Amino acid
Amino acids are organic compounds containing amine (-NH) and carboxyl (-COOH) functional groups, along with a side chain (R group) specific to each amino acid. The key elements of an amino acid are carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), although other elements are found in the side chains of certain amino acids. About 500 naturally occurring amino acids are known (though only 20 appear in the genetic code) and can be classified in many ways. They can be classified according to the core structural functional groups' locations as alpha- (α-), beta- (β-), gamma- (γ-) or delta- (δ-) amino acids; other categories relate to polarity, pH level, and side chain group type (aliphatic, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid residues form the second-largest component (water is the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis.
Benzoic acid
Benzoic acid occurs naturally as do its esters in many plant and animal species. Appreciable amounts have been found in most berries (around 0.05%). Ripe fruits of several "Vaccinium" species (e.g., cranberry, "V. vitis macrocarpon"; bilberry, "V. myrtillus") contain as much as 0.03–0.13% free benzoic acid. Benzoic acid is also formed in apples after infection with the fungus "Nectria galligena". Among animals, benzoic acid has been identified primarily in omnivorous or phytophageous species, e.g., in viscera and muscles of the rock ptarmigan ("Lagopus muta") as well as in gland secretions of male muskoxen ("Ovibos moschatus") or Asian bull elephants ("Elephas maximus").