A novel eco-friendly polymeric photosensitizer based on chitosan and flavin mononucleotide.

Flavin mononucleotide (FMN) is a dye belonging to the flavin family. These dyes produce photosensitized degradation of organic compounds via reaction with the excited states of the dye or with reactive oxygen species photogenerated from the triplet of the dye. This article presents a new polymeric dye (FMN-CS) composed of the photosensitizer FMN covalently bonded to chitosan polysaccharide (CS). FMN-CS obtained has a molecular weight of 230 × 103 g mol-1 and a deacetylation degree of 74.8%. The polymeric dye is an environmentally friendly polymer with spectroscopic and physicochemical properties similar to those of FMN and CS, respectively. Moreover, under sunlight, it is capable of generating 1O2 with a quantum yield of 0.31. FMN-CS, like CS, is insoluble in basic media. This allows easy recovery of the polymeric dye once the photosensitized process has been carried out and makes FMN-CS a suitable photosensitizer for the degradation of pollutants in contaminated waters. To evaluate whether FMN-CS may be used for pollutant degradation, the photosensitized degradation of two trihydroxybenzenes by FMN-CS was studied.

Oxonitrogenated Derivatives of Eremophilans and Eudesmans: Antiproliferative and Anti-Trypanosoma cruzi Activity.

Cancer is one of the most important causes of death worldwide. Solid tumors represent the vast majority of cancers (>90%), and the chemotherapeutic agents used for their treatment are still characterized by variable efficacy and toxicity. Sesquiterpenes are a group of natural compounds that have shown a wide range of biological activities, including cytotoxic and antiparasitic activity, among others. The antiproliferative activity of natural sesquiterpenes, tessaric acid, ilicic acid, and ilicic alcohol and their semisynthetic derivatives against HeLa, T-47D, WiDr, A549, HBL-100, and SW1573 cell lines were evaluated. The effect of the compounds on Trypanosoma cruzi epimastigotes was also assessed. The selectivity index was calculated using murine splenocytes. Derivatives 13 and 15 were the most antiproliferative compounds, with GI50 values ranging between 5.3 (±0.32) and 14 (±0.90) µM, in all cell lines tested. The presence of 1,2,3-triazole groups in derivatives 15−19 led to improvements in activity compared to those corresponding to the starting natural product (3), with GI50 values ranging between 12 (±1.5) and 17 (±1.1) µM and 16 being the most active compound. In relation to the anti-T. cruzi activity, derivatives 7 and 16 obtained from tessaric acid and ilicic acid were among the most active and selective compounds with IC50 values of 9.3 and 8.8 µM (SI = 8.0 and 9.4), respectively.

Preparation of Sesquiterpene Lactone Derivatives: Cytotoxic Activity and Selectivity of Action.

Cancer is one of the most important causes of death worldwide. Solid tumors represent the great majority of cancers (>90%) and the chemotherapeutic agents used for their treatment are still characterized by variable efficacy and toxicity. Sesquiterpene lactones are a group of naturally occurring compounds that have displayed a diverse range of biological activities including cytotoxic activity. A series of oxygenated and oxy-nitrogenated derivatives (4⁻15) from the sesquiterpene lactones cumanin (1), helenalin (2), and hymenin (3) were synthesized. The silylated derivatives of helenalin, compounds 13 and 14, were found to be the most active against tumor cell lines, with GI50 values ranging from 0.15 to 0.59 µM. The ditriazolyl cumanin derivative (11) proved to be more active and selective than cumanin in the tested breast, cervix, lung, and colon tumor cell lines. This compound was the least toxic against splenocytes (CC50 = 524.1 µM) and exhibited the greatest selectivity on tumor cell lines. This compound showed a GI50 of 2.3 µM and a SI of 227.9 on WiDr human colon tumor cell lines. Thus, compound 11 can be considered for further studies and is a candidate for the development of new antitumor agents.

Plant tissue cultures as sources of new ene- and ketoreductase activities.

While many redox enzymes are nowadays available for synthetic applications, the toolbox of ene-reductases is still limited. Consequently, the screening for these enzymes from diverse sources in the search of new biocatalyst suitable for green chemistry approaches is needed. Among 13 plant tissue cultures, Medicago sativa and Tessaria absinthioides calli, as well as Capsicum annuum hairy roots, were selected due to their ability to hydrogenate the CC double bond of the model substrate 2-cyclohexene-1-one. The three axenic plant cultures showed more preference toward highly activated molecules such as nitrostyrene and maleimide rather than the classical substrates of the well-known Old Yellow Enzymes, resembling the skills of the NAD(P)H-dependent flavin-independent enzymes. When the three biocatalytic systems were applied in the reduction of chalcones, T. absinthioides showed high chemoselectivity toward the CC double bond whereas the other two demonstrated abilities to biohydrogenate the CC double bounds and the carbonyl groups in a sequential fashion.

Cytotoxic and Antitumor Activity of some Coumarin Derivatives.

Several natural and synthetic coumarins were assayed against different cancer cell lines. Four of them have shown cytotoxicity against a panel of three human solid tumor cell lines (HeLa, T-47D, and WiDr) and a clearly activity/hydrophobicity relationship. Compound 13 proved to be the most active product in all cell lines tested, with values of 8.0 (±0.38) µM against HeLa cells and also able to inhibit Taq DNA polymerase. This dual activity of 13 makes it a candidate to be considered as a "lead" compound in the search for novel antitumor drugs.

Derivatives of grindelic acid: from a non-active natural diterpene to synthetic antitumor derivatives.

Using several reactions that include homologations and asymmetric epoxidations as well as Ugi and Huisgen couplings, we generated a small focused library of new derivatives from the labdane-type diterpene grindelic acid. These compounds were evaluated as cytotoxic agents against a panel of five human solid tumor cell lines (HBL-100, HeLa, SW1573, T-47D, and WiDr). The presence of the diamide functionalizations enhanced the cytotoxic effect. N-Benzyl-N-(1-(benzylamino)-2-methyl-1-oxopropan-2-yl)grindelicamide, proved to be the most active product in all cell lines tested, with values of 0.95 (±0.38) µM against HBL-100 cells.

Cytotoxic bioactivity of some phenylpropanoic acid derivatives.

In this study, we synthesized a series of phenylpropanoic acid derivatives based on modifications at four selected points of the molecular scaffold. The in vitro antiproliferative activities of the compounds were examined in representative human solid tumor cell lines. A SAR was established pointing out the relevance of the substituents. The best activity profiles were obtained for the derivatives bearing more lipophilic esters (GI50 3.1-21 microM).