title: Antibacterial effects of ellagitannins from Acalypha wilkesiana var. macafeana hort.: surface morphology analysis with environmental scanning electron microscopy and synergy with antibiotics.
abstract: The present study served to gain further insight into the bactericidal effects of ellagitannins from Acalypha wilkesiana var. macafeana hort. against pathogenic bacteria. Ellagitannins from the aerial parts of A. wilkesiana var. macafeana hort. (EAW) inhibited the growth of Bacillus cereus (ATCC 11778), Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 11632) and Methicillin-resistant Staphylococcus aureus (MRSA) clinical strain with inhibition zones equal to 11.01 ± 1.53 mm, 16.63 ± 0.11 mm, 11.40 ± 1.10 mm and 8.22 ± 0.19 mm, respectively. The minimal inhibition concentration and the minimal bactericidal concentration of ellagitannins from A. wilkesiana var. macafeana hort. (EAW) against MRSA were 750 µg/mL and 3000 µg/mL, respectively. We then examined the synergistic effect of EAW with three antibiotics, i.e. ampicillin, streptomycin and tetracycline, via the checkerboard assay and time-kill assay and observed that EAW is synergistic with ampicillin against S. aureus (ATCC 11632). Environmental electron scanning microscopy analysis showed cell lysis against S. aureus (ATCC 11632) upon treatment with the ellagitannin fraction. The ellagitannin fraction from A. wilkesiana var. macafeana hort. is bactericidal against gram-positive bacteria tested and works synergistically with ampicillin against S. aureus. Morphology analysis of the cell suggests that the bactericidal property of the ellagitannin fraction mechanism involves lysis of the cell wall. In summary, our studies demonstrate that A. wilkesiana var. macafeana hort. produces bactericidal ellagitannins of clinical and/or cosmetological value.
authors.affiliation: School of Biomedical Sciences, Faculty of Science, The University of Nottingham Malaysia Campus, Malaysia. khyx8wmd@nottingham.edu.my
authors.forename: Wardah Mustafa
authors.initials: WM
authors.lastname: Din
authors.forename: Khoo Teng
authors.initials: KT
authors.lastname: Jin
authors.forename: Ramliza
authors.initials: R
authors.lastname: Ramli
authors.forename: Tzar Mohd Nizam
authors.initials: TM
authors.lastname: Khaithir
authors.forename: Christophe
authors.initials: C
authors.lastname: Wiart
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004357:Drug Synergism; D019665:Euphorbiaceae / Q000737:chemistry*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D047348:Hydrolyzable Tannins / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D008855:Microscopy, Electron, Scanning; D010936:Plant Extracts / Q000494:pharmacology*; D013307:Streptomycin / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D047348:Hydrolyzable Tannins; D010936:Plant Extracts; C013515:ellagitannin; D000667:Ampicillin; D013752:Tetracycline; D013307:Streptomycin
keywords: A. wilkesiana var. macafeana hort; Staphylococcus aureus; antimicrobial; ellagitannins; synergistic studies