ABSTRACT

No abstract

-The classical protection of tomato plants against the late blight disease caused by the fungi Phytophthora infestans involves the use of synthetic fungicides. However, such a practice raises two major issues. First, synthetic fungicides are toxic substances that are a threat to the ecosystem. Second, the efficiency of synthetic fungicides is decreasing due to the development of fungicide resistance by the fungi. In addition, there is growing concern from consumers about food contamination due to heavy reliance on toxic and persistent chemicals in plant protection strategies. Therefore, there is a necessity to evaluate the efficacy of alternative compounds. Biologically active products occur in plants for protection against pests, pathogens and other plants. Such compounds could be valuable as biopesticides for controlling plant diseases because they are biodegradable and selective in their activities. In that context, we conducted laboratory and greenhouse experiments to assess the efficacy of nine extracts of native plants of Cameroon in controlling P. infestans. Sporangial germination was determined after 24 h of incubation on 1.5% water agar medium at 18• C in the dark. Lesion size, and late blight latency and severity were assessed on 7-8-week-old detached leaflets and whole tomato plants incubated in the greenhouse for 7 days. Our results showed that Cupressus benthamii and Vetiveria zizanioides extracts were the most effective preparations, leading to 23% and 35% inhibition of sporangial germination, respectively, and to 86% and 77% disease reduction. A clear relationship between disease latency and disease severity was established. The identification of C. benthamii and V. zizanioides extracts as potential alternate compounds for late blight control is a major step in the process of replacing harmful pesticides. Using these biopesticides in combination with other established disease management practices could help control late blight in a more sustainable and environmentally friendly way. plant extracts / Phytophthora infestans / late blight / tomato / antifungal activity / disease suppression / biopesticide

Fungal infections have substantially increased in number and severity in the last two decades and are generally associated with free radical generation. In a search for plant-derived antifungal and antioxidant agents, ethanolic extracts from Uvariodendron molundense, Uvariodendron calophyllum, and Piptostigma calophyllum (Annonaceace) were investigated for their antifungal activity against yeasts and moulds, using the agar well diffusion/dilution and the broth microdilution methods and their antioxidant activity, using the DPPH radical scavenging and the metal chelating techniques. Extracts were screened for their phytochemical content. The yield of extraction ranged from 3.72 to 9.51 %. All the extracts showed antifungal activity with MIC values ranging 1.30 mg/mL against C. glabrata to 36 mg/mL against Aspergillus fumigatus and Aspergillus flavus. The most potent extract was that of the twigs of U. molundense. The leaf extract of P. calophyllum showed the highest antioxidant activity with a SC 50 of 0.2 mg/mL. The extracts showed potent iron chelation, the most active having an IC 50 of 3.07 mg/mL. Tannins, phenols, and glycosides were found to be commonly present in all the extracts. The results achieved support further investigation of these plants for antifungal and antioxidant agents.

This study investigated the effect of vitamin A and iron on the treatment of malaria, when they are given as supplements to infected preschool children. In a placebo-controlled supplementation trial, 132 children aged between 6 and 60 months were recruited and divided into 4 groups: the first group received 68mg (6-30 months) or 102mg (30-60 months) iron daily and the second, 30mg (6-12 months) or 60mg (12-60 months) of vitamin A in single dose at the beginning of the treatment. The third group received both vitamin A and iron while the placebo received no supplement. Completed data was obtained on parasitaemia, clinical (weight, vitality) and haematological parameters (red blood cells, white blood cells and haemoglobin) using WHO (1982) methods, and micronutrients status (serum vitamin A and iron) respectively by spectrofluorimetry and atomic absorption spectrophotometry. From this study, it was observed that about 40.15% of the children suffering of malaria were anaemic (haemoglobin level from 9.02 ± 1.60 to 10.72 ± 1.21 g/dl and red blood cells level less than 3500000/ mm3 among 40.15% of infants recruited). They also had moderate to severe vitamin A deficiency (serum vitamin A between 0.53 ± 0.14 and 0.66 ± 0.24µmol/l). Compared with placebo group, infants receiving supplements improved considerably, for clinical and sub clinical parameters (weight gain from 0.49 ± 1.48 to 0.64 ± 1.97Kg, as against-0.76 ± 2.17Kg in placebo group), iron status (haemoglobin level varied from 0.63 ± 1.33 to 0.94 ± 1.2.10 g/dl as against-0.68 ± 0.98 g/l). A significant improvement of vitamin A status was observed within groups receiving vitamin A supplementation (serum level 0.08 ± 0.20 to 0.11 ± 0.17µmol/l), while there was a notable decrease in the non supplemented group (-0.04 ± 0.05µmol/l within the group that received iron, and-0.07 ± 0.13µmol/l in the placebo group). The improvement was most important in the group receiving either vitamin A or iron supplements than those who received iron or vitamin A alone. This study showed that vitamin A and iron could remarkably improve the treatment of malaria when they are given as supplements to infected children.

No abstract

No abstract