Phytochemical Screening and Biological Activities of Ethanolic Extracts from New Tropical Water Lilies Nymphaea ‘Blue Sakura’ and Nymphaea ‘Chularath’

Nymphaea ‘Blue Sakura’ (NB) and Nymphaea ‘Chularath’ (NC) are newly developed hybrid cultivars of Nymphaea nouchali Burm. F.; belonging to Nymphaeaceae family. The aims of this study were to investigate the phytochemicals of stamen, petal, and leaf extracts from three water lily strains including NB, NC, and Nymphaea nouchali Burm. (NN), to elucidate the structure of isolated Compound 1, and to determine the biological activities including anti-oxidative, anti-α-glucosidase, anti-α-amylase, and anti-tyrosinase activities. Tannins, terpenoids, and cardiac glycosides were found in all parts of water lily extracts. Phenolic compounds, especially gallic acid, were detected and correlated with the TLC fingerprint, HPLC and NMR spectra. Compound 1 structure was revealed to be a gallic acid that can be used as a chemical marker for quality control of the extracts. NN- and NC-stamen extracts showed higher anti-oxidative activity than that of their petal and leaf extracts. While NB-petal extract showed higher anti-oxidative activity than that of its stamen and leaf extracts. NN-stamen extract (EC50 of 50.48 ± 3.30 µg/ml) showed the higher anti-α-glucosidase activity than the NB- and NC-stamen extracts. Whereas the NC-stamen extract (EC50 of 408.21 ± 16.00 µg/ml) showed the higher anti-α-amylase activity. For the NB, its stamen extract showed stronger anti-α-glucosidase activity and anti-α-amylase activity than the petal and leaf extracts, respectively. In addition, the NB-stamen extract (EC50 of 36.29 ± 5.61 µg/ml) showed stronger anti-tyrosinase activity than the other extracts. These results indicated that the stamen, petal, and leaf extracts of water lilies in this study could be a good source of phytochemicals and had high anti-oxidative, anti-α-glucosidase, and anti-tyrosinase activities.