Abstract This study aimed to extract neem leaves components to determine their antimicrobial and antioxidants activities. In addition, their ability to suppress the proliferation of A549 and MCF-7 cells were studied to explore the possible underlying mechanisms involved during such effects. Therefore, the antimicrobial activity of the extract towards some bacterial and fungal strains was investigated using agar well diffusion method, minimum inhibition concentration (MIC) test, peroxidase (POX), and catalase (CAT) activities. Superoxide dismutase (SOD) and catalase (CAT) like activities as well as total antioxidant capacity (TAC) and DPPH scavenging activity were determined. Cells viabilities were also measured by the mitochondrial-dependent reduction of MTT on A549 and MCF-7 cell lines. Cell cycle was flowcytomerically analyzed to detect which phase was arrested. Quantitative real-time PCR (RT-PCR) was done to assess the changes in apoptotic and anti-apoptotic genes. Results showed that, neem leaves extract was more effective towards Gram-negative bacteria ( E. aerogenes and E. coli ) than that of Gram-positive type ( B. cereus and S. epidermidis ). Also, the extract has a high antioxidant activity compared to that of the ascorbic acid (DPPH IC 50 was 0.22 and 0.51 mg/ml for extract and ascorbic acid, respectively). Cytotoxicity assays confirm that the extract is able to suppress the proliferation of cell lines in a dose-dependent manner with IC 50 of 128.1 and 55.7 µg/ml for A549 and MCF-7, respectively. The extract promotes arrest of cell cycle at G0, inhibited the anti-apoptotic genes and stimulated the pro-apoptotic ones. In conclusion, neem leaves extract could have promising roles in pharmaceutical and medical applications.
Toson et al. (Sun,) studied this question.