Antibacterial and Antifungal Activity of the Extracts of Different Parts of Avicennia marina (Forssk.) Vierh

Abstract

Increased problems associated with side effects and bacterial resistance of chemical drugs has prompted the research focus on herbal medicines in the past few decades. In the present investigation, the antimicrobial activity of the various parts of Avicennia marina (AM), a mangrove plant, has been evaluated. The plants were collected from the Jazan area of the Kingdom of Saudi Arabia. Primary extracts of roots, stem, leaves, fruits, and seeds were made in ethanol and fractioned in ethanol, ethyl acetate, petroleum ether, chloroform, and water. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts were determined against Bacillussubtilis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. It has been observed that the chloroform extract of roots of the AM exhibited inhibitory effects against both S. aureus (MIC = 1.5 ± 0.03 mg/mL) and E. coli (MIC = 1.7 ± 0.01 mg/mL). The ethanolic extract of the AM roots has shown antibacterial activity against Pseudomonas aeruginosa (MIC = 10.8 ± 0.78 mg/mL), Bacillussubtilis (MIC = 6.1 ± 0.27 mg/mL), Staphylococcus aureus (MIC = 2.3 ± 0.08 mg/mL), and Escherichia coli (MIC = 6.3 ± 0.28 mg/mL). The leaf extract of the AM in ethyl acetate showed antibacterial activity against S. aureus and E. coli. Antifungal activity of these extracts was also investigated against Aspergillus fumigatus and Candida albicans. Ethanolic extract of roots and seeds of the AM has shown antifungal activity against Aspergillus fumigatus when applied individually. Ethanolic extract of the AM fruits has shown an inhibitory effect on the growth of Aspergillus fumigatus and Candida albicans. It is suggested that the plant extracts of AM have tremendous antimicrobial activity against a group of microbes, and this effect depends on both the plant part and the solvent used for extraction. Therefore, this plant can be considered to treat various diseases caused by antibiotic-resistant bacteria.

Keywords: Avicennia marina; Bacillus subtilis; Escherichia coli; Pseudomonas aeruginosa; Staphylococcus aureus; antibacterial; antifungal.

Figure 1

Minimal inhibitory concentration (MIC) values for ethanol and chloroform Avicennia marina roots extract against P. aeruginosa, B. subtilis, S. aureus, and E. coli. Tetracycline hydrochloride was a positive control. Aqueous, petroleum ether, and ethyl acetate extracts did not affect any of the tested bacterial strains. Chloroform extract did not affect B. subtilis. Values are the mean of five replicates (n = 5). Vertical bars show standard error.

Figure 2

MIC values for ethyl acetate Avicennia marina leaf extract against P. aeruginosa, B. subtilis, S. aureus, and E. coli. Tetracycline hydrochloride was a positive control. Aqueous, chloroform, ethanol, and petroleum ether extracts did not affect any of the tested bacterial strains. Ethyl acetate extract did not affect P. aeruginosa and B. subtilis. Values are the mean of five replicates (n = 5). Vertical bars show standard error.

Figure 3

MBC values for chloroform Avicennia marina roots extract against P. aeruginosa, B. subtilis, S. aureus, and E. coli. Tetracycline hydrochloride was a positive control. Aqueous, ethanol, petroleum ether, and ethyl acetate extracts did not affect any tested bacterial strains. Chloroform extract did not affect P. aeruginosa and B. subtilis. Values are the mean of five replicates (n = 5). Vertical bars show standard error.

Figure 4

MBC values for ethyl acetate Avicennia marina leaf extract against P. aeruginosa, B. subtilis, S. aureus, and E. coli. Tetracycline hydrochloride was a positive control. Aqueous, ethanol, petroleum ether, and chloroform extracts did not affect any tested bacterial strains. Ethyl acetate extract did not affect P. aeruginosa and B. subtilis. Values are the mean of five replicates (n = 5). Vertical bars show standard error.

Figure 5

MIC values for the ethanolic extract of the root (A), fruits (B), and seeds (C) of Avicennia marina against Aspergillus fumigatus, Candida albicans, and Mucor sp. Fluconazole was used as the control. Ethyl acetate, petroleum ether, chloroform, and aqueous extracts of root, fruit, and seeds of Avicennia marina did not show any inhibitory effects on the tested fungal strains. Only ethanol extract showed an inhibitory effect on A. fumigatus and C. albicans. Values are the mean of five replicates (n = 5). Vertical bars show standard error.

Figure 6

Scan electron microphotographs of untreated (A) and treated (B) Candida albicans.

Figure 7

Scan electron microphotographs of untreated (A) and treated (B) Aspergillus fumigatus.