Rapid Screening for Flavone C-Glycosides in the Leaves of Different Species of Bamboo and Simultaneous Quantitation of Four Marker Compounds by HPLC-UV/DAD

A strategy for analyzing flavone C-glucosides in the leaves of different species of bamboo was developed. Firstly, the flavone C-glycosides were extracted from the bamboo leaves (51 species in 17 genera) with methanol and chromatographed on silica gel 60 plates in automatic developing chamber (ADC2), and a qualitative survey using simple derivatization steps with the NP reagent was carried out. The flavone C-glycosides were found in 40 of 51 species of bamboo examined. Secondly, an HPLC method with photodiode array and multiple wavelength detector was optimized and validated for the simultaneous determination of flavone C-glycosides, including isoorientin, isovitexin, orientin, and vitexin in the leaves of three species of bamboo and the flavone C-glycosides were confirmed by LC/MS. The optimized HPLC method proved to be linear in the concentration range tested (0.2–100？μg/mL, ), precise ( %), and accurate (88–106%). The concentration ranges of isoorientin, isovitexin, orientin, and vitexin in three bamboo leaves samples were 1.00–2.78, 0–0.31, 0–0.07, and 0.20–0.68？mg/g, respectively. The proposed method was validated to be simple and reliable and can be a tool for quality control of bamboo leaf extract or its commercial products. 1. Introduction Bamboo leaves have been used in traditional Chinese medicine for treating fever and detoxification for over 1000 years. It was found that extract of bamboo leaves has multiple biological activities, such as cancer prevention [1, 2], anti-free radical, and antioxidation [3, 4], and can be used as a pharmaceutical intermediate and food additive. A new product named bamboo-leaf flavonoid has appeared on the market. The main functional components of the extract from bamboo leaf are flavone C-glycosides including isoorientin, isovitexin, orientin, and vitexin (Figure 1), which have been used as marker compounds for the determination of commercial products of bamboo-leaf flavonoids. Figure 1: Chemical structures of isoorientin, isovitexin, orientin, and vitexin. Isoorientin: R 1 = R 3 = R 5 = R 6 = OH, R 4 = H, R 2 = glucose; isovitexin: R 1 = R 3 = R 6 = OH, R 4 = R 5 = H, R 2 = glucose; orientin: R 1 = R 3 = R 5 = R 6 = OH, R 2 = H, R 4 = glucose; vitexin: R 1 = R 3 = R 6 = OH, R 2 = R 5 = H, R 4 = glucose. Bamboo is an important renewable resource and more than 1250 bamboo species, belonging to 75 genera, are distributed all over the world [5]. The quality of different batches of the same herb could vary significantly [6]. Hence, to investigate and determine these flavone C-glycosides in the leaves of different