Polyamine Oxidase and Diamine Oxidase Activities in Human Milk during the First Month of Lactation

Objective: Human milk (HM) is the ideal food for all newborns and infants. Apart from various bioactive compounds, including cytokines, antibodies, hormones, vitamines, it also contains polyamines, such as spermine (Sp), spermidine (Spd) and putrescine (Put).
Aim: The present study investigated polyamine metabolism in colostrum and mature human milk by measuring the polyamine oxidase (PAO) and diamine oxidase (DAO) enzyme activities, which are necessary for polyamine catabolism, as well as by determining the malondialdehyde (MDA) levels, the final product of polyamine biodegradation.
Methods: The PAO, DAO activity and MDA levels were quantified in colostrum (1st and 2nd day) as well as in mature human milk, 30th day of lactation.
Findings: We found the steady increase of PAO activity and steady decrease of DAO activity and MDA levels during first month of lactation.
Conclusion: Since the products of PAO activity such as, amino aldehydes and hydrogen peroxide (H2O2) might have potential antimicrobial effects, promoting the oxidative stress, it is likely that human milk PAO throughout the lactation period, contributes to the protective effects of human milk.

Keywords
Human Colostrum; Mature Milk; Polyamine Oxidase; Diamine Oxidase; Malondialdehyde