Chemical composition and antimicrobial activity of the essential oil of senescent leaves of guava ( L.).

The aim of the study was to investigate the chemical composition and antimicrobial activity of the essential oil of the senescent leaves of L. (Myrtaceae). The hydrodistilled essential oil of the leaves was analysed by GC-FID and GC-MS. The antimicrobial activity of the oil was assessed against human and plant pathogenic microorganisms by disc diffusion, microdilution broth and poison food techniques. A total of forty-six constituents, representing 90.9% of the total oil composition were identified. Major constituents of the oil were limonene (29.1%), ()-caryophyllene (15.7%), caryophyllene oxide (8.8%), caryophylla-4(12),8(13)-dien-5-ol (6.5%), ()-nerolidol (4.0%), -cadinol (3.4%), and muurola-4,10(14)-dien-1--ol (2.5%). The chemical composition of the examined essential oil was quite different from those reported earlier. The essential oil showed significant inhibition of human pathogenic bacteria (MIC: 0.065-0.261 mg/mL) and plant pathogenic fungi, namely (86.02%) and (82.80%).