If your case is mild, then it is certainly worthwhile to see whether Pentasa by itself can help. Yes, it can suppress inflammation and might be all you need. So you are taking 4 grams a day? That is the optimal dose for inducing remission and also for maintenance.
Pentasa is considered by GIs to be safer than the other meds, so if it works for you (8 days is too soon to tell), then great! However, if after you have been on it a month, the symptoms don't improve, then you might have to replace it with another med.