Comparative chemical composition and antimicrobial activity of essential oils from leaves and seeds of star apple (Chrysophyllum cainito L.)

In this study, the essential oils of seeds and leaves from Star Apple (Chrysophyllum cainito L) were profiled and screened for their antimicrobial potential. The volatile oils were isolated by means of hydro-distillation process using a Clevenger-type apparatus. The oils were analysed by gas chromatography coupled with mass spectrometry (GC-MS). Antimicrobial activity of the isolated essential oils was investigated by agar well diffusion method against seven bacterial isolates and two fungal isolates. The docking studies of the essential oil compounds and the reference drug were carried out using Maestro software. Docking calculation were executed on the Schrodinger suite molecular docking platform. A total of thirty-one chemical constituents were identified in essential oil of leaves with β-ocimene (12.37%), TMTT 1,3,7,11-Tridecatetraene (9.73%), α-farnesene (9.19%) and cyclofenchene (7.16%) as major components. Twenty-eight compounds were characterised in the seeds oil with citral (36.60%), Geranial, (28.50%) and (E)-3,7-Dimethylocta-3,6-dienal (10.82%) as main constituents. The two oils contained beta and alpha ocimene, cyclofenchene and pelargonaldehyde in common. The lowest MIC observed with essential oil of the leaves was 0.781251 mg/mL for Staphylococcus aureus and 1.625 mg/mL for Escherichia coli. The lowest MIC recorded for essential oil of the seeds was 12.5 mg/mL for Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae. Essential oil obtained from leaves exhibited higher antimicrobial and antifungal activities against all tested organisms than essential oil of seeds. Compound 11 with -3.303 kcal/mol, with the best docking score of all compound from the leaf and seed of all the sitemaps and this is close to that of reference compound on sitemap three with docking score of -5.055 kcal/mol. Also, the anti E. coli activities of both leaf and seed EOs could be associated with inhibitory activities of the compound on the active sites of the protein. In conclusion, the essential oils extracted from the leaves and seeds of Chrysophyllum cainito demonstrated notable antimicrobial potential, with the leaf oil exhibiting superior activity, likely due to its richer chemical profile and stronger interaction of its constituents with microbial target sites, as supported by both in vitro and in silico analyses.