Profiling and bioactivity of polyphenols from the Omani medicinal plant Terminalia dhofarica (syn. Anogeissus dhofarica)

Several polyphenol-rich Terminalia species (Combretaceae) are known to accelerate wound healing. Recently, the Omani medicinal plant Anogeissus dhofarica (now Terminalia dhofarica) was attributed to the genus Terminalia based on phylogenetic studies. Leaves, bark, and extracts of T. dhofarica are traditionally used for various medicinal purposes, including wound treatment and personal hygiene. In the present study, the phytochemical profile of leaves from T. dhofarica was evaluated by ultra-high-performance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (UHPLC-ESI-HRMS) and nuclear magnetic resonance (NMR) spectroscopy. Simple phenolics, polyphenolics (e.g., flavonoids and tannins) and their glucosides were characterized as major metabolite classes. In addition, 20 phenolics were isolated and structurally identified. Nine of these compounds were never described before for T. dhofarica. For the first time, we provide complete NMR data for 1-O-galloyl-6-O-p-coumaroyl-d-glucose (1). Biological screening demonstrated moderate efficacy against the Gram-negative bacterium Aliivibrio fischeri, the phytopathogenic fungus Septoria tritici, and the oomycete Phytophthora infestans. In summary, the data expand the knowledge of the phytochemistry of the underexplored species T. dhofarica and underscore its potential for therapeutic applications, particularly in the context of traditional medicine.