Antimicrobial Activity of Different Extracts and Fractions of Marrubium parviflorum

Marrubium plants have long been used as a traditional medicine in treatment of diseases. The aim of this study was to evaluate the antimicrobial effects of Marrubium parviflorum extracts and fractions.

In this experimental study, solvent extraction from aerial parts of the plant was done by Soxhlet method. The antimicrobial effect of the extracts was evaluated on six strains of gram-positive bacteria, four strains of gram-negative bacteria, and one strain of fungus. Also, effective extracts were fractionated by various chromatographic methods and their antimicrobial effects were investigated.

Chloroform extract of M. parviflorum was found to be effective against Micrococcus luteus, Staphylococcus epidermidis, and Bacillus cereus with a growth inhibition zone diameter (DIZ) of 16.6, 14.6, and 11.6 mm, respectively, and MBC 100 mg/ml. Methanolic extract also showed considerable antimicrobial effects against Proteus mirabilis and Psudomonas aeruginosa. Among the fractions obtained, 10%, 20%, 40%, and 60% fractions of the chloroform extract and 20% and 40% fractions of the methanolic extract showed the highest antimicrobial effect. The superior values ​​of MBC and DIZ in fractions indicate the condensation of certain antimicrobial compounds in some fractions and higher sensitivity of gram-positive bacteria compared with gram-negative bacteria.

Among the extracts studied, the chloroform and the methanolic extracts of M. parviflorum exhibited the strongest antimicrobial effect and Micrococcus luteus was the most sensitive microorganism.