Mesoporous Silica with an Alveolar Construction Obtained by Eco-Friendly Treatment of Rice Husks.

The high silicon content in rice plant waste, specifically rice husks, makes this waste by-product attractive for the extraction and valorization of silicon oxide, which is widely used as an inert support in catalysis, drug delivery and molecular sieving. The procedures currently used for the treatment of plant biomass make extensive use of mineral acids (HCl, H2SO4, HNO3), which, besides them being potential environmental pollutants, reduce the yield and worsen the chemical-physical properties of the product. In this study, an evaluation of the easy treatment of rice husks by benchmarking different, more eco-friendly carboxylic acids in order to obtain a mesoporous SiO2 with an alveolar structure and a relatively high surface area and pore volume (300-420 m2/g, 0.37-0.46 cm3/g) is presented. The obtained mesoporous silicas are characterized by worm-like pores with a narrow size distribution and a maximum in the range of 3.4-3.5 nm. The mesoporous structure of the obtained materials was also confirmed by TEM. The complete removal of the organic part of the rice husks in the final materials was evidenced by thermogravimetric analysis. The high purity of the obtained mesoporous silica was detected using ICP analysis (98.8 wt. %). The structure peculiarities of the obtained mesoporous silicas were also characterized by solid-state NMR and ATR-FTIR spectroscopies. The morphology of the mesoporous silica was investigated by SEM.

Low cytotoxicity and clastogenicity of some polymeric aminophosphonate derivatives.

Poly(oxyethylene aminophosphonate)s synthesized on the basis of biodegradable poly(phosphorester)s and Schiff bases were tested in vitro for antitumor activity against a panel of six human epithelial cancer cell lines, for cytotoxicity to mouse fibroblast cells and in vivo for clastogenicity and antiproliferative effects. The polymers showed lower cytotoxicity, both in vivo and in vitro and lower clastogenicity in vivo than the corresponding low-molecular aminophosphonates. The biological activities of the tested polymers correlate with their low in vitro antitumor activity.

Pharmacological Activities of Schiff Bases and Their Derivatives with Low and High Molecular Phosphonates.

This review paper is focused on the design of anthracene and furan-containing Schiff bases and their advanced properties as ligands in complex transition metal ions The paper also provides a brief overview on a variety of biological applications, namely, potent candidates with antibacterial and antifungal activity, antioxidant and chemosensing properties. These advantageous properties are enhanced upon metal complexing. The subject of the review has been extended with a brief discussion on reactivity of Schiff bases with hydrogen phosphonates and the preparation of low and high molecular phosphonates, as well as their application as pharmacological agents. This work will be of interest for scientists seeking new challenges in discovering advanced pharmacological active molecules gaining inspiration from the versatile families of imines and aminophosphonates.

In vitro antitumour activity, genotoxicity, and antiproliferative effects of aminophosphonic acid diesters and their synthetic precursors.

The Schiff bases N-furfurylidene-p-toluidine and N-(4-dimethylaminobenzilidene)-p-toluidine, and the recently synthesized aminophosphonic acid diesters p-[N-methyl-(diethoxyphosphonyl)-(2-furyl)]toluidine and p-[N-methyl(diethoxyphosphonyl)-(4-dimethylaminophenyl)]toluidine were tested for in vitro antitumour activity on six human epithelial cancer cell lines. The genotoxicity and antiproliferative activity of these compounds were tested in mice. The aminophosphonates showed high in vitro antitumour activity towards the breast cancer-derived cell lines (MCF-7 and MDA-MB-231), the cervical carcinoma cell line (HeLa), and the human colon adenocarcinoma cell line (HT-29). In addition, the Schiff base N-furfurylidene-p-toluidine significantly inhibited the growth of bladder carcinoma cells (647-V) and the hepatocellular carcinoma line HepG2, and U-shaped dose-response curves were observed after treatment of 647-V and MCF-7 cells. All studied compounds had a moderate genotoxic and antiproliferative activity in vivo.

Diethyl [(9-anthr-yl)(4-methyl-anilino)meth-yl]phospho-nate.

The title compound, C(26)H(28)NO(3)P, crystallized with two independent mol-ecules in the asymmetric unit. The structural features (bond lengths and angles) of the two mol-ecules are almost identical. The inter-planar angle between the anthracene and toluidine rings is similar in the two mol-ecules, with values of 82.92 (5) and 80.70 (5)°. In the crystal, both molecules form inversion dimers linked by pairs of N-H⋯O hydrogen bonds. Three of the four ethyl groups are disordered over two sets of sites, the major components having occupancies of 0.748 (15), 0.77 (4) and 0.518 (19).

rac-Dimethyl [(9-anthr-yl)(4-methyl-anilino)meth-yl]phospho-nate.

The title compound, C(24)H(24)NO(3)P, crystallizes as a racemate with two mol-ecules in the asymmetric unit. The structural features (bond lengths and angles) of the two mol-ecules are almost identical. The dihedral angle between the anthracene and toluidine rings is similar in the two mol-ecules, with values of 48.36 (9) and 51.15 (9)°. The methyl groups of one of the meth-oxy groups in one mol-ecule is disordered over two sets of sites, the major component having a site occupancy of 0.636 (3). In the crystal, both molecules are linked into inversion dimers by pairs of N-H⋯O hydrogen bonds.

Polymer complex of WR 2721. Synthesis and radioprotective efficiency.

Polymer complex constructed from WR 2721 and poly(hydroxyoxyethylene phosphate) was synthesized. The structure of complex formed was elucidated by (1)H-, (13)C, (31)P NMR and FT-IR spectroscopy. The radioprotector was immobilized via ionic bonds. Radioprotective efficacy was evaluated by clonal survival of stem cells in crypts of mouse small intestine, and incidence and latency of the acute radiation induced bone marrow syndrome. Protection factors were assessed for WR 2721 and for the polymer complex. Protection factors for the polymer complex ranged from 2.6 for intestinal stem cell survival to 1.35 for 30 day survival (LD50) following whole body radiation exposure. In all cases, the polymer complex was a significantly better radiation protector than the parent compound.