Potent fungicidal activity

In the course of their attempt to establish the identity of mucidin, Anke and Steglich isolated from the Porcelain fungus, apart from strobilurin A, also (-)-oudemansin A, which possesses hkewise potent fungicidal activity. 

Many compounds containing the N—S—CCI3 grouping have been shown to have broad-spectrum potent fungicidal activity. Captan is the best-known example and was introduced in the early 1950s as a seed dressing and for the control of apple and pear scab and botrytis. Note its easy and cheap synthesis which commences with a Diels-Alder reaction. 

Of agricultural importance is the plant-growth regulating activity of 6,8-dichloro-2-methyl-3-carboxymethyl-4(3H) quinazolinone which was as potent as 2,4-dichlorophenoxyacetic acid in the Lepidium test. 4-Hydroxy-5,6,7,8-tetrahydroquinazoline has been patented with reference to fungicidal activity. 

These natural substances are of great interest due to both their unusual structures and the potent wide-ranging spectrum of biological activities that they possess antitumor activity [10] in vitro and/or in vivo, antiinflammatory activity [7], fungicidal activity [11], herbivorous mammalian antifeedant activity [12], insecticide activity against house-fly larvae and other insects [13] and, lastly, a potent plant growth regulatory activity, both as inhibitors and as stimulants [14-15]. 

Several trehalase inhibitors have been isolated from natural sources these include deoxynojirimycin, validamycins, validoxylamines, salbastatin, calystigin B4, and trehazolin, the last one being the most potent. Trehazolin is used to control blight sheath of rice, caused by the plant pathogenic fungus Rhizoctonia solani, and it thus has potential fungicidal activity.12 15... 

The fungicidal activity of sceptrin at 10 ppm was found to be >65 % inhibition of Phytophthora infestans (potato late blight) [103]. In addition to its antimicrobial, antiviral [104], antimuscarinic [22], and antihistaminic [30] properties, sceptrin was shown to be the first and most potent nonpeptide somatostatin inhibitor in the submicromolar range [105]. 

While triphenyltin hydroxide (fentin hydroxide) in used as a potent fungicide, its saturated analogue, tricyclohexyltin hydroxide (34), is highly active against motile forms of plant-feeding mites (Kenaga, 1966 Allison el al., 1968). 

In the group of phosphorothioates, an increase in the number of sulfur atoms linked to the phosphorus atom increases the fungicidal effect of the aliphatic esters (Hacskaylo and Stewart, 1962). Thus, simple trialkyl phosphorodithioates are more efficient than trialkyl phosphorothioates, and the fungicidal activity of phosphorotrithioates and tetrathioates is even more potent (Mandelbaum et al.,... 

Apart from the flavone cochliophilin A methyl ether (10), it has been found that other, non-flavonoid, natural products (e.g. the anthraquinone, emodin) also exhibit potent antidote activity. Whilst the significance of these plant-produced chemicals, in reducing the efficiency of several widely used benomyl-type fungicides, has still to be evaluated, the fact that flavones occur widely in the Plant Kingdom may suggest that crop plants should be routinely screened for potential flavone (and non-flavone)... 

Although fluazinam has a broad spectrum of fungicidal activity it is less potent on rusts and powdery mildews [72, 156] (in contrast to the dinitrophenols, which are generally most effective against powdery mildews) and has not been commercialized for use on cereal crops. It has, however, found wide application in other crops since its first launch in New Zealand in 1988. 

UDP-7V-acetylglucosamine (uridine diphosphate), nikkomycins act as potent competitive inhibitors of chitin synthase and exhibit potent fungicidal, insecticidal, and acaricidal activities [320]. Nikkomycin X and Z, isolated as major components, contain the hydroxypyridylhomothreonine (HPHT) moiety, the aminohexuronic acid, and a nucleoside moiety N-glycosidically linked to 4-formyl-imidazolin-2-one or a uracil base, respectively [321, 322]. 

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