New antimalarial agents derived from nonlinear phenoxazine ring system

Anticancer Activity of Benzo[a]phenoxazine Compounds Promoting Lysosomal Dysfunction

Specific cancer therapy remains a problem to be solved. Breast and colorectal cancer are among the cancers with the highest prevalence and mortality rates. Although there are some therapeutic options, there are still few effective agents for those cancers, which constitutes a clinical problem that requires further research efforts. Lysosomes play an important role in cancer cells' survival, and targeting lysosomes has gained increased interest. In recent years, our team has been synthetizing and testing novel benzo[a]phenoxazine derivatives, as they have been shown to possess potent pharmacological activities. Here, we investigated the anticancer activity of three of the most potent derivatives from our library, C9, A36, and A42, on colorectal- and breast-cancer-derived cell lines, and compared this with the effect on non-neoplastic cell lines. We observed that the three compounds were selective for the cancer cells, namely the RKO colorectal cancer cell line and the MCF7 breast cancer cell line. In both models, the compounds reduced cell proliferation, cell survival, and cell migration, accumulated on the lysosome, and induced cell death accompanied by lysosomal membrane permeabilization (LMP), increasing the intracellular pH and ROS accumulation. Our results demonstrated that these compounds specifically target lysosomes from cancer cells, making them promising candidates as LMP inducers for cancer therapy.

Novel Benzo[a]phenoxazinium Chlorides Functionalized with Sulfonamide Groups as NIR Fluorescent Probes for Vacuole, Endoplasmic Reticulum, and Plasma Membrane Staining

The demand for new fluorophores for different biological target imaging is increasing. Benzo[a]phenoxazine derivatives are fluorochromophores that show promising optical properties for bioimaging, namely fluorescent emission at the NIR of the visible region, where biological samples have minimal fluorescence emission. In this study, six new benzo[a]phenoxazinium chlorides possessing sulfonamide groups at 5-amino-positions were synthesized and their optical and biological properties were tested. Compared with previous probes evaluated using fluorescence microscopy, using different S. cerevisiae strains, these probes, with sulfonamide groups, stained the vacuole membrane and/or the perinuclear membrane of the endoplasmic reticulum with great specificity, with some fluorochromophores capable of even staining the plasma membrane. Thus, the addition of a sulfonamide group to the benzo[a]phenoxazinium core increases their specificity and attributes for the fluorescent labeling of cell applications and fractions, highlighting them as quite valid alternatives to commercially available dyes.

Targeting Lysosomes in Colorectal Cancer: Exploring the Anticancer Activity of a New Benzo[a]phenoxazine Derivative

Colorectal cancer (CRC) has been ranked as one of the cancer types with a higher incidence and one of the most mortal. There are limited therapies available for CRC, which urges the finding of intracellular targets and the discovery of new drugs for innovative therapeutic approaches. In addition to the limited number of effective anticancer agents approved for use in humans, CRC resistance and secondary effects stemming from classical chemotherapy remain a major clinical problem, reinforcing the need for the development of novel drugs. In the recent years, the phenoxazines derivatives, Nile Blue analogues, have been shown to possess anticancer activity, which has created interest in exploring the potential of these compounds as anticancer drugs. In this context, we have synthetized and evaluated the anticancer activity of different benzo[a]phenoxazine derivatives for CRC therapy. Our results revealed that one particular compound, BaP1, displayed promising anticancer activity against CRC cells. We found that BaP1 is selective for CRC cells and reduces cell proliferation, cell survival, and cell migration. We observed that the compound is associated with reactive oxygen species (ROS) generation, accumulates in the lysosomes, and leads to lysosomal membrane permeabilization, cytosolic acidification, and apoptotic cell death. In vivo results using a chicken embryo choriollantoic membrane (CAM) assay showed that BaP1 inhibits tumor growth, angiogenesis, and tumor proliferation. These observations highlight that BaP1 as a very interesting agent to disturb and counteract the important roles of lysosomes in cancer and suggests BaP1 as a promising candidate to be exploited as new anticancer lysosomal-targeted agent, which uses lysosome membrane permeabilization (LMP) as a therapeutic approach in CRC.

Engineering of a kinetically driven phase of phenoxazine by surface crystallisation

Surface crystallisation yields an unknown polymorph of the phenoxazine molecule. Tuning the crystallisation conditions causes a defined crystal growth of either the thermodynamically stable phase or the kinetic phase observed exclusively within thin films.