Cordycepin: A review of strategies to improve the bioavailability and efficacy.

Cordycepin is a bioactive compound extracted from Cordyceps militaris. As a natural antibiotic, cordycepin has a wide variety of pharmacological effects. Unfortunately, this highly effective natural antibiotic is proved to undergo rapid deamination by adenosine deaminase (ADA) in vivo and, as a consequence, its half-life is shortened and bioavailability is decreased. Therefore, it is of critical importance to work out ways to slow down the deamination so as to increase its bioavailability and efficacy. This study reviews recent researches on a series of aspects of cordycepin such as the bioactive molecule's pharmacological action, metabolism and transformation as well as the underlying mechanism, pharmacokinetics and, particularly, the methods for reducing the degradation to improve the bioavailability and efficacy. It is drawn that there are three methods that can be applied to improve the bioavailability and efficacy: to co-administrate an ADA inhibitor and cordycepin, to develop more effective derivatives via structural modification, and to apply new drug delivery systems. The new knowledge can help optimize the application of the highly potent natural antibiotic-cordycepin and develop novel therapeutic strategies.

Ginsenoside Rb2: A review of pharmacokinetics and pharmacological effects.

Ginsenoside Rb2 is an active protopanaxadiol-type saponin, widely existing in the stem and leave of ginseng. Rb2 has recently been the focus of studies for pharmaceutical properties. This paper provides an overview of the preclinical and clinical pharmacokinetics for Rb2, which exhibit poor absorption, rapid tissue distribution and slow excretion through urine. Pharmacological studies indicate a beneficial role of Rb2 in the prevention and treatment of diabetes, obesity, tumor, photoaging, virus infection and cardiovascular problems. The underlying mechanism is involved in an inhibition of oxidative stress, ROS generation, inflammation and apoptosis via regulation of various cellular signaling pathways and molecules, including AKT/SHP, MAPK, EGFR/SOX2, TGF-ß1/Smad, SIRT1, GPR120/AMPK/HO-1 and NF-κB. This work would provide a new insight into the understanding and application of Rb2. However, its therapeutic effects have not been clinically evaluated. Further studies should be aimed at the clinical treatment of Rb2.

[Progress in the study of new cancer target Cdk5 and its inhibitors].

Cyclin-dependent kinase-5(Cdk5) is a kind of Ser/Thr kinases in the signaling pathway, which regulates the neural development. The recent studies have confirmed that hyperactivation of Cdk5 is closely associated with the evolution, progression and apoptosis of tumors. The Cdk5 inhibitors have been extensively studied in the drug discovery against cancer. The structure features of these inhibitors and molecular mechanisms of their activities have provided clues for the drug development. In the second generation Cdk5 inhibitors, the ATP-binding pocket, a highly conserved site, has been targeted in the drug design in most cases. In addition, a growing number of peptides has been generated by targeting the protein/protein interfaces of Cdk5.