The evolution of Tamiflu synthesis, 20 years on: Advent of enabling technologies the last piece of the puzzle?

Influenza is a serious respiratory disease responsible for significant morbidity and mortality due to both annual epidemics and pandemics; its treatment involves the use of neuraminidase inhibitors. (-)-Oseltamivir phosphate (Tamiflu) approved in 1999, is one of the most potent oral anti-influenza neuraminidase inhibitors. Consequently, more than 70 Tamiflu synthetic procedures have been developed to date. Herein, we highlight the evolution of Tamiflu synthesis since its discovery over 20 years ago in the quest for a truly efficient, safe, cost-effective and environmentally benign synthetic procedure. We have selected a few representative routes to give a clear account of the past, present and the future with the advent of enabling technologies.

Adsorptive potential of Zea mays tassel activated carbon towards the removal of metformin hydrochloride from pharmaceutical effluent.

In the present study, Zea mays tassel which is a zero-value agricultural waste was used to produce a low-cost activated carbon using phosphoric acid as the activating agent. The prepared Z. mays tassel activated carbon (ZMTAC) was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorbent was applied for adsorption of an emerging contaminant, metformin hydrochloride (MH) from pharmaceutical effluent. The effects of solution pH, contact time, adsorbent dosage, and initial MH concentration and their interactions were investigated using a response surface methodology following a central composite experimental design (CCD). The optimum experimental conditions were as follows: pH 9.5, contact time 67.50 min, dosage 0.5750 g, and MH concentration 152.50 mg/L. The isotherm data followed Langmuir isotherm model (R2 = 0.979; sum of square deviation, SSD = 0.321). The saturation adsorption capacity of ZMTAC was 44.84 mg/g at 20 °C. MH adsorption process followed pseudo-second-order kinetics (higher R2 and smaller SSD values). The thermodynamic properties obtained showed that the adsorption process was feasible, endothermic and spontaneous. Consequently, the study demonstrated that Z. mays tassel is a potential precursor for preparation of adsorbents for the removal of the MH from pharmaceutical effluent.

Removal of nickel(II) from aqueous solution by Vigna unguiculata (cowpea) pods biomass.

The potential to remove nickel(II) ions from aqueous solution using a biosorbent prepared from Vigna unguiculata pods (VUPs) was investigated in batch experiments. The batch mode experiments were conducted utilising the independent variables of pH (2 to 8), contact time (5 to 120 min), dosage concentration (0.2 to 1.6 g), nickel(II) concentrations (10 to 80 mg L(-1)) and temperature (20 to 50°C). The biosorption data fitted best to the Freundlich biosorption model with a correlation coefficient (R(2)) of 0.993 and lowest chi-squared value of 31.89. The maximum sorption capacity of the VUP for nickel(II) was 27.70 mg g(-1). Kinetics studies revealed that the biosorption process followed the pseudo-second-order model as it had the lowest sum of square error value (0.808) and correlation coefficient close to unity (R(2) = 0.998). The calculated thermodynamic parameters showed that the biosorption process was feasible, spontaneous and endothermic. Consequently, the study demonstrated that VUP biomass could be used as a biosorbent for the removal of nickel(II) from aqueous solution.