Calcitonin, eel is the thyroid hormone peptide that contributes to the regulation of calcium homeostasis, widely used in the research of postmenopausal osteoporosis.

Aristolochic acids are a family of carcinogenic, mutagenic, and nephrotoxic compounds commonly found in the Birthwort (Aristolochiaceae) family of plants.

ortho-Hydroxyphenylacetic acid (2-hydroxybenzeneacetic acid) can be found in a number of food items such as natal plum lemon verbena half-highbush blueberry and parsley which makes ortho-hydroxyphenylacetic acid a potential biomarker for the consumption of these food products. ortho-Hydroxyphenylacetic acid can be found primarily in blood feces and urine.