Poncirin and naringin which are the flavanone rhamnoglucoside showed anti-inflammatory activity as the major component of fruit of Poncirus trifoliata. Poncirin was metabolized by intestinal bacteria of human and rats. Among the human intestinal bacteria, Bacteroides JY-6 converted a poncirin to naringin, ponciretin-${eta}$-D-glucopyranoside, naringenin-${eta}$-D-glucopyranoside, naringenin and ponciretin and did a naringin to poncirin, ponciretin-${eta}$-D-glucopyranoside, naringenin-${eta}$-D-glucopyranoside, naringenin and ponciretin.