Abstract:

[Objective] Most flavonoids possess a variety of medical and biological activities such as anti-free radical, antioxidant, antiaging, anti-inflammatory, etc. They are widely used in pharmaceutical, health products and cosmetic fields. The objective of this paper was to establish a HPLC method for simultaneously qualitative-quantitative analysis of 13 flavonoids (isoorientin, orientin, vitexin, isovitexin, apigenin, luteolin, tricin, 7-methoxy-tricin, tricin-7-O-glucopyranoside, apigenin-7-O-glucopyranoside, demethyltorosaflavone, apigenin-7-O-glucopyranoside-6″-O-rhamnoside and 6-trans-(2″-O-α-rhamnopyranosyl)ethenyl-5,7,3',4'-tetrahydroxyflavone) in bamboo leaves, and leaf flavonoids in 10 species of Dendrocalamus (D. latiflorus, D. giganteus, D. strictus, D. membranceus, D. farinosus, D. minor var. amoenus, D. yunnanicus, D. fugongensis, D. brandisii and D. hamiltonii) were comparatively analyzed by the established method with the aims to provide a guidance for qualitative and quantitative analysis of flavonoids, the development and utilization of Dendrocalamus bamboo leaves and the selection of bamboo species for flavonoids extraction. [Method] The flavonoids were separated by HPLC gradient elution method, and the validation was guaranteed by accuracy of equipment, LOD, LOQ, intraday/interday precision and recovery rate. Bamboo leaves were extracted with 70% (v/v) ethanol-water by ultrasonic extraction, and then tested by HPLC after petroleum ether extraction. [Result] A good separation was found for each flavonoid, the retention times were ranged from 13.23 to 54.67 min. The standard curves showed a good linearity in the corresponding ranges between 0.01 and 500 mg·L^-1(R²≥0.999 6). The equipment accuracy RSD were 1.06%-2.55%, LOD and LOQ ranged from 0.01 to 0.10 mg·kg^-1, and from 0.03 to 0.34 mg·kg^-1, respectively. The RSD values of instrument accuracy, and intraday/interday precision indicated that it was reasonable to analyze the samples within 5 days. The RSD of intraday and interday precisions were 0.15%-0.67% and 0.44%-5.61%, respectively. Recovery rate for 7 kinds of flavonoids in spiked D. latiflorus were higher than 70%, and that for the other 6 kinds of flavonoids were ranged from 39.76% to 68.75%. The established HPLC method was valid in application for 10 species of Dendrocalamus. The results exhibited differences in flavonoids content among the bamboo leaves. As luteolin, 6-trans-(2″-O-α-rhamnopyranosyl)ethenyl-5,7,3',4'-tetrahydroxyflavone and demethyltorosaflavone were observed in some bamboo species, the other 10 flavonoids were detected in all 10 kinds of bamboo leaves. The concentrations of total 13 flavonoids were in the range of 419.94 to 5 155.84 mg·kg^-1. The maximum content of total flavonoids was found in D.minor var. amoenus, and the minimum was in D. fugongensis. [Conclusion] The established HPLC method for simultaneously qualitative-quantitative analysis of 13 flavonoids in bamboo leaves was simple, sensitive and accurate. The flavonoids content was rich in leaves of 10 bamboo species in Dendrocalamus genus which are potential resources for exploitation and utilization.

Key words: HPLC, flavonoids, bamboo leaves, Dendrocalamus