Significant advances have been made in the past decade in mapping the distributions and the physiological functions of extra-oral bitter taste receptors (TAS2Rs) in nongustatory tissues. In particular, it has been found that TAS2Rs are expressed in various muscle tissues and activation of TAS2Rs can lead to muscle cell relaxation, which suggests that TAS2Rs may be important new targets in muscle relaxation therapy for various muscle-related diseases. So far, however, there is a lack of potent extra-oral TAS2R agonists that can be used as novel drug agents in muscle relaxation therapies. Interestingly, traditional Chinese medicine (TCM) often characterizes a drug's property in terms of five distinct flavors (bitter, sweet, sour, salty, and pungent) according to its taste and function, and commonly regards "bitterness" as an intrinsic property of "good medicine." In addition, many bitter flavored TCM are known in practice to cause muscle relaxation after long term use, and in lab experiments the compounds identified from some bitter flavored TCM do activate TAS2Rs and thus relax muscle cells. Therefore, it is highly possible to discover very useful extra-oral TAS2R agonists for muscle relaxation therapies among the abundant bitter compounds used in bitter flavored TCM. With this perspective, we reviewed in literature the distribution of TAS2Rs in different muscle systems with a focus on the map of bitter flavored TCM which can regulate muscle contractility and related functional chemical components. We also reviewed the recently established databases of TCM chemical components and the bioinformatics software which can be used for high-throughput screening and data mining of the chemical components associated with bitter flavored TCM. All together, we aim to present a knowledge-based approach and technological platform for identification or discovery of extra-oral TAS2R agonists that can be used as novel drug agents for muscle relaxation therapies through screening and evaluation of chemical compounds used in bitter flavored TCM.

Pressure-induced structural changes could induce changes in transport properties and lead to a better understanding of the structure−property relationship. The evolution of the carrier transport properties of BiFeO 3 (BFO) ceramics under a high pressure was investigated through impedance spectroscopy measurements at room temperature combined with first-principles calculations. A pressure-induced abnormal transition from pure electronic to mixed ionic−electronic was found in the BFO ceramics Cmmm and Pnma phases at 7.67 and 11.01 GPa, respectively. The pressure-induced structural phase transition from the R3c phase to Cmmm and then to Pnma was responsible for the change in electrical transport behavior from pure electronic to mixed ionic− electronic conduction, accompanied by a decrease in ionic resistance. The calculations of electronic structures and electron localization function from 1 atm to 40 GPa indicated that the ionic conduction in the Pnma phase resulted from the weakened Coulomb screen of the localized electron background to O 2− between Bi 3+ and O 2− . This work provides a critical insight into the understanding of the relationship between structure and conduction and facilitates the application of ferroelectric materials in photoelectric fields.

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