Effect of by-products from hydrodistillation of Rosmarinus officinalis L. on some plant pathogenic fungi

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The present study aims to evaluate the chemical composition of the powder extract (PE), solid residue extract (SRE) and water residue (WR) of Rosmarinus officinalis using UHPLC-DAD-ESI/MS. The antifungal effect against five phytopathogenic fungi were also evaluated. UHPLC-DAD-ESI/MS analysis revealed that the predominant compounds in the PE are rosmarinic acid (18.83%) and carnosic acid (12.60%). Rosmanol (28.31%), rosmarinic acid (7.95%), carnosol (7.90%), and rosmadial (7.59%) are the major compounds in the SRE, while the dominant constituents in the WR are rosmarinic acid (17.90%) and luteolin-3-glucuronide (13.42%). The antifungal activity showed that the PE revealed a high inhibition effect on the mycelial growth of five strains, which are Fusarium avenaceum, Fusarium moniliforme, Aspergillus ochraceus, Penicillium sp., and Fusarium oxysporum, wheareas the SRE activity was variable depending on the tested species. In fact, theinhibition was greater than 50% at a 1000 µg/mL. Penicillium sp. was more susceptible to PE and SRE, with ED50 values of 105 µg/mL and 122 µg/mL, respectively. However, Rhizopus sp. was the most resistant to all extracts. Moreover, the results showed that the WR had the weakest antifungal activity. These findings suggest that PE and SRE may be an effective natural alternative for controlling the growth of phytopathogenic fungi.