Synthesis, antibacterial and antioxidant activities of 2-(4-chlorophenyl)-4H-chromen-4-one / Jessica Ann Luka

Flavones are a type of flavonoid that has the backbone of 2-phenylchromen-4-one (2-phenyl-1 benzopyran-4-one) with C15H10O2 as its molecular formula. Flavones are abundant in fruits and vegetables. Besides that, flavones are known to have a special role in natural and synthetic organic chemistry because of their useful biological activities like antibacterial and antioxidant. The research of flavones has grown in popularity, as well as the demand for it in the market. However, due to the extraction procedure and the time required for plants to grow, the high demand for flavones is difficult to meet. Hence, this study aims to synthesize flavone which is 2-(4-chlorophenyl)-4H-chromen-4-one from chalcone via Claisen-Schmidt condensation without any extraction methods involving plants. The synthesis of the flavone along with chalcone was confirmed through the analysis from FTIR, GC-MS and NMR. Apart from that, the antibacterial activity was carried out. Four species of bacteria such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, as well as Streptococcus pyogenes were used in this study. However, 2-(4-chlorophenyl)-4H-chromen-4-one and its chalcone were concluded to be weak inhibitors as they have weak activities against all four species of bacteria in both MIC and MBC. Meanwhile, the antioxidant activity was determined by DPPH free radical scavenging activity assay and was assessed in terms of inhibition concentration (IC50). The positive control for this was quercetin. The IC50 of a substance is inversely related to its antioxidant activity. As a result, a sample with a lower IC50 has greater antioxidant activity. The chalcone, 3-(4-chlorophenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one has greater free radical scavenging activity compared to the flavone, 2-(4-chlorophenyl)-4H-chromen-4-one with values of 1.5876 μg/mL and 1.6927 μg/mL, respectively. The chalcone also displayed greater free radical scavenging activity than the positive control, quercetin.