Chemistry & Pharmacology

The chemistry of Sutherlandia was studied by Prof. Ben-Erik van Wyk and Dr. Carl Albrecht. Four known key compounds contribute to the efficacy of this medicinal plant : the non-protein amino acid L-canavanine; pinitol; GABA ; and asparagine. In addition a novel triterpenoid glucoside has been isolated and characterized.

The published biological activities of these compounds appear to validate some of the traditional uses of the plant, and further support the use of the plant as a quality-of-life tonic in cancer and AIDS patients.

Microchemical tests in laboratories indicated the presence of tannins but no alkaloids, cardiac glycosides, saponins or anthraquinone derivatives. Free amino acids are reported as common constituents of Sutherlandia frutescens.¹

TLC - Sutherlandia frutescens Thin layer chromatography on silica gel using as solvent a mixture of toluene:diethyl ether:1.75M acetic acid (1:1:1). Reference compound cineole (0,1% in chloroform). HPLC Rf values of major compounds: 0, 50 (yellow-green); 0, 63 (purple); 0, 91 (purple); cineole: 0, 81 (blue-purple)	HPLC
TLC	Sutherlandia frutescens - microscopical features 2

Pharmacology/bioactivity
Studies using 50% ethanol extracts of fresh flowers of Sutherlandia frutescens found no antitumour activity against CA-Lewis lung, Leuk-L1210 or Sarcoma 180 (solid) tumours in the mouse. Similar extracts, assayed for cytotoxicity against CA-9KB cell lines, at a concentration of 20.0 mcg/ml, proved inactive.6

No in vitro antimicrobial activity against Pseudomonas aeruginosa, Candida albicans or Mycobacterium smegmatis was observed in the concentrations used for disc assays in our laboratories. Some activity was recorded against Staphylococcus aureus.

Research into anticancer and immunomodulatory activity of this species is
currently in progress. The results appear promising.

L-Canavanine
L-Canavanine is known to occur in high levels in certain seeds. What is unusual is that significant levels of this compound are found in Sutherlandia leaves. This potent non-protein amino acid is an L-arginine antagonist with documented antiviral, anti-bacterial, anti-fungal and anticancer activities. An average of 2.2 mg of L-canavanine per dry gram of leaf material of Sutherlandia was found. L-Canavanine is a potent L-arginine antagonist that has patented anticancer (Swaffar, 1995; Crooks, 1994.) and antiviral activity, including against influenza virus and retroviruses (Green, 1988.). L-Canavanine is also a selective inhibitor of inducible nitric oxide synthase and therefore has possible application in the treatment of septic shock and chronic inflammation (Anfossi, G. et al. 1999; Levy, B. et al. 1999).

The non-protein amino acid canavanine has been detected in the seeds of this species but not in other organs.¹

Pinitol
Pinitol, a known anti-diabetic agent (Narayanan, 1987), has been isolated from Sutherlandia leaves, and quantitative work is in progress. A US Patent (Ostlund, 1996) suggests that pinitol may have clinical application in treating the wasting in cancer and AIDS patients.

GABA
GABA was isolated from dry Sutherlandia leaves in levels up to 14 mg/g dry weight. This inhibitory neurotransmitter could account for the use of the plant for anxiety and stress, and for the improvement in mood and well-being experienced by many patients.

Novel Triterpenoid Glucoside
A novel triterpenoid glucoside has been isolated and characterized, and is one of the key compounds used in the selection of raw material for propagation. This compound has promising biological activities, but this is still the subject of ongoing research.

Comments
Preliminary scientific research, published peer-reviewed scientific research, and clinical experience suggests that key phyto chemicals in select chemotypes of Sutherlandia varieties are:

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