Boswellia carterii Essential Oil and Constituents Alleviate Anxiety-like Behavior in Zebrafish Larvae Model

Herbal medicines are increasingly recognized as alternative therapies for anxiety. Boswellia species are traditionally used in East Africa to manage central nervous system disorders. In the present study, Boswellia carterii, its major compound α-pinene, and the enantiomers (-)-α-pinene and (+)-α-pinene were investigated for potential anxiolytic activity using an in vivo zebrafish larvae model. Chiral analysis using Gas Chromatography-Time-of-Flight Mass Spectrometry confirmed α-pinene as a scalemic mixture of (-)-α-pinene and (+)-α-pinene in B. carterii essential oil. In behavioral assays, B. carterii essential oil exhibited significant anxiolytic activity at 50 and 100 μL/L (p < 0.05), and α-pinene at all tested concentrations (p < 0.05), as measured by anxiolytic effect indicators. When tested individually across a concentration range, both enantiomers displayed significant anxiolytic activity in vivo (p < 0.05). Molecular docking and MM/GBSA analysis further demonstrated the interactions of α-pinene and its enantiomers with various receptor targets, with the strongest binding affinity observed for the CB2 receptor, although pharmacological validation is still required. Both (-)- and (+)-α-pinene exhibited binding energies comparable to the known CB2 agonist AM1241, indicating that the in vivo anxiolytic-like effects were not distinctly enantioselective. The stereochemistry did, however, affect the predicted binding orientation in the active site and in-silico ligand-receptor interactions, supporting further investigation of the α-pinene enantiomers as lead compounds with activity at the CB2 receptor.