Nuttapon Apiratikul

Synthesis and in vitro transfection efficiency of spermine-based cationic lipids with different central core structures and lipophilic tails

Twelve spermine-based cationic lipids with four different central core structures (di(oxyethyl)amino, di(oxyethyl)amino carboxy, 3-amino-1,2-dioxypropyl and 2-amino-1,3-dioxypropyl) and three hydrophobic tails (lauric acid, myristic acid and palmitic acid) were synthesized. The liposomes containing lipids and DOPE showed moderate to good in vitro DNA delivery into HeLa cells. GFP expression experiments revealed that liposomes composed of lipids with 3-amino-1,2-dioxypropyl as a central core structure exhibited highest transfection efficiency under serum-free condition. Whereas, lipid with 2-amino-1,3-dioxypropyl core structure showed highest transfection under 10% serum condition. Moreover, the liposomes and lipoplexes composted of these cationic lipids exhibited low cytotoxicity.

Novel racemic tetrahydrocurcuminoid dihydropyrimidinone analogues as potent acetylcholinesterase inhibitors.

The synthesis of racemic tetrahydrocurcumin- (THC-), tetrahydrodemethoxycurcumin- (THDC-) and tetrahydrobisdemethoxycurcumin- (THBDC-) dihydropyrimidinone (DHPM) analogues was achieved by utilizing the multi-component Biginelli reaction in the presence of copper sulphate as a catalyst. The evaluation of acetylcholinesterase inhibitors for Alzheimers disease of these compounds showed that they exhibited higher inhibitory activity than their parent analogues. THBDC-DHPM demonstrated the most potent inhibitory activity with an IC50 value of 1.34±0.03μM which was more active than the approved drug galanthamine (IC50=1.45±0.04μM).

Cholesterol-based cationic liposome increases dsRNA protection of yellow head virus infection in Penaeus vannamei.

Protection of shrimp from yellow head virus (YHV) infection has been demonstrated by injection and oral delivery of dsRNA-YHV protease gene (dsYHV) or shrimp endogenous gene (dsRab7). However, to achieve complete viral suppression and to prolong dsRNA activity, the development of an effective dsRNA delivery system is required. In this study, four cationic liposomes were synthesized and tested for their ability to increase dsRNA efficiency. The results demonstrated that entrapping dsYHV in a cholesterol-based cationic liposome gave the best protection against YHV infection when compared with other cationic lipids. The cholesterol-based cationic liposome-dsYHV (Chol-dsYHV) complex conferred YHV protection in a dose-dependent manner. Injection with Chol-dsYHV at 0.05μg dsYHV/g shrimp could give comparable level of YHV protection to the injection with 1.25μg naked dsYHV/g shrimp. The shrimp injected with Chol- dsYHV at 1.25μg dsRNA/g shrimp showed only 50% mortality at 60days post injection whereas the naked dsYHV at the same concentration gave 90% mortality. Thus, the liposome-entrapped dsYHV could lower an effective dsRNA concentration in viral protection and prolong dsRNA activity. In addition, encapsulating dsRab7 in the cholesterol-based cationic liposome could protect the dsRab7 from enzymatic digestion, and continuous feeding the shrimp with the diet formulated with the liposome-entrapped dsRab7 for 4days in the total of 960μg dsRab7/g shrimp could enhance YHV protection efficiency compared with the naked dsRab7. Our studies reveal that cholesterol-based cationic liposome is a promising dsRNA carrier to enhance dsRNA efficiency in both injection and oral delivery systems.

In vitro delivery of curcumin with cholesterol-based cationic liposomes.

A new cholesterol-based cationic lipid was synthesized; liposomes prepared on its basis were evaluated as drug delivery vehicles for curcumin. Free and liposome-encapsulated curcumin cytotoxicity against HeLa, A549, HepG2, K562 and 1301 cell lines was assessed. Liposomal curcumin with ED50 values ranging from 2.5–10 μM exhibited 2–8 times higher cytotoxicity than free curcumin. The synthetic cholesterol-based cationic lipid also enhanced cellular uptake of curcumin into tested cells. Cationic liposome alone showed low cytotoxicity at high doses with ED50 values of 90–210 μM.

Synthesis of bis, tris and tetra(dihydrocaffeoyl)polyamine conjugates as antibacterial agents against VRSA

Bis, tris and tetra(dihydrocaffeoyl)polyamine conjugates were synthesized using solid phase synthesis technique. These compounds were screened for antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) (11 strains) and vancomycin-resistant S. aureus (VRSA) (4 strains). Bis, tris and tetra(dihydrocaffeoyl)polyamine analogues showed antibacterial activity against VRSA which were better than the reference drugs, vancomycin. Tetra(dihydrocaffeoyl) polyamine conjugate exhibited the highest activity. These compounds showed no cytotoxicity against vero cells.

New bioactive cyclopeptide alkaloids with rare terminal unit from the root bark of Ziziphus cambodiana

Six new 14-membered ring cyclopeptide alkaloids, cambodines A–F (1–6), and two known compounds, frangufoline (7) and lotusanine B (8), were isolated from the root bark extract of Ziziphus cambodiana Pierre. Their structures and configurations were established based on 1D and 2D NMR, HRMS, ECD, and X-ray crystallographic data. Compounds 1 and 3 are rare 5(14)-type cyclopeptide alkaloids that possess an imidazolidin-4-one ring in the terminal unit. The cyclopeptides were tested for their in vitro antiplasmodial, antitubercular, and cytotoxic effects against three cancer cell lines. Compound 3 showed significant antiplasmodial activity against the malarial parasite Plasmodium falciparum, with an IC50 value of 6.09 μM.

Cytotoxic alkaloids against human colon adenocarcinoma cell line (HT-29) from the seed embryos of Nelumbo nucifera

Phytochemical investigation of the CHCl3 extract of the seed embryos of Nelumbo nucifera Gaertn resulted in the isolation of a new naturally occurring bisbenzylisoquinoline alkaloid, O-methylneferine (1), together with five known alkaloids, neferine (2), armepavine (3), (–)-(1R)-N-methylcoclaurine (4), nuciferine (5), and pronuciferine (6). The structures of these compounds were characterized by spectroscopic methods and comparison of physical properties with those reported in the literature. Among them, compounds 1 and 2 exhibited significant activity against human colon adenocarcinoma cell line (HT-29), with IC50 values of 0.70 and 1.61 µM, respectively, which were 8- and 3.5-fold higher than that of the reference anticancer drug, doxorubicin (IC50 5.63 µM). Moreover, compounds 1 and 2 displayed less cytotoxic activity against the non-cancerous HEK 239 cells with the IC50 values of 42.48 and 12.19 μM, respectively, whereas the cytotoxicity of doxorubicin against this cell line was 0.22 μM. The very potent cytotoxicity against HT-29 cell line and very high selectivity index (60.6-fold) of the alkaloid 1 is of particular significant; it could be considered as a promising structure lead for anti-colon cancer drug development.