Those who do not have a β-lactone ring are (E)-4-amino styryl acetate, ε–polylysine and caulerpenyne.[2] Lipase inhibitors have also been made synthetically, e.g. cetilistat, based on the structure of triglycerides and other natural lipase substrates.[8] However, the synthetic lipase inhibitors differ in structure and some of them lack the β-lactone ring.[4]