Pyrethrin II

Alkyl phenols (HOC6H4CH2—), pyrethrin II (MW = 372) See benzoin isopropyl ether (MW = 254)... 

Recently a new constituent of pyrethrum extract was described by Godin et al. (9) jasmolin II, the cir-pent-2-enylrethronyl ester of pyrethric acid. Jasmolin II differs from pyrethrin II in that the terminal double bond of the alcoholic side chain is saturated. This constituent forms about 3% of the total pyrethrins. Jasmolin II is less toxic to the insects tested than a similar concentration of pyrethrins. The pyrethrum extract was 16 to 17 times as toxic as jasmolin II to Aedes aegypti and Fhaedon cochlearia adults, less than 17 times... 

Sawicki and Elliott (31) re-examined the insecticidal activity of pyrethrin extracts and its four insecticidal constituents against four strains of houseflies, and checked the relative toxicity of pyrethrins I and II. This work confirmed the earlier results, showing that pyrethrin II was 1.3 to 1.6 times more toxic than pyrethrin I, but that the relative toxicities of pyrethrins I and II against the four strains of flies differed little. Resistance to knockdown but not to killing was associated in these strains with resistance to organophos-phorus and chlorinated insecticides. 

Synergist Extract Pyrethrin 1 Pyrethrin II Cinerin l Cinerin II... 

Figure 5. Infrared spectrum of pyrethrin II Fraction isolated from silicic acidr-acetonitrile-hexane partition column...

The columns labeled PI reflect the total of pyrethrin I and cinerin I just as in the AO AC procedure. The gas chromatographic results are in terms of the total amount of the mixture but were analyzed as the methyl ester of chrysanthemic acid. The present state of the determination of PII (pyrethrin II plus cinerin II) is not complete because of the erratic extractability of the dicarboxylic acids from the hydrolysis mixture. The gas chromatographic pattern is distinct and straightforward. As the extraction procedure for PII is improved, the gas chromatographic method will be more applicable. The present recovery of PII is in the range of 80 to 90%. The average of the values shown in Table II for PI is 98.0%. 

IV as a cinerin-type compound, peak V as cinerin II, and peak VI as pyrethrin II. It is evident that peak IV also contains another component. The peaks beyond peak VI are known to be of the pyrethrin type as they respond to the color test. This gas chromatography pattern was obtained with a 6-foot lA -inch column packed with 20% SE-30 on 40-60-mesh Chromosorb P. Later work provided good resolution of the peaks with a 2-foot 4-inch column packed with 20% Dow-11 silicone oil on 45-60-mesh Chromosorb P. 

Purpuric acid lb 174 Pyrazolidine derivatives la 426 3,5-Pyrazolidindione derivatives lb 20 Pyrazolinone derivatives lb 277 Pyrazolin-5-one derivatives lb 327,329 Pyrazone lb 332 Pyrene lb 379 PyrethrinI lb 18 Pyrethrin II lb 18 Pyrethroids lb 86,87 Pyrethroid insecticides la 359 Pyridine alkaloids la 66 lb 279 Pyridine derivatives lb 119,244 Pyridinium carbinols lb 65 Pyridinium glycols lb 65 Pyridoxal la 157,158,253 Pyridoxamine la 253 Pyridoxine la 253... 

Determination of the contents of pyrethrin I and pyrethrin II was then made, for about 2 years (Fig. 2). Having detected pyrethrin I throughout the whole growing process of pyrethrum leaves, they reported that the pyrethrin I content, which had a close relationship with flowering, reached a peak of 0.27-0.40 wt% during flowering and was slightly lower than that in dried flowers. 

Pyrethrin II was also detected in young leaves 2 months after seeding, similarly to pyrethrin I, but the content remained at about 0.05 wt% without seasonal change for 2 years. The insecticidal potency of pyrethrins obtained from pyrethrum leaves was confirmed with Musca domestica. 

While it is conceivable that a part of pyrethrin I is biosynthesized in pyrethrum leaves and moves to flowers sequentially, biosynthesis of pyrethrin II is quite an interesting theme. 

Fig. 2 Seasonal changes in pyrethrins contents in pyrethrum leaves. Filled circles pyrethrin I, open circles pyrethrin II, filled triangles pyrethrin I + pyrethrin II. There were significant differences between changes in pyrethrin I contents and those in pyrethrin II contents (F test, P < 0.05)...

Except for the side chain structure of the alcohol moiety, there is a great difference between natural pyrethrins and dxT/ram-allethrin in that the former consists of the mixture of pyrethrins I and II (5-10, Fig. 5), whereas the latter does not contain pyrethrin II homologs. 

Through extensive studies during the past 60 years, natural pyrethrins proved to possess ample possibilities for structural modifications. Namely, just after elucidation of the structures of pyrethrin I (1) and pyrethrin II (2) of natural pyrethrins in 1947 [2], extensive efforts began to modify mainly the alcohol moieties. In Fig. 2 commercialized household use pyrethroids from Sumitomo Chemical Co.Ltd are listed. 

Pyrethrum (Chrysanthemum) dnerarifolium (Asteraceae) namely cinerin I (CMC cineralone ester), cinerin II (CDC monomethyl ester cinerolone ester), pyrethrin I (CMC pyrethrolone ester) and pyrethrin II (CDC monomethyl ester pyrethrolone ester). The chrysanthemum carboxylic acids are cyclopropane-based monoterpenes and cineralone and pyrethrolone are cyclopentanone monoterpene alcohols. The pyrethrins (and their insecticidal synthetic derivatives) are toxic to insects through keeping cell membrane voltage-gated Na+ channels open and thus impairing neurotransmission. 

Pyrethrin II (= Chrysanthemum dicarboxvlic acid monomethyl ester pyrethrolone ester) (monoterpene)... 

Pyrantel embonate, 947 Pyrantel pamoate, 947 Pyrantel tartrate, 947 Pyrazinamide, 947 Pyrazinecarboxamide, 947 Pyrazinecarboxylic acid, 947 Pyrazinoic acid amide, 947 Pyrazolopyrimidinol, 327 Pyrazolylethylamine, 335 Pyrethrin I, 77, 85 Pyrethrin II, 77, 85 Pyrethrolone, 77 Pyribenzamine, 1052 Pyridacil, 873... 

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