Physiological Indicators of Paeoniflorin and Caffeine in Modulating the Motility of Caenorhabditis elegans Via Adenosine Receptor

Aims: Paeoniflorin exhibits a broad range of in vitro and in vivo pharmacological effects. However, its potential as a drug targeting adenosine receptors remains largely unexplored.

Methodology: In this study, the wild-type N2 strain and the Ador-1 gene knockout EG6890 strain of Caenorhabditis elegans were used to compare the effects of different drug concentrations on nematode locomotion and feeding behavior. Four behavioral indicators—swimming, head swing, body bending, and pharyngeal pumping—were quantitatively assessed. 0.03, 0.3, and 3 mM paeoniflorin and 0.05, 0.5, and 5 mM caffeine were involved for physiological evaluation. Additionally, molecular docking analysis was performed to evaluate the interaction between paeoniflorin and the adenosine receptor, Ador-1 protein.

Results: The results demonstrated that paeoniflorin (0.03–3 mM) inhibited motility in a dose-dependent tendency (P<0.01). Caffeine significantly enhanced the movement ability of N2 nematodes at low concentrations (0.05–0.5 mM) (P<0.01), whereas higher concentrations (5 mM) exerted an inhibitory effect. Molecular docking analysis revealed that paeoniflorin exhibited a binding energy of -6.9 kcal/mol with the Ador-1 protein, confirming its targeting capability. Specific interaction analysis showed that paeoniflorin formed van der Waals interactions with SER6 of Ador-1, π–π and amide–π stacking interactions with GLY5 and TYR271, C–H bonding with TRP68, and alkyl and π–alkyl interactions with LEU267, VAL8, and LEU272.

Conclusion: This study highlights the critical role of nematode adenosine receptors in the drug's mechanism of action and provides an experimental foundation for receptor-based drug screening using the nematode model.