The chemical profile and seasonal variation of the composition of the phenolic acids in different plant parts of Centaurea sp.

This study investigated the seasonal variation (over seven months) of phenolic acid (PHA) components in different parts of Centaurea sp. The primary objective was to determine the pattern of variation, while the secondary objective was to identify which month or growth stage provides a greater total PHA content or percentage of bioactive components. Different patterns of seasonal variations were highlighted for the different PHA components and their classes (hydroxybenzoic and -cinnamic acids) in different parts of the plant. The leaves exclusively provided the highest PHA contents, with maximum values reached in April (1368.06 μg/g). The major hydroxybenzoic acid derivatives (HBAs) identified in the leaves were vanillic acid (VaA) "154.18-374.06 μg/g" and protocatechuic acid (PA) "9.37-595.61 μg/g", while the major hydroxycinnamic acid derivatives (HCAs) were p-coumaric acid (p-CoA) "109.35-261.77 μg/g", m-coumaric acid (m-CoA) "10.22-70.57 μg/g", and ferulic acid (FeA) "35.54-109.13 μg/g". The maximum percentage of PA was obtained in April "595.61 μg/g", while the maximum p-CoA content was obtained in January "261.77 μg/g". Therefore, the leaves can be recommended as the optimal source of PHAs. If there is a specific interest in certain PHA components, we recommend collection in either January or April. Multivariate statistical analysis (PCA & AHC) showed the existence of two main clusters. The first cluster comprised the leaves, distinguished by the highest VaA, PA, and p-CoA contents. The second cluster comprised roots and the root bark samples. This study provides information on the development of PHAs in different parts of Centaurea sp. and explores potential applications. It will be of considerable interest for determining the optimal harvesting time of shrub species used for their medicinal properties and bio-active phenolic contents.