Propolis recently been isolated from red propolis, and prenylated acids such as 4-hydroxy-3,5-diprenyl cinnamic acid have been documented. An analysis of propolis from Henan, China found sinapinic acid, isoferulic acid, caffeic acid, and chrysin, with the first three compounds demonstrating antibacterial properties. Also, Brazilian red propolis, largely derived from "Dalbergia ecastaphyllum" plant resin, has high relative percentages of the isoflavonoids 3-hydroxy-8,9-dimethoxypterocarpan and medicarpin. Other flavonoids commonly present include galangin and pinocembrin. Caffeic acid phenethyl ester (CAPE) is also a component of some varieties of propolis from New Zealand. Occasionally, worker bees will even gather various caulking compounds of human manufacture, when
Animal glue times, although its usage was not widespread. Glue deriving from horse tooth can be dated back nearly 6000 years, but no written records from these times can prove that they were fully or extensively utilized. The first known written procedures of making animal glue were written about 2000 BC. Between 1500–1000 BC, it was used for wood furnishings and mural paintings, found even on the caskets of Egyptian Pharaohs. Evidence is in the form of stone carvings depicting glue preparation and use, primarily utilized for the pharaoh’s tomb’s furniture. Egyptian records tell that animal glue would be made by melting