Sze Wei Leong

Synthesis of unsymmetrical monocarbonyl curcumin analogues with potent inhibition on prostaglandin E2 production in LPS-induced murine and human macrophages cell lines.

The syntheses and bioactivities of symmetrical curcumin and its analogues have been the subject of interest by many medicinal chemists and pharmacologists over the years. To improve our understanding, we have synthesized a series of unsymmetrical monocarbonyl curcumin analogues and evaluated their effects on prostaglandin E2 production in lipopolysaccharide-induced RAW264.7 and U937 cells. Initially, compounds 8b and 8c exhibited strong inhibition on the production of PGE2 in both LPS-stimulated RAW264.7 (8b, IC50=12.01μM and 8c, IC50=4.86μM) and U937 (8b, IC50=3.44μM and 8c, IC50=1.65μM) cells. Placing vanillin at position Ar2 further improved the potency when both compounds 15a and 15b significantly lowered the PGE2 secretion level (RAW264.7: 15a, IC50=0.78μM and 15b, IC50=1.9μM while U937: 15a, IC50=0.95μM and 15b, IC50=0.92μM). Further experiment showed that compounds 8b, 8c, 15a and 15b did not target the activity of downstream inflammatory COX-2 mediator. Finally, docking simulation on protein targets COX-2, IKK-β, ERK, JNK2, p38α and p38β were performed using the conformation of 15a determined by single-crystal XRD.

Synthesis and Sar Study of Diarylpentanoid Analogues as New Anti-Inflammatory Agents

A series of ninety-seven diarylpentanoid derivatives were synthesized and evaluated for their anti-inflammatory activity through NO suppression assay using interferone gamma (IFN-γ)/lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Twelve compounds (9, 25, 28, 43, 63, 64, 81, 83, 84, 86, 88 and 97) exhibited greater or similar NO inhibitory activity in comparison with curcumin (14.7 ± 0.2 µM), notably compounds 88 and 97, which demonstrated the most significant NO suppression activity with IC50 values of 4.9 ± 0.3 µM and 9.6 ± 0.5 µM, respectively. A structure–activity relationship (SAR) study revealed that the presence of a hydroxyl group in both aromatic rings is critical for bioactivity of these molecules. With the exception of the polyphenolic derivatives, low electron density in ring-A and high electron density in ring-B are important for enhancing NO inhibition. Meanwhile, pharmacophore mapping showed that hydroxyl substituents at both meta- and para-positions of ring-B could be the marker for highly active diarylpentanoid derivatives.

Nitric oxide inhibitory activity and antioxidant evaluations of 2-benzoyl-6-benzylidenecyclohexanone analogs, a novel series of curcuminoid and diarylpentanoid derivatives

A series of twenty-four 2-benzoyl-6-benzylidenecyclohexanone analogs were synthesized and evaluated for their nitric oxide inhibition and antioxidant activity. Six compounds (3, 8, 10, 17, 18 and 19) were found to exhibit significant NO inhibitory activity in LPS/IFN-induced RAW 264.7 macrophages, of which compound 10 demonstrated the highest activity with the IC50 value of 4.2 ± 0.2 μM. Furthermore, two compounds (10 and 17) displayed antioxidant activity upon both the DPPH scavenging and FRAP analyses. However, none of the 2-benzoyl-6-benzylidenecyclohexanone analogs significantly scavenged NO radical. Structure-activity comparison suggested that 3,4-dihydroxylphenyl ring is crucial for bioactivities of the 2-benzoyl-6-benzylidenecyclohexanone analogs. The results from this study and the reports from previous studies indicated that compound 10 could be a candidate for further investigation on its potential as a new anti-inflammatory agent.

Synthesis, biological evaluation and QSAR studies of diarylpentanoid analogues as potential nitric oxide inhibitors

A series of forty-five 1,5-diphenylpenta-2,4-dien-1-one analogues were synthesized and evaluated for their nitric oxide (NO) inhibition activity in IFN-γ/LPS-activated RAW 264.7 cells. Compounds 3h, 7a, 7d and 7e exhibited comparable or significantly higher activity than the standard, curcumin (IC50 = 14.69 ± 0.24 μM). Compound 7d, a 5-methylthiophenyl-bearing analogue, displayed the most promising NO-inhibitory activity with an IC50 value of 10.24 ± 0.62 μM. The 2D and 3D QSAR analyses performed revealed that a para-hydroxyl group on ring B and an α,β-unsaturated ketone moiety on the linker are crucial for a remarkable anti-inflammatory activity. Based on ADMET and TOPKAT analyses, compounds 3h, 7a and 7d are predicted to be nonmutagenic and to exhibit high blood–brain barrier (BBB) penetration, which indicates that they are potentially effective drug candidates for treating central nervous system (CNS) related disorders.

Zebrafish phenotypic screen identifies novel Notch antagonists

SummaryZebrafish represents a powerful in vivo model for phenotype-based drug discovery to identify clinically relevant small molecules. By utilizing this model, we evaluated natural product derived compounds that could potentially modulate Notch signaling that is important in both zebrafish embryogenesis and pathogenic in human cancers. A total of 234 compounds were screened using zebrafish embryos and 3 were identified to be conferring phenotypic alterations similar to embryos treated with known Notch inhibitors. Subsequent secondary screens using HEK293T cells overexpressing truncated Notch1 (HEK293TΔE) identified 2 compounds, EDD3 and 3H4MB, to be potential Notch antagonists. Both compounds reduced protein expression of NOTCH1, Notch intracellular domain (NICD) and hairy and enhancer of split-1 (HES1) in HEK293TΔE and downregulated Notch target genes. Importantly, EDD3 treatment of human oral cancer cell lines demonstrated reduction of Notch target proteins and genes. EDD3 also inhibited proliferation and induced G0/G1 cell cycle arrest of ORL-150 cells through inducing p27KIP1. Our data demonstrates the utility of the zebrafish phenotypic screen and identifying EDD3 as a promising Notch antagonist for further development as a novel therapeutic agent.

Suppression of PGE2 production via disruption of MAPK phosphorylation by unsymmetrical dicarbonyl curcumin derivatives

Curcumin is an important molecule found in turmeric plants and has been reported to exhibit some profound anti-inflammatory activities by interacting with several important molecular targets found in the mitogen-activated protein kinase and NF-κβ pathways. As part of our continuing effort to search for new anti-inflammatory agents with better in vitro and in vivo efficacies, we have synthesized a series of new unsymmetrical dicarbonyl curcumin derivatives and tested their effects on prostaglandin E2 secretion level in interferon-γ/lipopolysaccharide-activated macrophage cells. Among those, five compounds exhibited remarkable suppression on prostaglandin E2 production with IC50 values ranging from 0.87 to 18.41 µM. The most potent compound 17f was found to down-regulate the expression of cyclooxygenase-2 mRNA suggesting that this series of compounds could possibly target the mitogen-activated protein kinase signal transduction pathway. Whilst the compound did not affect the expression of the conventional mitogen-activated protein kinases, the results suggest that it could disrupt the phosphorylation and activation of the proteins particularly the c-Jun N-terminal kinases. Finally, the binding interactions were examined using the molecular docking and dynamics simulation approaches.

Erratum to: Zebrafish phenotypic screen identifies novel Notch antagonists

The authors would like to note that in the original online first version of this article, the symbol ɣ is missing from the text where ɣ-secretase is stated. Also, labels to figures in the Results section should be BCYCLIN D1 levels were also reduced in a similar dose dependent manner while those of HES1 and NOTCH1 (shown by densitometry in Figure S6c) were marginally reduced and remained unaffected, respectively (Fig. 5d)^ and BAlso, we were able to show as mentioned earlier, that EDD3 treatment resulted in decreased CYCLIND1 levels and induction of p27 (Figure S8g)^. Subtitle in the Result section should be BIdentification of 3 novel compounds with potential anti-Notch activity in zebrafish embryos^ and ‘EDD3 inhibits proliferation and cell cycle progression of ORL-150 cells’. The original article was corrected.

In vitro and in silico evaluations of diarylpentanoid series as α-glucosidase inhibitor

A series of thirty-four diarylpentanoids derivatives were synthesized and evaluated for their α-glucosidase inhibitory activity. Eleven compounds (19, 20, 21, 24, 27, 28, 29, 31, 32, 33 and 34) were found to significantly inhibit α-glucosidase in which compounds 28, 31 and 32 demonstrated the highest activity with IC50 values ranging from 14.1 to 15.1 µM. Structure-activity comparison shows that multiple hydroxy groups are essential for α-glucosidase inhibitory activity. Meanwhile, 3,4-dihydroxyphenyl and furanyl moieties were found to be crucial in improving α-glucosidase inhibition. Molecular docking analyses further confirmed the critical role of both 3,4-dihydroxyphenyl and furanyl moieties as they bound to α-glucosidase active site in different mode. Overall result suggests that diarylpentanoids with both five membered heterocyclic ring and polyhydroxyphenyl moiety could be a new lead design in the search of novel α-glucosidase inhibitor.

Synthesis, bioactivity evaluation, and docking study of 5-aminosalicylic acid’s fatty acid derivatives

Some new oleic acid, linoleic acid, lauric acid derivatives of 5-aminosalicylic acid were produced in order to enhance bioactivity properties of 5-aminosalicylic acid. All new compounds’ structures were confirmed by spectroscopic methods. Moreover, in vitro antibacterial, anticancer, and anti-inflammatory activities of new synthesized compounds were investigated. Antibacterial activity was studied against pathogenic Gram-negative bacteria, Escherichia coli and Gram-positive bacteria, Staphylococcus aureus via disc diffusion method. Additionally, all derivatives’ anti-inflammatory activity were evaluated through NO suppression assay using interferon gamma (IFN-γ)/lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Furthermore, in vitro cytotoxicity assay was probed using MTT test against 3T3 and HT-29 cell lines. In another effort, docking studies were performed to predict the possible interactions and binding energy of new compounds against cyclooxygenase (COX-1/COX-2) and lipoxygenase (5-LOX) proteins. In conclusion, all new compounds exhibited moderate to better bioactivity improvements in comparison with parent drug. Also study of interactions between the new derivatives with active sites of proteins presented greater binding affinities than 5-aminosalicylic acid.Graphical abstract

Asymmetrical meta-methoxylated diarylpentanoids: Rational design, synthesis and anti-cancer evaluation in-vitro

In the present study, a series of forty-five asymmetrical meta-methoxylated diarylpentanoids have been synthesized, characterized and evaluated for their in-vitro anti-cancer potential. Among the forty-five analogs, three compounds (20, 33 and 42) have been identified as lead compounds due to their excellent inhibition against five human cancer cell lines including SW620, A549, EJ28, HT1080 and MCF-7. Structure-activity relationship study on cytotoxicity of tested compounds suggested that the presence of meta-oxygenated phenyl ring played a critical role in enhancing their cytotoxic effects. Compounds 33 and 42 in particular, exhibited strongest cytotoxicity against tested cell lines with the IC50 values ranging from 1.1 to 4.3 μM. Subsequent colony formation assay on SW620 cell line showed that both compounds 33 and 42 possessed strong anti-proliferative activity. In addition, flow cytometry based experiments revealed that these compounds could trigger intracellular ROS production thus inducing G2/M-phase cell arrest and apoptosis. All these results suggested that poly meta-oxygenated diarylpentnoid is a promising scaffold which deserved further modification and investigation in the development of natural product-based anti-cancer drug.