Abstract
Contamination of food commodities by fungal species and their associated mycotoxin pose a serious threat to human and animal health as well as food security. Of all the mycotoxins characterized so far, aflatoxin B1 (AFB1) has been deemed the most potent and commonly occurring carcinogen in foods. Its carcinogenic potential has been attributed to the formation of DNA adducts and reactive oxygen species (ROS). Control and eradication of contamination by AFB1 in feed and food have proven to be difficult throughout the world due to its complex nature. Various physical, chemical, and biological methods have been described for the detoxification of mycotoxins including AFB1. Plant extracts contain numerous phytochemical components many of which are known to be biologically active and are responsible for acting against ROS through various biological mechanisms. Therefore, the aim of the study was to assess phytochemical content, antioxidant, and antifungal activities of methanolic extracts from medicinal plant species and their detoxification potentials against AFB1. Preliminary screening methods together with total phenolic content (TPC), total flavonoid content (TFC), gas chromatography/high-resolution time-of-flight mass spectrometry (GC-HRTOF-MS) analysis and antioxidant assays (DPPH and ABTS+) were used to qualitatively and quantitatively screen 9 methanolic plant extracts for their phytochemical profile. LC-MS analysis was used to assess AFB1 detoxification activities of the plant extracts after 24 and 48 h. The TPC, TFC, DPPH and ABTS+ content of the extracts ranged from 88.92 ± 6.54 to 210.19 ± 7.90 mg GAE/g, 4.01 ± 0.94 to 32.48 ± 1.02 mg QE/g, 4.18 ± 1.37 to 251.53 ± 9.30 μg/mL and 8.36 ± 1.65 to 279.22 ± 8.33 μg/mL, respectively. GC-HRTOF-MS analytical results revealed a total of 291 peaks of chemical compounds belonging to various classes of phytochemicals including phenols, flavonoids, terpenoids, steroids, etc. The extracts showed potent to weak antifungal activities with minimum inhibitory concentrations (MICs) ranging from 0.63 to 2.5 mg/ml. 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 (P < 0.05) 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 48h. These extracts also possessed high TPC and TFC as well as
IV
antioxidant and antifungal activities compared to all other extracts. Finding from this study demonstrate the abundance of bioactive compounds with antioxidant activity playing a role in potent antifungal and/or AFB1 detoxification activity.
Keyword: Reactive oxygen species, aflatoxin B1, detoxification, phytochemicals, antioxidant, and antifungal.