Inhibitory Effect of Curcuminoids on Aspergillus Flavus Growth

Curcuminoids, a group of bioactive polyphenolic compounds extracted from Turmeric (Curcuma longa) rhizomes, have been used for centuries in traditional medicine due to their antioxidant, anti-inflammatory and antimicrobial properties. Aspergillus flavus, a highly invasive opportunistic pathogen, contaminates grains and foods, producing aflatoxins, a toxic and carcinogenic secondary metabolite which poses significant health risks. This study thus, aimed to determine the inhibitory effect of curcuminoids on Aspergillus flavus growth. Soxhlet extraction was used to extract curcuminoids from Turmeric rhizomes. The Phytochemical compositions of curcuminoids were determined using chemical screening and the antioxidant activity was evaluated using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay, with ascorbic acid as a reference standard. The antifungal activity of curcuminoids on Aspergillus flavus was evaluated using Agar well diffusion method while the minimum inhibitory concentration (MIC) and were also evaluated using Broth dilution technique. The result indicated that the percentage yield of Curcuminoids from 1,200 g of turmeric powder was 8% (w/w). The result also showed that curcuminoids contained flavonoids, tannins, saponins, alkaloids and significantly higher phenols (188.30 ± 1.45 mg/100g). The result further revealed that ascorbic acid had a significantly higher (p < 0.05) antioxidant activity having a 95.58% ± 0.255 mean inhibition of DPPH radicals at 1000 µg/mL, compared to curcuminoids with 78.84% ± 0.396 inhibition of DPPH radicals at 1000 µg/mL. Antifungal screening revealed that Aspergillus flavus was susceptible to curcuminoids, with zones of inhibition ranging from 18.00mm-21.00mm. Both MIC and MFC also ranged from 25.00 mg/mL to 125.00 mg/mL. The above results thus suggest that curcuminoids may be employed as an alternative to chemical fungicides to mitigate fungal contamination and mycotoxin production in foods and feeds.