Phytochemical investigation of three erythrina species and tecleanobilis

Abstract

The acetone extract of the root bark of Etythrina burttii showed in vitro antiplasmodial activity against the chloroquine sensitive (D6) and chloroquine resistant (W2) strains of Plasmodium [alcipanun with IC50 values of 0.97 ± 0.2 and 1.73 ± 0.5 ug/rnl respectively. The extract also had radical scavenging activity against 2,2-diphenyl-l-picrylhydrazyl (DPPH) radical with EC50 value of 12.5 ug/ml and antimicrobial activity against a range of organisms. Previously reported isotlav-3-enes; burttinol-A and burttinol-C, and 2-arylbenzofuran derivative burttinol-D were identified as the most active antiplasmodial (1C50 < 10 u.M) and free radical scavenging (EC50 ca. 10 ~LM) principles. In addition, three more compounds were isolated and characterized as bidwillon A (1), 5-hydroxy-2-methoxybenzaldehyde (2) and erythrinasinate (3). The 2arylbenzofuran derivative burttinol-D was identified as a potent antibacterial and antifungal compound of the root bark of Erythrina burttii. The acetone extract of the roots of Erythrina abyssinica showed antip lasmod iaI [IC50 9.7 ± 1.1 ug/ml (against the D6) and 5.3 ± 0.7 ug/ml (W2) strains] and radical scavenging [against 2, 2diphenyl-I-picrylhydrazyl (DPPH) radical with EC50 value of 18.62 ug/rnl] activities. Chromatographic separation resulted in the isolation and identification of erycristagallin (4) as one of the active principles among other compounds. The acetate derivative (4a) was completely inactive showing the importance of free phenolic groups for both antiplasmodial and radical scavenging activities. Extending the interest on the phytochemistry and biological activity of this genus, the stem bark of Erythrina brucei was extracted with CI-{2Cb and MeOI-{ (I: I) by cold percolation. The extract was subjected to chromatographic separation, which led to isolation of four alkaloids (5-8). The structures of the compounds were determined using NMR C H, 13C, NOESY, COSY). Compound (8), is a new alkaloid and the trivial name IO-oxo-eryhtraline has been assigned. The other three known alkaloids were identified as crystarnidine (5), 8-oxo-erythraline (6), and erythraline (7). Besides this document, there has been only one other report on the occurrence of alkaloids in the stem bark of Erythrina species which otherwise elaborate flavonoids. The isolated compounds from Erythrina brucei were tested for radical scavenging activities; however none of them showed significant activity. Phytochemical investigation of Teelea nobilis (stem bark), another alkaloid containing plant with wide traditional uses, led to isolation of five compounds (9-13). The structures of the compounds were again determined using NMR (IH, 13C, NOESY, COSY). These include four alkaloids [rnaculine (9), flindersiamine (l0), 4,7 -dimethoxyfuro [2,3-b] quino lin-6-0 I (11), 7-(3methylbuta-l,3-dienylloxy)-4,6-dimethoxyfuro [2,3-b] quinoline (12)] and a triterpene derivative Lupeol (\3). Among these, compound 12 is a new alkaloid. The crude extract and the isolated compounds; maculine (9) and flindersiamine (10) isolated from the stem bark of Teelea nobilis were tested against certain bacteria tStaphyiococcus aureus and Escherichia coli) and fungi (Candida albicans, Aspergillus niger). The crude extract and the isolated compounds did not show any activity against the four pathogens. structures of the compounds were determined using MR CH, 13C, OESY, COSY). Compound (8), is a new alkaloid and the trivial name j O-oxo-eryhtraline has been assigned. The other three known alkaloids were identified as crystamidine (5), 8-oxo-erythraline (6), and erythraline (7). Besides this document, there has been only one other report on the occurrence of alkaloids in the stem bark of Erythrina species which otherwise elaborate flavonoids. The isolated compounds from Erythrina brucei were tested for radical scavenging activities; however none of them showed significant activity. Phytochemical investigation of Teclea nobilis (stem bark), another alkaloid containing plant with wide traditional uses, led to isolation offive compounds (9-13). The structures of the compounds were again determined using NMR (IB, 13C, NOESY, COSY). These include four alkaloids [maculine (9), flindersiamine (10), 4,7-dimethoxyfuro [2,3-b] quinolin-6-ol (11), 7-(3methylbuta-I ,3-dienylloxy)-4,6-dimethoxyfuro [2,3-b] quinoline (12)] and a triterpene derivative Lupeol (13). Among these, compound 12 is a new alkaloid. The crude extract and the isolated compounds; maculine (9) and flindersiamine (10) isolated frorn the stem bark of Teclea nobilis were tested against certain bacteria (Staphylococcus aureus and Escherichia coli) and fungi (Candida albicans, Aspergillus niger). The crude extract and the isolated compounds did not show any activity against the four pathogens.