Helminthosporium 77. sativum

As an example of the fascinating current progress, Dr. Spencer will describe a beautiful piece of research on the isolation and structure proof of the toxin from Helminthosporium sativum, an important... 

Biologically Active Agents from Helminthosporium sativum... 

During the course of this work Tamura et al. (1,14,15) isolated a metabolite from another strain of Helminthosporium sativum. By comparison with the bis-3,5-dinitrobenzoate of the diol from helminthosporal they identified it as the unsaturated aldehyde-saturated alcohol, helminthosporol (VIII, IX). 

Figure 3. Conidium of Helminthosporium sativum Treated With 10 ppm of Fenarimol.

Money et al. have accomplished the chemical functionalization of (-)-bornyl acetate, to yield (206) as the major product with smaller amounts of the 3-keto- and 6-keto-isomers of (206) and exo-(207 R = Ac), as well as microbiological hydrox-ylation using Helminthosporium sativum, to yield endo- and exo-(207 R=H) 6-exo-hydroxybofneol (208 R=H)/5 1 2/ ... 

Fermentation procedures for preparing uridine 5 -(2-acetamido-2-deoxy-a-D-glucopyranosyl pyrophosphate) have also been reported. One of them255 involves the cultivation of Helminthosporium sativum in the presence of 2-amino-2-deoxy-D-glucose and the antibiotic polyoxin the latter is an inhibitor of chitin biosynthesis. The other256 utilized the incubation of yeast cells with uridine 5 -phosphate in the presence of an excess of 2-amino-2-deoxy-D-glucose and inorganic phosphate.257... 

Sorokinianin, an unusual sesquiterpenoid, is isolated from Bipolaris sorokiniana, a fungal phytopathogen that causes spot blotch or foot and root rot diseases in wheat, barley, and oat. It is biosynthesized from phytotoxic prehelminthosporol and C3 unit derived from oxaloacetic acid.328 Prehelminthosporol itself was isolated as a phytotoxin of Helminthosporium sativum. Sorokinianin is more phytotoxic than prehelminthosporol in inhibiting the germination of barley seeds. 

The structure and stereochemistry of cis-sativenediol (111) and trans-sativenediol (112) have been established57 by n.m.r. spectroscopy and, in the case of the ris-isomer, by conversion into the diethyl acetal (113) of helminthosporal (115). Both diols co-occur with prehelminthosporol (114), helminthosporal (115), and helminthosporol (116) in Helminthosporium sativum and Cochliobolus setariae and a definitive statement on the possible biosynthetic relationship between these compounds is expected in the near future. Two related sesquiterpenoids, (117) and (118), having the isosativane skeleton have also been identified as metabolites of H. sativum.5 The structures assigned to these compounds are based on chemical correlation with cis-sativenediol (111) (cf. Scheme 16) and it is reasonable to... 

The key step in a reported laboratory synthesis of sativene, a hydrocarbon isolated from the mold Helminthosporium sativum, involves the following base treatment of a keto tosylate. What kind of reaction is occurring How would you complete the synthesis ... 

One of the most significant findings this year has been the isolation and identification of (—)-helminthogermacrene (431) from Helminthosporium sativum.209... 

Helminthosporal (5.50) and helminthosporol (5.51) were first isolated from Helminthosporium sativum, now known as Bipolaris sorokianum. Their structures were established by de Mayo in 1962 and confirmed by synthesis by Corey in 1963. The structures were established at a time when NMR spectroscopy... 

In 1974 Marumo and coworkers synthesized the enantiomers of JH II by microbial asymmetric hydrolysis of the epoxy ring of ( )-JH II (prepared by Mori) with a fungus Helminthosporium sativum 23 The hydrolysed diol was converted to (+)-JH II, while the epoxide remained intact was (—)-JH II. Their enantiomeric purities, however, were rather low (66-73% ee), and no definite biological data could be obtained. 

Trichothecin is effective against several fungi, for example root rot of cereals (Helminthosporium sativum), loose smut of wheat (Ustilago tritici), diseases of sour cherry and cherry (Voros, 1955), fusarium wilt of Pinaceae (Belimova and Lopatin, 1963) and powdery mildew of tobacco (Manucharjan, 1964). Its most promising practical applications are the control Verticillium wilt of cotton and of the fusarium diseases of field crops (Askarova and Joffe, 1962 Bunina, 1960 1963). 

Microbial oxidation of (-i-)-bornyl acetate (to 5-exo- and 5-endo-hydroxy-borneol) using Helminthosporium sativum is more efficient and regiospecific than that reported previously (Vol. 8, p. 51) with the enantiomer, in contrast to the conversion of (+)- and (-)-bornyl acetate, using Fusarium culmorum, into 5-exo-hydroxybornyl acetate. 

The cis-sativenediol (118) is a metabolite that was isolated from the fungus Helminthosporium sativum [48], Its structure was independently determined by Narumo [49] and Arigoni [50]. The cis-sativenediol (118) which possesses gibberelin-like plant growth promoter activity has been synthesized by Piers [51], McMurry [52] and Matsumoto [53]. The synthesis of cis-sativenediol by McMurry [52] utilizes the Wieland-Miescher ketone (1). The synthetic route is described in "Fig (10)". 

CijHjjOj, Mr 234.34, mp. 56-59X, [a]p -49° (CHCI3) a toxic sesquiterpene dialdehyde from phy-topathogenic fungi, mainly Cochliobolus sativus and its asexual form, Helminthosporium sativum (Bipola-ris sorokiniana) both are major pests for cereal crops. The reduced form, helminthosporol, is a natural plant growth regulator. 

Secolongifolene diol is one of the metabolites of the fungus Helminthosporium sativum (725). Recently, a simple synthesis of its optical antipode (193) has been achieved by exploiting the electrophilic addition-fragmentation reaction (726) of homoallylic alcohols. The homoallylic alcohol (191), which can be obtained from longicyclene (44) by cyclo-... 

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