NMR investigations of rotenoids

This review is mainly concerned with the structures, sources and biological properties of those natural products containing the 1,2-diphenyl-propane ring system (see Chart 1, and compare with the isomeric 1,3-diphenylpropane skeleton common to flavonoid compounds), and which collectively are known as isoflavonoids. Also briefly considered, however, are the glucosidic deoxybenzoin derivative, onospin (630), as well as several 2-arylbenzofurans (Table 2, Section R) of leguminous origin which lack a carbon atom corresponding to that marked (Chart 1) with an asterisk (*). These latter compounds and onospin are included because whilst they cannot be regarded as isoflavonoids, it is by no means uncommon to find that in the family Leguminosae they co-occur with (and in certain instances may originate from) isoflavonoids having similar aromatic substitution.

Naturally Occurring Isoflavonoids (1855–1981)

Aliquots of powdered dried leaves of Tephrosia vogelii (Leguminosae – Papilionoideae) were extracted with hexane, acetone and ethanol. The extracts were tested for their potential to protect stored legume seeds from damage by the bruchids Acanthoscelides obtectus, Callosobruchus maculatus and Callosobruchus chinensis (Coleoptera – Bruchidae). While the acetone and ethanol extracts were ineffective except for a significant but low effect on A. obtectus, the hexane extract had a relatively high efficacy, providing similar control of all three bruchid species. This effect was manifested in slowly-reduced adult survival within 7 days and in reduced numbers of eggs laid and of F1 progeny produced, resulting in seed damage averaging 7.1% compared to 99.8% in the untreated controls after one generation. These findings are discussed in the context of previously identified constituents of T. vogelii, the rotenoids rotenone, tephrosin and deguelin.

Extracts from Tephrosia vogelii for the protection of stored legume seeds against damage by three bruchid species

Life tables of Tetranychus urticae Koch were used to assess resistance to spider mites in five varieties of cotton in the southern San Joaquin Valley of California. Experiments were conducted during midseason and again in mid- to late season. The most resistant variety was ‘Pima S-5’ and the most susceptible was ‘Acala SJ-2’. Resistance of S-5 was expressed primarily as lower mite survivorship and fecundity. Developmental rates were similar on all 5 varieties. Although differences in the net reproductive rate (R0) were large, there were only slight differences in the intrinsic rate of increase (r). Comparisons of the data in the first and second experiment, showed that resistance to spider mites increased as the plants matured. It is hypothesized that increased resistance associated with plant maturation results from a decrease in available nutrients in the leaves of older plants.



RESUME

L'utilisation de tables de vie pour mettre en evidence la resistance varietale du coton a Tetranychus urticae



Les tables de vie de T. urticae Koch ont servi a la mise en evidence de la resistance de cinq varietes de coton dans la partie meridionale de la vallee de San Joaquin en Californie. Les experiences ont eu lieu a la mi-saison et a nouveau de la mi a la fin saison. La variete la plus resistante a ete ‘Pima S-5’ et la plus sensible ‘Acala SJ-2’. La resistance de S-5 s'est traduite d'abord par une diminution de la survie et de la fecondite des acariens. Les taux de developpement ont ete les memes sur les cinq varietes. Bien que les differences entre les taux de reproduction nets (R0) aient ete importants, il n'y a eu que de legeres differences entre les taux intrinseques d'accroissement (r). La comparaison des resultats des lere et 2eme experiences a montre que la resistance aux acariens a augmente quand les plantes ont muri. L'hypothese est emise d'un accroissement de la resistance lie a la maturation par suite d'une diminution de la quantite de'elements nutritifs dans les feuilles des plantes âgees.

The use of life tables to assess varietal resistance of cotton to spider mites

Rotenoid content and in vitro acaricidal activity of Tephrosia vogelii leaf extract on the tick Rhipicephalus appendiculatus

Changes in rotenone (R) and deguelin (D) concentrations were followed by thin-layer densitometry in the leaflets and other parts of two lines of Tephrosia vogelii Hook. f. In one line, relatively free of R, total leaflet D increased from 1.6 to 3.2 %. In the other line leaflet R increased with plant age from 0.3 to 1.1 %and leaflet D increased from 1.1 to 1.9 %. Rotenoid levels were higher in leaves formed later

Joseph J. Higgins

Papers

Rotenone and deguelin in Tephrosia vogelii at several stages of maturity