In vitro bioactivity of Combretum elaeagnoides Klotzsch methanol leaf extract and fractions against pathogens causing bovine mastitis

Bovine mastitis, an inflammatory disease affecting cows, causes severe economic consequences in the dairy industry. The bioactivity of Combretum elaeagnoides methanol extract and fractions against six clinical isolates of Staphylococcus aureus (SA1-SA6) and two ATCC strains (S. aureus ATCC 29213, S. epidermidis ATCC 35984) was investigated. The antibacterial potential of the extracts was determined via serial microdilution. Quorum quenching (QQ) activity was ascertained via inhibition of violacein production in Chromobacterium violaceum. Antioxidant activity was determined using in vitro chemical assays. The 15- lipoxygenase enzyme and nitric oxide (NO) inhibition assays were utilised to ascertain the anti-inflammatory activity of the extracts. Tetrazolium-based colorimetric reduction assay was used to determine the cytotoxicity of the extracts against Vero and bovine dermis cell lines. The ethyl acetate fraction had the best inhibition against all test bacteria (MIC=0.07- 0.23 mg/mL). The dichloromethane fraction at different test times (T0, T24, T48) had the best biofilm biomass inhibition against most of the test strains with inhibition

≥50%. The extract and fractions had excellent QQ activity with IC₅₀ ˃ 1.25 mg/mL and good lipoxygenase inhibition (IC₅₀=28 to ˃ 100 µg/mL). All extracts had antioxidant efficacy against the DPPH and ABTS free radicals. The extract and fractions had moderate to good NO inhibition (IC₅₀=43.81 – 95.76 µg/mL). The methanol extract and fractions were non-toxic to the bovine dermis cells (LC₅₀ ˃ 20 µg/mL). Thus, C. elaeagnoides extract or fractions may be recommended for the development of herbal preparations for the prevention and treatment of bovine mastitis.

 

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Publication History

Article published online:
16 November 2023