Antioxidant and Compositional HPLC Analysis of Three Common Bamboo Leaves

Bamboo leaves of Phyllostachys nigra (PN), Lophatherum gracile (LG), and Pleioblastus amarus (PA) are three common herbs in China. In this work, a new high performance liquid chromatography (HPLC) method for the simultaneous determination of seven compounds in bamboo leaves has been developed; and PN, LG, and PA leaves were analyzed. PN showed four times as much chlorogenic acid (CA) than the other two, and contained the most isoorientin (iso-ORI) and isovitexin (iso-VIT) as well. The PA presented the most orientin (ORI) and LG covered a majority of cynaroside (CYN). We measured the antioxidant activity by scavenging the stable 2,2-diphenyl-1-pyridinohydrazinyl (DPPH) free radicals, and found that Luteolin (inhibitory concentration (IC)₅₀ = 0.42 µM, LUT) and CYN (IC₅₀ = 0.43 µM) showed 2-3 times higher antioxidant activity than iso-ORI (IC₅₀ = 0.81 µM), ORI (IC₅₀ = 0.84 µM), and other related antioxidant standards such as trolox (IC₅₀ = 0.97 µM) and ascorbic acid (IC₅₀ = 0.93 µM, VC). Among extracts, PN and PA showed considerable antioxidant activity, which was related well with the contents of CA, iso-ORI, and iso-VIT (p < 0.05). This study firstly provides evidence for functional antioxidant compounds of bamboo leaves based on statistical analysis of the HPLC analysis and DPPH assay, and it lays a foundation for its further development or utilization.