Six spice essential oils (sage, rosemary, caraway, cumin, clove, and thyme) and their basic ingredients were tested for their inhibitory effect against 3 strains of Gram-negative bacteria, 4 strains of Gram-positive bacteria, one acid fast bacterium, and one yeast. Preliminary screening of antimicrobial activity of the essential oils was done using the filter paper disc agar diffusion method. The minimum inhibitory concentration for each essential oil against various micro-organisms was also measured. Very low concentrations (0.25 – 12 mg/ml) of the various essential oils were sufficient to prevent microbial growth. The data show that Gram-positive bacteria were more sensitive to the antimicrobial compounds in spices than Gram-negative. The inhibition zones of different microbial growth produced by various essential oils were similar to those produced by their basic compounds. Thyme and cumin oils possessed very strong antimicrobial activity compared with the other essential oils. There was a relationship...

• Agricultural and food industrial byproducts can be used as source of health-promoting compounds. • Pomegranate leaves and peels, fig leaves, guava leaves and olive leaves was evaluated. • No solvent was used in the extraction to avoid the bad effects of many solvents on human health. • Pomegranate peels crude juice exhibited the strong antioxidant activity. • Pomegranate peels crude juice can be used as food supplement and to retard lipid oxidation.