Chemical constituents of polyalthia cauliflora var. cauliflora / Nurunajah Ab. Ghani

The stem bark of Polyalthia cauliflora var. cauliflora from the family of Annonaceae was investigated for its chemical content and biological activity. A total of ten compounds was isolated from this plant. Various chromatographic methods were used to separate all compounds including VLC, glass column, centrifugal chromatography and preparative thin layer chromatography. Phytochemical studies on the stem bark of P. cauliflora var. cauliflory resulted in the isolation of seven flavonoids; five flavones and two chalcones and two oxo aporphine alkaloids. The flavonoids obtained were 3,7-dimethoxy-5-hydroxyflavone, 5,8-dihydroxy-6,7- dimethoxyflavone, tectochrysin, 6,7-dimethoxy-5-hydroxyflavone, 5-hydroxyl-3,7,8- trimethoxy flavone, 2',4'-dihydroxy-3'-methoxychalcone and 2',4'- dihydroxy chalcone while alkaloids isolated were liriodenine and lanuginosine. In addition, a mixture of phytosterol; P-sitosterol and stigmasterol was also isolated from the stem bark, of P. cauliflora var. cauliflora. Structural elucidation was performed with the aid of spectroscopic methods such as ultraviolet (UV), infrared (IR), mass spectrometry (MS), ID and 2D nuclear magnetic resonance (NMR)- COSY, HMQC and HMBC. The alcoholic crude extract was subjected to antioxidant assays which gave good activity with the percent inhibition of 98-100 % of FTC assays and 73-89 % of TBA assays. A comparison on the strength of two variety of P. cauliflora (P. cauliflora var. cauliflora and P. cauliflora var. beccarii) against six bacteria in antimicrobial assays was also carried out. Both crudes show weak activities against Bacillus spizizenii and Staphylococcus aureus and no activity at all against other four bacteria; Pseudomonas aeruginosa, Escherichia coli, Salmonella typhimurium and Streptococcus pyogene. Selected compounds PCB4 and PCB6 (6,7-dimethoxy-5-hydroxyflavone and 2',4'-dihydroxy-3'-methoxychalcone) were subjected to cytotoxic assays against three different cell lines which were HeLa (cervical cancer), HL-60 (leukemia) and MCF-7 (breast cancer). 2',4'-dihydroxy-3'- methoxy chalcone (PCB6) shows strong activity against HL-60 and moderate activity against HeLa and MCF-7 with the IC50 5.1 p.g/ml, 12.2 ng/ml and 12.5 |xg/ml, respectively. 6,7-dimethoxy-5-hydroxyflavone (PCB4) shows a weak activity against HeLa and HL-60 with the IC50 25.1 ug/ml and 25.2 ^ig/ml, respectively and no activity at all against MCF-7.