Correlation between Genetic Variability, Chemical Composition and Antimicrobial Activity of Essential Oils Isolated from Avocado Cultivars Grown in Egypt

Abstract

Persea americana Mill. (Lauraceae) has been successfully propagated in Egypt for the commercial production of avocado fruits. Four cultivars (one pure Mexican and three Mexican-Guatemalan hybrids) were investigated for the chemical composition and antimicrobial activity of their leaves' essential oils. The hydro-distilled oils from Bacon, Duke, Ettinger and Pinkerton cultivars were analyzed using Gas Chromatography/ Mass spectrometry (GC/MS) and Gas Chromatography/ Flame Ionization Detector (GC/FID). Total of 20 compounds were identified with estragole, methyl eugenol and -pinene as the major constituents. Chemometric analysis performed on the GC/FID data indicated close similarity between the essential oils of Bacon and Ettinger cultivars, while that of the Duke cultivar was the most distant. This classification was further supported by comparative DNA fingerprinting using Random Amplified Polymorphic DNA (RAPD) technique. Essential oils of all cultivars had no antifungal activity against Candida albicans or Aspergillus niger but showed good antimicrobial activities against Streptococcus mutans and Salmonella typhimurium with IC50 values between 0.4 and 20 L/mL