Isolation and identification of cyclic polyketides from Endiandra kingiana gamble (lauraceae), as BCL-XL/BAK and MCL-1/BID dual inhibitors, and approaches toward the synthesis of kingianins / Mohamad Nurul Azmi Mohamad Taib
The preliminary screening showed that the bark of Endiandra kingiana Gamble exhibited potency as a modulating agent between Bcl-xL and Bak, which prompted its chemical investigation. Two groups of compounds were isolated and characterized; the endiandric acid series and the kingianin series. Eigh...
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| Format: | Thesis |
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2015
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| Online Access: | http://studentsrepo.um.edu.my/14661/ http://studentsrepo.um.edu.my/14661/1/Mohamad_Nurul_Azmi.pdf |
| Summary: | The preliminary screening showed that the bark of Endiandra kingiana Gamble
exhibited potency as a modulating agent between Bcl-xL and Bak, which prompted its
chemical investigation. Two groups of compounds were isolated and characterized; the
endiandric acid series and the kingianin series. Eight new endiandric acid analogues
(kingianic acids A-H [120-127]) and three new kingianin analogues (kingianin O-Q
[128-130]) were isolated and structurally elucidated. The isolated compounds were
evaluated for two bioassays; Bcl-xL/Bak and Mcl-1/Bid of binding affinities and
cytotoxic effects against various human tumour cells. The second part describes the
progression towards the total synthesis of kingianin analogues. The pentacyclic
kingianin skeleton was formed by Diels-Alder reaction between two monomers having
a bicyclo[4.2.0]octadiene backbone formed by a stereospecific electrocyclization of
polyenes. The research was focusing on construction of bicyclo[4.2.0]octadiene
monomer using [2+2] ketene cycloaddition approach at the early stage of the synthesis.
One of the main advantages of such a strategy is the rapid assembly of the carbon
skeleton of kingianins, thus maximizing the chances for good overall yields of the final
products. So far, an efficient synthesis of the bicyclo[4.2.0]octene backbone was
successfully achieved. Five approaches to synthesize this backbone starting from [2+2]
cycloaddition of the cyclohexadienes to functionalized ketenes followed by
functionalization of substituent at C-7 and C-8 positions with the correct relative
configuration were described. From these approaches, compounds 280 and 311 were
identified as the key intermediates. This key step of the synthesis provided an access to
the kingianins skeleton.
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