Synthesis, spectral characterization, crystal structure, cytotoxicity and apoptosis-Inducing activity of two derivatives of 2-hydroxy-1,4-naphthaquinone.

A phenaxazone compound [5H-Benzo[a]phenoxazin-5-one (BP)] along with an aminoquinone[2-[(o-hydroxyphenyl)amino]-1,4-naphthaquinone (HAN)] derivatives were synthesized from lawsone using ultrasound irradiation technique. The structure of the compounds were characterized by elemental analysis and various spectral studies. Optoelectronic properties were studied using Schrodinger material science suit (2015). The compounds exhibit fluorescence emission in longer wave length it may find applications in photodynamic therapy. Single crystal X-ray diffraction studies reveals that the compound BP crystallizes in monoclinic space group. The antioxidant activity of HAN and BP were determined using DPPH radical scavenging assay and the results indicate that both the compounds have good antioxidant capacity, HAN having more scavenging activity than BP. Lead molecules were identified using in silico molecular docking studies as a green chemistry approach. iGEMDOCK, GOLD and Schrödinger softwares were used for these studies. The docking studies reveal that the structural modification of the parent compound gave more active compounds making them promising lead molecules. The lead molecules were subjected to in vitro studies. The cytotoxicity of BP and HAN was studied using human breast cancer (SKBR3) cell lines. The IC50 value of HAN was found to be 19.8μM while BP was found to have cell viability, less than 10% even at 25μM concentration. The chemotherapeutic agents kill the cancer cells mainly through apoptosis. HAN and BP were subjected to apoptosis studies. BP was found to more active than HAN. Thus it can be suggested that the mechanism of cell death may be through apoptosis.