Safety, Tolerability, Efficacy Study of PUR 0110 Rectal Enema in Mild-to-Moderate Distal Ulcerative Colitis

Safety/Primary Outcome Parameters: * Incidence, nature and severity of adverse events * Incidence, nature and severity of clinical laboratory test abnormalities Efficacy/Secondary Outcome Parameters: * Clinical remission defined as an endoscopy score of ≤ 1, a rectal bleeding score of 0, and an improvement or no change from baseline in the stool frequency score at the end of 2 weeks of treatment / withdrawal visit; * Clinical response rate defined as the percentage of patients with a drop of ≥3 points from the baseline overall modified Mayo score; * Patient defined response and remission rates; * Change from baseline in the overall modified Mayo score (Disease Activity Index); * Change from baseline in each of the 4 individual sub-scores of the modified Mayo score; * Change from baseline in Investigator Assessment of UC Symptom Score (total and individual symptom scores) * Change from baseline in IBDQ score (total and the 4 individual dimension scores) * Proportion of patients with treatment failure; * Change from baseline in serum lutein levels; * Change from baseline in C-reactive protein (CRP), high sensitivity CRP (hs-CRP), erythrocyte sedimentation rate (ESR), fecal calprotectin (FCP), and fecal lactoferrin (FL). * Change from baseline in exploratory biomarkers including: serum interleukin-2 (IL-2), IL-6, IL-8, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-α), transforming growth factor-beta (TGF-beta), IL-4, IL-10, IL-17, IL-23, human beta-Defensin-2 (hBD-2), malondialdehyde (MDA), lipoxin A4 (LXA4), glutathione (GSH), M30 and M65 apoptosomes in serum and biopsies, and plasma and urinary isoprostane levels.