Pusat Pengajian Sains Kimia - Tesis

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Synthesis, Characterisation Of Stilbene–Arylcinnamide Hybrids And Cytotoxic Studies Against Lung Cancer Cell A549
(2024-07)
Mohd Zaki, Nurain Syazwani
Numerous anticancer drugs have been designed from natural products. Several compounds derived from nature such as alkaloid, flavonoid, cinnamic acid and stilbene, were reported to possess various biological properties primarily as an anticancer agent. In this study, a total of 24 compounds of a new hybrid series has been designed and synthesised, resulting from the coupling of stilbene and arylcinnamide scaffolds. All synthesised stilbene-arylcinnamide hybrids were obtained in 42-80% yield. Elucidation and characterisation of these hybrids have been validated using Fourier Transform Infrared (FT-IR), Nuclear Magnetic Resonance (NMR) spectroscopy and High-Resolution Mass Spectrometry (HRMS). The cytotoxicity against human lung cancer A549 cell line was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay, using cisplatin as the positive control. Particularly, compounds 66b and 74b have displayed potent activities on A549 cancer cells with IC50 value of 20.0 μM and 19.9 μM, respectively. This result is comparable to cisplatin with IC50 value of 19.9 μM after 72 hrs post-treatment. The structural activity relationship (SAR) analysis revealed that the presence of an isopropyl group attached to para-position of stilbene phenyl ring (ring A) of compounds 66b and 74b was crucial for a good cytotoxic effect on A549 cells. Additionally, 4-methyl group as the substituents on cinnamide phenyl ring (ring C) contributed to an innumerable cancer cell death.
Genetic Diversity Of The Beetle, Paederus Fuscipes Curtis (Coleoptera: Staphylinidae) And Its Symbiotic Diversity With Pederin Polymorphism Based On 16S Rrna Metagenomics Profiling
(2023-02)
Teoh, Miao Ching
Paederus rove beetles are known to carry the pederin toxin that causes linear dermatitis when crushed on skin. The toxin is produced by an unculturable Pseudomonas sp. harboured by the female Paederus beetles. Pederin polymorphism has been observed several Paederus and Paederidus beetle species wherein the (+) female beetles carried the toxin pederin and (−) females lacking this toxic amide. It has been stated that the (−) female Paederus beetles are infected with more bacterial species than (+) females, but the microbial profiles between the two female groups were not revealed. Besides, the association of pederin polymorphism with the host beetle’s genetic is yet to be investigated. Herein, the objectives of this dissertation are to investigate the microbial profile of the two groups of P. fuscipes beetles, and to study the host beetle’s mtDNA COI in association with pederin polymorphism. Pederin polymorphism studies on P. fuscipes beetles were carried out by PCR detection of pederin (ped) biosynthesis genes. The female beetles were then subjected to 16S rRNA amplicon sequencing and mtDNA COI analysis. This study also attempts to culture and isolate the pederin-producing bacteria.
Evaluation Of The Insecticidal Activity Of Cashew (Anacardium Occidentale L.) Nut Shell Liquid Against Adult Bactrocera Dorsalis (Hendel) (Diptera: Tephritidae)
(2023-10)
Keita, Sainey
The Oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most notorious pests of agricultural fruits. It has been found to attack over 250 host plants, including commercial fruits and a wide variety of crops. The insecticidal activity of Cashew (Anacardium occidentale L.) nut shell liquid (CNSL) against adult B. dorsalis (Hendel) was investigated under laboratory and field conditions. Two extracting solvents, dichloromethane and hexane were used to extract the CNSL from the cashew nut shell. Contact toxicity, topical application and repellency tests were carried out in the laboratory. For both the contact and topical experiments, concentrations of 0.625, 1.25, 2.5, 5.0, 10.0 and 20.0 x 104 ppm were prepared, whereas 0.07, 0.14, 0.21, 0.28 and 0.35 μL/cm2 concentrations were prepared for the repellency tests. The LC50 values recorded after 24 hours of exposure for the contact toxicity tests of the dichloromethane extract was 4.66 x 104 ppm, whereas 6.58 x 104 ppm was recorded for the hexane extract, which showed the dichloromethane extract to be significantly higher with 1.32 times more lethal than the hexane extract against B. dorsalis (t-test, P<0.05).
Sintesis Dan Pencirian Polimer-polimer Terbitan Daripada Getah Asli 50%-Terepoksida Dan Natrium 1,3,3,5,5, -Pentakis(Trifluoroetoksi) -1-Oksosiklotrifosfazenat
(1993-04)
Loo Swee Chow
Getah asli SO%-terepoksida (ENR-SO) telah ditindakbalaskan dengan natrium 1,3,3,S,S-pentakis(trifluoroetoksi)-1-oksosiklotrifosfazenat (mononatrium fosfazenat) dalam 1,4- dioksana refluks. Polimer-polimer terbitan yang diperolehi daripada nisbah berat ENR-SO:mononatrium fosfazenat yang berlainan (1.00:0.50, 1.00:1.00, 1.00:2.00, 1.00:3.00, 1.00: 4.50 dan 1.00:5.50) didapati mempunyai nilai-nilai suhu peralihan kaca (Tg) yang lebih tinggi daripada nilai Tg ENR- 50. Walau bagaimanapun, kesemua polimer terbitan didapati larut dalam 1,4-dioksana, tetrahidrofuran dan etanol.
Diversity And Distribution Of Benthic Foraminifera In Mangrove Forests Of Penang Island
(2023-02)
Malek, Muhamad Naim Abd
Foraminifera is one of the diverse groups of organisms inhabiting mangrove environment, but local studies regarding benthic foraminifera are limited. Therefore, this study was conducted to examine the diversity and distribution patterns of the foraminifera species in mangrove forests around Penang Island, which were Teluk Tempoyak, Pulau Betong, and Kuala Sungai Pinang. A total of 648 surface sediment samples (N=18 points × 3 mangrove forests × 12 months) of 1 cm thick were randomly collected using scoops during the lowest spring tide. The sampling was conducted monthly from March 2017 to February 2018. The results showed low to moderate species diversity (H’ index: 0-1.4), typical of a mangrove environment. Overall, 29 benthic foraminifera species were identified, predominantly agglutinated with some combination of hyaline and porcelaneous tests. Benthic foraminifera in Pulau Betong mangrove recorded the highest species diversity (29 species), followed by Teluk Tempoyak (25 species) and Kuala Sungai Pinang (19 species). The species idetified are commonly found in mangrove swamps and in the coastal environment. Species distribution demonstrated significant variation among the different locations, zones, and seasonal factors in the three mangrove forests (p < 0.05).

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