Isolation and characterization of limonoids from swietenia macrophylla and their antioxidant and antimicrobial activities
| dc.contributor.author | Seok Keik, Tan | |
| dc.date.accessioned | 2015-08-25T07:02:33Z | |
| dc.date.available | 2015-08-25T07:02:33Z | |
| dc.date.issued | 2009 | |
| dc.description.abstract | Swietenia macrophylla King, a tree up to 30-35 m tall, is used traditionally by local folks to cure diabetes and high-blood pressure. The leaves of this tree, collected from the campus of Universiti Sains Malaysia, were air-dried, powdered and extracted with n-hexane, dichloromethane and methanol. The dichloromethane and n-hexane extracts were separated by column chromatography and preparative thin layer chromatography on silica gel to give seven limonoids, among which four are new limonoids, namely swietephragmins H-J [1-3] and swietemacrophine [4]. The structures of the new compounds were elucidated by spectroscopic methods using lD and 2D NMR, HRESIMS, UV and IR, and were identified as phragmalin-type limonoids. Meanwhile, the known compounds were identified as swietenine (5], swietenolide [ 6] and 3-0-tigloylswietenolide [ 7], which are mexicanolide-type limonoids. These known compounds were identified based on their spectroscopic data and also by comparison with related literature. The total phenolic, total tannin and total flavonoid contents of Swietenia macrophylla leaf extracts were examined and the contents were decreased in the following order: methanol extract > dichloromethane extract > n-hexane extract. The methanol, dichloromethane and n-hexane extracts, together with swietephragmin H [1], swietephragmin I [2] and swietenolide [6) were further evaluated for their antioxidant activity using DPPH· radical scavenging assay. The results showed that all of the extracts tested were active as radical scavengers, with methanol extract, dichloromethane extract and n-hexane extract showing IC50 at 7.67 ± 0.29, 15.00 ± 0.50 and 26.00 ± 1.73 ~g/mL, respectively. For the pure compounds tested, swietenolide [6] showed IC50 at 121.50 ± 0.87 ~g/mL, while the ICso value for swietephramin H [J] and swietephragmin I [2], which showed low activity, cannot be determined in this study. The antimicrobial activity of the extracts and compounds [J]-[7] isolated from the leaves of S. macrophylla were also evaluated against four species of bacteria and one species of yeast. The methanol and dichloromethane extracts were active against the Gram-positive bacteria tested, Staphylococcus aureus and Bacillus subtilis, and were moderately or inactive against the Gram-negative bacteria tested, Escherichia coli and Pseudomonas aeruginosa. The methanol extract also showed antifungal properties. On the other hand, then-hexane extract and compounds [J][ 7] were found inactive towards all the microorganisms tested. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/1090 | |
| dc.language.iso | en | en_US |
| dc.subject | Swietenia macrophylla | en_US |
| dc.subject | Antimicrobial activities | en_US |
| dc.title | Isolation and characterization of limonoids from swietenia macrophylla and their antioxidant and antimicrobial activities | en_US |
| dc.type | Thesis | en_US |
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