Fluorine-containing heterocycles: Part III. Synthesis of some new furo[2,3-b]-, pyrazolo[3,4-b]- and thieno[2,3-b]pyridines with anticipated biological activities

1H-Pyrazolo[3,4-b]pyridines: Synthesis and Biomedical Applications

Pyrazolo[3,4-b]pyridines are a group of heterocyclic compounds presenting two possible tautomeric forms: the 1H- and 2H-isomers. More than 300,000 1H-pyrazolo[3,4-b]pyridines have been described which are included in more than 5500 references (2400 patents) up to date. This review will cover the analysis of the diversity of the substituents present at positions N1, C3, C4, C5, and C6, the synthetic methods used for their synthesis, starting from both a preformed pyrazole or pyridine, and the biomedical applications of such compounds.

Synthesis and Antibacterial Activities of Different Five-Membered Heterocyclic Rings Incorporated with Pyridothienopyrimidine

Certain pyridothienopyrimidine derivatives exhibit antiatheroscleorotic, antibacterial, antiviral, antidepressant, antidiabetic, antihypertensive, anticancer, antihistaminic, antiallergic, anti-inflammatory, spasmolytic, analgesic, and neurotropic activities. 4-Hydrazino-7,9-dimethylpyrido[3',2':4,5]thieno[3,2-d]pyrimidine (1) is a reported pyridothienopyrimidine derivative. In the current study, (1) has been reacted with different reagents to obtain 12 new pyridothienopyrimidine derivatives. The newly synthesized five-membered heterocyclic rings incorporated with pyridothienopyrimidines have been screened for their antibacterial activities. The results encourage further studies on other possible biological activities.

Lappaconitine trifluoroacetate contained polyvinyl alcohol nanofibrous membranes: Characterization, biological activities and transdermal application

Lappaconitine (LA), a potent analgesic drug extracted from the root of natural aconitum species, has been clinically used for years because of its effectiveness and non-addictive properties. However, it is mainly limited in oral and intravenous administration in the form of Lappaconitine Hydrobromide (LAH). In this work, Lappaconitine trifluoroacetate (LAF), a new derivative of LA, was successfully obtained by introducing organofluorine group to LA. This new compound had a lower toxicity (LD₅₀ of 21.14 mg·kg^-1), improved analgesic effect and longer half-life (T_1/2 of 2.24 h) when compared with LAH. Moreover, in vitro transdermal permeation (J_ss of 206.82 μg·cm^-2·h^-1) of LAF was 30.54% higher than that of LAH, means that LAF can be conveniently used for transdermal drug delivery (TDD). Therefore, drug membranes with PVA solution (10 wt%) containing LAF in various amounts were fabricated by electrospinning. The in vitro release tests confirmed that up to 81.43% of LAF in the PVA/LAF nanofibrous membranes could be released in 72 h, accompanied by significant analgesic effect when compared with the blank control group. In conclusion, the prepared LAF-loaded membrane is a novel formulation for the treatment of chronic and long-term pain.

Synthesis of novel hydrazone and azole functionalized pyrazolo[3,4-b]pyridine derivatives as promising anticancer agents

A series of novel pyrazolo[3,4-b]pyridine based target compounds were synthesized starting from the key intermediate ethyl 2-(3-amino-6-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridin-1-yl)acetate 5 on reaction with hydrazine hydrate followed by reaction with different aldehydes, acid chlorides and isothiocyanates to form hydrazones 7, oxadiazoles 8, 1,2,4 triazoles 10 and thiadiazoles 11 respectively in high yield. All the final compounds were screened for anticancer activity against four human cancer cell lines. Among them, 1,2,4 triazole derivatives showed promising activity and compound 10d is identified as a lead molecule.