Antimicrobial activity of aqueous methanolic extracts of Algerian cultivars of sorghum (Sorghum bicolor (L.) Moench)

Certain phenolics have been recognized to possessing antibacterial and antifungal activities and high levels of flavonoids and tannins have been reported in several varieties of Sorghum bicolor (L.) Moench. Antimicrobial activity and phenolics contents were investigated in five Algerian sorghum seeds. AS20 sorghum extract showed the highest levels of: total phenolics (3214.46±263.64 mg/100 g), flavonoids (32.03±1.64 mg/100 g) and tannins (615.35±6.10 mg/g) contents; however, comparable flavonoids content was recorded in I27 extract. FZ40 and AS12 flavonoids contents were comparable. Screening for antimicrobial activity, carried out by the disc’s diffusion method revealed an antimicrobial potential of sorghum crude extracts against Gram-positive and Gram-negative bacteria and candida albicans yeast. Minimal inhibition concentration determined by microdilution method varied between 0.2 and 2 mg/ml. the lowest value was recorded with F11 and FZ40 extract against Streptococcus pneumoniae and F11 against Escherichia coli. Bacillus subtilis, Staphylococcus aureus ATTCC6538 and MRSA strains showed sensitivity to all extracts. The results show these sorghums as a potential source of natural anti-streptococcal, anti-staphylococcal and anti-candida substances.