title: Galbanic acid from Ferula szowitsiana enhanced the antibacterial activity of penicillin G and cephalexin against Staphylococcus aureus.
abstract: In this study the enhancement effect of Ferula szowitsiana roots' acetone extract on the antibacterial activity of penicillin G and cephalexin was evaluated against Staphylococcus aureus. Disk diffusion and broth dilution methods were used to determine the antibacterial activity of these antibiotics in the absence and presence of plant extract and its various fractions separated by TLC plate. The active component of plant extract involved in enhancement of penicillin G's and cephalexin's activities had Rf=0.336 on a TLC plate. The spectral data ((1)H-, (13)C-NMR) of this compound revealed that this compound was 7-[6-(beta-carboxyethyl)-5-isopropylidene-1,2-dimethylcyclo-hexylmethoxy]coumarin (galbanic acid), previously isolated from Ferula assa-foetida. In the presence of sub-inhibitory concentration of galbanic acid (100 microg/ml) the MIC of penicillin G for S. aureus decreased from 64 to 1 (a sixteen four-fold decrease) and for cephalexin from 128 to 1 microg/ml (a one hundred twenty eight-fold decrease). The highest fold decrease in MIC was observed for cephalexin in combination of galbanic acid against test strain. These results signify that the low concentration of galbanic acid (100 microg/ml) potentiates the antimicrobial action of penicillin G and cephalexin suggesting a possible utilization of these compounds in combination therapy against S. aureus.
authors.affiliation: Department of Pharmaceutical Biotechnology and Medicinal Plant Research Center, Faculty of Pharmacy, Medical Sciences/University of Tehran, Tehran 1417614411, Iran. shahverd@sina.tums.ac.ir
authors.forename: Ahmad Reza
authors.initials: AR
authors.lastname: Shahverdi
authors.forename: Ali
authors.initials: A
authors.lastname: Fakhimi
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Zarrini
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Dehghan
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Iranshahi
mesh_terms: D000096:Acetone; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002506:Cephalexin / Q000494:pharmacology*; D002855:Chromatography, Thin Layer; D003374:Coumarins / Q000302:isolation & purification / Q000494:pharmacology*; D005309:Ferula / Q000737:chemistry*; D007492:Iran; D008826:Microbial Sensitivity Tests; D010400:Penicillin G / Q000494:pharmacology*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018517:Plant Roots / Q000737:chemistry; D012997:Solvents; D013211:Staphylococcus aureus / Q000187:drug effects*