R.B.N. Prasad

A green recyclable SO3H-carbon catalyst derived from glycerol for the production of biodiesel from FFA-containing karanja (Pongamia glabra) oil in a single step.

Simultaneous esterification and transesterification method is employed for the preparation of biodiesel from 7.5% free fatty acid (FFA) containing karanja (Pongamia glabra) oil using water resistant and reusable carbon-based solid acid catalyst derived from glycerol in a single step. The optimum reaction parameters for obtaining biodiesel in >99% yield by simultaneous esterification and transesterification are: methanol (1:45 mole ratio of oil), catalyst 20wt.% of oil, temperature 160°C and reaction time of 4h. After the reaction, the catalyst was easily recovered by filtration and reused for five times with out any deactivation under optimized conditions. This single-step process could be a potential route for biodiesel production from high FFA containing oils by simplifying the procedure and reducing costs and effluent generation.

Biodiesel production from used cooking oil by two-step heterogeneous catalyzed process.

The present study demonstrates the production of biodiesel from used cooking oil containing high free fatty acid by a two-step heterogeneously catalyzed process. The free fatty acids were first esterified with methanol using a 25 wt.% TPA/Nb(2)O(5) catalyst followed by transesterification of the oil with methanol over ZnO/Na-Y zeolite catalyst. The catalysts were characterized by XRD, FT-IR, BET surface area and CO(2)-TPD. In the case of transesterification the effect of reaction parameters, such as catalyst concentration, methanol to oil molar ratio and reaction temperature, on the yield of ester were investigated. The catalyst with 20 wt.% ZnO loading on Na-Y exhibited the highest activity among the others. Both the solid acid and base catalysts were found to be reusable for several times indicating their efficacy in the two-step process.

Preparation of biodiesel from rice bran fatty acids catalyzed by heterogeneous cesium-exchanged 12-tungstophosphoric acids.

Biodiesel synthesis from rice bran fatty acids (RBFA) was carried out using cesium exchanged 12-tungstophosphoric acid (TPA) catalysts. The physico-chemical properties of the catalysts were derived from X-ray diffraction (XRD), Fourier transform infrared (FTIR), temperature programmed desorption (TPD) of NH(3) and scanning electron microscopy (SEM). The characterization techniques revealed that the Keggin structure of TPA remained intact as Cs replaced protons. The partial exchange of Cs for protons resulted in an increase in acidity and the catalysts with one Cs(+) (Cs(1)H(2)PW(12)O(40)) showed highest acidity. Under optimized conditions about 92% conversion of RBFA was obtained. The catalyst was reused for five times and retained of its original activity. Pseudo-first order model was applied to correlate the experimental kinetic data. Modified tungstophosphoric acids are efficient solid acid catalysts for the synthesis of biodiesel from the oils containing high FFA.

Synthesis, antimicrobial and anti-biofilm activities of novel Schiff base analogues derived from methyl-12-aminooctadec-9-enoate.

A novel library of Schiff base analogues (5a-q) were synthesized by the condensation of methyl-12-aminooctadec-9-enoate and different substituted aromatic aldehydes. The synthesized compounds were thoroughly characterized by spectroscopic techniques (FT-IR, (1)H NMR, (13)C NMR, ESI-MS and HRMS). The Schiff base analogues with different substitutions were screened for in vitro antibacterial activity against 7 different bacterial strains. Among these, the compounds with electron withdrawing substituent, namely chlorine (5a) and electron donating substituents, namely hydroxy (5 n) and methoxy (5 o), were found to exhibit excellent to good antimicrobial activities (MIC value 9-18 μM) against Staphylococcus aureus MTCC 96, Staphylococcus aureus MLS-16 MTCC 2940 and Bacillus subtilis MTCC 121. The products were also screened for anti-biofilm and MBC (Minimum Bactericidal Concentration) activities which exhibited promising activities.

Esterification of glycerol over a solid acid biochar catalyst derived from waste biomass

Karanja seed shells were subjected to pyrolysis in an inert atmosphere at different temperatures to prepare a biochar. The biochar was characterized by X-ray diffraction, FT-infrared spectroscopy, laser Raman spectroscopy, thermogravimetric analysis, CHNS-elemental analysis, BET surface area analysis and for the temperature programmed desorption of ammonia. These biochar carbon catalysts were used as catalysts without any functionalization/treatment for the esterification of glycerol with acetic acid. Carbonization at 400 °C led to the formation of biochar with a greater number of strong acidic sites. Amorphous carbon obtained by high temperature carbonization was composed of aromatic carbon sheets oriented in a considerably random fashion. The biochar obtained at 400 °C exhibited the highest glycerol esterification activity. The catalytic activity of the biochar was explained based on its properties derived from the different characterization methods. The biochar catalyst can be reused with consistent activity.

Hydrolysis of biomass using a reusable solid carbon acid catalyst and fermentation of the catalytic hydrolysate to ethanol

Solid acid catalysts can hydrolyze cellulose with lower reaction times and are easy to recover and reuse. A glycerol based carbon acid catalyst developed at CSIR-IICT performed well in acid catalysis reactions and hence this study was undertaken to evaluate the catalyst for hydrolysis of biomass (alkali pretreated or native rice straw). The catalyst could release 262 mg/g total reducing sugars (TRS) in 4h at 140 °C from alkali pretreated rice straw, and more importantly it released 147 mg/g TRS from native biomass. Reusability of the catalyst was also demonstrated. Catalytic hydrolysate was used as sugar source for fermentation to produce ethanol. Results indicate the solid acid catalyst as an interesting option for biomass hydrolysis.

Biotransformation of ferulic acid to acetovanillone using Rhizopus oryzae

Microbial transformation of ferulic acid to acetovanillone was studied using growing cells of Rhizopus oryzae. Ferulic acid was added to the growing medium (0.5 g L−1) and incubated for 12 days. The progress of formation of metabolites was monitored by GC and GC-MS after extraction with ethyl acetate. The major metabolite was acetovanillone with minor metabolites formed, such as dihydroferulic acid, coniferyl alcohol and dihydroconiferyl alcohol. Traces of metabolites (≤1–3%), such as vanillin, vanillyl alcohol, vanillic acid and phenyl ethyl alcohol, were also produced. Formation of 4-vinyl guaiacol increased from day 1 (12.4%), reaching a maximum on day 4 (31.7%), and reducing to a minimum on day 12 (3.1%). The formation of acetovanillone increased only from day 2 onward, and reached a maximum (49.2%) on day 12. The optimum concentration of ferulic acid to be added into the medium was found to be only 0.5 g L−1, as any increase in concentration (0.75 and 1.0 g L−1) precipitated the precursor, resulting in no further degradation.

Synthesis and in vitro antioxidant and antimicrobial studies of novel structured phosphatidylcholines with phenolic acids

Novel phenoylated phosphatidylcholines were synthesized from 1,2-dipalmitoyl phosphatidylcholine/egg 1,2-diacyl phosphatidylcholine and phenolic acids such as ferulic, sinapic, vanillic and syringic acids. The structures of phenoylated phosphatidylcholines were confirmed by spectral analysis. 2-acyl-1-lyso phosphatidylcholine was synthesized from phosphatidylcholine via regioselective enzymatic hydrolysis and was reacted with hydroxyl protected phenolic acids to produce corresponding phenoylated phosphatidylcholines in 48-56% yields. Deprotection of protected phenoylated phosphatidylcholines resulted in phenoylated phosphatidylcholines in 87-94% yields. The prepared compounds were evaluated for their preliminary in vitro antimicrobial and antioxidant activities. Among the active derivatives, compound 1-(4-hydroxy-3,5-dimethoxy) cinnamoyl-2-acyl-sn-glycero-3-phosphocholine exhibited excellent antioxidant activity with EC50 value of 16.43μg/mL. Compounds 1-(4-hydroxy-3-methoxy) cinnamoyl-2-acyl-sn-glycero-3-phosphocholine and 1-(4-hydroxy-3,5-dimethoxy) cinnamoyl-2-palmitoyl-sn-glycero-3-phosphocholine exhibited good antioxidant activity with EC50 values of 36.05 and 33.35μg/mL respectively. Compound 1-(4-hydroxy-3-methoxy) cinnamoyl-2-palmitoyl-sn-glycero-3-phosphocholine exhibited good antibacterial activity against Klebsiella planticola with MIC of 15.6μg/mL and compound 1-(4-hydroxy-3-methoxy) benzoyl-2-acyl-sn-glycero-3-phosphocholine exhibited good antifungal activity against Candida albicans with MIC of 15.6μg/mL.

Synthesis of novel ethyl 1-ethyl-6-fluoro-7-(fatty amido)-1,4-dihydro-4-oxoquinoline-3-carboxylate derivatives and their biological evaluation

A series of novel ethyl 1-ethyl-6-fluoro-7-(fatty amido)-1,4-dihydro-4-oxoquinoline-3-carboxylate derivatives were prepared through multistep synthesis. The key step in the synthesis was to obtain the C-7 fatty amide derivative. The azide was selectively formed at C-7 position using sodium azide at 60°C. Subsequently, the azide was reduced under mild conditions using zinc and ammonium chloride to form the corresponding amine. The synthesized derivatives were further subjected to biological evaluation studies like cytotoxicity against a panel of cancer cell lines such as DU145, A549, SKOV3, MCF7 and normal lung cells, IMR-90 as well as with antimicrobial and antioxidant activities. It was observed that the carboxylated quinolone derivatives with hexanoic (8a), octanoic (8b), lauric (8d) and myristic (8e) moieties exhibited promising cytotoxicity against all the tested cancer cell lines. The results also suggested that hexanoic acid-based fatty amide carboxylated quinolone derivative (8a) exhibited promising activity against both bacterial and fungal strains and significant antibacterial activity was observed against Staphylococcus aureus MTCC 96 (MIC value of 3.9μg/mL). The compound 8a also showed excellent anti-biofilm activity against Staphylococcus aureus MTCC 96 and Bacillus subtilis MTCC 121 with MIC values of 2.1 and 4.6μg/mL, respectively.

An anti-oxidant, α-lipoic acid conjugated oleoyl-sn-phosphatidylcholineas a helper lipid in cationic liposomal formulations

Development of safe non-viral carrier systems for efficient intra-cellular delivery of drugs and genes hold promise in the area of translational research. Liposome based delivery systems have emerged as one of the attractive strategies for efficient delivery of drugs and nucleic acids. To this end, number of investigations was carried on liposomal formulations using lipids for achieving higher efficiency in transfection with lower cytotoxicities. In our efforts to develop safer and efficient liposomal delivery systems, we synthesized a novel anti-oxidant lipid, α-lipoyl, oleyl-sn-phosphatidylcholine (LOPC) and used as a helper lipid in combination with a cationic amphiphile, Di-Stearyl Dihydroxy Ethyl Ammonium Chloride (DSDEAC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) at varying concentrations of LOPC. DNA binding properties of the liposomal formulations (DS, DS LA1, DS LA2 and DS LA3) revealed that increasing the percentage of single aliphatic chain lipid LOPC, did not affect the DNA binding properties. But, transfection profiles of these liposomal formulations in 3 different cell lines (HeLa, HEK 293 and MCF7) showed difference in their efficacies. Results showed that optimal percentage of LOPC i.e. 25% in DSDEAC and DOPC at 1:1 molar ratio (DS LA1) enhanced transfection as compared to DSDEAC:DOPC alone. The endosomal escape studies with NBD labelled lysotracker and Rhodamine labelled liposomal formulations revealed that DS LA1 and DS LA2 facilitated the release of genetic cargo with a better efficiency than their counter parts. Reactive Oxygen Species (ROS), a key modulator of necroptosis were lowered with the treatment of DS LA1 than other liposomal formulations. Here in, we present a novel liposomal formulation using DSDEAC and DOPC at 1:1 molar ratio doped with 25-50% (mole ratio) LOPC as an efficient delivery system for enhanced transfection with quenching of ROS levels compared to formulations without LOPC.