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 earth and hoof glue. It would also be used to bind feathers and equipment together. The first commercial glue factory opened in Holland circa 1700, manufacturing animal glue from hides. The United States’ first glue factory opened in 1899, established by the Milwaukee Tanning Industry. The L.D. Davis company thrived producing animal glue during the Great Depression after shifting its focus from stenciling, selling to local box makers and other users; L.D. Davis' animal glue formula for bookbinding remains in production. During the 18th and 19th centuries, ranchers disposed of old animals – horses in particular – to glue factories.