Tran Thu Ha

C29 sterols with a cyclopropane ring at C-25 and 26 from the Vietnamese marine sponge Ianthella sp. and their anticancer properties.

Two new C(29) sterols with a cyclopropane ring at C-25 and C-26, petrosterol-3,6-dione (1) and 5alpha,6alpha-epoxy-petrosterol (2), along with petrosterol (3), were isolated from the Vietnamese marine sponge Ianthella sp. The structures of the new compounds were elucidated by comprehensive spectroscopic analyses. Compounds 1-3 showed cytotoxic activities on A549, HL-60, MCF-7, SK-OV-3, and U937 cancer cell lines with IC(50) in the range of 8.4-22.6 microM, whereas compounds 1-3 exhibited only weak cytotoxic activities on HT-29 cell. After HL-60 cells were treated with the compounds, several apoptosis events like chromatin condensation and the increase of the population of sub-G1 hypodiploid cells were observed. These data supported that the compounds might have potential for leukemia treatment.

Cytotoxic and anti-inflammatory cembranoids from the Vietnamese soft coral Lobophytum laevigatum

Four new cembranoids, namely laevigatol A-D (1-4), and six known metabolites (5-10), were isolated from the Vietnamese soft coral Lobophytum laevigatum. The structures of these compounds were elucidated by extensive spectroscopic analyses, and the absolute stereochemistry of 1 was determined using the modified Moshers method. Compounds 5, and 7-10 exhibited cytotoxic activity against selected human cancer cell lines. Compounds 1, 2, 8, and 9 showed dose-dependent inhibitory effects on the TNFα-induced NF-κB transcriptional activity in Hep-G2 cells. Moreover, compounds 1, 2, 8, and 9 significantly inhibited the induction of COX-2 and iNOS mRNA dose-dependently, indicating that these compounds attenuated the synthesis of these transcripts at the transcriptional level.

Cytotoxic and PPARs transcriptional activities of sterols from the Vietnamese soft coral Lobophytum laevigatum

A new unusual sterol, named lobophytosterol (1), and five known metabolites (2-6) were isolated from the methanol extract of the soft coral Lobophytum laevigatum. Their chemical structures were elucidated by extensive spectroscopic analysis and comparison with those reported in the literature. The absolute stereochemistry of 1 was determined using a modified Moshers method. Compounds 1-3 showed cytotoxic activity against HCT-116 cells with IC(50) values of 3.2, 6.9 and 18.1 μM, respectively. Compound 1 additionally displayed cytotoxic effects on A549 and HL-60 cells with IC(50) values of 4.5 and 5.6 μM, respectively. Treatment of these cells with compound 1 resulted in an induction of apoptosis evident by chromatin condensation in treated cells. Besides, compounds 2, 4, and 6 significantly upregulated PPARs transcriptional activity dose-dependently in Hep-G2 cells. Taken together, these data suggest that compound 1 might inhibit the growth of the cancer cells by the induction of apoptosis, and compounds 2, 4, and 6 might act as specific agonists for PPARα, PPARδ, and PPARγ and may therefore regulate cellular glucose, lipid, and cholesterol metabolism.

A new C29-sterol with a cyclopropane ring at C-25 and 26 from the Vietnamese marine sponge lanthella sp.

One new C29 sterol with a cyclopropane ring at C-25 and C-26, aragusteroketal B (1), and aragusterol B (2) were isolated from the Vietnamese marine sponge Ianthella sp. Their structures were elucidated by extensive spectroscopic analyses. Both 1 and 2 showed moderate cytotoxic activity against MCF-7, SK-Hep-1, and HeLa cell lines with IC50 in the range of 12.8–27.8 μM.

2D-model of contaminant water transmission processes and numerical simulation on a natural lake

Nowadays, the water pollution problems in the lakes are urgent matters. The simulation of contaminant water transmission process plays important role in reality to improve people’s life qualities. In this paper the 2Dmathematical model simulating transmission processes of some contaminant substances in one lake of Hanoi is studied. The finite volume method is used in model. The actions between substances are considered and the simulation results are compared with the measurements.

Super cavity model with the coupling reaction of slender body motion and water flow

On the imperfect water entry, a high-speed slender body moving in the forward direction, rotates inside the cavity. The bodys motion makes super cavity phenomena in the water flow. The water velocity and pressure fields interact during the bodys motion. In this paper, the coupling simulation model is a combination of two sub-models: In the first sub-model, the motion of slender body running very fast underwater is simulated. The equation system of this sub-model is solved by Runge-Kutta method; In the second sub-model, the water flow and pressure field under reaction of very fast slender body motion are simulated by CFD model. The simulation results of this coupled model are compared with experiments based on magnitudes of velocity U by x0 direction and error percents for cavity diameter and length.

Body parameters with application of optimal differential variation method in super cavity model

When a slender body moves very fast through water at sufficient speed the cavity phenomena is happened. In a cavity model the bodys lengths and cavitator diameter are determined by the differential variation optimal method so that the velocity of body is maximum.

On the motion of incompressible viscous fluid with flotation on free surface

In the works [1, 15j the problems about the motions of ideal fluid contained in an elastic bottom vessel or in a solid vessel with flotations on the free surfaces were investigated. In this paper we consider the motion of incompressible viscous tluid contained in a vessel with flotation on the free surface. The unique existence theorem of solution is proved, the spectrum structure and the completeness of the characteristic vector system are studied.