Simultaneous characterisation and quantitation of flavonol glycosides and aglycones in noni leaves using a validated HPLC-UV/MS method Shixin Deng * , Brett J. West, C. Jarakae Jensen Research and Development Department, Tahitian Noni International, 737 East, 1180 South, American Fork, Utah 84003, USA article info Article history: Received 14 December 2007 Received in revised form 20 March 2008 Accepted 5 April 2008 Keywords: Noni Morinda citrifolia L. Leaves Flavonoids Quercetin-3-O-a-l-rhamnopyranosyl- (1 ? 6)-b-d-glucopyranoside Rutin Kaempferol-3-O-a-l-rhamnopyranosyl- (1 ? 6)-b-d-glucopyranoside Quercetin Kaempferol HPLC-UV/ESI-MS Quantitative determination abstract The leaves of Morinda citrifolia L. (noni) have been utilized in a variety of commercial products marketed for their health benefits. This paper reports on a rapid and selective HPLC method for simultaneous char- acterization and quantitation of four flavonols in an ethanolic extract of noni leaves by using dual detec- tors of UV (365 nm) and ESI-MS (negative mode). The limits of detection and quantitation were between 0.012 and 0.165 lg/mL. The intra- and inter-assay precisions, in terms of percent relative standard devi- ation, are less than 4.38% and 3.50%, respectively. The accuracy, in terms of recovery percentage, ranged from 96.66% to 100.03%. Good linearity (correlation coefficient >0.999) for each calibration curve of stan- dards was achieved in the range investigated. The contents of four flavonoids in the noni leaves varied from 1.16 to 371.6 mg/100 g dry weight. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Noni (Morinda citrifolia L.), belonging to the family Rubiaceae, is an indigenous tree of the tropical zones of South Asia, Australia, Hawaii, and the islands of French Polynesia. Its fruit, leaves, seeds, bark, and roots have been traditionally used for prevention or improvement of various diseases, including arthritis, infections, colds, cancers, diabetes, etc. (Mc Clatchey, 2002; Wang et al., 2002). In the past decade, noni fruit juice has emerged on the world-wide market as a safe and popular health product due to its phytochemicals and nutrients. Also, noni leaves are well- known for their strong antioxidant activity, and have been shown to be safe in acute, subacute, and subchronic oral toxicity tests on mice (West, Tani, Palu, Tolson, & Jensen, 2007). Sparked by an- cient Polynesian legends, noni leaves have been developed into health teas. The leaves are also the source for a variety of other health-promoting commercial products. Commercial noni leaf products have been available in Japan and United States for more than seven years, mainly for use in making infusions. However, some manufacturers produce capsules containing powdered noni leaves. The major world-wide source of noni leaves is French Polynesia, with leaves from this nation having undergone a safety evaluation (West et al., 2007). Other sources include Panama, Fiji, and Hawaii. Previous phytochemical studies reveal that noni leaves contain a variety of phytochemical constituents, including terpenoids (Ah- mad & Bano, 1980; Saludes, Garson, Franzblau, & Aguinaldo, 2002; Takashima et al., 2007); phytosterols, fatty acids, and their glyco- sides (Takashima et al., 2007); iridoids and their glycosides (Sang et al., 2001a,b,c,d; Sang et al., 2003); flavonol glycosides (Sang et al., 2001a), among others. Flavonol glycosides appear to predominate in noni leaves, ru- tin and other flavonol glycosides have previously been identified in raw noni leaves (Sang et al., 2001a). However, the presence of flavonol aglycones in noni leaves has not been previously re- ported. Flavonoids have been indicated to possess a variety of biological activities (Garcia-Mediavilla et al., 2006; Kampkotter et al., 2007), and may play an important role in noni leaves. To date, there has been no validated analytical method for determin- ing the flavonol constituents of noni leaves. In this paper, we re- port a rapid, simple, and selective HPLC method to simultaneously characterize and quantitate the contents of flavo- nol aglycones and their glycosides in noni leaves. As shown 0308-8146/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2008.04.021 * Corresponding author. Tel.: +1 801 234 3598; fax: +1 801 234 3597. E-mail address: shixin_deng@tni.com (S. Deng). Food Chemistry 111 (2008) 526–529 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem