Antioxidant and Antifungal Activity of Selected Medicinal Plant Extracts Against Phytopathogenic Fungi.

Abstract

Background: Medicinal plants are used by many ethnic groups as a source of medicine for the treatment of various ailments in both humans and domestic animals. These plants produce secondary metabolites that have antimicrobial properties, thus screening of medicinal plants provide another alternative for producing chemical fungicides that are relatively non-toxic and cost-effective. Materials and methods: Leaf extracts of selected South African plant species (Bucida buceras, Breonadia salicina, Harpephyllum caffrum, Olinia ventosa, Vangueria infausta and Xylotheca kraussiana) were investigated for activity against selected phytopathogenic fungi (Aspergillus niger, Aspergillus parasiticus, Colletotricum gloeosporioides, Penicillium janthinellum, P. expansum, Trichoderma harzianum and Fusarium oxysporum). These plant fungal pathogens causes major economic losses in fruit industry such as blue rot on nectaries and postharvest disease in citrus. Plant species were selected from 600 evaluated inter alia, against two animal fungal pathogens (Candida albicans and Cryptococcus neoformans). Antioxidant activity of the selected plant extracts were investigated using a qualitative assay (2, 2-diphenyl-1-picrylhydrazyl (DPPH)). Bioautography assay was used to determine the number of antifungal compounds in plant extracts. Results: All plant extracts were active against the selected plant phytopathogenic fungi. Moreover, Bucida buceras had the best antifungal activity against four of the fungi, with minimum inhibitory concentration (MIC) values as low as 0.02 mg/ml and 0.08 mg/ml against P. expansum, P. janthinellum, T. harzianum and F. oxysporum. The plant extracts of five plant species did not possess strong antioxidant activity. However, methanol extract of X. kraussiana was the most active radical scavenger in the DPPH assay amongst the six medicinal plants screened. No antifungal compounds were observed in some of the plant extracts with good antifungal activity as shown in the microdilution assay, indicating possible synergism between the separated metabolites. Conclusion: The results showed that acetone was the best extractant. Furthermore, our findings also confirm the traditional use of Breonadia salicina and demonstrate the potential value of developing biopesticides from plants.

Nutraceutical and Ethnopharmacological Properties of Vangueria infausta subsp. infausta

“…Based on in vitro and animal studies, a wide range of pharmacological activities of VI extracts and phytochemical compounds have been reported in literature and these include antibacterial [ 25 , 34 , 64 , 74 , 93 , 96 , 97 ], antimycobacterial [ 98 , 99 ], antifungal [ 34 , 74 , 93 , 100 , 101 ], anti-inflammatory [ 102 ], antileishmanial [ 103 ], antioxidant [ 93 , 94 ], antiplasmodial [ 58 , 72 , 73 , 95 , 104 , 105 ], antifeedant [ 106 ] and prostaglandin synthesis inhibitory [ 107 ].…”

“…The MIC values of extracts ranged from 5.0 mg/mL to >10.0 mg/mL [ 74 ]. Mahlo et al [ 100 , 101 ] evaluated antifungal activities of acetone, methanol, hexane and dichloromethane leaf extracts of VI against Aspergillus niger , Aspergillus parasiticus , Colletotricum gloeosporioides , Fusarium oxysporum , Penicillium expansum , Penicillium janthinellum and Trichoderma harzianum using micro-dilution assay with amphotericin B and 100% acetone as positive and negative controls, respectively. The extracts exhibited activities against all tested fungi species with MIC values ranging from 0.32 mg/mL to 2.50 mg/mL [ 100 , 101 ].…”

Plant Metabolites in Plant Defense Against Pathogens

“…The phytochemicals that produce medicinal plants derived from their secondary metabolism represent a safe and effective alternative to control various phytopathogens that affect various crops of agricultural products of economic and nutritional Table 4. Secondary metabolites of medicinal plants with biological activity against phytopathogens [86][87][88][89][90][91][92][93][94].…”

Anticandidosic activity of selected medicinal plants from Cte dIvoire

“…This could be explained by the fact that some of the active compounds were volatile and evaporated during drying period prior to bioautography. Biological activity synergism between different compounds in the extracts is also a possible reason (Mahlo et al, 2016).…”

“…Medicinal plants contain bioactive compounds with healing ability. These include saponins, tannins, essential oils, flavonoids, alkaloids and other chemical compounds found as secondary metabolites in plants (Mahlo et al, 2016). Africa medicinal flora is rich and medicinal plant knowledge nowadays has a great development espacilly in Côte d'Ivoire.…”