Antibacterial Effects of Ellagitannins from Acalypha wilkesiana var. macafeana hort.: Surface Morphology Analysis with Environmental Scanning Electron Microcopy 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.

Ellagitannins of Davidia involucrata. I. Structure of Davicratinic Acid A and Effects of Davidia Tannins on Drug-Resistant Bacteria and Human Oral Squamous Cell Carcinomas

“…It has been reported that the extract containing ellagitannins of Acalypha wilkesiana var. macafeana exerts antibacterial effects by causing cell wall damage which eventually results in cell lysis [ 25 ]. Besides, the significance of the galloyl group in polyphenols on the instability of cell membrane was also reported [ 26 ].…”

Prevention of cell-surface attachment and reduction of penicillin-binding protein 2a (PBP2a) level in methicillin-resistant Staphylococcus aureus biofilms by Acalypha wilkesiana

“…This was corroborated by another group that previously reported the isolation of corilagin, geraniin and ellagitannin from the same plant and these tannin compounds demonstrated anti-staphylococcal activity. It was proposed that these tannins exert their antibacterial effects by causing cell wall damage which eventually results in cell lysis [ 29 ]. Besides, tannins were reported to be capable of binding to peptidoglycan and destroy the bacterial cell wall integrity [ 24 ].…”

Modulation ofmecA Gene Expression by Essential Oil fromSalvia sclareaand Synergism with Oxacillin in Methicillin ResistantStaphylococcus epidermidisCarrying Different Types of Staphylococcal Chromosomal Cassettemec

“…The synergistic effect is shown graphically by applying isobole method. The shape of the isobologram curve can be convex, linear, or concave, which is indicative of the synergistic, indifferent, and antagonistic interactions, respectively [ 40 ].…”