Cancer cells are hypersensitive to nutrient limitation because oncogenes constitutively drive glycolytic and tricarboxylic acid (TCA) cycle intermediates into biosynthetic pathways. Because the anaplerotic reactions that replace these intermediates are fueled by imported nutrients, the cancer cell’s ability to generate ATP becomes compromised under nutrient-limiting conditions. In addition, most cancer cells have defects in autophagy, the catabolic process that provides nutrients from internal sources when external nutrients are unavailable. Normal cells, in contrast, can adapt to nutrient stress that kills cancer cells by becoming quiescent and catabolic. We show that FTY720, a water soluble sphingolipid drug that is effective in many animal cancer models, selectively starves cancer cells to death by down-regulating nutrient transporter proteins. Consistent with a bioenergetic mechanism of action, FTY720 induced homeostatic autophagy. Cells were protected from FTY720 by cell permeable nutrients or by reducing nutrient demand, but blocking apoptosis was ineffective. Importantly, AAL-149, an FTY720 analog that lacks FTY720’s dose limiting toxicity, also triggered transporter loss and killed patient-derived leukemias while sparing cells isolated from normal donors. Because they target the metabolic profile of cancer cells rather than specific oncogenic mutations, FTY720 analogs like AAL-149 should be effective against many different tumor types, particularly in combination with drugs that inhibit autophagy.

No abstract

Antibiotics are the chemotherapeutic agents that kill or inhibit the pathogenic microorganisms. Resistance of microorganism to antibiotics is a growing problem around the world due to indiscriminate and irrational use of antibiotics. In order to overcome the resistance problem and to safely use antibiotics, the correct measurement of potency and bioactivity of antibiotics is essential. Microbiological assay and high performance liquid chromatography (HPLC) method are used to quantify the potency of antibiotics. HPLC method is commonly used for the quantification of potency of antibiotics, but unable to determine the bioactivity; whereas microbiological assay estimates both potency and bioactivity of antibiotics. Additionally, bioassay is used to estimate the effective dose against antibiotic resistant microbes.Simultaneously, microbiological assay addresses the several parameters such as minimal inhibitory concentration (MIC), minimum bactericidal concentration (MBC), mutation prevention concentration (MPC) and critical concentration (Ccr) which are used to describe the potency in a more informative way. Microbiological assay is a simple, sensitive, precise and cost effective method which gives reproducible results similar to HPLC. However, the HPLC cannot be a complete substitute for microbiological assay and both methods have their own significance to obtain more realistic and precise results.

The aggregates of pentacenequinone, HPB and PDI derivatives 3, 5 and 7 having aldehyde groups bind strongly with Ag+ and serve as reactors and stabilizers for the preparation of AgNPs at room temperature. In situ generated AgNPs show high catalytic efficiency for industrially important organic dye degradation.