Antibacterial activity of native California medicinal plant extracts isolated from Rhamnus californica and Umbellularia californica

Abstract

BackgroundAntimicrobial resistance (AMR) is a major threat to global public health. Medicinal plants have long been used as remedies for infectious diseases by native cultures around the world and have the potential for providing effective treatments for antibiotic-resistant infections. Rhamnus californica (Rhamnaceae) and Umbellularia californica (Lauraceae) are two indigenous California plant species historically used by Native Americans to treat skin, respiratory and gastrointestinal infections. This study aimed to assess the in vitro antimicrobial activity of methanolic extracts of leaves and bark of R. and U. californica against methicillin-resistant Staphylococcus aureus (MRSA) and other Gram-positive and Gram-negative bacteria.MethodsMethanolic extracts of leaves and bark of R. and U. californica were prepared by soxhlet extraction and evaluated for their antimicrobial activity against Bacillus cereus, Streptococcus pyogenes, Mycobacterium smegmatis, Staphylococcus aureus, MRSA, Escherichia coli and Pseudomonas aeruginosa using disc diffusion and minimal inhibitory concentration (MIC) assays. Chemical profiling of the extracts was performed using standard methods.ResultsAll extracts inhibited the growth of MRSA and other Gram-positive bacteria with MICs of 3.3-6.0 mg/ml. Gram-negative organisms were unaffected by these extracts. U. californica extracts (leaves and bark) had the lowest MIC values. Chemical profiling detected the presence of quinones, alkaloids, flavonoids, cardenolides, tannins and saponins in these extracts. Our study is the first to report the antimicrobial properties of R. and U. californica and illustrates their promising anti-MRSA potential.ConclusionsOur results give scientific credence to the traditional medicinal uses of these plants by the indigenous peoples of California. Further investigation of the secondary metabolites responsible for the antimicrobial activity of these extracts against MRSA is warranted.

Antibacterial Activity study of Musizin isolated from Rhamnus wightii Wight & Arn.

“…The antibacterial activity of the extracts against K. pneumoniae is noteworthy because plant extracts and their compounds have previously been reported to be more active against Gram-positive bacteria than Gram-negative ones 24. Our results are also in agreement with the previous reports 25 of Carranza et al (2015) who have shown a significant antibacterial activity of the leaf extract of Rhamnuscalifornica against two bacterial pathogens with the zones of inhibition ranging from 10.0 ± 2.1 to 14.0 ± 1.4 (mm). Similarly, the crude extract obtained from a Rhamnous member Ventilago madraspatana has been shown to have broad-spectrum antimicrobial activity against a panel of Gram positive, Gramnegative bacteria and Candida pathogens 26.…”

Large-Scale Screening of 239 Traditional Chinese Medicinal Plant Extracts for Their Antibacterial Activities against Multidrug-Resistant Staphylococcus aureus and Cytotoxic Activities

“…In addition, these biomolecules possess a wide spectrum of chemical properties including unique chemical scaffolds and complex structures, providing potentiating inhibitory effects associated with possible distinctive mechanisms of action against microorganisms [15,16]. There have been several previous studies reporting a significant advantage of these phytochemicals to impede the development of drug-resistant bacteria [17,18]. Some of these phytochemicals and plant extracts are designated by the United States Food and Drug Administration (FDA) as Generally Recognized As Safe (GRAS), and have low toxicity and good acceptability to food and medical applications [18].…”

Green Synthesis and Antibacterial Properties of Silver Nanoparticles of Lawsonia inermis, Rhamnus frangula, Camellia sinensis and Thymus vulgaris Extracts

“…Ciprofloxacin antibiotic disc inhibition zone diameters were 22 mm, 0 mm, 30 mm, 0 mm, 30 mm, and 28 mm for S. pneumoniae, E. coli, S. aureus, P. aeruginosa, B. subtilis, and K. pneumoniae, respectively. The extract of R. californica leaves was the most active among the three extracts, whereby the strongest effect was noted on the only antibiotic-resistant strain tested, MRSA 23 . C. sinensis extract-AgNPs have also shown potent antimicrobial activity against pathogenic bacteria 20 .…”