Among the eight Calophyllum species found on the American continent, Calophyllum brasiliense is the most widely distributed. Chemical analysis of this species has shown the presence of xanthones with cancer chemopreventive properties and antifungal activity. Recently, three new coumarins with antineoplastic properties have been found. In this study, we have evaluated the biological effects of the antiproliferative activity of coumarins isolated from C. brasiliense on the survival, cell cycle and apoptosis of cells in-vitro and their antitumour effects in mice. The cytological study showed that coumarins from C. brasiliense reduce the survival of BMK cells (baby mouse kidney cells) by inducing apoptosis and, to a lesser degree, necrosis. The cell cycle was arrested in S-phase and the division of BMK cells was inhibited. Coumarins had caused a reduction of experimental tumours in 83% of animals by the end of the treatment. Therefore, coumarins have the potential to be used alone or in combination with other antineoplastic drugs, and they might increase the effectiveness of other treatments for cancer.

The safe use in biomedicine of semiconductor nanoparticles, also known as quantum dots (QDs), requires a detailed understanding of the biocompatibility and toxicity of QDs in human beings. The biological characteristics and physicochemical properties of QDs entail new challenges regarding the management of potential adverse health effects following exposure. At certain concentrations, the synthesis of semiconductor nanoparticles of CdS using dextrin as capping agent, at certain concentration, to reduce their toxicity and improves their biocompatibility. This study successfully synthesized and characterized biocompatible dextrin-coated cadmium sulfide nanoparticles (CdS-Dx/QDs). The results show that CdS-Dx/QDs are cytotoxic at high concentrations (>2 μg/mL) in HepG2 and HEK293 cells. At low concentrations (<1 μg/mL), CdS-Dx/QDs were not toxic to HepG2 or HeLa cells. CdS-Dx nanoparticles only induced cell death by apoptosis in HEK293 cells at 1 μg/mL concentrations. The in vitro results showed that the cells efficiently took up the CdS-Dx/QDs and this resulted in strong fluorescence. The subcellular localization of CdS-Dx/QDs were usually small and apparently unique in the cytoplasm in HeLa cells but, in the case of HEK293 cells it were more abundant and found in cytoplasm and the nucleus. Animals treated with 100 μg/kg of CdS-Dx/QDs and sacrificed at 3, 7 and 18 h showed a differential distribution in their organs. Intense fluorescence was detected in lung and kidney, with moderate fluorescence detected in liver, spleen and brain. The biocompatibility and toxicity of CdS-Dx/QDs in animals treated daily with 100 μg/kg for 1 week showed the highest level of fluorescence in kidney, liver and brain. Less fluorescence was detected in lung and spleen. There was also evident presence of fluorescence in testis. The histopathological and biochemical analyses showed that CdS-Dx/QDs were non-toxic for rodents. The in vitro and in vivo studies confirmed the effective cellular uptake and even distribution pattern of CdS-Dx/QDs in tissues. CdS-Dx/QDs were biocompatible with tissues from rodents. The CdS-Dx/QDs used in this study can be potentially used in bio-imaging applications.

Nanotechnology currently plays a pivotal role in several fields and has enabled substantial advances in a relatively short time. In biomedicine, nanomaterials can be potentially employed as a tool for early diagnosis and an innovative mode of drug delivery. Novel nanomaterials are currently widely manipulated without a full assessment of their potential health risks. It is commonly thought that nanomaterials’ first contact with the organism is through the different components of the immune system. However, if the entry route is intravenous, the first contact will be with the blood’s components (erythrocytes, platelets, white cells, plasma and complement proteins). The presence of nanomaterials within a dynamic environment such as the bloodstream can produce potential harmful effects following interaction with several blood components. The design of innovative strategies leading to the development of more hemocompatible nanomaterials is also necessary.

Amphotericin B is the most potent antimycotic known to date. However due to its large collateral toxicity, its use, although long standing, had been limited. Many attempts have been made to produce derivatives with reduced collateral damage. The molecular mechanism of polyene has also been closely studied for this purpose and understanding it would contribute to the development of safe derivatives. Our study examined polyene action, including chemical synthesis, electrophysiology, pharmacology, toxicology and molecular dynamics. The results were used to support a novel Amphotericin B derivative with increased selectivity: L-histidine methyl ester of Amphotericin B. We found that this derivative has the same form of action as Amphotericin B, i.e. pore formation in the cell membrane. Its reduced dimerization in solution, when compared to Amphotericin B, is at least partially responsible for its increased selectivity. Here we also present the results of preclinical tests, which show that the derivative is just as potent as Amphotericin B and has increased safety.