Monday, 28 September 2015

In vitro anti-Neisseria gonorrhoeae activity of Senna podocarpa root extracts

Volume 76, 15 December 2015, Pages 467–471


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.

Graphical abstract

Image for unlabelled figure


  • 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;
  • Gonorrhoea;
  • Neisseria gonorrhoeae;
  • Rhein

Corresponding author at: iMed.ULisboa, Department of Pharmacological Sciences, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisbon, Portugal.