Antimycobacterial and cytotoxic properties of lupanetriterpenoids and dimericnaphthoquinones isolated from diospyroskabuyeana and d. mafiensis

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Date
2015
Journal Title
Journal ISSN
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Publisher
University of Dar es Salaam
Abstract
This dissertation reports on the isolation and structure determination of lupanetriterpenes and dimericnaphthoquinones from D. kabuyeana, as well as in vitroantimycobacterial and cytotoxic activities of D. kabuyeanaand D. mafiensisextracts. The crude extracts of the two plant species exhibited antimycobacterial activity with Minimum Inhibitory Concentration (MIC) values ranging from 0.07 mg/mL to 2.5 mg/mL with the dichloromethane root extract of D. kabuyeana being the most active with MIC value of 0.07mg/mL. Likewise the extracts from the plant species exhibited cytotoxic activity with IC50 values ranging from 22.3 µg/mL to >100µg/mL. Phytochemical investigations of D. kabuyeanayielded four lupanetriterpenes namely (lupeol (43), betulin (44), betulinic acid (37) and betulinaldehyde (25)) and two dimericnaphthoquinones (diospyrin (24) and diosquinone (33)) while D. mafiensis afforded quercitol (45) and stigmasterol (46). The structures of the isolated compounds were determined by detailed analysis of the NMR spectroscopic data as well as mass spectrometry. The, dimericnaphthoquinonesdiospyrin (24) exhibited significant antimycobacterial activity with MIC value of 1.04 mg/mL and 0.52 mg/ml against Mycobacterium madascariense(MM) and Mycobacterium indicapranii(MIP) respectively while diosquinone (33) exhibited antimycobacterial activity with MIC value of < 0.03 mg/mL against MM and MIP. The triterpenes were inactive to MM except for betulinaldehyde (25) which was active against MIP with MIC value of 0.52 mg/mL.Diosquinone (33) exhibited the highest toxicity having an IC50 value of 9.55µg/mL against human breast cancer cells while compounds 43 and 37 exhibited an IC50 of 17.11 µg/mL and 20.89 µg/mL respectively. Compounds 24, 44 and 45 showed lower activity at IC50< 100 µg/mL while compounds 25 and 46 were not tested. The results indicate the potentiality of some of the investigated secondary metabolites from D.kabuyeana as a source of antimycobacterial and anticancer agents.
Description
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF QK495.E25M63)
Keywords
Diospyros, Antimycobacterial, Terpenes, Naphthaquinones
Citation
Moh’d, N.K. (2015) Antimycobacterial and cytotoxic properties of lupanetriterpenoids and dimericnaphthoquinones isolated from diospyroskabuyeana and d. mafiensis, Master dissertation, University of Dar es Salaam, Dar es Salaam