Citrus grandis Osbeck is endemic to Jeju Island and called ‘Dang Yuja’ or ‘Dengwooji’ in Jeju. The size of the fruit grows up to 8 -12 cm in diameter and looks similar to Citrus junos, but C. grandis has a more uneven peel. Since the Joseon Dynasty (17th Century), Citrus genera in Jeju has been taken care of by the government directly for medicinal uses and for offering the first harvest of the season to the gods.

Methanol extract of the fruit peel of C. grandis showed significantly higher anti-oxidant activity than the fruit flesh extract in accordance with flavonoid contents by a scientific article. It was also reported that the unpolar part from unripe C. grandis methanol extract inhibits IL-6, iNOS and COX-2 expression in RAW264.7 cells and medium polar part of extract suppressed TARC and MDC known as inflammatory markers.