Thioether and Ether Furofuran Lignans: Semisynthesis, Reaction Mechanism, and Inhibitory Effect against α-Glucosidase and Free Radicals.

The transformation of sesame lignans is interesting because the derived products possess enhanced bioactivity and a wide range of potential applications. In this study, the semisynthesis of 28 furofuran lignans using samin (5) as the starting material is described. Our methodology involved the protonation of samin (5) to generate an oxocarbenium ion followed by the attack from two different nucleophiles, namely, thiols (RSH) and alcohols (ROH). The highly diastereoselective thioether and ether furofuran lignans were obtained, and their configurations were confirmed by 2D NMR and X-ray crystallography. The mechanism underlying the reaction was studied by monitoring 1H NMR and computational calculations, that is, the diastereomeric α- and ß-products were equally formed through the SN1-like mechanism, while the ß-product was gradually transformed via an SN2-like mechanism to the α-congener in the late step. Upon evaluation of the inhibitory effect of the synthesized lignans against α-glucosidases and free radicals, the lignans 7f and 7o of the phenolic hydroxyl group were the most potent inhibitors. Additionally, the mechanisms underlying the α-glucosidase inhibition of 7f and 7o were verified to be of a mixed manner and noncompetitive inhibition, respectively. The results indicated that both 7f and 7o possessed promising antidiabetic activity, while simultaneously inhibiting α-glucosidases and free radicals.

New turn-on fluorescent and colorimetric probe for cyanide detection based on BODIPY-salicylaldehyde and its application in cell imaging.

Development of cyanide sensor is important as the anion is harmful to human health and the environment. Herein, a new colorimetric and fluorescent probe GSB based on boron dipyrrole-methene (BODIPY) containing salicylaldehyde group for cyanide detection has been reported. GSB undergoes exclusive colorimetric change from orange to colorless and exhibits selective fluorescence turn-on at 504nm upon the addition of cyanide. Other 13 anions give almost no interference under physiological condition. Detection limit of the new cyanide-sensing GSB is 0.88µM, which is below World Health Organization (WHO) recommended level in drinking water. A calculation by density functional theory (DFT) shows suppression of photoinduced electron transfer (PET) mechanism along with the interruption of π-conjugation between salicylaldehyde and BODIPY core by cyanide anion. Cell imaging studies demonstrated that GSB is compatible and capable of sensing cyanide anion in living cells.

Paclitaxel delivery using carrier made from curcumin derivative: synergism between carrier and the loaded drug for effective cancer treatment.

To fully make use of the synergism between paclitaxel and curcumin (CUR) in cancer treatment, carrier made from CUR derivative was synthesized and used to deliver paclitaxel into cancer cells. The methoxylpolyethylene oxide-linked palmitate-modified curcumin (mPEO-CUR-PA) was synthesized and the obtained amphiphilic mPEO-CUR-PA molecules were allowed to self-assemble into microspheres. In vitro release of free CUR from mPEO-CUR-PA in the presence of lipase was proofed and the ability of cells to endocytose mPEO-CUR-PA microspheres was verified. Cytotoxic activity of the mPEO-CUR-PA microspheres toward cancer cell lines (S102 and A549) was evaluated and compared with that of the unmodified CUR. Paclitaxel was then loaded into the microspheres and the paclitaxel-loaded mPEO-CUR-PA microspheres showed up to fivefold to 44-fold increased in vitro cytotoxicity (in terms of % cell mortality) in susceptible (HCC-S102 and A549) and paclitaxel-resistant (A549RT-eto) cancer cells, respectively, compared with that of free paclitaxel.