Human Body Malodor and Deodorants: The Present and the Future

Human axillary malodor negatively influences impression-related appearance, confidence, and hygiene, and ultimately decreases quality of life. Malodor formation involves three steps: vesiculation of odorless precursors within the human body, influx of these precursors into the intracellular space of bacteria, such as <i>Corynebacterium striatum</i> and <i>Staphylococcus hominis</i>, and efflux of malodorous metabolites into the axilla after conversion by axillary malodor-releasing enzymes (AMREs). Malodor deodorants are currently in use, and their formulation strategies, based on the ingredients, can be classified as follows: anti-sweating, antiproliferation of malodor-forming bacteria, masking (neutralizing) effects against malodor, and deodorization. However, current deodorants have several adverse effects. To reduce such effects while enhancing malodor suppression, a strategy targeting the specific step in malodor formation should be developed, such as the use of ABCC11 pump inhibitors, specific bacterial active pump controllers, and AMRE blockers.