StructureActivity Relationships of Antimicrobial Gallic Acid Derivatives from Pomegranate and Acacia Fruit Extracts against Potato Bacterial Wilt Pathogen

• Published in: Chemistry & biodiversity 2015-06, Vol.12 (6), p.955-962
• Main Authors: Farag, Mohamed A., Al-Mahdy, Dalia A., Salah El Dine, Riham, Fahmy, Sherifa, Yassin, Aymen, Porzel, Andrea, Brandt, Wolfgang
• Format: Article
• Language: English
• Subjects: Acacia; Acacia - chemistry; Acacia arabica; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - isolation & purification; Anti-Bacterial Agents - pharmacology; Bacteria; Fruit - chemistry; Gallic Acid - chemistry; Gallic Acid - isolation & purification; Gallic Acid - pharmacology; Lycopersicon esculentum; Microbial Sensitivity Tests; Molecular Structure; Plant Extracts - chemistry; Plant Extracts - isolation & purification; Plant Extracts - pharmacology; Punica granatum; Punicaceae - chemistry; Ralstonia solanacearum; Ralstonia solanacearum - drug effects; Ralstonia solanacearum - growth & development; Solanum tuberosum; Structure-Activity Relationship; Structureactivity relationships (SAR)
• ISSN: 1612-1872; 1612-1880
• DOI: 10.1002/cbdv.201400194

Bacterial wilts of potato, tomato, pepper, and or eggplant caused by Ralstonia solanacearum are among the most serious plant diseases worldwide. In this study, the issue of developing bactericidal agents from natural sources against R. solanacearum derived from plant extracts was addressed. Extracts prepared from 25 plant species with antiseptic relevance in Egyptian folk medicine were screened for their antimicrobial properties against the potato pathogen R. solancearum by using the disc‐zone inhibition assay and microtitre plate dilution method. Plants exhibiting notable antimicrobial activities against the tested pathogen include extracts from Acacia arabica and Punica granatum. Bioactivity‐guided fractionation of A. arabica and P. granatum resulted in the isolation of bioactive compounds 3,5‐dihydroxy‐4‐methoxybenzoic acid and gallic acid, in addition to epicatechin. All isolates displayed significant antimicrobial activities against R. solanacearum (MIC values 0.5–9 mg/ml), with 3,5‐dihydroxy‐4‐methoxybenzoic acid being the most effective one with a MIC value of 0.47 mg/ml. We further performed a structure–activity relationship (SAR) study for the inhibition of R. solanacearum growth by ten natural, structurally related benzoic acids.