A Bioactive Benzyl Terpene from Acridocarpus smeathmannii Inhibits Human Prostate Smooth Muscle Contractility

Abstract

The roots of Acridocarpus smeathmannii were identified as a natural source of the benzyl-terpene 2-(5-isopropyl-4-methoxy-2-methylbenzyl)phenol (FAH-01, chamanen), which was isolated and structurally characterized by chromatographic and spectroscopic techniques, including two-dimensional NMR analysis. Functionally, FAH-01 exerted pronounced inhibitory effects on human prostate smooth muscle contractility. In organ bath experiments, it reduced noradrenaline-induced contractions by up to 72% and phenylephrine-induced contractions by up to 63%, without affecting agonist potency (pEC50). During electrical field stimulation (2–32 Hz), FAH-01 suppressed neurogenic contractile responses, indicating interference with adrenergic and nerve-mediated signaling pathways. Beyond smooth muscle modulation, FAH-01 showed antioxidant activity in the DPPH radical-scavenging assay and exhibited early-stage toxicity in the Artemia salina cysts. Collectively, these findings identify FAH-01 as a bioactive natural product with potent inhibitory effects on adrenergic and neurogenic contraction in human prostate smooth muscle, supporting its therapeutic potential in conditions associated with increased smooth muscle tone. Further preclinical studies are needed to elucidate its mechanisms of action, toxicity, and in vivo efficacy.