Isoflavones from Calpurnia Aurea subsp. aurea and their anticancer activity.
BACKGROUND
Calpurnia aurea is an African medicinal plant used in many countries in Africa to treat a range of medical conditions or disorders. Extracts of the plant were shown to be active in antibacterial and antioxidant assays as well as against lice, ticks and maggots. The aim of the study was to isolate the phytochemical constituents from the plant and to test them in appropriate bioassays dependent on the compounds isolated in order to provide a rationale for the use of the plant in ethno-medicine or to provide some information on its constituents.


METHODS
The stem and bark of the plant was extracted with organic solvents of varying polarity and the extracts separated and purified using column chromatography. The isolated compounds were identified by NMR spectroscopy and the compounds were tested for their in vitro anticancer activity against breast (MCF7), renal (TK10) and melanoma (UACC62) human cell lines using an in house method developed at the CSIR, South Africa.


RESULTS
The isoflavones, 4',5,7-trihydroxyisoflavone (1), 7,3'-dihydroxy-5'-methoxyisoflavone (2), 7-hydroxy-4',8-dimethoxyisoflavone (3), 7-acetoxy-4',8-dimethoxyisoflavone (4) and 3',7-dihydroxy-4',8-dimethoxyisoflavone (5), a pterocarpan (3-acetoxy-9-methoxypterocarpan) and a quinolizidine alkaloid (calpurnine) were isolated from the stem and bark of Calpurnia aurea. The tetrasubstituted isoflavone 5 was found to be the most active in the three cell lines amongst all the compounds tested. This was followed by trisubstituted isoflavone 2.


CONCLUSIONS
The isoflavones showed moderate activity against the renal, melanoma and breast cancer cell lines tested against, with the isoflavones 2 and 5 showing the best activity of the compounds tested. These isoflavones may have a synergistic effect with other anticancer drugs.
School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa.
Erick
E
Korir
School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa.
Joyce J
JJ
Kiplimo
School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa ; Ethnobotany Unit, South African National Biodiversity Institute, PO Box 52099, Berea Road, 4007, Durban, South Africa.
Neil R
NR
Crouch
Defence, Peace, Safety and Security (DPSS), Centre for Scientific and Industrial Research (CSIR), Pretoria, South Africa.
Nivan
N
Moodley
School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa.
Neil A
NA
Koorbanally
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology / Q000627:therapeutic use*; D007887:Fabaceae / Q000737:chemistry*; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology / Q000627:therapeutic use*; D061986:MCF-7 Cells; D009369:Neoplasms / Q000188:drug therapy*; D024301:Plant Bark; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use*; D018547:Plant Stems
D000972:Antineoplastic Agents, Phytogenic; D007529:Isoflavones; D010936:Plant Extracts
5,6′-dihydroxy-2′,6-dimethoxyisoflavone; Calpurnia aurea; Fabaceae; anti cancer