BBKA Forum

Hi, I am studying 5.16 on the correspondance course and it talks about polyphenols. Various books mention that polyphenols 'tan the anthropidin'. But what does that actually mean? I can't find anything that actually explains it and Google just talks about sunbeds and leather!

Try looking up arthropodin.

Hi, I have Google anthropodin but nothing about the tanning of it which is the bit I am confused about.

Basically it's a complex chemical reaction that stabilizes the exoskeleton making it more durable or waterproof.
Look up sclerotization (same thing).
In more detail....
Sclerotization or tanning is a process in which specific regions of the newly secreted cuticle are stabilized by the formation of cross-links between biopolymers such as protein and chitin. Solid state NMR analysis of pupal cuticle has detected covalent bonding between aromatic or aliphatic carbons of catecholamines and protein nitrogen. Weaker secondary bonding and dehydration may also occur as phenolic content increases. The tanning agents are electrophilic derivatives (o-quinones and ρ-quinone methides or free radicals) of catecholamines that may be involved in both sclerotization and pigmentation. Phenoloxidases such as laccases and tyrosinases and other types of enzymes such as isomerases catalyze the formation of reactive tanning agents from N-acylcatecholamines.

Excellent! Thank you.