Potential impacts of Pinus halepensis Miller trees as a source of phytochemical compounds: antibacterial activity of the cones essential oil and n-butanol extract

Abstract

The Aleppo pine (Pinus halepensis Miller) trees grown in the agricultural lands with high biodiversity, and considered as a potential source for chemical and therapeutic compounds. Essential oil (EO) and n-butanol fraction (But-fr) of Aleppo pine cones were evaluated against the growth of four plant bacterial pathogens (Dickeya solani, Pectobacterium atrosepticum, Ralstonia solanacearum, and Agrobacterium tumefaciens) and four human pathogenic bacteria (Bacillus subtilis ATCC 6633, Sarcina lutea ATCC 9341, Escherichia coli ATCC 8739, and Staphylococcus aureus ATCC 6538). The diameter of the inhibition zone (IZ) and the minimum inhibitory concentrations (MICs) were measured. At 2000 μg/mL, But-fr showed the strongest activity against D. solani, P. atrosepticum, and R. solanacearum with inhibition zones (IZs) of 14.33 mm, 12.33 mm, and 15.33 mm, respectively. At 2000 μg/mL, EO showed the best activity against A. tumefaciens with an IZ value of 12.67 mm. Weak activity was observed by applying the EO and But-fr against B. subtilis and S. lutea, while good activity was recorded by But-fr against E. coli and S. aureus with IZs values of 13.67 mm and 11.33 mm, respectively, at 2000 μg/mL. Gas chromatography-mass spectrometry (GC/MS) analysis reported that the EO from cones contained mainly caryophyllene (15.17%), α-pinene (13.51%), and caryophyllene oxide (12.57%); But-fr contained 3,4-dimethyldihydrofuran-2,5-dione (36.25%), and 2-methylenecholestan-3-ol (18.12%). The phytochemical But-fr extract of Aleppo pine cones demonstrated moderate antibacterial effects against the studied bacteria.