Antibacterial and anti-biofilm effects of a polyherbal formula and its constituents against coagulase-negative and -positive staphylococci isolated from bovine mastitis

Concerns about antibiotic residues in milk and emergence of antimicrobial resistant pathogens necessitate exploration of alternative therapeutic strategies for the treatment of mastitis. This study aims to investigate anti-infective properties of a Thai traditional polyherbal formula, namely Ya-Sa-Marn-Phlae (YSMP), its herbal components (Curcuma longa, Areca catechu, Oryza sativa, and Garcinia mangostana), and representative chemical constituents (catechin, a-mangostin, and curcumins). Ethanol extracts of YSMP and G. mangostana, and a-mangostin exhibited potent antibacterial effects against Staphylococcus spp. isolated from mastitis cows with MIC values of 1-32 mu g/mL. These tested agents inhibited biofilm formation of the isolates on both polypropylene (hydrophobic) and glass (hydrophilic) surfaces. The current study indicated that YSMP had strong antibacterial activity and anti-biofilm abilities against the tested isolates similar to that of a-mangostin and G. mangostana. The antistaphylococcal effects were confirmed with both scanning and transmission electron microscopes. The main abnormalities in the microstructure of the treated cells were the severe alterations of the cell wall with the formation of holes and morphological disorganization. Therefore, it might be proposed that G. mangostana is the major active component of YSMP and a-mangostin may be used as an active marker compound for YSMP to indicate its activity against bovine mastitis-isolated staphylococci.