A Review of Secondary Metabolites and Inhibitory Effect of Medicinal Plants on

Effective compounds in medicinal plants include alkaloids, glycosides, volatile oils (essential oils) and other effective compounds (bitter compounds, flavones, flavonoids, mucilages, vitamins, tannins, salicylic acid). The use of these metabolites is considered as one of the new methods of controlling, preventing or treating plant diseases. Plant extracts and essential oils have antifungal and antibacterial effects and so far no microbial resistance has been reported against them. In this article, the antifungal properties of different concentrations of extracts and essential oils was reviewed, analyzed and discussed. The authors searched the main related keywords of medicinal plants in main biological data centers e.g. Science Direct, PubMed and Google Scholar and then the articles classified and only the valid full papers about inhibitory effects of medicinal plants on plant pathogens were discussed. The importance of medicinal plants in controlling plant pathogenic agents is due to the presence of compounds and their effective substances under the title of secondary metabolites such as terpenes, phenolic compounds, and nitrogenous (alkaloids, morphine, codeine and nicotine) compounds can inhibit the growth of plant pathogens. Different studies have proven the role of the active ingredients of medicinal plants in controlling of plant pathogens and several extracts and oil essential of medicinal plants with effective active ingredients were used in controlling various plant pathogens. According to the results of different researches, the use of extracts and oil essential of medicinal plant to inhibit the growth of plant pathogens and plant diseases can be recommended. Considering the abundance and diversity of medicinal plants in Iran, further studies on the effects of the active ingredients of native medicinal plants in controlling a wider range of plant pathogenic agents are suggested in order to obtain plant-based pesticides.