The rhizome of Curcuma longa L. or turmeric is a popular herbal drug of Thailand and is used as a coloring agent,
household medicine and spice. Medicinal uses of the rhizome are based on the volatile
oil which has carminative and antifungal activity [1] and yellow curcuminoids which
have anti-oxidative and anti-inflammatory properties [2]. At present, the extract
of turmeric is used in herbal cosmetics as natural colorant and additive, and also
in drug preparations. So, it is necessary to develop analytical methods for quality
assessment of C. longa extracts. TLC-densitometric and HPLC methods were used for quantitative analysis
of major antioxidant components; curcumin, demethoxycurcumin, and bisdemethoxycurcumin,
in 10 ethanolic extracts of C. longa cultivated in several parts of Thailand. The contents of curcumin, demethoxycurcumin,
and bisdemethoxycurcumin in the extracts were in the range of 12.57–18.41, 6.29–9.99,
and 9.55–15.68% (w/w), respectively when determined by TLC-densitometry. By HPLC,
the contents of these compounds were 8.55–15.88, 1.50–4.16, and 5.54–9.33% (w/w),
respectively. Free radical scavenging activity of the ethanolic extracts of C. longa was evaluated using DPPH scavenging method. EC50 values of all extracts ranged from 18.24–26.36µg/ml. The content of these bioactive
compounds and the free radical scavenging activity of the extracts will be useful
as a guidance for further standardization of turmeric extracts used in pharmaceutical
and cosmetic products.
Acknowledgements: This study was supported by research grants from Drug program of National Research
Council of Thailand (NRCT), Mahidol University, Bangkok, Thailand and ASEA UNINET.
References: [1] Apisariyakul A, Vanittanakorn N, et al. (1995) J Ethnopharmocol 49: 163–69. [2]
Masuda T, Jitoe A, et al. (1993) Phytochemistry 32(6): 1557–60.
