Phytochemical content and antioxidant activity of leaf extracts from nine bamboo species and determination of flavone C-glycosides by TLC and HPLC

Bamboo leaf extract (BLE) is a rich source of phytochemicals and antioxidants, which has been used to stimulate immune-activity and alleviate several chronic diseases. The effective ingredients in alcoholic BLE are phenolic acid and flavonoids, especially flavone C-glycosides. This study aimed to examine the alcoholic solvents that could generate the highest content of phytochemicals and antioxidants and evaluate the simplest method to determine the flavone C-glycosides in BLE by TLC and HPLC. The results showed that 60% ethanol could extract the highest yield of total phenolic content (TPC) compared to 80% ethanol, absolute methanol and absolute ethanol, respectively. Thus, TPC, total flavonoid contents, anthocyanin and antioxidant activities were then analyzed in leaves of nine bamboo species which extracted by 60% ethanol. Pai Pak King (Dendrocalamus sp.) contained the highest contents of total phytochemicals and antioxidant activity. Moreover, TLC showed that flavone C-glycoside content was highest in BLE of Pai Pak King, Pai Sang Mon (D. sericeus) and Pai Dum (Phyllostachys nigra), respectively corresponded to HPLC analysis. HPLC showed that BLE of Pai Pak King significantly contained higher contents of orientin (6.68 µg mL^‑1) and vitexin (2.81 µg mL^‑1) than Pai Sang Mon and Pai Dum while the contents of isoorientin (2.18 µg mL^‑1) and isovitexin (2.05 µg mL^‑1) were not significantly different. This study suggested that TLC could be used as a simplest method for screening the effective flavone C-glycosides in a commercial BLE.