Antidermatophytic Properties of Ar-Turmerone, Turmeric Oil, and Curcuma longa Preparations

Curcuma longa L. or turmeric of the family Zingiberaceae is widely used in Thai traditional medicines for the treatment of rash, itching, tinea, and ringworm. Previous studies on turmeric oil reported effective antifungal activity against dermatophytes, a group of fungi that causes skin diseases. In this study, turmeric creams containing 6 and 10% w/w turmeric oil were prepared and tested against clinical strains of dermatophytes using broth dilution technique. Minimum fungicidal concentrations of 6 and 10% w/w turmeric creams were found to be 312 μg/mL. Ar-turmerone, a major compound separated from turmeric oil, promoted more effective antidermatophytic activity with the MICs of 1.56–6.25 μg/mL, compared to 3.90–7.81 μg/mL of standard ketoconazole. The results indicated that 6% w/w turmeric oil in the cream was suitable to be formulated as antidermatophytic preparation. Further research should be done on long-term chemical and antifungal stabilities of the preparation.


Introduction
Dermatophytosis (tinea or ringworm) is a prevalent form of fungal infections found in Thailand because of the tropical climate. The infection is caused by a group of keratinophilic fungi called dermatophytes. Fungi commonly involved are of the genera Trichophyton, Microsporum, and Epidermophyton. Dermatophytosis can transfer from soil and animals to humans and cause infection on many parts of the body [1,2]. Historically, Thai traditional medicines containing Curcuma longa have been used for the treatment of dermatophytes. The dry powdered rhizome is mixed with a small volume of water and the mixture is applied onto infected skin [3].
C. longa L. or turmeric is a well-known medicinal plant of the family Zingiberaceae [4]. It has been used for the treatment of skin diseases, rash, itching, tinea and ringworm. Turmeric is a perennial herb with thick and ellipsoidovate rhizome with orange cortex inside. It is cultivated easily, wildly distributed in Thailand and other tropical and subtropical countries, and is also famous as a spice and coloring agent [5]. Medicinal uses of the rhizomes arise from volatile oil as a carminative and antifungal activity and yellow curcuminoids for antioxidative and anti-inflammatory properties. Active constituents in turmeric volatile oil are turmerone, atlantone, and zingiberone [6,7]. Turmeric oil isolated from turmeric rhizome possesses effective antifungal activity against dermatophytes [8,9]. The creams containing 3-8% w/w turmeric oil showed similar antidermatophytic activity [10].
To determine a suitable concentration of turmeric oil in a cream preparation, turmeric creams containing 6 and 10% w/w of turmeric oil were formulated and determined in this study for their antidermatophytic activities. The activities of turmeric oil and ar-turmerone, a major compound in the oil, were also determined and compared. The results will be useful for the development of appropriate turmeric cream as an alternative antidermatophytotic preparation.

Plant Materials.
Turmeric rhizomes were purchased from a local market in Bangkok in April 2009. The sample was identified by Dr. Wandee Gritsanapan, and the voucher specimen (WCL0409) was kept at Department of Pharmacognosy, Faculty of Pharmacy, Mahidol University. The fresh rhizomes were cleaned and sliced into small pieces, dried in a hot air oven at 60-80 ∘ C for 48 hours, and then ground into moderate powder. Turmeric dried powder was extracted by water distillation for 60 hours to obtain volatile turmeric oil which was stored in a closed container, protected from light in a refrigerator (4 ∘ C) until used.

Preparation of Turmeric Cream.
Oil in water turmeric creams was prepared by two-phase system containing 6 and 10% w/w turmeric oil. Both creams were separately kept in foam tubes protected from light until used.

Results and Discussion
By water distillation, the yield of turmeric oil from the dried rhizomes was 6.3% v/w. MICs of turmeric oil and cream base against all tested dermatophytes were 1.56-6.25 and 2500 g/mL, respectively. Turmeric oil possesses higher antifungal activity than cream base, indicative of the effective and active constituent in turmeric cream preparations. MICs of 6 and 10% w/w turmeric creams were found to be 78-312 and 78-156 g/mL, respectively while MICs of Daktarin cream solution was 54.68 g/mL. MICs of 10% w/w turmeric cream proved more effective than the 6% w/w cream, but MFCs of the both creams expressed relatively equal activity ( Table 1). The major compound in turmeric oil, identified as Ar-turmerone, promoted effective antidermatophytic activity against all dermatophytes with MICs of 3.90-7.81 g/mL, which is lower than the MIC values of standard ketoconazole at 6.25-25 g/mL as shown in Table 1. This study reveals that turmeric creams exhibits antifungal activity and is effective against dermatophytes. This is confirmative of the ethnopharmacological use of this medical plant to treat skin diseases, especially tinea and ringworm. As a result, the 6% w/w turmeric cream is suitable as an alternative antidermatophytic preparation and could be subjected to further development.

Conclusions
Ar-turmerone, a major compound in turmeric oil, showed effective antidermatophytic activity. It could be used as an active marker for quality assessment of turmeric oil and active ingredient in turmeric creams and other finished antifungal products. The turmeric cream with 6% w/w turmeric oil was suitable for further development as an alternative antidermatophytic preparation. All samples have effective antifungal activity against tested dermatophytes, especially against T. rubrum, a common dermatophyte which is widely spread throughout the world. However, further research on longterm physical, chemical and antifungal activity stabilities of the turmeric cream should be done to find the optimum storage condition. The clinical trial of the cream could also be tested on the affected patients to explore the practicality of the cream and the possibility of commercial development.