A natural preservative composition obtained from plant materials provides antimicrobial activity for use as an antifungal agent. The antifungal agent is effective in inhibiting the growth of Epidermophyton floccosum, Trichophyton mentagrophytes and Microsporum canis. The antimicrobial agent has a MIC as low as 0.03 .mu.l/ml capable of inhibiting and/or killing these organisms. The antimicrobial agent includes selective mixtures of Origanum vulgare L., Thymus vulgaris L., Cinnamomum zeylanicum Nees, Rosmarinus officinalis L., Lavandula officinalis L., Mentha piperita L., Citrus Limon L., Hydrastis canadensis L. and Olea europaea L.