Background: Antioxidants are proficient of stabilizing agents in the target cells and biological
systems. The homeostatic equilibrium between the reactive oxygen species and endogenous
antioxidants is important in maintaining healthy tissues. As some antioxidant agent’s show improved
resistance, it is necessary to design the new heterocyclic molecules to form potent antioxidant
agents with promising pharmacological applications. Moreover, thienopyrimidine derivatives
has been the subject of much research due to their significance in different applications and their
extensive potential pharmacological and medicinal activities like antibacterial, antifungal, anticancer,
anticonvulsant, anti-inflammatory, analgesic, anti-viral, anti-oxidant, anti-diabetic and antimalarial
properties. Although, recently rhodanine was reported as privileged hybrid in drug discovery
and exhibited pharmacological activities such as anti-malarial, antibacterial, antiviral, antidiabetic
agents. Hence, the development of new molecules within the scope of synthetic procedure
of thienopyrimidine scaffold for heterocyclic synthesis would be worthy and well desired.
Methods: All the target thienopyrimidine-rhodanine derivatives (5a-l) prepared from the Knoevenagel
condensation with different substituted benzaldehydes in the presence of glacial acetic acid
and 3-(thieno[2,3-d]pyrimidin-4-yl)-2-thioxothiazolidin-4-one (4). Although, all the synthesized
compounds tested for their anti-oxidant activity investigated using DPPH radical scavenging, nitric
oxide (NO) and ABTS activity.
Results: All the thienopyrimidine-rhodanine derivatives (5a-l) were evaluated for their in vitro
anti-oxidant activity. In fact, (Z)-5-(4-methylbenzylidene)-3-(thieno[2,3-d]pyrimidin-4-yl)-2-
thioxothiazolidin-4-one (5c) with IC50 value 17.64 ± 0.06 µg/mL and (Z)-5-(2-nitrobenzylidene)-3-
(thieno[2,3-d]pyrimidin-4-yl)-2-thioxothiazolidin-4-one (5j) with IC50 value 17.54 ± 0.23µg/mL
showed excellent antioxidant activity nearly similar to the standard drug as an ascorbic acid (IC50 =
17.45 ± 0.03µg/mL).
Conclusion: The objective of the present work was to design, synthesis and screened for their antioxidant
activities of novel thienopyrimidine containing rhodanine derivatives with the hope of discovering
new structure leads as the most potent antioxidant agents. Our aim has been achieved by
the synthesis of thienopyrimidines with diver functionalities by exploiting 2-thioxothiazolidin-4-one
chemistry and tested for antioxidant activity. The compounds 5c and 5j were found most potent
activity compare to the standard ascorbic acid. Furthermore, the electron withdrawing groups at
position-4 in benzene ring enhanced the activity, whereas the compounds 5d, 5f, 5i and 5l showed
good activity all the three radical scavenging methods.