Characterization of the antibacterial activity from ethanolic extracts of the botanical, Larrea tridentata.

BACKGROUND: ß-lactam antibiotics are a class of broad-spectrum antibiotics consisting of all antibiotic agents that contain a ß-lactam ring in their molecular structures. ß-lactam antibiotics are only known to be isolated from fungi (e.g. Acremonium chrysogenum, Penicillium chrysogenum and Aspergillus nidulans) and bacteria (e.g. Streptomyces clavuligerus). We have shown that botanical extracts prepared from Larrea tridentata have strong antimicrobial activity against several bacteria, including members of Staphylococcus and Streptococcus genera. METHODS: Through resistance studies, inhibitor assays, and ELISA testing, we demonstrated L. tridentata extracts may contain a ß-lactam type antibiotic activity. RESULTS: Based on the estimated ß-lactam concentration within the extract, the antimicrobial activity of the L. tridentata extract was approximately 2000-8000-fold greater against Staphylococcus as compared to other ß-lactams, penicillin or ampicillin. In the L. tridentata extract, this increased activity was found to be associated with the likely presence of a cofactor leading to increased potentiation of the ß-lactam activity. This potentiation activity was also observed to enhance the activity of exogenously added natural penicillin antibiotics. CONCLUSIONS: Although constituents were not isolated in this study, the results obtained strongly support the presence of ß-lactam type antibiotic activity and antibiotic potentiation activity present in ethanolic extracts prepared from L. tridentata.

Identification of botanicals with potential therapeutic use against methicillin-resistant Staphylococcus aureus (MRSA) infections.

Staphylococcus aureus is an opportunistic pathogen. Over- and improper-use of pharmaceuticals against S. aureus has led to the development of antibiotic resistance, including methicillin-resistant S. aureus (MRSA). This study examined the efficacy of botanical extracts as an alternative form of treatment to S. aureus and MRSA, including penicillin/methicillin-resistant S. aureus (PenR ), and multidrug resistant S. aureus (MDR). Initial screening of botanicals was done via a minimum inhibitory concentration procedure. In addition, a temporal growth curve was performed in order to quantify the growth of the bacteria in the presence of the extracts. Results demonstrated 13 botanicals that had varying activities against S. aureus, PenR , and MDR. These botanicals were separated into mild, moderate, and highly efficacious based on the concentration needed to inhibit bacterial growth. These results propose a comparison of botanical-derived antimicrobial extracts that may be utilized against S. aureus and different antibiotic resistant strains of MRSA.