siouxsie Wiles 20/01/2014

As a parent, I have watched the Ice Age movies more times than I care to admit. I quite like Sid the sloth but had no idea just how important his descendants could be in our fight against disease.


Sloths are slow-moving tree-dwelling mammals found in the jungles of central and south America. They have unusual fur that under certain conditions plays home to photosynthetic bacteria (cyanobacteria) whose blue/green colour is thought to provide camouflage.

In a paper just published in the open access journal PLOS One, Sarah Higginbotham and colleagues from the Smithsonian Tropical Research Institute in Panama, have looked at the fungal communities associated with the coarse, outer hair of nine three-toed sloths of the species Bradypus variegatus living in Panama.

The researchers cultivated over 80 species of fungi and then screened extracts made from these fungi for the production of compounds that could kill bacteria, parasites and cancer cells. They found 2 extracts with activity against Plasmodium falciparum, the parasite that causes malaria, and eight extracts with activity against Trypanosoma cruzi, the parasite that causes Chagas disease. This is exciting as the current treatments for Chagas disease have serious side effects which can be so bad, patients stop taking their medicine. They also found three extracts with activity against a breast cancer cell line, and an extract with activity against Gram-negative bacteria such as E. coli and Pseudomonas aeruginosa. This is good news, as multi-drug resistant Gram-negative bacteria are fast-becoming untreatable using current antibiotics.

Fingers crossed some of these sloth-hair fungi compounds turn into new drugs. We certainly need them.


Higginbotham S, Wong WR, Linington RG, Spadafora C, Iturrado L, et al. (2014) Sloth Hair as a Novel Source of Fungi with Potent Anti-Parasitic, Anti-Cancer and Anti-Bacterial Bioactivity. PLoS ONE 9(1): e84549. doi:10.1371/journal.pone.0084549