Phytochemical Extraction and Antibacterial Efficacy of Artemisia herba-alba against Staphylococcus aureus and Escherichia coli
Abstract
Background: With the continuous emergence of antimicrobial resistance (AMR), the effectiveness of traditional antibiotics is declining and alternative antibacterial agents from medicinal plants are being sought. Arthremisia herba-alba Asso is an aromatic shrub widely distributed in arid regions, which contains a variety of bioactive secondary metabolites, but yet there is no systematic study or comparative study between different phytochemical fractions and representative Gram-positive and Gram-negative bacteria. Methods: The aerial parts of A. herba-alba were extracted in aqueous and ethanolic and qualitatively analyzed for the presence of phenols, tannins and glycosides and quantitatively analyzed for its total phenolic (TPC) and tannin (TTC) content using UV–Vis spectrophotometry. The antibacterial activity of tannin, glycoside and phenolic fractions (50, 100 and 200 mg/mL) was tested against Staphylococcus aureus and Escherichia coli by the agar well-diffusion method and compared with the benchmark drugs – ceftriaxone, ciprofloxacin, doxycycline and clindamycin. The data presented as mean ± standard error (n = 3) and analysed by the least significant difference (LSD) test at P < 0.05. Results: All of the extracts inhibited the growth of S. aureus dose dependently, with maximum activity in the ethanolic phenolic fraction (16.0 ± 0.57 mm at 200 mg/mL) which exceeded both ceftriaxone and ciprofloxacin. All aqueous fractions were inactive against E. coli (6.0 mm; no inhibition) while the ethanolic phenolic and glycoside fractions had appreciable activity (13.0 ± 0.57 and 12.0 ± 0.57 mm, respectively, at 200 mg/mL) with the ethanolic phenolic fraction showing higher activity than all four reference antibiotics. Conclusion: A. herba-alba and especially its ethanol-soluble phenolic fraction is a potential natural source of antibacterial agents active against Gram-positive and Gram-negative pathogens, which makes it a very promising scaffold against the emergence of AMR.