Evaluation of antimicrobial activity and phytochemical screening of Silene macrosolen and Solanum incanum: A common medicinal plant in Eritrea

Background: The periodically emerging new and old infectious microorganisms greatly magnify the global burden of infectious diseases. The majority of emerging infectious events are caused by bacteria, which can be associated with the evolution of drug-resistant strains and the overwhelming of the natural host defenses. Medicinal plants play an important role in the treatment of various infectious diseases. The objective of this study is to evaluate the in vitro antimicrobial activities of crude extracts of aqueous and solvents from two Eritrean traditional medicinal plants (Silene macrosolen and Solanum incanum). Methodology: Roots and leaves of Solanum incanum and stems and roots of Silene macrosolen were collected and extracted using standard methods. The extracted ingredients were then subjected to standard bacterial strains (Escherichia. coli ATCC-25923, Staphylococcus. aureus ATCC-25922, and Pseudomonas. aeruginosa ATCC-27853) to determine their antibacterial activity by measuring their zone of inhibition. Phytochemical analysis of the crude extract to see the presence of phytochemical compounds in the extract of selected plants. Results: The highest inhibition zone was observed for methanol extracted S. macrosolen stem and chloroform extracted S. incanum root against S. aureus in 400 mg / ml with 23mm and 24.5mm respectively. Methanol and cold aqueous extracted stem of S. macrosolen also showed the highest inhibition of 26mm and 23mm diameter, against P. aeruginosa and E. coli respectively. The MIC and MBC of the cold aqueous extract of S. macrosolen stem were found at 25 mg / ml and 50mg/ml respectively, against both E. coli and P. aeruginosa, while the MIC of the chloroform-extracted root of S. incanum was found at 50mg/ml, however, the MBC could not be found in the concentration tested against S. aureus. Conclusion: Based on the finding of this study S. aureus was found to be more susceptible to the plant extracts than E. coli and P. aeruginosa, and the methanolic and cold aqueous extracts of the S. macrosolen stem revealed the highest antibacterial activity.