GPCR Pharmacological Profiling of Aaptamine from the Philippine Sponge Stylissa sp. Extends Its Therapeutic Potential for Noncommunicable Diseases

We report the first isolation of the alkaloid aaptamine from the Philippine marine sponge Stylissa sp. Aaptamine possessed weak antiproliferative activity against HCT116 colon cancer cells and inhibited the proteasome in vitro at 50 µM. These activities may be functionally linked. Due to its known, more potent activity on certain G-protein coupled receptors (GPCRs), including [Formula: see text]-adrenergic and [Formula: see text]-opioid receptors, the compound was profiled more broadly at sub-growth inhibitory concentrations against a panel of 168 GPCRs to potentially reveal additional targets and therapeutic opportunities. GPCRs represent the largest class of drug targets. The primary screen at 20 µM using the [Formula: see text]-arrestin functional assay identified the antagonist, agonist, and potentiators of agonist activity of aaptamine. Dose-response analysis validated the [Formula: see text]-adrenoreceptor antagonist activity of aaptamine (ADRA2C, IC(50) 11.9 µM) and revealed the even more potent antagonism of the [Formula: see text]-adrenoreceptor (ADRB2, IC(50) 0.20 µM) and dopamine receptor D4 (DRD4, IC(50) 6.9 µM). Additionally, aaptamine showed agonist activity on selected chemokine receptors, by itself (CXCR7, EC(50) 6.2 µM; CCR1, EC(50) 11.8 µM) or as a potentiator of agonist activity (CXCR3, EC(50) 31.8 µM; CCR3, EC(50) 16.2 µM). These GPCRs play a critical role in the treatment of cardiovascular disease, diabetes, cancer, and neurological disorders. The results of this study may thus provide novel preventive and therapeutic strategies for noncommunicable diseases (NCDs).