Phytochemical Analysis and Antifungal Effects of the Extracts and Oils of Harjel (Solenostemma argel) Basil (Ocimum basilicum) and Parsley (Petroselinum crispum) on the Fungus Aspergillus flavus Growth and Aflatoxin Production, Sudan

Abstract

Sudan is one of the largest countries in Africa and is rich in many valuable plants that produce materials important for human and animal health.  Some of these were used in traditional medicine. The present study aims to investigate the antifungal activities and the phytochemical composition of the extracts and oils of three plants (Hargel et al.). The study was conducted at the Food Microbiology Laboratory, Faculty of Engineering and Technology, University of Gezira. The mycelial growth and spore germination methods were used for the antifungal tests, using a selective medium, while thin-layer chromatography was used for phytochemical tests and aflatoxin analysis. The effects of clove oil and some amino acids were used for comparison. The results of the fungal growth showed that the leaf extracts of Hargel were highly effective and gave complete inhibition (0.0 cm radial growth), while the stem extracts and oil of Hargel were less effective, given (0.3 mm).  Rehan (Basil) oil was the most effective (0.0 cm) compared to (0.4cm) and (0.5cm) for the extracts of the leaf and stem, respectively.  The oil, leaf, and stem extracts of Parsley and clove oil were all highly effective, giving (0.0 cm) radial growth. The results of the effects of the amino acids on radial growth indicated that they were all highly effective, giving complete (0.0 cm) at a higher concentration (100mg/ml). The results of the effect on mycelial weights showed that the oils of the three plants, as well as that of clove, gave complete inhibition (0.0 mg weight); in contrast, the extracts of leaf of Hargel,  Parsley, and Basil showed (1.74, 3.26 and 3.34, mg respectively)  while,  the extracts of the stems gave (3.29, 1.86 and 1.86, mg respectively). Among the amino acids tested, only methionine, leucine, and arginine were adequate (7.0, 7.4, and 7.4 mg, respectively).   Concerning the effects of the spore germination, it was found that all the oils tested gave complete inhibition (0.0 %, pore germination) and the stem extracts of the three plants.  However, only the leaf extracts of Parsley were highly influential; those of Harjel and Rehan were less effective (7.69% and 15.0 % germination, respectively). All the amino acids tested were less effective, giving about (10.0 % germination). The leaf and stem extracts of Harjel and both Parsley and Clove oils inhibited aflatoxin production by the fungus at all concentrations. The stem extracts of Rehan, the leaf extracts of Parsley, and the oil of Harjel inhibited aflatoxin production at higher concentrations only. The stem extracts and Rehan's oil were found to be unable to inhibit aflatoxin production at all tested concentrations.  The chemical analysis of the tested plants' extracts and oils revealed that they contained saponins, tannins, flavonoids, alkaloids, and phenolics but not Steroids. However, glutamic acid was the only amino acid that inhibited aflatoxin production at all concentrations. From the results, it could be concluded that the oils of the plants were more effective than the extracts, and the leaf and stem extracts of Parsley were better among the extracts. It could be recommended that more plant extracts be tested since some plants may be more effective.