Genipin
Genipin is the active compound found in the gardenia fruit extract, which is used in traditional Chinese medicine to relieve the symptoms of type 2 diabetes. Research conducted at the Beth Israel Deaconess Medical Center and Harvard Medical School indicated that the chemical is indeed effective.
Genipin is an aglycone derived from an iridoid glycoside called geniposide present in fruit of Gardenia jasmindides Ellis. Genipin is an excellent natural cross-linker for proteins, collagen, gelatin, and chitosan cross-linking. It has a low acute toxicity, with LD50 i.v. 382 mg/kg in mice, therefore, much less toxic than glutaraldehyde and many other commonly used synthetic cross-linking regents. It is also used for pharmaceutical purposes, such as choleretic action for liver diseases control.