Antimicrobial Potential of Ethanol Extract and Fractions of Caesalpinia benthamiana (Caesalpinaceae) Root on Some Organisms Implicated in Oral Infections

This study investigated the activities of ethanol root extract of Caesalpinia benthamiana (Baill) Herend. and Zarucchi. (Caesalpiniaceae) against some microbial isolates implicated in oral infections and determined the killing rate of the most active fraction. It also investigated the phytochemical properties of the root extract. This was with a view to providing scientific basis for the use of the root in the treatment of oral infections.

The plant root was collected from the wild, washed, air-dried, ground to powder and macerated using ethanol and water at ratio 7:3 (v/v) with constant shaking for 72 hours in a mechanical shaker. The filtrate was concentrated in-vacuo at 50°C using a rotary evaporator and freeze dried. The crude extract was screened for phytochemical and antimicrobial properties. The extract was further partitioned into fractions using different organic solvents in order of their polarity. The antimicrobial potential of the different fractions was determined using agar-well diffusion and agar dilution method respectively. Time-kill-assay of the most active fraction was carried out on each of the organisms namely, Staphylococcus aureus (NCIB 8588) clinical isolates of Streptococcus mutans, S. pyogenes, S. salivarius, Staphylococcus aureus and Candida albicans. The values obtained were subjected to inferential statistical analysis.

Phytochemical screening revealed the presence of flavonoids, tannins, terpenes, saponins, phenolics and phenolic glycosides and anthraquinones. The root extract showed appreciable activity against all the test organisms, with the ethyl acetate fraction demonstrating highest activity and lowest MIC (0.16 mg/mL) compared with the crude extract and the other fractions. The activity was also time and concentration dependent. At triple the MIC all cells of respective organisms were killed at 5 minutes as was the case with all the standard antibiotics and anti-fungi used as positive control.

It was concluded that C. benthamiana ethanol root extract was highly active against oral isolates with its ethyl acetate fraction being the most effective.