Isolation of coumarins from the stembark of calophyllum symingtonianum and their antioxidant and antimicrobial activities /
Genus of Calophyllum is well known as a source of biologically active compounds such as coumarin, xanthones, triterpenoid, benzophenones, neoflavonoid, biflavonoid. Previous work has focused on the characterisation of xanthones and coumarins especially since the isolation of calanolide A, a new clas...
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| Format: | Thesis |
| Language: | English |
| Published: |
Kuala Lumpur:
Kulliyyah of Science, International Islamic University Malaysia,
2014
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| Subjects: | |
| Online Access: | Click here to view 1st 24 pages of the thesis. Members can view fulltext at the specified PCs in the library. |
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| Summary: | Genus of Calophyllum is well known as a source of biologically active compounds such as coumarin, xanthones, triterpenoid, benzophenones, neoflavonoid, biflavonoid. Previous work has focused on the characterisation of xanthones and coumarins especially since the isolation of calanolide A, a new class of HIV-1 reverse transcriptase inhibitors. The objectives of the present study were to determine the antioxidant and antimicrobial activities of crude extracts as well as the isolated compounds from Calophyllum symingtonianum and to isolate and elucidate the structure of the active compounds. The plant was extracted with soxhlet using three solvents n-hexane, dichloromethane and methanol succesively. The active compounds were isolated using silica gel column chromatography technique. The antimicrobial activity was tested using disc diffusion method and the MIC and MBC values were determined. The antioxidant tests were conducted using DPPH radical scavenging test, β-carotene bleaching and FRAP assays. The crude extracts of n-hexane, dichloromethane (DCM) and methanol showed positive results as free radical scavengers with IC50 of 1.93, 0.56 and 0.1 mg/mL. The antioxidant activity of n-hexane, DCM and methanol were 78, 42.8 and 20 %, respectively, in β-carotene bleaching assay and the FRAP values of 0.976, 1.010, 0.970 mM Fe (II)/mg of extracts, respectively. The antimicrobial study against Staphylococcus aureus showed considerable results for the n-hexane extract (inhibition zone of 10 mm and MIC value of 0.3 mg/mL), DCM extract (inhibition zone of 11 mm and MIC value of 0.25 mg/mL) and methanol extract (inhibition zone of 12 mm and MIC value of 0.25 mg/mL). Eight compounds were isolated among which two of them (symingtonide A and symingtonide B) were active as antioxidant and antimicrobial agents. Five compounds including myricetin, friedelan-3-one, D:A-friedooleanan-7-ol, symingtonide A and symingtonide B were characterized.The results for symingtonide A (5-hydroxy-6-(3-hydroxybutan-2-yl)-2-isopropyl-10-phenylpyrano[2,3-f] chromen-8(2H)-one) and stmingtonide B (6-(3-ethoxybutan-2-yl)-5-hydroxy-2-isopropyl-10-phenylpyrano[2,3-f] chromen-8(2H)-one) showed antioxidant activity as radical scavenger with IC50 values of 1.35 and 1.7 mg/mL, respectively. The FRAP values were 0.731 and 0.749 mM Fe (II)/mg of compounds, respectively. Results also indicated that symingtonide A is active against S. aureus (inhibition zone of 13 mm and MIC value of 25 μg/mL) and Pseudomonas aeruginosa (inhibition zone of 10 mm and MIC value of 111 μg/mL) while symingtonide B was only active against P. aeruginosa (inhibition zone of 7 mm and MIC values of 111 μg/mL). |
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| Physical Description: | xviii, 131 leaves : ill. ; 30cm. |
| Bibliography: | Includes bibliographical references (leaves 103-121). |