Newest sunscreen product on the market: hippo sweat

By Evelyn Puspitasari

We have less than a month before spring hits, then soon after summer will be here. We're also  located in Central Coast. You know what that means? THE BEACHES.

Stock up on sunscreen everyone. We're hitting the beach.

We all know that forgetting to put sunscreen on may result in sunburn. Most of us have unfortunately experienced the painful reddish burn on our skin due to prolong exposure to the sun. Sunburn is actually a burn to living tissue such as our skin tissue by overexposure to ultraviolet radiation, commonly from the sun's rays. If you're lucky, less exposure to UV radiation will produce suntan instead.

Okay, sunscreen is good. Got it. But is it really? Turns out that well... sunscreen sort of has bad side effects... Autier et al. (2007) suggests that increase sunscreen usage in individuals may increase risk of cutaneous melanoma because people feel it is okay to be out in the sun for longer period of time. Some people also believed that applying sunscreen could reduce risk to skin cancer, unfortunately this is not true either. Hence, there is a lot of research going on to find a safer alternative to our commonly used sunscreen.

Well. I propose to use hippo sweat as sunscreen.

Yes, hippopotami are cute beasts. The common hippopotamus, Hippopotamus amphibious L. is the third largest and heaviest mammal after elephants and white rhinos. They are widespread across lakes and rivers throughout Africa, although you can probably go to your local zoo and find hippos there too. They are herbivores, but they are also vicious. Water is actually required for their thermoregulation, which is why hippos are known amphibious and always found near water. They have unique skin with thin epidermis and no sweat glands. Out of water, they lose water much more quickly than other mammals, which is why they spend a lot of time in the water to keep their bodies cool since they don't sweat.

Although they don't have sebaceous glands, they do have mucus-secreting glands that produce "sweat". Hippos' subdermal glands are the ones responsible to produce the colorless viscous "sweat" that will cover their entire hairless body and keep their skin moist. Within a few minutes, the colorless "sweat" will turn red, then gradually turning brown after a few hours because of pigment polymerization. This would explain the story of "Hippos secrete a blood-like sweat" that was spread by ancient travelers all over the world.

A study done in Japan by Saikawa et al. (2004, 2007) with the help of animal keepers at the Ueno Zoological Gardens and the Kyoto Municipal Zoo succeeded in isolating hippos sweat! The Saikawa team bravely wiped hippos bodies with paper towels to get the "sweat" secretion, so that pigment purification could be done.

They managed to isolate two pigments - a red and an orange pigment. They dubbed the red one as hipposudoric acid, whereas the orange one is called norhipposudoric acid. These pigments are apparently stabilized to some extent by interacting with the highly alkaline (pH 8.5-10) hippo "sweat", altough overtime will still turn into a brown polymeric material.

Knowing the behaviors of hippos, they almost always have wounds and scratches due to battles between one another or with predators. Is it possible that these pigments have antibacterial properties? The Saikawa team asked the same question and proceeded to grow bacteria in the presence of the red and orange pigments. Turns out both pigments are effective at inhibiting growth of some Gram-negative bacteria such as Pseudomonas aeruginosa and Klebsiella pnemoniae, although the red pigment has a stronger antibiotic effect than the orange one.

Wait, they are pigments! Think! Wavelength! Absorbance! Apparently the pigments absorb light in the UV-visible range (200-600 nm) indicating that the pigments may behave like sunscreen. The researchers conclude that hippo "sweat" not only cools the body, but also acts as sunscreen and protects the hippos against bacterial infection. Win win!

So why don't we have this on the market yet, you ask? Well remember how I said that hippos were vicious beasts? Yeah.... Getting "sweat" samples from hippos is not the easiest thing to do, which means producing a synthetic version of their "sweat" will take longer than expected. If you'd like to witness how scary a hippo can be, feel free to watch this R-rated video below:

Are you terrified now? Here. I'm sorry. This is my peace offering. Click it, you'll feel better afterwards, I promise.


References:
Berwick, M. 2011. The good, the bad, and the ugly of sunscreens. Clinical Pharmacology & Therapeutics 89:31-33.
Donawho, C. and P. Wolf. 1996. Sunburn, sunscreen, and melanoma. Current opinion in oncology 8:159-166.
Hashimoto, K, Y. Saikawa, and M. Nakata. 2007. Studies on the red sweat of the Hippopotamus amphibius. Pure and Applied Chemistry 79:507-517.
Saikawa, Y., K. Hashimoto, M. Nakata, M. Yoshihara, K. Nagai, M. Ida, and T. Komiya. 2005. Pigment chemistry: the red sweat of the hippopotamus. Nature 429:363-363.
Timbuka, C.D. 2012. The ecology and behaviour of the common hippopotamus, Hippopotamus amphibious L. in Katavi National Park, Tanzania: Responses to varying water resources: University of East Anglia.

Image and video references:
http://giphy.com/gifs/beach-water-ocean-f45816CTsKd7G
http://giphy.com/gifs/friends-black-sun-smMHbiEP5jyla
http://giphy.com/gifs/cute-hippo-yRtpTJ2Sz3Yvs
https://www.youtube.com/watch?v=c5Pmd515u5U&spfreload=10
http://cen.acs.org/content/cen/articles/82/i22/HIPPOS-SWEAT-PROTECTION/_jcr_content/articlebody/subpar/articlemedia_1.img.gif/1375723112826.gif
https://www.youtube.com/watch?v=WfrG95GyU9U