Catalysis of the reaction: pheophorbide a + H2O = pyropheophorbide a + methanol + CO2. The reaction occurs in two steps; pheophoridase catalyzes the conversion of pheophorbide a to a precursor of pyropheophorbide a, C-13(2)-carboxylpyropheophorbide a, by demethylation, and then the precursor is decarboxylated non-enzymatically to yield pyropheophorbide a.