Antibacterial effects of oak bark (Quercus robur) and heather herb (Calluna vulgaris L.) extracts against the causative bacteria of bovine mastitis

Abstract

Background and Aim: Bovine mastitis has a negative impact on animals, and improper antibiotic use has caused an increase in bacterial resistance. Therefore, medicinal plants could serve as an alternative treatment for this condition. Polyphenols have potential as antibiotic agents. Oak bark has long been used as a medicine and has shown antibacterial effects. Moreover, research on heather plant demonstrated that it has antibacterial properties. This study aimed to assess the antibacterial effects of oak (Quercus robur) bark and heather (Calluna vulgaris L.) herb extracts against common bovine mastitis pathogens. Materials and Methods: Dried oak bark and heather herb were used to prepare extracts using 30%, 50%, and 70% ethanol and acetone as solvents. Their polyphenol content was determined using the Folin–Ciocalteu method. Bovine mastitis-inducing clinical isolates of Escherichia coli, Streptococcus agalactiae, Streptococcus uberis, Serratia liquefaciens, Staphylococcus aureus, and reference cultures of S. aureus and E. coli were used for antibacterial tests. All extracts were screened through a disk diffusion test to ascertain their antibacterial effects, and the minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined for the most effective extracts. Results: Oak bark extracts had variable antibacterial effects against S. aureus and Streptococcus strains, but no statistically significant difference was observed in activity against E. coli. The disk diffusion test showed that the oak bark extracts obtained using acetone and ethanol at 30% yielded the best results. However, the 70% acetone oak extract alone affected all types of bacteria. Further antibacterial tests of 70% acetone and 30% ethanol oak extracts revealed that the lowest MIC and MBC scores were against S. aureus strains and E. coli reference cultures. Conversely, the heather herb extracts exhibited broader activity against all types of bacteria, although better results were observed against Gram-positive bacteria. There was also a negative correlation between solvent concentration and antibacterial effect (p < 0.05, r = –0.507). The highest inhibition zone scores and broadest spectrum were observed in samples prepared in 30% ethanol. There was no statistically significant correlation between the phenolic content of plants and their antibacterial effects. Conclusion: Oak bark and heather extracts could be used as potential antibacterial agents against bovine mastitis pathogens.

Forest tree extracts induce resistance toPseudomonas syringaepv.tomatoin Arabidopsis

“…Previous studies have reported the pharmacological and therapeutic benefits of forest tree extracts in animals and humans, notably including the extracts of English oak and related species of the Quercus genus [24,25,26]. In complement, our findings suggest the potential of such extracts as antibacterial phytosanitary agents in crop protection, similar to Cibele et al [27] reporting the antibacterial activity of aqueous extracts from twelve Brazilian medicinal plants against the plant pathogens Acidovorax citrulli , Pectobacterium carotovorum subsp.…”

Antibacterial Activity of Tanacetum vulgare L. Extracts against Clinical Isolates of Bovine Mastitis

“…Extracts from the flowers of T. vulgare minimally inhibited the growth of S. agalactiae, but extracts from the leaves had minimal effects against S. uberis and Serratia liquefaciens. When the same bacterial isolates of bovine mastitis were tested, 70% acetone extracts of Quercus robur bark and 30% ethanol extracts of Calluna vulgaris herb had broader antibacterial spectra and lower MIC and MBC [48]. One study reported that Serratia liquefaciens was sensitive to ethanolic extracts of Mentha pulegium, Nepeta cataria, Melissa officinalis, Agastache foeniculum, Lavandula angustifolia, Origanum vulgare, Althaea officinalis, Plantago lanceolata, Artemisia absinthium, Populus nigra, and Evernia prunastri, all of which contain both essential oil and phenolic compounds.…”

Phenolic and Antioxidant Compound Accumulation of Quercus robur Bark Diverges Based on Tree Genotype, Phenology and Extraction Method

“…Similarly, Šukele et al presents results on using different extrahents on oak bark. They report acetone and 30% ethanol having the best outcome in terms of using these extracts for growth control of Streptococcus agalactiae , Streptococcus uberis , Serratia liquefaciens , and Staphylococcus aureus [ 18 ]. In a 2018 article Valencia-Aviles et al report that hot water extracts were more effective that using 90% ethanol for both phenols and antioxidants [ 37 ].…”

“…Oak bark extracts were also shown to work in treating periodontal disease [ 17 ]. Additionally, multiple studies reported that oak bark derivatives were demonstrated to have antibacterial properties [ 13 , 18 , 19 , 20 ]. Similarly, as with oak leaves, oak bark derivatives were reported to positively affect digestion in the rumen [ 21 ].…”