Antimicrobial activity of juglone

Abstract

The juice of freshly macerated unripe hulls of the black walnut (Juglans nigra) has been used for many years in folk medicine as a treatment for localized, topical fungal infections such as ringworm. It has been proposed that the biological activity of the walnut hulls is due to the presence of the simple naphthoquinone, juglone (5‐hydroxy‐1,4‐naphthoquinone), which has been isolated from the unripe hulls by sublimation. Since the fresh juice of unripe walnut hulls is utilized for the treatment of ringworm, and since it has been speculated that the activity is due to the presence of juglone, it was of interest to determine the efficacy of juglone as compared to standard commercially available antifungal agents. The comparative efficacy was determined by evaluation of the minimum inhibitory concentration (MIC) values of juglone and the standard antifungal agents clotrimazole, triacetin, tolnaftate, griseofulvin, zinc undecylenate, selenium sulfide as well as two investigational antifungal antibiotics, liriodenine and liriodenine methiodide, for two dermatophytes, Trichophyton mentagrophytes and Microsporum gypseum. MIC values for juglone showed it to have moderate antifungal activity and to be as effective as certain commercially available antifungal agents such as zinc undecylenate and selenium sulfide.

Antimicrobial Activity of Catechol and Pyrogallol as Allelochemicals

“…For example, juglone which is produced by walnut trees was found active against a broad spectrum of microorganisms, including bacteria and fungi (Krajci and Lynch, 1978;Dawson and Seymour, 1983;Clark et al, 1990). Rhein which is the most active compound of rhubarb roots was found to have strong antibacterial capacity (Didry et al, 1994).…”

Seasonal variation of the main individual phenolics and juglone in walnut (Juglans regia) leaves

“…Juglone variation in fresh leaves was found within the range of 13.1-1556.0 mg/100 g dry weight on the basis of 1121 trees leaf samples (Thakur & Cahallan, 2011). Juglone is known for its antimicrobial effect (Clark et al, 1990), and it was also reported to decrease the incidence of tumors (Sugie et al, 1998). Phenolics contents in walnut depend on many environmental conditions, genotype of different cultivars (Colarič et al, 2005;Solar et al, 2005), as well as sampling date (Cosmulescu & Trandafir, 2011a,b;Solar et al, 2006).…”

Comparison of the Effects of Juglans nigra Green Husk and Clotrimazole on Candida albicans in Rats

“…Other studies have shown that juglone has antimicrobial and antifungal effects (25,26). Grover et al, assessed the effect of juglone on planktonic and sessile C. albicans cells.…”