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In the present work it was shown that total saponins originated from M. hybrida and M. sativa substantially limited mycelium growth of F. oxysporum f. sp. tulipae and symptoms of fusariosis on tulip bulbs. Out of 15 individual tested saponins originated from M. arabica, M. hybrida and M. sativa, four compounds: 3-O-[β-D-glucopyranosyl (1→2)α-L-arabinopyranosyl] hederagenin, hederagenin 3-O-β-D-glucopyranoside, medicagenic acid, medicagenic acid 3-O-β-D-glucopyranoside had the strongest inhibitory effect on mycelium growth of Fusarium oxysporum f. sp. tulipae on PDA medium. The total saponins from M. arabica, M. hybrida and M. sativa inhibited the number of colony forming units of Fusarium oxysporum f. sp. tulipae in artifi cially infested substrate. The use of saponins originated from Medicago as a fungicide is suggested.
The total saponins of alfalfa, Medicago sativa L., included in the diet of Colorado potato beetle larvae reduced their feeding, growth rate and survival. The biological activity of those compounds coming both from the roots and from the aerial parts is ,y correlated with the dose. Larvae reared on leaves treated with a 0.5% dose virtually did not feed at all and died after 4-6 days. Lower saponin doses (0.0 I and %) reduced the insects - feeding to a lesser degree. However, they inhibited their ,caused an extension of the larval stage and mortality at a level of76.7- 100%. No major differences have been found in saponin activity depending on its localization in the plant.
The total saponins isolated from aerial parts and roots of alfalfa (Medicago sativa L.) at the concentration of 0.01 %, 0.05% and 0.1 % showed differential influence on the mycelium growth of Alternaria zinniae, Botrytis cinerea, Botrytis tulipae, Phoma narcissi, Phoma poolensis and Rhizoctonia solani. A higher inhibitory effect on ill vitro growth of mycelium of all tested pathogens indicated saponins from roots of alfalfa than from aerial parts. Tested saponins from roots at the concentration of 0.1 % totally inhibited linear growth of Phoma narcissi, and linear growth of Alternaria zinniae was limited about 67%, Botrytis cinerea about 74%, Botrytis tulipae about 68%, Phoma poolensis about 38%, and Rhizoctonia solani about 74% in comparison to the control. The saponins of alfalfa from roots at the concentration of 0.1 % and 0.2% applied as preinoculation sprays evidently inhibited the development of Phoma narcissi on Hippeastrum leaves. This dose of aerial saponins of alfalfa did not effect the development of necrotic spots on the leaves.
Antifungal activity of total saponins originated from roots of Medicago hybrida (Pourret) Trautv. were evaluated in vitro against six pathogenic fungi and eight individual major saponin glycosides were tested against one of the most susceptible fungi. The total saponins showed fungitoxic effect at all investigated concentrations (0.01%, 0.05% and 0.1%) but their potency was different for individual fungi. The highest saponin concentration (0.1%) was the most effective and the inhibition of Fusarium oxysporum f. sp. callistephi, Botrytis cinerea, Botrytis tulipae, Phoma narcissi, Fusarium oxysporum f. sp. narcissi was 84.4%, 69.9%, 68.6%, 57.2%, 55.0%, respectively. While Fusarium oxysporum Schlecht., a pathogen of Muscari armeniacum, was inhibited by 9.5% only. Eight major saponin glycosides isolated from the total saponins of M. hybrida roots were tested against the mycelium growth of Botrytis tulipae. The mycelium growth of the pathogen was greatly inhibited by hederagenin 3-O-β -D-glucopyranoside and medicagenic acid 3-O-β -D-glucopyranoside. Medicagenic acid 3-O-β -D-glucuronopyranosyl-28-O-β -D-glucopyranoside and oleanolic acid 3-O-[β -D-glucuronopyranosyl(1→2)-α -L-galactopyranosyl]-28-O-β -D-glucopyranoside showed low fungitoxic activity. Medicagenic acid 3-O-β-D-glucopyranosyl- 28-O-β -D-glucopyranoside, hederagenin 3-O-[α -L-rhamnopyranosyl(1→-2)-D-glucopyranosyl( 1→2)-D-glucopyranosyl]- 28-O-β -D-glucopyranoside and hederagenin 3-O-α -D-glucuronopyranosyl-28-O-β -D-glucopyranoside did not limit or only slightly inhibited growth of the tested pathogen. While 2β, 3β-dihydroxyolean-12 ene-23-al-28-oic acid 3-O-β -D-glucuronopyranosyl-28-O-β -D-glucopyranoside slightly stimulated mycelium growth of B. tulipae.
The study aimed at assessing effect of dried root and aerial parts of Medicago spp. on growth of Trichophtyton mentagrophytes. Fungus strains were inoculated onto microcultures with Sabouraud agar supplemented each with l g of dried and pulverised roots or aerial parts of 3 species: Medicago arabica, M. sativa, and M. murex. The strongest inhibitory effect on T. mentagrophytes growth was that of aerial parts of M. arabica (median diameter 6 mm compared to 13 mm of control), followed by root of M. arabica (10 mm) and root of M. murex (10.5 mm) - in all cases p < 0.001. Slight inhibitory effect was also found in the case of aerial parts of M. murex (median diameter 12 mm, p = 0.03). In contrast, M. sativa has shown stimulating effect on growth of T. mentagrophytes (15 mm for root and 16.5 mm for aerial part, p < 0.001).
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