Biological Activities of Extracts of Some Green Seaweeds from the Coast of Gaza Strip, Palestine

Abstract

Problem: During the past several years, the indiscriminate use of antibiotics has resulted in the emergence of microbial resistance to common antibiotics which will ultimately threatens the effective of treatment of infections caused by bacteria and fungi. This forced researchers to search for novel antimicrobial substances from various sources e.g. seaweeds. Objectives and aims: To evaluate and compare the antimicrobial activity of extracts of three locally abundant green seaweeds Enteromorpha compressa, Ulva lactuca and Chaetomorpha sp. against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae, Fusarium oxysporum and Candida albicans. Methodology: The three seaweed species were shade dried and extracted separately with methanol, hexane and chloroform by using the soxhlet extraction apparatus. All extracts were screened for their antimicrobial activity by using the disk diffusion method. The minimum inhibitory concentrations (MICs), the minimum bactericidal concentrations (MBCs) and the minimum fungicidal concentrations (MFCs) of the extracts were assessed by using microdilution technique. Results: The average diameter of inhibition zones that resulting from the effect of algae extracts against the bacteria and fungi was ranged from 7 to 12.5 mm. Methanol extracts has shown strong activity against tested bacterial and fungal species compared to other solvent extracts. The average diameter of inhibition zones were ranged from 7 to 11 mm, 8 mm and 10 to 12.5 for methanol, hexane and chloroform extracts respectively. The average (MICs) values for tested bacteria ranged from 3.125 to 25 mg/ml for methanol extracts and 12.5 to 50 mg/ml for hexane and chloroform extracts. While antifungal activity was 1.56 to 25 mg/ml for methanol extracts, 6.25 to 50 mg/ml for hexane and 50 to 100 mg/ml for chloroform. While MBCs values ranged from 50 to > 100 mg/ml for tested bacteria, the MFCs values ranged from 25 to > 100 mg/ml for tested fungi. Conclusions & Recommendations: Overall, the present study provides data to show the potential use of algae extracts for development of anti-microbial agents for treating infectious diseases.