Phase Chemistry for Hydration Sensitive (De)intercalation of Lithium Aluminum Layered Double Hydroxide Chlorides.

Lithium aluminum layered double hydroxide chlorides (LADH-Cl) have been widely used for lithium extraction from brine. Elevation of the performances of LADH-Cl sorbents urgently requires knowledge of the composition-structure-property relationship of LADH-Cl in lithium extraction applications, but these are still unclear. Herein, combining the phase equilibrium experiments, advanced solid characterization methods, and theoretical calculations, we constructed a cyclic work diagram of LADH-Cl for lithium capture from aqueous solution, where the reversible (de)hydration and (de)intercalation induced phase evolution of LADH-Cl dominates the apparent lithium "adsorption-desorption" behavior. It is found that the real active ingredient in LADH-Cl type lithium sorbents is a dihydrated LADH-Cl with an Al:Li molar ratio varying from 2 to 3. This reversible process indicates an ultimate reversible lithium (de)intercalation capacity of ∼10 mg of Li per g of LADH-Cl. Excessive lithium deintercalation results in the phase structure collapse of dihydrated LADH-Cl to form gibbsite. When interacting with a concentrated LiCl aqueous solution, gibbsite is easily converted into lithium saturated intercalated LADH-Cl phases. By further hydration with a diluted LiCl aqueous solution, this phase again converts to the active dihydrated LADH-Cl. In the whole cyclic progress, lithium ions thermodynamically favor staying in the Al-OH octahedral cavities, but the (de)intercalation of lithium has kinetic factors deriving from the variation of the Al-OH hydroxyl orientation. The present results provide fundamental knowledge for the rational design and application of LADH-Cl type lithium sorbents.

Icaritin Preparation from Icariin by a Special Epimedium Flavonoid-Glycosidase from Aspergillus sp.y848 Strain.

In this study, to obtain icaritin with high pharmacological activities from icariin, which has a content ratio of over 58% in the total flavonoids of Epimedium herb, a special Epimedium flavonoid-glycosidase was produced, purified and characterized from Aspergillus sp.y848 strain. The optimal enzyme production was gained in a medium containing 5% (w/v) wheat bran extract and 0.7% (w/v) Epimedium leaf powder as the enzyme inducer, and strain culture at 30°C for 6-7 days. The molecular weight of the enzyme was approximately 73.2 kDa; the optimal pH and temperature were 5.0 and 40°C. The enzyme Km and Vmax values for icariin were 15.63 mM and 55.56 mM/h. Moreover, the enzyme hydrolyzed the 7-O-glucosides of icariin into icariside II, and finally hydrolyzed 3-O-rhamnoside of icariside II into icaritin. The enzyme also hydrolyzed 7-O-glucosides of epimedin B to sagittatoside B, and then further hydrolyzed terminal 3-O-xyloside of sagittatoside B to icarisiede II, before finally hydrolyzing 3-O-rhamnoside of icarisiede II into icaritin. The enzyme only hydrolyzed 7-O-glucoside of epimedin A or epimedin C into sagittatoside A or sagittatoside C. It is possible to prepare icaritin from the high-content icariin in Epimedium herb using this enzyme. When 2.5% icariin was reacted at 40°C for 18-20 h by the low-cost crude enzyme, 5.04 g icaritin with 98% purity was obtained from 10 g icariin. Also, the icaritin molar yield was 92.5%. Our results showed icaritin was successfully produced via cost-effective and relatively simple methods from icariin by crude enzyme. Our results should be very useful for the development of medicines from Epimedium herb.

[Microorganisms of special herb-glycosidases and their fermentation, enzyme properties].

Herb-glycosides are main active elements of Zhongcaoyao (Chinese traditional medicines, Chinese medical herbs). However, the herb-glycoside structures are not optimal active structure for the human bodies. After orally taken up, the herb-glycosides of Zhongcaoyao could be changed into other more active structures by the digestive system such as enzymes and intestinal microorganisms; then degraded and absorbed in the human body and play the real role of pharmic effect; but only a small amount could be changed and controlled by circadian state of the human body. If this biochange of herb-glycosides to more active structures in vivo was finished in vitro, it is very useful for the development of the Chinese traditional medicines, new plant medicines, health food, and function cosmetics. To biotransformate herb-glycosides to more active structure, this paper introduced the studies of author's team on the new microorganism isolation of the special herb-glycosidases and enzyme fermentation, the special enzyme purification and characterization.