Structural characterization, neuroprotective and hepatoprotective activities of flavonoids from the bulbs of Heleocharis dulcis

Chinese water chestnut, the bulb of Heleocharis dulcis, has been widely consumed as fruit or vegetable in China since ancient times. It exhibits health-promoting properties that leads to an extensive study of their active components. Successive chromatography of active fragments of H. dulcis resulted in isolation of five new chalcone-flavonone heterodimers (1-3, 6, 9), four new diverse flavonoids (4, 5, 7, 8), and sixteen known flavonoids derivatives (10-25) were elucidated on the basis of their IR, UV, NMR, MS spectrometry data analysis and references from H. dulcis for the first time. Among these isolates, compounds 4, 7, 9, 12, 13, and 17 showed moderate neuroprotective activity, which increased the cell survival rate from 49.23 +/- 3.68% for the model to 67.75 +/- 2.75%, 57.83 +/- 2.46%, 67.98 +/- 2.74%, 58.65 +/- 3.43%, 56.14 +/- 1.99%, and 56.70 +/- 1.38% at 10 mu M, respectively. Moreover, compounds 1-3, 15, 16, 18, and 20 were found to moderately improve the HepG2 cell survival rates from 39.53% (APAP, 10 mM) to 45.53-53.44%. The outcome of the study provided crucial information regarding the structural diversity and health benefits of the edible bulbs of H. dulcis.