Roquefortine C, a cyclopeptide derived from the diketopiperazine cyclo(Trp-dehydroHis), is a secondary metabolite produced by several Penicillium species, especially by Penicillium roqueforti, which is used as starter culture for blue cheese production. Although roquefortine C is frequently detected in the products, it obviously has an insignificant toxicity to humans after ingestion. However, intoxications in dogs and cattle have been reported. Its bacteriostatic activities against Gram-positive bacteria lead to Roquefortine C potential use in antibiotics, but its development as a drug has been stopped due to its neurotoxic effects in mice. Roquefortine C activates P-gp and inhibits P450-3A and other haemoproteins. Roquefortine C can serve as a sensitive biomarker for penitrem A intoxication.

Riboflavin 5'-sulfate is a derivative of riboflavin conjugated with a sulfate group at the terminal end of the ribityl moiety. Riboflavin 5' and 3' sulfate have been observed to accumulate in the roots of iron-deficient sugar beets.

Ricinine is an alkaloid originally isolated from the Ricinus communis, or castor-oil plant. Ricinine can be found in all parts of the plant and it is a quite strong insecticide. The castor seeds contain approximately 0.2% of the alkaloid. Ricinine or 3-cyano-4-methoxy-N-methyl-2-pyridone (CAS 524-40-3) belongs to the group of piperidine alkaloids. Ricinine is a useful scaffold for the synthesis of new antimicrobial and antiquorum-sensing derivatives in spite of its poor contribution to the antimicrobial activity of the plant extracts. Ricinine activated the Wnt signaling pathway by inhibiting casein kinase 1α. Ricinine-elicited seizures as a novel chemical model of convulsive seizure.