- Senna podocarpa hydro-ethanol root extract is active against Neisseria gonorrhoeae.
- The antimicrobial activity covers strains with diverse susceptibility to antibiotics.
- Bioguided fractionation shows that diethyl ether (dE) is the most active fraction.
- Rhein is the most active compound (MIC = 3.13 mg/L) of the extract and dE fraction.
- Emodin, chrysophanol, sennosides A and B are inactive (MIC > 75 mg/L).
Senna podocarpa (Guill. & Perr.) Lock leaf and root are used in African countries to treat sexually transmitted diseases, namely gonorrhoea.
A bioguided fractionation study was performed to evaluate the antibacterial activity of a S. podocarpa root hydro-ethanol extract (Spr).
Spr, its major compounds and liquid–liquid partition fractions (Spr-1, diethyl ether; Spr-2, ethyl acetate; Spr-3, water) as well as chromatographically isolated main compounds of Spr-1, were tested against nine Neisseria gonorrhoeae reference and clinical strains, including strains with diminished susceptibility to penicillin, tetracycline, and ciprofloxacin. Spr showed anti-N. gonorrhoeae activity against all tested strains with minimum inhibitory concentrations (MIC) ranging from 100 to 400 mg/L.
The main compounds isolated from the most active fraction, Spr-1 (MIC: 50–100 mg/L) were identified as rhein (1), emodin (2), chrysophanol (3) and physcione (4) by LC-UV/DAD co-chromatography with reference standards. Rhein (MIC: 3.13 mg/L against all test strains) proved to be the most active of the isolates, while 2–4 and sennosides A and B (5–6), the major compounds of the total extract, were inactive in the range of tested concentrations (MIC > 75 mg/L).
Rhein was shown to be responsible for the anti-N. gonorrhoeae activity of S. podocarpa root and it can be used as a marker compound to assess the antibacterial activity of this medicinal plant.
- Spr, Senna podocarpa root hydro-ethanol extract;
- Spr-1, diethyl ether liquid–liquid fraction of S. podocarpa root extract;
- Spr-2, ethyl acetate liquid–liquid fraction of S. podocarpa root extract;
- Spr-3, water liquid–liquid fraction of S. podocarpa root extract
- Senna podocarpa;
- Antibacterial activity;
- Neisseria gonorrhoeae;
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