Sloths may help world cure breast cancer

Between 1981 and 2006, approximately 50 percent of all medicines introduced were from natural products. Fungi in particular have been developed to help advance “natural” drugs and have been known for helping create some of the most important medicines known today in medicine, including Lactam antibiotics, griseofulvin, cyclosporine, fusidic acid, lovastatin and penicillin. However, where we are getting our fungi now for research may surprise you: sloths (PLoS, “Sloth hair as a novel soure of fungi with potent anti-parasitic, anti-cancer and anti-bacterial bioactivity,” 01.15.14).

You know what they are. They are those slow-moving animals we see photos of hanging off of trees. They are medium-sized mammals that live in Central and South America and feed off leaves and small plants. Their diet provides little energy, which is why they are so slow moving. Sloths are furry creatures, and their coat consists of two definite layers: an inner layer of soft hair close to the skin, and an outer layer of coarse hairs. What matters here is the outer layer, which is often home to other organisms such as bugs, fungi and bacteria. As I bet you could’ve deduced, they are rather dirty animals. So why exactly should we care about the sloth? Well, the sloth might just help be a great help with curing breast cancer.

Yes, filthy sloth fur may be what we have been searching for all these years. In a recent study published by the Public Library of Science (PLoS), 74 samples of fungi were collected from sloths’ outer hair layers in Panama. From the samples, Phylogenetic analyses revealed a diverse group of Ascomycota belonging to 28 distinct operational taxonomic units (OTUs). The samples were then tested from in vitro activity, and the results might surprise you: Researchers found that the fungi examined were active against Malaria, Changas Disease and a human breast cancer cell (line MCF-7) (Geekosystem, “Sloths could be carrying cancer treatment around on their backs,” 01.28.14).

Popular Science elaborated on the findings, saying that sloth’s fur was in fact a “potential goldmine for drug discovery.” This is because the chemicals found in the sloth fur attack bacteria differently than man-made drugs. However, we still aren’t sure how the chemicals are embedded in the fur and what combinations of organisms in the fur are ideal for having active fungi (, “Study finds sloth fur may cure breast cancer, treat various diseases,” 01.23.14). It has been suggested that there are over five million fungal species in existence, but less than 100,000 have actually been discovered and documented, which leaves a lot of work and research to be done in this field of fungal fact-finding.

However, the study did point out that the fungi isolated in the study were taxonomically consistent with groups of fungi known to occur in soil and in plants as pathogens, saprotrophs or endophytes commonly found in Panama. Sloths may encounter such fungi incidentally from the air or by direct contact when they descend from trees in order to excrete waste. This act may also be important in the chemical process, as they dig a hole in the soil that they subsequently then cover with leaf litter (PLoS, “Sloth hair as a novel source of fungi with potent anti-parasitic, anti-cancer and anti-bacterial bioactivity,” 1.15.14).

So are sloths the answer for curing cancer and other deadly diseases? They might just be, but researchers believe it will take five to 10 years to develop any sort of drug that can be made available for practical use, and that is only if research can continue. Several organizations, such as OneGreenPlanet and The New England Anti-Vivisection Society, have called to end the exploitation of sloths in research. OneGreenPlanet’s Aisling Maria Cronin states that she is not okay with the testing, even if it could be hugely beneficial for the medical field, stating, “While nobody is disputing the fact that the rising incidence of breast cancer is a critical issue that must be addressed, is harvesting the fur of peaceful sloths really the best solution?” (OneGreenPlanet, “Oh come on! Sloth fur is apparently the latest ‘wonder cure’ for breast cancer,” 01.27.14).

At this time, it should be noted that no sloths appeared to have been harmed in the current study reported. The group did receive approval from Institutional Animal Care and Use Committee (IACUC) of the Smithsonian Tropical Research Institute, and collection permits were obtained from Panama’s Autoridad Nacional del Ambiente (ANAM). No animals appeared to have been injured or hurt in any manner, for only a single sample of hair was collected.

At the moment, it appears research will carry on, and the researchers of the study state that “our work suggests that fruitful exploration of the sloth microbiota is warranted for potential applications in drug discovery.” With more fungal discovery and documentation, I hope that soon a cure for one or multiple life-taking diseases will be found.


—Delaney Fischer ’15 is a neuroscience major.

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