Ritalinic acid is an inactive, major metabolite of methylphenidate, a schedule II drug in the United States commonly used as a psychostimulant drugs methylphenidate and ethylphenidate. The elimination half-life of methylphenidate is relatively short (approximately 2 hours); therefore it is also available in extended release (ER) forms. The main metabolite is ritalinic acid, and the methylphenidate metabolites are mostly excreted in urine.

Traumatic acid (TA) is a plant hormone (cytokinin) that in terms of chemical structure belongs to the group of fatty acids derivatives. It was isolated from Phaseolus vulgaris. It was discovered, that TA showed a stimulatory effect on antioxidative enzyme activity, reduced glutathione, thiol group content, and lipid peroxidation in physiological conditions. TA exhibited protective properties against ROS production. Thus, TA could be a potentially powerful agent with applications in the treatment of many skin diseases connected with oxidative stress and collagen biosynthesis disorders.

p-Toluenesulfonic acid (PTSA) is an organic compound with the formula CH3C6H4SO3H. An aromatic sulfonic acid, often used as a strong acid catalyst. p-Toluenesulfonic acid monohydrate has been used as a reducing agent for the reductive amination of ketones and aldehydes. In the presence of p-Toluenesulfonic acid monohydrate novel deazaflavin-cholestane hybrid compounds have been synthesized in a condensation reaction. 2-Phenylethyl alpha-glucoside has also been synthesized in the presence of p-Toluenesulfonic acid monohydrate. p-toluenesulfonic acid esters, are a common class of reagents used in the pharmaceutical industry as alkylating agents, catalysts, and in purification steps of the chemical synthesis of a drug substance.

Picolinic acid is an organic compound, is a derivative of pyridine with a carboxylic acid substituent at the 2-position. Picolinic acid is a bidentate chelating agent of elements such as chromium, zinc, manganese, copper, iron, and molybdenum in the human body. Many of its complexes are charge-neutral and thus lipophilic. After its role in absorption was discovered, zinc dipicolinate dietary supplements became popular as they were shown to be an effective means of introducing zinc into the body. Picolinic Acid is an endogenous metabolite of L-tryptophan (TRP) that has been reported to possess a wide range of neuroprotective, immunological, and anti-proliferative effects within the body. However, the salient physiological function of this molecule is yet to be established. The synthesis of picolinic acid as a product of the kynurenine pathway (KP) suggests that, similar to other KP metabolites, picolinic acid may play a role in the pathogenesis of inflammatory disorders within the CNS and possibly other organs.