Naphthoquinone is one of secondary metabolites that are widespread in nature and found in large amounts [1]. Naphthoquinones are clinically important antitumor drugs containing a quinone moiety, such as anthracyclines, mitoxantrones and saintopin, show excellent anticancer activity [2]. In the previouse studies, Polo like kinase 1 (Plk1) is the preferential target for inhibition of mitotic processing and hence can be chosen as drug target for the treatment of cancer [3]. The aim of the study is lead finding of potential plk1 inhibitor from naphthoquinone derivatives through binding free energy analysis into plk1 using molecular docking. We conducted docking simulation to 50 naphthoquinone derivatives as ligands into plk1 as receptor. The 3D structure of plk1 was downloaded from PDB (PDB ID 3THB). Docking process, the interaction and binding of ligands-protein was done and visualized using Molegro Virtual Docking (MVD). The result showed the predicted docking energy and contact residue which reflected the binding affinities. Somenaphthoquinone derivatives showed reasonably low internal energy binding into Plk1 indicating the docked conformation of the ligands were in their most favorable conformations. It is predicted that naphthoquinone derivative has potency as lead compound to find a new antimitotic candidates for possible therapeutic agents.

Background: Lipopeptide-based gene carriers have shown low cytotoxicity, are capable in cell membrane penetration, are easy to manufacture and therefore are great potential candidates for gene delivery applications. Objectives: This study aims to explore a range of short synthetic lipopeptides, (Lau: Lauryl; Pal: Palmitoyl) consisting of an alkyl chain, one cysteine (C), 1 to 2 histidine (H), and lysine (K) residues by performing in-silico molecular interaction and in-vitro evaluation. Methods: The molecular interactions between the lipopeptides and Importin-α receptor were performed using AutoDock Vina and Amber14. The lipopeptide/DNA complexes were evaluated in-vitro for their interactions, particle size, zeta potential and transgene expression. Transfection efficiency of the lipopeptides and Pal-CKKHH-derived liposome was carried out based on luciferase transgene expression. Results: The in-silico interaction showed that Lau-CKKH and Pal-CKKHH hypothetically expedited nuclear uptake. Both lipopeptides had lower binding energy (-6.3 kcal/mol and -6.2 kcal/mol, respectively), compared to the native ligand, viz, nuclear localization sequence (-5.4 kcal/mol). The short lipopeptides were able to condense DNA molecules and efficiently and formed compacted nanoparticles. Based on in-vitro evaluation on COS-7, Pal-CKKHH was found to be the best transfection agent amongst the lipopeptides. It transfection efficiency (ng Luc/mg total protein) increased up to ~3-fold higher (1163 + 55) as it was formulated with helper lipid DOPE (1:2). The lipopeptide-based liposome (Pal-CKKHH: DOPE=1:2) also facilitated luciferase transgene expression on human embryonic kidney cells (293T) and human cervical adenocarcinoma cells (HeLa) with transfection efficiency 1779 +52 and 260 + 22, respectively. Conclusion: Our study for the first time has shown that the fully synthesized short lipopeptide Pal-CKKHH is able to interact firmly with the Importin-α he lipopeptide is able to condense DNA molecules efficiently, facilitate transgene expression, expedite nuclear uptake process, and hence has the characteristics of a potential transfection agent.

One of the crucial problems in B20 implementation is fuel filter clogging problem, due to the presence of some glyceride impurities in biodiesel. The existence of monoglyceride in B20 fuel, even in a very low amount, could cause the formation of a precipitate, especially at low-temperature conditions. The accumulated precipitate could accelerate fuel filter clogging. To anticipate the problem, the precipitate formed in the B20 fuel based on the monoglyceride content in biodiesel should be tested using different pore sizes of fuel filter. This research was conducted by applying a modified CSFT method of ASTM D7501 for the precipitation test at 20°C using fuel filter pore sizes of 0.8, 3, 5 and 8 microns, respectively. Monopalmitin was added to biodiesel with low monoglyceride content to vary monoglyceride content so that each had approximate monoglyceride content of 0.623% and 0.824%, respectively. Each biodiesel sample with varied monoglyceride content was then blended with petroleum diesel fuel to produce B20 fuel samples. Each sample in the 100 ml separating funnel was separately soaked at 20°C for 21 days, then filtered, washed with petrol-ether, vacuum-dried, and weighed for constant amount of precipitate retained on the filter. The result showed that the wider the filter pore size was, the less the precipitate amount could be maintained on the filter.

The main requirement of transfection agent has to condense DNA in nanoparticle size, protect the DNA from nucleases and other degrading enzymes during its transport in cell cytoplasm and nucleus and should not toxic to target cells. In this research, lipopeptide composed of palmitoyl (C-16) and short peptide sequence have been designed fully synthesized and tested to DNA condensation capability and toxicity. The DNA condensation study was performed using EtBr exclusion assay and cytotoxicity determination was carried out by colorimetric MTT assay. It was revealed that lipopeptide-based transfection agent of Pal-CKKHH and Pal-CKKHH-YGRKKRRQRRR-PKKKRKV condensed DNA molecules efficiently. The lipopeptide was less toxic compared to Lipofectamine and Poly-L-Lysine, that shown by 90% of CHO-K1 cells remained viable when they were treated with 4.36 µM Pal-CKKHHYGRKKRRQRRR-PKKKRKV. Meanwhile, there were only ~75% and 80% of CHO-K1 viable cells when it was treated with PLL and Lipofectamine®2000, respectively. Moreover, cell viability of HepG2 was ~ 75% after treated with 2.18 µM of Pal-CKKHH-YGRKKRRQRRR-PKKKRKV and decreased to ~65% when the lipopeptide concentration increased to 8.72 M. In summary, the synthesized lipopeptide condenses DNA molecules efficiently, less toxic than Lipofectamine®2000 and PLL and has possibility to be explored as a non-viral gene delivery vehicle.

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