Phenylpyruvic acid is a keto-acid that is an intermediate or catabolic byproduct of phenylalanine metabolism. It has a slight honey-like odor. Levels of phenylpyruvate are normally very low in blood or urine. High levels of phenylpyruvic acid can be found in the urine of individuals with phenylketonuria (PKU) an inborn error of metabolism.

Ricinine is a major alkaloid in Ricinus communis plant with hepatoprotection in CCl4 -induced liver damage.

N-3-Oxo-octanoyl-L-homoserine lactone, a quorum-sensing signal, is an Agrobacterium autoinducer.