Growth Inhibition of Human Gynecologic and Colon Cancer Cells by Phyllanthus watsonii through Apoptosis Induction

Phyllanthus watsonii Airy Shaw is an endemic plant found in Peninsular Malaysia. Although there are numerous reports on the anti cancer properties of other Phyllanthus species, published information on the cytotoxicity of P. watsonii are very limited. The present study was carried out with bioassay-guided fractionation approach to evaluate the cytotoxicity and apoptosis induction capability of the P. watsonii extracts and fractions on human gynecologic (SKOV-3 and Ca Ski) and colon (HT-29) cancer cells. P. watsonii extracts exhibited strong cytotoxicity on all the cancer cells studied with IC50 values of ≤ 20.0 µg/mL. Hexane extract of P. watsonii was further subjected to bioassay-guided fractionation and yielded 10 fractions (PW-1→PW-10). PW-4→PW-8 portrayed stronger cytotoxic activity and was further subjected to bioassay-guided fractionation and resulted with 8 sub-fractions (PPWH-1→PPWH-8). PPWH-7 possessed greatest cytotoxicity (IC50 values ranged from 0.66 – 0.83 µg/mL) and was selective on the cancer cells studied. LC-MS/MS analysis of PPWH-7 revealed the presence of ellagic acid, geranic acid, glochidone, betulin, phyllanthin and sterol glucoside. Marked morphological changes, ladder-like appearance of DNA and increment in caspase-3 activity indicating apoptosis were clearly observed in both human gynecologic and colon cancer cells treated with P. watsonii especially with PPWH-7. The study also indicated that P. watsonii extracts arrested cell cycle at different growth phases in SKOV-3, Ca Ski and HT-29 cells. Cytotoxic and apoptotic potential of the endemic P. watsonii was investigated for the first time by bioassay-guided approach. These results demonstrated that P. watsonii selectively inhibits the growth of SKOV-3, Ca Ski and HT-29 cells through apoptosis induction and cell cycle modulation. Hence, P. watsonii has the potential to be further exploited for the discovery and development of new anti cancer drugs

EXPERIMENTAL-STUDY ON THERMAL-CONDUCTIVITY OF NON-NEWTONIAN FLUIDS DURING SHEAR - APPLICATION TO CARBOPOL 940 SOLUTIONS

Polymers exhibit physical properties intermediate to those of elastic solids which follow Hook\u27s law and those of viscous fluids which behave according to Newtonian shear law, therefore, they are designated non-Newtonian fluids. Under a steady shear, non-Newtonian fluids exhibit not only the shear rate dependent viscosity but also their thermal conductivity changes with shear. It is the purpose of this paper to report on our investigation on the dependence of thermal conductivity on shear rate. Aqueous solutions of Carbopol 940 have been used as test fluids to investigate the effects of temperature and shear rate on thermal conductivity

Numerical and experimental investigation of direct electric conduction in a channel flow

Heat generation by direct electric conduction in a fully developed channel flow was studied to clarify interaction between the hydrodynamic, electric and thermal phenomena involved. The equations governing the system were solved numerically by a finite volume code. It was found that the difference between the residence time of the fluid flowing close to the wall and in the center of the channel causes deformation of the velocity profiles. This phenomenon creates a competition between the fluid particles flowing in these two regions and results in equalizing the temperature and velocity distribution in the channel span. An experimental investigation carried out in parallel with the numerical study yielded good agreement. An array of longitudinal streaks found on the channel electrode wall, with LIF visualization, is attributed to an instability phenomenon caused by electric body force. The wavelength of the streaks was measured and the control parameters of the instability were determined

BULK HEATING OF LIQUIDS BY DIRECT ELECTRIC CONDUCTION - PRINCIPLE AND MODELING

Heating of liquids by means of direct electric conduction or ohmic heating provides a uniform fluid heating while avoiding the operational problems related to convective heating. The aim of this work is to contribute to the modelling, design and optimization of ohmic heaters. Many physical phenomena (hydrodynamic, thermal and electric) are involved in this type of heaters. We have established the equations that govern these phenomena, and have solved them by using a finite volume algorithm. A parametric study has been performed on effects of each of the non-dimensional parameters A, Re, Pe and Ri which govern the system. This study carried out in a rectangular channel flow geometry shows that the temperature uniformity at the exit section of the channel increases with A and Ri augmentation and with Re diminution. This numerical model will be validated by the results of an on going experimental investigation

OHMIC HEATING OF COMPLEX FLUIDS

This paper describes the basic principles and physical modelling of systems based on the ohmic heating of liquids by passage of mains frequency electric current through the liquid itself, in order to heat it on a continuous flow regime. Preliminary numerical results for non-Newtonian fluids of Herschel-Bulckley type (Carbopol 940) are presented and the effect of natural convection, and shear and temperature dependence are emphasized