DPP4 and arthritic joint disease: Given the various side effects of currently available DPP-4 inhibitors (or ‘gliptins’), which include hypersensitivity reactions, gastrointestinal discomfort, pancreatitis, diarrhea, urinary tract infections, arthritis, and congestive heart failure (Chen et al., 2015; Mascolo et al., 2016; Packer, 2018), the development of natural product-like DPP-4 inhibitors with fewer adverse effects is of considerable importance.