Argentinean medicinal plants against postharvest phytopathogenics fungi isolated from oranges, strawberries and peaches.

DI LIBERTO, MELINA; SVETAZ, LAURA; DERITA, MARCOS

Modena

Congreso; XXV SILAE Congress; 2016

Società Italo-LatinoAmericana di Etnomedicina

Introduction: Continuous and excessive use of synthetics compounds in order to prevent fungal infection in postharvested fruits has caused dangerous consequences not only to the environment but also to human health. In this context, exploring natural sources based on native plant extracts or compounds isolated from them, turns out to be of great economic and social importance.1 In this work, three Argentinean native species with previously reported human antifungal properties (Solidago chilensis Meyen2, Polygonum acuminatum Kunth3,4 and Drimys winterii Forst5), were evaluated against three pathogenic fungi (Penicilium digitatum, Botrytis cinerea and Monilinia fructicola) which strongly affect oranges, strawberries and peaches respectively.Method: S. chilensis, P. acuminatum and D. winterii were collected during the flowering season (March 2014) in Santa Fe province (Argentina) and deposited at the Herbarium FCA-UNL (Arturo Ragonese) with identifying data SF # MD16, MD97 and MD108 respectively. Air-dried aerial parts of each species (100 g) were powdered and successively macerated (3×24 h each) with petroleum ether (H), ethyl acetate (EtOAc) and methanol (MeOH) with mechanical stirring to obtain the corresponding extracts, after filtration and evaporation.For the antifungal evaluation, standardized strains from National Institute of Agricultural Investigation (INIA) Salto (Uruguay) and National Institute of Agricultural Technology (INTA) San Pedro (Argentina) were used. P. digitatum INIA-S22 (P.d.), B. cinerea INIA-S26 (B.c.) and M. fructicola INTA-SP345 (M.f.) strains were grown on Potato-Dextrose-Agar (PDA) using Petri dishes for 48 h up to 6 days at 15-18 °C (as needed for each fungi growth). Inocula of spore suspensions were obtained according to reported procedures (CLSI)6 and adjusted to 1 x104 Colony Forming Units (CFU)/mL.1 Minimum Inhibitory Concentrations (MICs) of each plant extract were determined by using broth microdilution techniques according to the guidelines of the CLSI for filamentous fungi (M 38 A2).6 Imazalil and carbendazim were used as positive controls. Endpoints were defined as the lowest concentration of extract resulting in total inhibition (MIC100) of visual growth compared to the growth in the control wells containing no antifungal. Results / Discussion / Conclusion: Results are shown in Table 1. Regarding S. chilensis, MeOH extract was the most active one, with MICs between 250-1000 µg/mL and showing the highest potency against P.d., H and EtOAc extracts were more active against M.f. (MICs= 125 µg/mL) but hardly active against B.c. (MICs= 1000 µg/mL). P. acuminatum H and EtOAc extracts were moderately active against P.d. and B.c. (MICs between 250-500 µg/mL) but showed important inhibition for M.f. (MICs= 31.2 µg/mL), while MeOH extract resulted inactive. D. winterii H and EtOAc extracts were hardly active against P.d. and B.c. (MICs between 500-1000 µg/mL) but they exhibited activity against M.f. (MICs= 125 µg/mL), MeOH extract also turned out inactive.