As reported by ZME Science, after mating, some tropical frogs secure their eggs in foam to nurture and shield growing embryos. In relation, a recent open access article published by The Royal Society Publishing suggests a novel application for this foam: the topical delivery of actives through human skin.
Foams are often used to deliver cosmetic and topical therapeutic molecules. However, according to these authors, there is high variability in the foamability and long-term stability of synthetic foams. As such, there is interest in developing pharmaceutical foams that exhibit desirable foam properties, deliver appropriate amounts of active and have excellent biocompatibility.
See archived: Practical Foam Science
The production of stable foams in nature is rare, according to these authors, but some species of frogs, e.g., the túngara frog (Engystomops pustulosus), produce foam to protect their eggs and larvae against predators and parasites; prevent desiccation; control gaseous exchanges; buffer temperature extremes; and even reduce UV damage. These foams are also reported to show good stability—i.e., up to 10 days in tropical environments. They are also highly biocompatible due to the sensitive nature of amphibian skin.
The presented work demonstrated that foam nests of the túngara frog are stable ex situ and present useful physiochemical and biocompatible properties. These protein foam mixtures are capable of encapsulating compounds including antibiotics and they share some properties with pharmaceutical foams, suggesting their utility in other topical delivery applications.
For more information, see the full open access article.