So one of my relatives went to an ayurvedic treatment center in India and papaya was one of the main agents they used to alleviate constipation and treat various bowel issues. Although I can't provide any studies for UC, the seeds seem to be a good anti-parasitic agent (many of us are infected with parasites and don't even know it). It also contains digestive enzymes, antioxidants and anti-inflammatory compounds, with the most notable being
bromelain and
papain.
My doc had a segment where papaya was featured here:
vimeo.com/75935205