الفهرس 
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Abstract
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SUMMARY
This thesis entitled comprises three chapters and ends with a list of references.
The first chapter covers the literature survey up to date on the peptide synthesis (solution
and solid phase synthesis) as well as 1,3,5-triazine based amino acid and peptide derivatives and
relevance of their biological and therapeutical applications.
The second chapter consists of the equipments and chemicals used in the work. Also, it
contains the method of preparation of 4,6-dimethoxy-, 4,6-dipiperidino- and 4,6-morpholino-
1,3,5-triazine derivatives of amino acids, di-, tri-, tetra- and pentapeptides. The synthesis based
on two types of mechanisms, nucleophilic aromatic substitution reaction and acyl nucleophilic
substitution one. The MAO-A and MOA-B inhibition activity of the synthesized compounds
were also performed.
The last chapter deals with the discussion and interpretation of the results obtained from
the above mentioned chapter as well as the MAO-inhibition activity studies from experimental
and theoretical point of view. The third chapter deals with four main topics:
1. Preparation of 1,3,5-triazine based amino acid and peptide derivatives.
2. Chemical structure elucidation by spectroscopic techniques including NMR, IR as well as
the elemental analysis.
3. Purity evaluation and molecular weights determination were performed by HPLC and
MALDI-TOF/TOF mass spectrometer respectively.
3. The biological applications were represented by measuring MOA’s (A and B) inhibition
activity theoretically and experimentally.
N-(4,6-Dimethoxy-1,3,5-triazin-2-yl) amino acids 179-185 were prepared by reaction of
iminodiacetic acid or free amino acids with 2-chloro-4,6-dimethoxy-1,3,5-triazine 161 in
presence of triethyl amine as an acid scavenger for the liberated HCl (Scheme 1).
Scheme 1: Synthesis of N-(4,6-dimethoxy-1,3,5-triazin-2-yl) amino acids 179-185.
On the other hand, the N-(4,6-dipiperidino-) and N-(4,6-dimorpholino-1,3,5-triazin-2-yl)
amino acid derivatives were synthesized starting from 2,4-dichloro-6-(piperidin-1-yl)-1,3,5-
triazine 197 and 2,4-dichloro-6-morpholino-1,3,5-triazine 211, respectively. Compounds 197 and
211 were allowed to react with amino acids, where the resulting product was allowed
subsequently to react with piperidine /morpholine to afford the corresponding products 198-204
and 212-218 (Scheme 2).
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Scheme 2: Synthesis of N-(4,6-dsubstituted-1,3,5-triazin-2-yl) amino acid derivatives 198-204 and 212-
218.
In addition, N-(4,6-disubstituted-1,3,5-triazin-2-yl) dipeptide ethyl ester derivatives 186-
190, 205-209 and 219-223 series were prepared by coupling of N-(4,6-disubstituted-1,3,5-triazin-
2-yl) amino acid with glycine ethyl ester in presence of coupling reagent (HATU) and tertiary
base (DIEA) in DMF as solvent (Scheme 3).
Scheme 3: Synthesis of N-(4,6-disubstituted-1,3,5-triazin-2-yl) dipeptide ethyl ester derivatives 186-190,
205-209 and 219-223.
Furthermore, N-(4,6-dimethoxy-1,3,5-triazin-2-yl) dipeptide amide derivatives 191-195
were prepared by coupling of N-(4,6-dimethoxy-1,3,5-triazin-2-yl) amino acid with valine amide
hydrochloride in presence of coupling reagent (HATU) and tertiary base (DIEA) in DMF as
solvent (Scheme 4).
N
N
N
N
O O
O
OH
R2
H2N
NH2
+ O
HATU
DIEA, DMF
N
N
N
N
O O
O
HN
R2
NH2
O
191-195
R1 R1
Scheme 4: Synthesis of N-(4,6-dimethoxy-1,3,5-triazin-2-yl) dipeptide amide derivatives 191-195.
The tripeptide amides, N-(4,6-disubstituted-1,3,5-triazin-2-yl)-Gly-Phe-Val-NH2
derivatives 196, 211 and 224 were prepared by multistep reaction including activation, coupling
and deprotection steps in C to N direction. The synthesis started by activation of Boc-phenyl
alanine using HATU, then coupling with L-valine amide hydrochloride in presence of DIEA as a
base and DMF solvent to afford the dipeptide Boc-Phe-Val-NH2. The crude Boc-Phe-Val-NH2
and p-toluene sulfonic acid was dissolved in acetonitrile, and stirred to remove the Boc-group
forming the H-Phe-Val-NH2.p-TsOH. The crude H-Phe-Val-NH2.p-TsOH was allowed to
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undergo a further coupling with N-(4,6-disubstituted-1,3,5-triazin-2-yl)-Gly-OH in presence of
HATU and DIEA in DMF to afford the desired products (Scheme 5).
Scheme 5: Synthesis of N-(4,6-disubstituted-1,3,5-triazin-2-yl)-Gly-Phe-Val-NH2 derivatives 196, 211
and 224.
Fmoc/tBu Solid-Phase synthesis strategy of model tetra- and pentapeptides 225-228 were
assembled on Fmoc-Rinkamide-AM-PS resin using HATU as coupling agent and DIEA as a base
in DMF solvent. The general synthesis was carried out manually using a disposable plastic
syringe attached to a water aspirator as a reaction vessel. The synthesis was carried out as
follows: Fmoc-Rinkamide-AM-PS resin contained in a 10 mL disposable syringe fitted with a
teflon filter was washed with CH2Cl2 and DMF, then deprotected with 20 % piperidine in DMF.
The deprotected resin was washed with DMF, CH2Cl2 and again with DMF. Preactivation was
carried out using Fmoc-amino acid (4-fold excess), HATU (4-fold excess), and DIEA (8-fold
excess) in DMF. The solution of the activated Fmoc-amino acid was added to the resin, and the
resulting mixture was periodically stirred. The loaded resin was washed with DMF and the Fmoc
group was removed with 20 % piperidine in DMF. Washing of the deblocked resin with DMF,
CH2Cl2, and DMF was followed by an analogous coupling step with the second Fmoc-amino
acid. Subsequent amino acids were added in the same manner (Scheme 6). The Fmoc-deprotected
peptide-resin undergoes one of the following three routes:
i) React with 2-chloro-4,6-dimethoxy-1,3,5-triazine 161 in the presence of triethyl amine to give
N-(4,6-dimethoxy-1,3,5-triazin-2yl)-Tyr-Gly-Gly-Phe-Leu-resin, which subsequently
deblocked from the resin by shaking with 10 % TFA in CH2Cl2 to give N-(4,6-dimethoxy-
1,3,5-triazin-2yl)-Tyr-Gly-Gly-Phe-Leu-NH2 225.
ii) Deblocked from the resin by shaking with 10 % TFA in CH2Cl2 then react with 2-chloro-4,6-
dimethoxy-1,3,5-triazine 161 in presence of Et3N to give N-(4,6-dimethoxy-1,3,5-triazin-2yl)-
Gly-Gly-Phe-Val-NH2 226.
iii) Deblocked from the resin by shaking with 10 % TFA in CH2Cl2 then coupled with N-(4,6-
disubstituted-1,3,5-triazin-2yl)-Gly-OH (199 or 213) to give N-(4,6-disubstituted-1,3,5-triazin-
2yl)- Gly-Gly-Phe-Val-NH2 227 and 228.
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Scheme 6. Solid phase peptide synthesis.
The newly synthesized 4,6-disubstituted-1,3,5-tiazine-based amino acid and peptide
derivatives were evaluated for their MAO-A and MAO-B inhibitory activity. Furthermore, the
synthesized compounds were tested to determine their activity toward MAO-A and MAO-B
selectivity in the presence of the specific substrate, serotonin or benzylamine respectively. The
results revealed that these derivatives showed MAO-A inhibition activity more or less
comparable to the standard clorgyline. In addition, these compounds showed higher MAO-A
inhibitory activity than MAO-B inhibitory activity.
On the hand, molecular docking studies were further performed for some derivatives to
help understanding the various interactions between the ligands and enzyme active sites in detail.
The test compounds were further evaluated for their oral acute toxicity. The results
revealed that all the test compounds were non-toxic up to 100 mg/kg. We could conclude that the
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synthesis and biochemical evaluation of the newly synthesized N-(2,4-disubstituted-1,3,5-triazin-2-yl) amino acid and peptide derivatives led to the design of a novel class of MAO-A inhibitors with good safety margin.