Studies on the in vitro antitumor activity of fatty acids. I. 10-Hydroxy-2-decenoic acid from royal jelly.

Whole royal jelly, when premixed with tumor cells before inoculation, has been shown to inhibit completely the development of transplantable AKR leukemia and of three lines of mouse ascitic tumors. Fractionation studies have established that all, or nearly all, of the in vitro antitumor activity of whole royal jelly can be accounted for in the major component of the ether-soluble fatty acid fraction, 10-hydroxy-2-decenoic acid. Concentration studies have shown that 1.5 mg. of 10-hydroxy-2-decenoic acid or 40.0 mg. whole royal jelly per ml. of cell suspension completely prevented tumor forma tion with all four types of tumors. The in vitro antitumor activity has been shown to be demonstrable only at low pH values. No activity with either compound could be shown above pH 5.6. Time studies have shown that the reaction between the tumor cells and 10-hydroxy-2-decenoic acid was completed within 6 minutes. Some variations in suscep tibility to royal jelly or 10-hydroxy-2-decenoic acid have been demonstrated within the four test tumors.