HPLC and GC–MS analyses of phytochemical compounds in Haloxylon salicornicum extract: Antibacterial and antifungal activity assessment of phytopathogens

Abstract

The present study investigated the phytochemical constituents and antimicrobial effects of aqueous methanolic extract of Haloxylon salicornicum against some phytopathogenic bacterial and fungal strains. The selected bacterial strains were Pectobacterium carotovorum, Pectobacterium atrosepticum, Ralstonia solanacearum, and Streptomyces scabiei, while fungal strains were Fusarium oxysporum, Botrytis cinerea, and Rhizoctonia solani. The extract demonstrated significant efficacy against P. atrosepticum and P. carotovorum at a concentration of 1,000 µg/mL, resulting in inhibition zones measuring 12.3 and 11 mm, respectively. Furthermore, the extract demonstrated considerable effectiveness against fungal strains, achieving an impressive fungal growth suppression rate of 68.8% against R. solani at a concentration of 5,000 µg/mL. The high-performance liquid chromatography analysis identified nine notable phenolic compounds and six common flavonoid compounds in the extract. The identified phenolic compounds in the highest quantities were gallic acid (6427.5 µg/g), vanillin (1145.4 µg/g), chlorogenic acid (498.1 µg/g), and syringic acid (322.5 µg/g). Apigenin (1155.9 µg/g), daidzein (460.9 µg/g), quercetin (382.7 µg/g), and naringenin (160.4 µg/g) exhibited the most significant concentrations of flavonoid compounds. Gas chromatography–mass spectrometry analysis revealed that n-hexadecanoic acid (53.7%), 9-octadecenoic acid (26.9%), 9,12-octadecadienoic acid (Z,Z) (8.67%), palmitic acid, and TMS derivative (4.36%) were the predominant compounds in the extract. Consequently, the H. salicornicum aqueous methanolic extract could be used for the first time as an environmentally safe antimicrobial pesticide agent against plant pathogens to reduce the excessive use of chemical pesticides.