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The interactions of the silane coupling agent methacryloxypropyltrimethoxysilane (MPS) with both fumed silica and a polymethylmethacrylate (PMMA) resin matrix were investigated using thermogravimetric analysis and Fourier transform infrared spectroscopy. OX 50 fumed silica was silanated with MPS at concentrations of 1% and 5% in aqueous ethanol (95%), acetone, and anhydrous toluene. Methyl methacrylate was polymerized with the silanated fumed silica (5% wt/wt) to form composites. The amount of MPS adsorption on the fumed silica and the amount of PMMA attached to the silanated fumed silica were determined by thermogravimetric analysis. MPS could be removed from the fumed silica after washing with methanol, but not after it underwent a drying process at 25 degrees C under vacuum. After vacuum drying at 25 degrees C, two types of adsorbed silane were found, i.e., firmly adsorbed and loosely adsorbed silane. The loosely adsorbed silane could desorb from silica and be incorporated into the polymer matrix through copolymerization with monomeric methyl methacrylate, resulting in crosslinking of the matrix. When the silanated silica was dried at 110 degrees C for 2 h, the loosely adsorbed silane was removed and the amount of firmly adsorbed silane increased. There was a positive correlation between the amount of firmly adsorbed MPS and the amount of PMMA attachment. The highest efficiency for PMMA attachment was found when MPS was adsorbed as a monolayer, because the loosely adsorbed silane did not contribute to the bonding of PMMA, and this suggested that not all of the double bonds of the MPS were accessible for reaction with the methacrylate monomer. Drying at 110 degrees C may also decrease the number of unsaturated double bonds of MPS.

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Leishmanial diseases, posing a public health problem worldwide, are caused by Leishmania parasites with a dimorphic life cycle alternating between the promastigote and amastigote forms. Promastigotes transmitted by the vector are transformed into amastigotes residing in the host tissue macrophages. Presently, new antiparasitic agents are needed against Leishmania donovani and Leishmania major, the respective organisms causing visceral and cutaneous leishmaniasis, since the available treatments are unsatisfactory due to toxicity, high cost, and emerging drug resistance. Over the years, traditional medicinal flora throughout the world enriched the modern pharmacopeia. Hence, roots of 'Indian Valerian' (Valeriana wallichii DC) were studied for its antileishmanial activity for the first time. The methanol and chloroform extracts showed activity against L. donovani promastigotes and both promastigotes and amastigotes of L. major. The most active fraction, F3, obtained from the chloroform extract, showed IC(50) at ∼ 3-7 μg/ml against both the promastigotes and 0.3 μg/ml against L. major amastigotes. On investigation of the mechanism of cytotoxicity in L. donovani promastigotes, the 'hall-mark' events of morphological degeneration, DNA fragmentation, externalization of phosphatidyl serine, and mitochondrial membrane depolarization indicated that F3 could induce apoptotic death in leishmanial cells. Therefore, the present study revealed a novel and unconventional property of V. wallichii root as a prospective source of effective antileishmanial agents.