Organ-specific distribution of chlorophyll-related compounds from dietary spinach in rabbits

The distribution of chlorophyll-related compounds (CRCs) derived from dietary spinach was investigated in different organs the rabbits. The rabbits in the experimental group consumed 100 g of freeze-dried spinach powder after a 24 h fasting period and sacrificed 2, 4, 8, 12 and 24 h later and in the control group sacrificed after the 24 h fasting period. The main CRCs in the liver were found to be chlorophyll (Chl a) and b, chlorophyllide (Chlide) a and b, pheophytin (Phe) a and b and pheophorbide (Pho) a and b, which reached their peak values at 8 h post-feeding. The gallbladder contained mainly Chlide a and a', Pho a and a', Pho b and b', which peaked their values at 2 h post-feeding. Pho a and b were consistently observed in the blood and peaked at 12 h post-feeding. The earlier appearance of Chlide a', Pho a' and Pho b' in the gallbladder compared to the liver indicated that these CRCs were compartmentalized differently and might undergo the same type of vectorialized transport as characterized for the bile salts. Pho levels peaked later in the blood compared to the liver, suggesting that Pho might be released into the peripheral blood circulation from the liver. In conclusion, Chlide and Pho were the principal Chl metabolites in the rabbits. Our data may expand our understanding of the metabolism and biodistribution of CRCs in the human body. A number of biological functions, including anti-oxidation, anti-tumor and anti-aging have recently been attributed to CRCs, it will be interesting to explore, if the binding of Chlide and Pho to other nutrients or trace metal ions in the body mediate their biological functions.