Phytochemical screening, antioxidant activity of selected methanolic plant extracts and their detoxification capabilities against AFB1 toxicity

Abstract

Aflatoxin B1 (AFB1) is a secondary metabolite produced principally by Aspergillus parasiticus and A. flavus. It is one of the most potent and commonly occurring dietary carcinogen with its carcinogenic potential being linked to the formation of DNA adducts and reactive oxygen species (ROS). Plant extracts contain a plethora of biologically active phytochemicals that act against ROS. This study aimed to assess the phytochemical content and antioxidant activity of methanolic extracts of some medicinal plants and investigate their detoxification potentials against AFB1. Phytochemical screening together with total phenolic content (TPC), total flavonoid content (TFC), and antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS+)) assays) were performed on nine methanolic plant extracts. Extracts were incubated with AFB1 for 24 and 48 h and liquid chromatography mass spectrometry (LC-MS) analysis done to assess their AFB1 detoxification activities. The TPC of the extracts ranged from 88.92 ± 6.54 to 210.19 ± 7.90 mg GAE/g, while TFC ranged between 4.01 ± 0.94 and 32.48 ± 1.02 mg QE/g. Radical scavenging activities of extracts varied from 4.18 ± 1.37 to 251.53 ± 9.30 μg/mL and 8.36 ± 1.65 to 279.22 ± 8.33 μg/mL based on DPPH and ABTS+ assays, respectively. Six of the plant extracts showed a time-dependent detoxification activity against AFB1 after 48 h ranging from 20.17 to 38.13 %. C. dentata bark extract showed the highest percentage of AFB1 reduction, with mean percentages of 43.57 and 70.96 % at 24 and 48 h, respectively. This was followed by C. asiatica leaves and A. melegueta seeds with a maximum of 40.81 and 38.13 %, respectively after 48 h. These extracts also possessed high TPC, TFC, and antioxidant activities compared to all the other extracts. Findings from this study demonstrate the abundance of bioactive compounds with antioxidant activity playing a role in potent AFB1 detoxification activity.