Estimation of relationship between descriptors and cytotoxicity of newly synthesized 1,2,3,4-tetrahydroisoquinoline derivatives.

We recently demonstrated that the cytotoxicity of nineteen 1,2,3,4-tetrahydroisoquinoline derivatives depends on the molecular size (surface area, volume, width measured at 3-dimensional configuration), but not on most of the other electronic factors (Ishihara et al., Anticancer Res 29: 2265-2272, 2009). However, the information regarding cytotoxicity and molecular size in these compounds is limited. Here, a quantitative structure-activity relationship (QSAR) analysis using nineteen newly synthesized 1,2,3,4-tetrahydroisoquinoline derivatives was carried out. A semiempirical molecular-orbital method (CAChe 4.9, PM5) was applied to delineate the relationship between the cytotoxicity (evaluated by 50% cytotoxic concentration, CC(50)) of the nineteen derivatives (TD1-19) against human promyelocytic leukemia HL-60 and human oral squamous cell carcinoma (HSC-2, HSC-3, HSC-4) cell lines and sixteen chemical descriptors determined by CONFLEX/PM5 method or the molecular weight. There was some correlation between the CC(50) and the dipole moment for HSC-4 cells (r(2)=0.273), between the CC and log P for HL-60 and HSC-3 cells (r(2) 50 =0.191-0.212), and between the CC(50) and distance of C-R(2) (at three dimensional configuration) (r(2)=0.394) and molecular weight (r(2)=0.292) for HL-60 cells. On the other hand, there was little or no correlation between the CC(50) and other descriptors. The present study demonstrated the dependency of the cytotoxicity of 1,2,3,4-tetrahydroisoquinoline derivatives on hydrophobicity and distance between C-R(2) in the 3-dimensional configuration. These descriptors obtained from the CONFLEX/PM5 method may be utilized as a tool to analyze the biological effect of 1,2,3,4-tetrahydroisoquinolines.

Tumor-specific cytotoxic activity of 1,2,3,4-tetrahydroisoquinoline derivatives against human oral squamous cell carcinoma cell lines.

The tumor-specific cytotoxicity and the type of cell death induced by thirty-eight newly synthesized tetrahydroisoquinoline derivatives in human oral squamous cell carcinoma cell lines were investigated. 6,7-Dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)(3,4-dimethoxyphenyl) methanone that has bulky substituents (such as 3,4-dimethoxybenzoyl group) (TQ9) and ethyl 2-benzyloxycarbonyl-1,2,3,4-tetrahydroisoquinoline-1-carboxylate that has ethoxycarbonyl group and benzyloxycarbonyl group (TD13) showed the highest tumor-specific cytotoxicity (TS=12.5 and 5.3, respectively). This supports the importance of molecular size for the cytotoxicity induction. TQ9 induced internulceosomal DNA fragmentation and caspase-3 activation only marginally in HL-60 cells, whereas it enhanced the formation of acidic organelles (stained with acridine orange) without induction of DNA fragmentation or caspase-3 activation in human squamous cell carcinoma cell lines (HSC-2, HSC-4), suggesting the induction of autophagy in the latter cells.

Re-evaluation of anti-inflammatory activity of mastic using activated macrophages.

Mastic is a resinous exudate obtained from the stem and the main leaves of Pistacia lentiscus. Mastic has shown several beneficial pharmaceutical properties such as antibacterial and apoptosis-modulating activities. The aim of this study was to investigate whether mastic affects the function of activated macrophages. Both solid and liquid types of mastic inhibited the production of pro-inflammatory substances such as nitric oxide (NO) and prostaglandin (PG)E(2) by lipopolysaccharide (LPS)-activated mouse macrophage-like RAW264.7 cells. This was accompanied by the decline of viable cell number. Western blot and RT-PCR analyses showed that mastic inhibited the expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 at both protein and mRNA levels. ESR spectroscopy revealed that mastic scavenged NO and superoxide radicals very poorly, in contrast to its potent hydroxyl radical scavenging activity. These data demonstrate that mastic inhibits the production of both NO and PGE(2) by activated macrophages mostly via its cytotoxic action. The narrow range of effective concentration of mastic due to its cytotoxicity may limit its potential application as an anti-inflammatory agent.

Estimation of relationship between the structure of 1,2,3,4-tetrahydroisoquinoline derivatives determined by a semiempirical molecular-orbital method and their cytotoxicity.

A semiempirical molecular-orbital method (CAChe 4.9, PM5) was applied to delineate the relationship between the cytotoxicity (evaluated by 50% cytotoxic concentration, CC(50)) of nineteen 1,2,3,4-tetrahydroisoquinoline derivatives, their molecular weight and the sixteen chemical parameters (descriptors) determined by CONFLEX/PM5 method. There was little or no correlation between the CC(50) in HL-60 cells and the heat of formation, stability of hydration (DeltaH), dipole moment, electron affinity, ionization potential, highest occupied molecular orbital energy (E(HOMO)), lowest unoccupied molecular orbital energy (E(LUMO)), absolute hardness (eta, softness and hardness of the molecule) or molecular weight (r(2)<0.312). On the other hand, there was a good correlation between the CC(50) and the hydrophobicity (log P) (r(2)=0.503), and the descriptors for the molecular size such as surface area (r(2)=0.771), volume (r(2)=0.805) and width (r(2)=0.757). Similar, but not so clear-cut correlation was found in HSC-2, HSC-3 and HSC-4 human oral squamous cell carcinoma cell lines. The present study demonstrates that the cytotoxicity of 1,2,3,4-tetrahydroisoquinoline derivatives depends more on the descriptors for molecular size rather than the physicochemical descriptors.

Non-apoptotic cell death induced by nutritional starvation in J774.1 mouse macrophage-like cell line.

The growth and amino acid utilization of a mouse macrophage-like cell line J774.1 was investigated in two different culture media supplemented with 10% fetal bovine serum (FBS). The J774.1 cells grew faster, and consumed glutamine and serine at higher rates in DMEM than in RPMI1640 medium. The consumption of other amino acids was much less, while considerable quantities of alanine, glutamic acid and glycine were produced by the J774.1 cells. When the cells became confluent, serine, but not glutamine, was nearly depleted from the culture medium, followed by cell death characterized by smear DNA fragmentation, slight caspase-3 activation and structural damage of the mitochondria. Serine is required for the growth of mouse macrophage-like cell lines, and DMEM is superior to RPMI1640 for long-term cell culture.

Waveguide for transmitting and radiating high-frequency, high-power ultrasound using higher mode vibrations of a cylindrical rod.

It was shown that a cylindrical solid rod, with a diameter several times larger than the wavelength, can be used as an efficient waveguide for transmitting and radiating high-power ultrasound at higher frequencies. A number of cylindrical rods of varying size and material were tested, and their efficiency as a waveguide was evaluated by the measurements of mechanoacoustic efficiency when the radiating end of the rod was immersed in water for an acoustical load. As an example of waveguide application, a mock-up water atomizer was constructed and shown to work stably at a continuous input of 200 W at 500 kHz. As a consequence of analytical and experimental considerations of the higher mode vibrations of cylindrical rods, a diagram for the optimal design of the waveguides was constructed. For instance, an aluminum alloy rod 6.9 cm in diameter and 23.3 cm in length yielded a mechanoacoustic efficiency as high as 88% at 500 kHz. For high temperature applications, the cylindrical rod can be used as a radiator of heat, as well as for a separator of the piezoelectric transducer from the hot object.