Effects of annulatophenone, annulatophenonoside, and acetylannulatophenonoside on brain synaptosomes and small cerebral vessels

Three benzophenones (annulatophenone Hd15, annulatophenonoside Hd21, and acetylannulatophenonoside Hd22) isolated from the aerial parts of Hypericum annulatum Moris were evaluated for their neuroprotective properties. All compounds demonstrated significant neuroprotection in an in vitro 6-hydroxydopamine model using isolated rat brain synaptosomes. Annulatophenone Hd15 exhibited the strongest effect, enhancing synaptosomal viability and GSH levels by 35% and 25%, respectively, surpassing the positive control, silybin (25% and 15%). The lower activity of annulatophenonoside Hd21 is attributed to its sugar moiety, while acetylation in acetylannulatophenonoside Hd22 further reduced efficacy. The effects of the benzophenones on the contractility of the rat basilar artery ( a. basilaris ) were also evaluated, with only Hd22 increasing vascular tone.