Essential oils from the leaves of Mitrephora calcarea Diels ex Weeras. & R.M.K.Saunders and M. maingayi Hook.f. & Thomson: Chemical analysis, biological activity, and molecular docking

The current study first describes the chemical profile of the leaf essential oils from two Annonaceous plants. Hydro-distillation and sequential GC-FID/MS analyses resulted in the  identification of (E)-caryophyllene (29.35%), γ-curcumene (22.91%), β-pinene (12.37%), and bicyclogermacrene (6.16%) as the major compounds in Mitrephora calcarea leaf essential oil. In the meantime, M. maingayi leaf essential oil was associated with the appearance of the main compounds (E)-caryophyllene (31.94%), (E)-β-ocimene (12.23%), α-humulene (9.00%), γ-elemene (6.82%), germacrene B (7.57%), and δ-cadinene (5.79%). These two essential oils had moderate cytotoxicity towards A549 cancer cells with IC50 values of 56.85±0.35 – 59.16±0.43 μg/mL. M. calcarea leaf essential oil showed strong antimicrobial activity against the yeast Candida albicans ATCC 10231 with a MIC value of 32 μg/mL. Both essential oils also strongly exhibited mosquito larvicidal activity against the third-instar stage of Aedes aegypti and Culex quinquefasciatus larvae with 24-h and 48-h LC50 values of less than 50 μg/mL. The molecular docking study highlighted (E)-caryophyllene to exert the highest binding affinity for the target protein C. albicans sterol 14α demethylase (CYP51), while bicyclogermacrene demonstrated a strong affinity for Cx. quinquefasciatus odorant-binding protein (OBP). The key interactions driving these affinities were predominantly hydrophobic.