Miroslav Romaňuk

A Series of Bicyclic Insect Juvenile Hormone Analogs of Czech Origin: Twenty Years of Development

Research results are summarized from a series of insect juvenile hormone analogs derived from 2-(4-hydroxybenzyl)-1-cycloalkanones, which have been investigated at the Institute of Organic Chemistry and Biochemistry in Prague during the past 20 years. At present, practical application of several prospective structures for insect control is under investigation. Biological activity values were determined to delineate the most important subseries of compounds and the most promising insect juvenile hormone analogs selected from the subseries. Carbamates, and in particular compound 47 proved to be highly active against aphids, cockroaches, flies, and many other insect species.

Biotransformation of 2-(4-methoxybenzyl)-l-cyclohexanone by cell cultures ofSolatium aviculare

During the search for compounds with insect juvenile hormone activity, the biotransformation of 2-(4-methoxybenzyl)-l-cyclohexanone, of 2-(4-methoxybenzyl)-l-cyclohexanone ethylene acetal and of both isomers of 2-(4-methoxybenzyl)-l-cyclohexanol by plant cells was examined. The compounds were metabolized by cell suspension culture of Solatium aviculare Forst. The reaction conditions were optimized and the metabolic products isolated and identified. A scheme of biotransformation pathway has been proposed.

Action of some aromatic juvenogen esters on insects

Abstract New types of juvenogens, which are biochemically activated juvenoid esters, have been assayed for juvenile hormone activity in three species of insects. The hormonally active component, liberated from the juvenogen substrate by carboxylesterase enzymes within the insects body, was a secondary juvenoid alcohol related to the well-known group of juvenile hormone analogs derived from 4-substituted (7-alkoxygeranyloxy)benzenes. Juvenogen esters obtained by acylation of this juvenoid alcohol with a homologous series of C 2 to C 18 straight-chain monocarboxylic acids retain the juvenile hormone activity of the parental alcohol. The corresponding formyl derivative, as a first member of the series, was inactive and the activity of esters with longer acyl radicals than C 18 also successively diminished. Such a weak dependence for juvenile hormone activity on the size of the molecule has not previously been encountered in juvenoid esters which do not yield biologically active hydrolysis products. These findings favor an assumption that juvenogens may represent selective, nontoxic, hormonally acting pesticides whose physicochemical properties (volatility, lipophility, stability) can be adjusted to suit practical requirements by simple alterations of the biologically unimportant acyl component. Moreover, this can be done without affecting the species-specific properties in the juvenile hormone activity of the built-in juvenoid product.

Natural and synthetic materials with insect hormone activity: juvenile activity of methyl 3,7,11,11-tetramethyl-2-dodecenoate and its homologues

Abstract A series of acyclic sesquiterpenoid esters and homologous derivatives with quaternary alkylated terminal C-atoms and different chain lengths have been tested for juvenile hormone activity on representative species belonging to six families of insects. Substitution of hydrogen for an additional methyl group at C11 atom results in increased biological activity, although this has appeared less effective than the presence of heterogenous atoms or heterogenous groups as a halogen or an epoxy group at this position. Homologous compounds with a shortened chain length between the original positions C7, C11 retain the hormonal activity, whereas compounds with a shortened chain both between C3, C7 and C7, C11 are inactive. One compound, methyl 3,11,11-trimethyl-7-ethyl-2-dodecenoate, has relatively high juvenile hormone activity on orthopterous insects.

The Chemistry and Physiology of Juvenoids

This most extensive part of the book deals with compounds generally known as juvenile hormone analogues or juvenile hormone mimics. These materials encompass a wide range of mainly synthetic compounds with a relatively smaller amount of natural products isolated from plants and animals. The compounds have been characterized by certain size and shape of the molecule, low polarity, presence of specific functional groups and substituents, and by some other common structural features. However, the only criterion for classification of a compound as a juvenile hormone analogue is its property to exhibit or mimic some morphological and physiological effects of the hormone secreted by the corpora allata. Since the chemical nature of the endogenous corpus alla-tum hormone is still incompletely known with respect to diversity of insect species, these compounds cannot be viewed as analogues of the corpus allatum hormone in the chemical sense of the word. It is more appropriate to regard them as its bio-analogues or pharmaco-analogues. To facilitate further discussions we have selected a generic name juvenoids for all the compounds with juvenile hormone activity.

Brief Survey of the Neuroendocrine System in Insects

This introductory chapter represents a condensed review of the components of the neuroendocrine system of insects and the effects of their extirpation or transplantation on development. We have separated these effects from those of plant and animal extracts, other isolation products, or synthetic compounds, which will be described in the following chapters. The recent literature pertaining to insect hormones has been reviewed in several monographs. The results obtained by classical endocrinological techniques are described in detail in the book by Pflugfelder [237] which contains detailed descriptions of insect endocrines from the period when morphological studies predominated. An extensive list of the literature pertaining to the endocrine glands of insects with discussions on developmental theories in insect endocrinology is contained in a book by Novak [218]. Comparative data on insects and other invertebrates, especially crustaceans, may be found in a monograph by Gersch [90] and a brief but very instructive book of comparative endocrinology of invertebrates containing numerous illustrations has been prepared by Highnam and Hill [126]. Comparative data on the structure and function of neurosecretory system may be found in an extensive work by Gabe [88]. The basic physiological data for understanding the mode of action of insect hormones are contained in a book by Wigglesworth [370], and a monograph by Wigglesworth [371] on the physiology of metamorphosis of Rhodnius.