In vivo antidiabetic activity of Greek propolis and Royal Jelly
Diabetes is a chronic disease affecting an important part of the population in our days. A wealth of epidemiological data show that diabetes has increased significantly over the past several years and continues to increase at an alarming rate. In the pathogenesis of diabetes oxidative stress is involved as one of the main mechanisms. In the literature, there are no systemic studies relating bee-keeping products as propolis and royal gelly, which have been used traditionally against diabetes. In the framework of investigations of natural products as potent antidiabetic agents, water and methanol extracts from Greek Royal Jelly and propolis  as well as 10-hydroxy-2-decenoic acid and 3,10-dihydroxydecanoic acid isolated from Royal Jelly , have been tested for their hypoglycemic activity in vivo, in normal and diabetic hairless mice.
Diabetes type I was experimentally induced after intravenous injection of streptozotocin and the blood glucose levels was electrochemically measured. The extracts and the pure compounds were evaluated after single intra-peritoneal injection and glucose measurements for a period of one day.
The results of all extracts showed a stronger hypoglycemic activity (30–40% reduction of the levels of glucose in blood) than the pure isolated substances (up to 15% reduction respectively). The enhanced result obtained by the extracts is probably due to a synergy of the different chemical components while the interesting antidiabetic profile of propolis could be partly due to its high phenolic content known for its antioxidant properties.
References: 1. Melliou, E., et al. (2004) Planta Medica 70:1–5. 2. Melliou, E., et al. (2005)J. Agric.Food. Chem. 53: 987–8992.