Transesterification of waste cooking oil with a commercial liquid biocatalyst: Key information revised and new insights

The transesterification of the waste cooking oil (WCO) with various linear alcohols (C1 to C4) using the commercial biocatalyst Eversa® Transform in its liquid form is addressed in this investigation. The influence of the amount of the liquid formulation of lipase Eversa® Transform, nature of alcohol, oil to alcohol molar ratio and water addition in the transesterification of fresh sunflower oil and WCO was investigated. In addition, an innovative combination of that fungal based biocatalyst with a native vegetable lipase, known as Araujia sericifera (ASL), in a liquid formulation fashion was investigated. The assays carried out at 35°C for 24 h, an oil: alcohol molar ratio of 1:6.8, 2% v/w water added and 1% v/w of biocatalyst allowed to obtain up to 90% conversion and yield towards fatty acid methyl, ethyl and propyl esters. In the particular case of 1-butanol (C4) a 79% conversion and 72% yield to the esters was obtained. The biocatalyst maintains about 60% of its activity in the conversion of glycerides and yield towards the esters. The combination of process using Eversa® Transform and then the ASL lipase in the transesterification of the WCO probed efficient in the conversion of triglycerides using 1-butanol. A shift from 73 wt % of fatty acid butyl esters (FABE) towards 90 wt % was achieved.     

Discovery of Anti-tubercular Analogues of Bedaquiline with Modified A-, B- and C-Ring Subunits

To date, the clinical use of the anti-tubercular therapy bedaquiline has been somewhat limited due to safety concerns. Recent investigations determined that modification of the B- and C-ring units of bedaquiline delivered new diarylquinolines (for example TBAJ-587) with potent anti-tubercular activity yet an improved safety profile due to reduced affinity for the hERG channel. Building on our recent discovery that substitution of the quinoline motif (the A-ring subunit) for C5-aryl pyridine groups within bedaquiline analogues led to retention of anti-tubercular activity, we investigated the concurrent modification of A-, B- and C-ring units within bedaquiline variants. This led to the discovery that 4-trifluoromethoxyphenyl and 4-chlorophenyl pyridyl analogues of TBAJ-587 retained relatively potent anti-tubercular activity and for the 4-chlorophenyl derivative in particular, a significant reduction in hERG inhibition relative to bedaquiline was achieved, demonstrating that modifications of the A-, B- and C-ring units within the bedaquiline structure is a viable strategy for the design of effective, yet safer (and less lipophilic) anti-tubercular compounds.