New Insights into Identification, Distribution, and Health Benefits of Polyamines and Their Derivatives

Polyamines and their derivatives are ubiquitously present in free or conjugated forms in various foods from animal, plant, and microbial origins. The current knowledge of free polyamines in foods and their contents is readily available; furthermore, conjugated polyamines generate considerable recent research interest due to their potential health benefits. The structural diversity of conjugated polyamines results in challenging their qualitative and quantitative analysis in food. Herein, we review and summarize the knowledge published on polyamines and their derivatives in foods, including their identification, sources, quantities, and health benefits. Particularly, facing the inherent challenges of isomer identification in conjugated polyamines, this paper provides a comprehensive overview of conjugated polyamines' structural characteristics, including the cleavage patterns and characteristic ion fragments of MS/MS for isomer identification. Free polyamines are present in all types of food, while conjugated polyamines are limited to plant-derived foods. Spermidine is renowned for antiaging properties, acclaimed as antiaging vitamins. Conjugated polyamines highlight their anti-inflammatory properties and have emerged as the mainstream drugs for antiprostatitis. This paper will likely help us gain better insight into polyamines and their derivatives to further develop functional foods and personalized nutraceuticals.

Conjugated Polyamines in Root Plasma Membrane Enhanced the Tolerance of Plum Seedling to Osmotic Stress by Stabilizing Membrane Structure and Therefore Elevating H+-ATPase Activity

Polyamines are small positively charged molecules in plants and play important functions in many biological processes under various environmental stresses. One of the most confounding problems relating to polyamines (PAs) in stresses is the lack of understanding of the mechanisms underlying their function(s). Furthermore, a limited number of studies have addressed this issue at the sub-cellular level, especially in tree plants under drought stress. Therefore, in this research, by simulating natural drought stress with polyethylene glycol (PEG) osmotic stress, the relationship between the levels of conjugated polyamines and the activity of H⁺-ATPase in the plasma membrane was elucidated with the roots of two plum (Prunus salicina L.) cultivars, which were different in drought tolerance, as experimental materials. Furthermore, free PA levels and the activities of S-adenosylmethionine decarboxylase (SAMDC) and transglutaminase (TGase), which were closely associated with the levels of free and conjugated PAs, were also detected. Results showed that under osmotic stress, the increases of the levels of non-covalently conjugated (non-CC) spermidine (Spd) and spermine (Spm), covalently conjugated (CC) putrescine (Put) and Spd in the plasma membrane of drought-tolerant Ganli No. 5 were more significant than those of drought-sensitive Suli No. 3, indicating that these conjugated PAs might be involved in the tolerance of plum seedlings to stress. Furthermore, the conjugated PAs were closely correlated with plum seedling growth, water retention capacity, plasma membrane damage degree, and hydrogen (H⁺)-ATPase activity in the plasma membrane. To get more complementary pieces of evidence, we subjected plum seedlings to combined treatments of PEG and exogenous PA (Spd and Spm), and an inhibitor of SAMDC [methylglyoxal-bis (guanylhydrazone), (MGBG)] or TGase (o-phenanthroline). These results collectively suggested that non-CC Spd and Spm, CC Put and Spd in plasma membrane might function in enhancing the tolerance of plum seedlings to osmotic stress by stabilizing membrane structure and therefore elevating H⁺-ATPase activity.