CHEMICAL COMMUNICATIONS 1968 23 Isolation of a Substance that suppresses Feeding in Locusts By J. H. BUTTERWORTH and E. D. MORGAN* (Department of Chemistry Keele University Keele Staffs.) WE report the isolation of a substance from the seeds of Melia azadirachta (M. indica or Azadirachta indica A. Juss) which inhibits feeding in the desert locust (Schistocerca gregaria) . We are prompted to record our preliminary investigations by the report that meliantriol from the fresh fruit of Melia azedarach and the oil of M . azadirachta is a feeding repellant for the desert 1ocust.l The inhibiting substance which we call azadirachtin, is not related to meliantriol and is of notably high activity as a feeding repellant. Feeding tests were carried out by impregnating filter paper (6.5 cm.discs of Whatman No. 1) with methanol solutions of fractions from the seeds at various dilutions. The papers were momentarily dipped in the solution allowed to dry sprayed with O-B5~-sucrose and dried again. These test papers were presented to separate groups of mid 5th instar hoppers of S. gregaria which had been starved for about 24 hr. The seeds of M . azadirachta were macerated with ethanol in the cold and the ethanol extract subjected to successive solvent partitions followed by alumina chromatography. Fractionation was monitored by feeding tests and thin-layer chro-matography. It was possible to correlate all activity with a narrow range of RF values in t.1.c. Further chromatography gave colourless amorphous material which completely inhibited the feeding response at a concentration of 5 mg./l.Further purification by multiple-elution prepara-tive layer chromatography and crystallization from carbon tetrachloride gave azadirachtin as a microcrystalline powder m.p. 155-158" [aI 24 CHEMICAL COMMUNICATIONS 1968 I ' I 2 3 I 4 I 5 I 6 FIGURE -53" [G 0.5 (CHCI,)] M+ 642.222 (calc. for C29~38018r 642.216) A,, 217 mp (EtOH) log (CCl,). The n.m.r. spectrum (Figure) showed a complex series of absorptions between T 3-3 and T 8.8 there were no strong absorptions between T 8.6 and T 10.0 corresponding to the angular methyl groups of a triterpenoid nor were there any absorptions in either the n.m.r. or infrared spectra characteristic of the furan ring present in many of the triterpenoids found in this and other members of the family Meliaceae. The absence of absorption in the T 9.3-8-6 region is taken as E 3.9 Vmax 3460 1745 1720 1655 1620 cm.-l clear indication that azadirachtin is not related to meliantriol. Azadirachtin has 100% anti-feeding activity at a concentration of 70 pg./l. In the absence of details from Lavie et aZ.,l we tentatively calculate this to be equivalent to 1 ng./cm.2 by their method. The elucidation of the structure of azadirachtin is proceeding and will be reported later. We thank Professor J. W. Cornforth F.R.S., for bringing this problem to our attention and Dr. P. E. Ellis and the Anti-Locust Research Centre London for help and advice. (Received October 30th 1967; Corn. 1169.) D. Lavie M. K. Jain and S. R. Shpaii-Gabrielith Chsm. Coinm. 1967 910