AUTHOR(S)
Hans E. Hummel1,2, D.F. Hein1 and H. Schmutterer3

ABSTRACT

Azadirachtins(azas) are known as a family of natural phagorepellents and antifeedantsisolated from the seeds of the neem tree Azadirachta indica A. Juss.(Meliaceae). They exert a strong negative influence on behavior (feeding andmating activity), postembryonic development (molts), and fecundity of insectsresulting in significant reduction of general fitness. The history of discoveryand characterization of azas as a unique family of natural products was full ofsurprises and obstacles. But after the labors lasting 4 decades in various labsin Europe (Kraus, Schmutterer, Butterworth and Morgan, Ley) and in North America(Nakanishi), the complicated multifunctional tetranortriterpenoid aza A emergedand was characterized by elemental composition of C35H44O16. The structureproposals, although arrived at independently in competition and by completelydifferent methods (NMR and X-ray analysis), ultimately converged into acommonly accepted structure individually published side by side in 1987. It wasreconfirmed by Veitch et al. in 2007 in Ley’s group in Cambridge,England, through total synthesis and therefore can be considered as ultimateproof and as valid without any remaining doubt. The 25^th anniversaryof this scientific achievement is reason for celebration. A new member of theazadirachtin family was discovered at Giessen in 1991 and named marrangin. Itoccurs in seeds of the marrango tree Azadirachta excelsa (Jack)Jacobs and has the elemental composition of C35H44O15. In some insect speciesbut also in mites like Tetranychus urticae, its biological activity issignificantly superior to azadirachtin A. The value of these biorationalcompounds, with their very low vertebrate toxicity and their low toxicity toinsect members of the third level of the food chain, today is globallyrecognized. Quite recently, azas and analogs are gaining increasing acceptancein veterinary and human medicine.

DOI
https://doi.org/10.57182/jbiopestic.5.0.82-87

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