Novel and Highly Efficient Regioselective Route to Helicid Esters by Lipozyme TLL

<div><p>Highly regioselective acylation of helicid with fatty acid vinyl esters catalyzed by the lipase from <i>Thermomyces lanuginosus</i> has been successfully performed for the first time. For the enzymatic caproylation of helicid, under the optimal conditions, initial reaction rate was 33.2 mM/h, and substrate conversion and regioselectivity were greater than 99%. In addition, the acyl recognition of the enzyme in the regioselective acylation of helicid was investigated. The results showed that although 6’-<i>O</i>-acyl derivatives of helicid were exclusively obtained with all the tested acyl donors, the enzymatic reaction rate varied widely with different acyl donors, presumably owing to their different interactions with the active site of the lipase. It is also interesting that the different configuration of only one hydroxyl group at C-3 in helicid couldn’t affect the lipase-catalyzed esterification and helicid has the same regioselectivity as that of D-glucose and arbutin.</p></div

Regioselective caproylation of helicid catalyzed by various lipases.

<p>Reaction conditions: 0.02 mmol helicid, 0.1 mmol vinyl hexanoate, 10 µ lipase, 2 ml anhydrous THF, 40°C, 200 rpm.</p>a<p>Reaction time when the maximum conversion was achieved.</p><p>n.d.: no detected.</p

Media 1: Gain-assisted trapping of light in tapered plasmonic waveguide

Originally published in Optics Letters on 15 February 2013 (ol-38-4-558

Media 1: Dispersionless slow light in MIM waveguide based on a plasmonic analogue of electromagnetically induced transparency

Originally published in Optics Express on 10 September 2012 (oe-20-19-20902

Media 3: Dispersionless slow light in MIM waveguide based on a plasmonic analogue of electromagnetically induced transparency

Originally published in Optics Express on 10 September 2012 (oe-20-19-20902

Time course of enzymatic caproylation and operational stability of <i>Thermomyces lanuginosus</i> lipase.

<p>Reactions conditions: 0.02 mmol helicid, 0.15 mmol vinyl hexanoate, 20 U <i>Thermomyces lanuginosus</i> lipase, 2 ml anhydrous THF, 45°C, 200 rpm. Symbols: (▽) the conversion, (△) the regioselectivity, (□) the relative activity.</p

Media 2: Dispersionless slow light in MIM waveguide based on a plasmonic analogue of electromagnetically induced transparency

Originally published in Optics Express on 10 September 2012 (oe-20-19-20902

Enzymatic regioselective acylation of helicid.

<p>Enzymatic regioselective acylation of helicid.</p

Enzymatic synthesis of various esters of helicid.

<p>Reaction conditions: 0.02 mmol helicid, 0.15 mmol fatty acid vinyl ester, 20 µ lipase, 2 ml anhydrous THF, 45°C, 200 rpm.</p>a<p>Reaction time when the maximum conversion was achieved.</p

Optimization of enzymatic caproylation of helicid.

<p>Reactions conditions: 0.02 mmol helicid.</p