Influence of seasonality on the phenolic composition of Secondatia floribunda A.DC (Apocynaceae) during its phenological cycle

This study had as its objective to analyze the phenolic composition variations of the Secondatia floribunda A.DC stem bark and heartwood under the influence of seasonality and in different phenological phases. To analyze the chemical composition variation, quarterly collections were performed over 2 years, including both rainy and dry seasons as well as the different vegetative and reproductive phases of the species. Phenolic compounds were identified and quantified by HPLC–DAD. During the study period, S. floribunda presented leaf fall, budding, flowering, and fruiting, the last two phases coinciding with the rainy season. The ethanolic extracts from the stem bark and heartwood showed yields varying from 1.8 to 36%, with higher values between the rainy season (with low levels of precipitation) and the dry season, showing no relation with the phenological phases. The phenolic composition of the stem bark and heartwood extracts over the 2 years of study was qualitatively identical, except for the absence of the flavonoid apigenin in the heartwood. The compounds varied within the plant parts and showed level alterations during all the collections, responding both quantitatively and qualitatively to seasonality and phenology. The extracts presented high phenolic compound quantities during the rainy season, especially during the reproductive phases. These informations are useful to increase the knowledge surrounding this species and to contribute to the understanding of defense mechanisms and adaptation to different seasonal periods and to the establishment of the best period to obtain higher concentrations of phenolic compounds responsible for different therapeutic activities.