Antioxidant and antibiofilm activity of Ageratum conyzoides L, and Bidens pilosa L against wound pathogens

Abstract

Biofilm infections represent a significant challenge in the medical field due to escalating antibiotic resistance. Plants offer a promising avenue for addressing this issue, as they harbor a diverse array of phytochemicals with various biological activities, including antioxidant properties crucial for preventing biofilm formation in wounds. This study aimed to explore the antioxidant and antibiofilm capabilities of Ageratum conyzoides L. and Bidens pilosa L. The plants underwent quantitative phytochemical screening, antioxidant activity assessment via the DPPH scavenging assay, and antibiofilm activity evaluation using the microtiter plate assay. All plants were found to contain tannins, flavonoids, polyphenols, and alkaloids, with alkaloids being particularly abundant. The antioxidant activity (IC50) of A. conyzoides was measured at 50.52 µg, while that of B. pilosa was 45.94 µg. Regarding the minimum concentration needed to inhibit 50% of Pseudomonas aeruginosa biofilms (MBIC50), it was 24.9 mg/ml for B. pilosa and 28.3 mg/ml for A. conyzoides, with the MBIC90 being 147.7 mg/ml for A. conyzoides and 139.5 mg/ml for B. pilosa. For Staphylococcus aureus biofilms, the MBIC50 was 11.4 mg/ml for B. pilosa and 18.6 mg/ml for A. conyzoides, while the MBIC90 was 69.3 mg/ml for B. pilosa and 97 mg/ml for A. conyzoides. In the biofilm removal assay for P. aeruginosa, the minimum concentration required to eliminate 50% of the formed biofilms (MBEC50) was 38.1 mg/ml for A. conyzoides and 200 mg/ml for B. pilosa. The MBEC90 was 151.7 mg/ml for A. conyzoides and 261 mg/ml for B. pilosa. For S. aureus, the MBEC50 was 96.93 mg/ml for A. conyzoides and 195 mg/ml for B. pilosa, with the MBEC90 being 334 mg/ml and 250 mg/ml for A. conyzoides and B. pilosa, respectively. The study findings confirm that plant extracts possess antioxidant activity and the potential to inhibit biofilm formation and disrupt mature biofilms. The antibiofilm activity observed in these plants underscores their potential as a solution to antibiotic resistance, warranting further research.