Chemical Profiling and Vascular Effects of a Hydroalcoholic Extract of Calophyllum longifolium Willd: Role of Nitric Oxide and Potassium Channels

<i>Calophyllum</i> spp. infusions are used to treat varicose veins, hemorrhoids, and hypertension. However, the chemical composition and mechanisms of action are poorly understood. Accordingly, the aim of this study was to investigate the phytochemical composition and vascular effects of hydroalcoholic extracts of <i>Calophyllum longifolium</i>. Phytochemical profiling was performed using ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF-MS). Extract effects on rat aortic rings and aortic vascular smooth muscle cells (VSMCs) were evaluated using wire myography and photometric measurement of intracellular Ca²⁺, respectively. UHPLC-ESI-Q-TOF-MS revealed the presence of coumarins, xanthones, flavonoids, triterpenes, and phenolic acids. Coumarin-resveratrol hybrids, such as gut-70 derivatives, were also abundant. In aortic rings from normotensive rats, <i>C. longifolium</i> induced a biphasic vascular response whereby low concentrations (1 μg/mL) produced significant vascular relaxation, whereas high concentrations (100 μg/mL) produced contraction. Blockade of ATP-sensitive (K_ATP) or voltage-gated (K_V) potassium channels attenuated these effects. Furthermore, effects were not observed in preparations preincubated with L-NG-Nitro-L-arginine methyl ester (L-NAME) or in endothelium-denuded rings. In aortic VSMCs, extracts (1 µg/mL) rapidly reduced sarcoplasmic reticulum (SR) Ca²⁺ content. This study provides the first UHPLC-ESI-Q-TOF-MS chemical profile of <i>C. longifolium</i>, revealing diverse bioactive metabolites. It is also the first to demonstrate that <i>C. longifolium</i> exerts an endothelium-dependent, nitric oxide- and Ca²⁺-mediated biphasic effect on vascular function. Taken together, these findings highlight <i>C. longifolium</i> as a potential novel source of vasculotropic phytopharmaceuticals.