Antibacterial activity of different composition of aglycone and glycosidic saponins from tuber of Cyclamen coum Miller

Abstract

Many plants biosynthesize biochemical compounds with antibacterial properties that can be used in industrial or food technology. They have effect on growth of bacteria thus, natural constituents in the plant extracts open new trends to control microbial infections. Cyclamen is a wild plant that can be used as a drug. Aim of this work is to reveal antibacterial activity of the cyclamen tuber extracts and to determine its effective concentration against five different bacteria. Crude and hydrolyzed extracts of Cyclamen coum tuber were prepared by soxhlet and the extracts were separated to more polar and less polar phases via fractional solvents. After that, antibacterial impact of the extracts was investigated using disk diffusion method and it was determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The results showed that the extracts of Cyclamen coum were relatively rich in saponin but poor in phenolic compounds. The most antibacterial effect of n-butanolic saponin extracts were assayed against E. faecalis (PTCC 1393), which contained 0.87 μg saponin and resulted 16.6 mm diameter of inhibition zone. Furthermore, aqueous part of the aglycone extract with 0.08 μg total saponin revealed higher activity on P. aeruginosa (ATCC 1430) with 14 mm inhibition zone. Ethyl acetate phase of the aglycone extract with 0.2 μg of total saponin, showed 9.3 and 13.6 mm diameter of inhibition zone only against P. aeruginosa and S. aureus (ATCC 1431), respectively. Other extracts showed 7–13 mm inhibition zone, which was less effective. In addition, MIC n-butanolic extract was 0.4- 0.86 mg total saponin/mL whereas MIC of aqueous glycoside was 0.05- 0.86 mg saponin/mL. However, the later extract had no any bactericidal and bacteriostatic effect against S. aureus and E. faecalis. MIC and MBC of the ethyl acetate extract were 0.05 mg saponin/mL against clinical S. typhi whereas its MIC and MBC on P. aeruginosa and E. faecalis were 0.2 mg saponin/mL. Maximum MIC and MBC of the aqueous aglycone extract was assayed with 0.007 mg saponin/mL on clinical S. typhi, and MIC of 0.01 mg saponin/mL was estimated on S. aureus. Consequently, saponin tuber extracts of Cyclamen coum could be used as moderate to strong antimicrobial substance against gram-negative bacteria.