S. M. A. D. ZAYED, I. Y. MOSTAFA, AND M. FARGHALY
180
stanz 252 cal entspricht. Dieser Wert ist mit 1 g
In Wirklichkeit handelt es sich aber nicht um eine
pro 461 cal Gärungswärme bei anaerober Vermeh-
rung von Bäckerhefe zu vergleichen.
einzige Reaktion, vielmehr um einen komplexen
Vorgang. Er besteht darin, daß während der Ver-
brennung ( —128 kcal) von 180 g Glucose für die
Bildung von 1370g lebendiger Zellsubstanz (s.o.)
aus Nährstoff chemische und physikalische Arbeit
geleistet wird. Dies bedeutet, daß 1 g Trockensub-
Der Deutschen Forschungsgemeinschaft
haben wir für die Förderung dieser Arbeit sehr zu
danken.
Preparation and Fungicidal Properties of Some Arylthioalkanoyl-
and (Arylsulphonyl)-aceto-hydroxamic Acids
S. M. A. D. Z a y e d , I. Y. Mostafa, and M. F a r g h a l y
National Research Centre, Dokki, Cairo, and Department of Biology, Atomic Energy Establishment,
U.A.R.
(Z. Naturforschg. 21 b, 180— 182 [1966] ; eingegangen am 18. Oktober 1965)
Some (phenylthio) - and (phenylsulphonyl) acetohydroxamic acids which are substituted in the
para-position of the benzene ring, as well as a- and ß-(phenylthio) propionyl hydroxamic acids have
been synthesized. The compounds were tested for their fungicidal activity against Rhizoctonia solani
and Fusarium sp. The (phenylthio) acetohydroxamic acids investigated were found to possess fungici-
dal properties. Whereas the fungicidal activity of a-(phenylthio) propionyl hydroxamic acid was
comparable with that of (phenylthio) acetohydroxamic acid, the ß-(phenylthio) propionyl hydroxamic
acid was found to be biologically inactive. On the other hand, the corresponding phenylsulphonyl
compounds did not show any fungitoxic activity, and some of them, unexpectedly and strikingly, led
to promotion of mycelial growth of the fungi tested.
have been prepared. These compounds were investi-
gated for their effect on the mycelial growth of
Rhizoctonia solani and Fusarium sp. The p-sub-
stituents in the benzene ring were chlorine, bromine,
methyl and methoxyl groups.
The fungicidal activity of (phenylthio) aceto-
hydroxamic acids has been recently demonstrated
by Z a y e d et al.1. (4,5-Dimethoxy-2-nitrophenylthio)-
(Ia) and (2,5-dimethoxy-4-nitrophenylthio) aceto-
hydroxamic acid (lb) were found to possess signifi-
cant fungicidal properties against the phytopatho-
genic mould Rhizoctonia solani. The inhibition of
the mycelial growth was obviously due to the
hydroxamic acid group, as the corresponding carb-
oxylic acids were inactive. It seemed, therefore, of
interest to extend this work and investigate the
effect of chemical structure on the biological activity
of arylthioalkanoyl hydroxamic acids. These com-
pounds would be expected to possess significant
fungitoxic effects, since the parent arylthioalkanoic
acids are known to inhibit the mycelial growth of
several fungi 2>3.
Experimental
The hydroxamic acids were prepared from the
corresponding methyl esters of (arylthio) acetic acids
by the action of alkaline hydroxylamine in methanol at
40 °C *. They are colourless crystalline substances,
easily soluble in alcohol and in dilute sodium hydroxide
solution. Their aqueous or alcoholic solutions give an
intense violet colour with ferric chloride solution and a
bright green ppt. with copper acetate solution in acetic-
acid. The properties and analytical data of the hydrox-
amic acids are listed in Table I. All compounds were
tested in concentrations of 10-3, 10~4 and 10-5 M.
The biological tests were carried out as described by
Z ayed et al. *. Compounds IIa-e and Ilg—h were tested
as their potassium salts, after, being recrystallised from
90% methanol. The other compounds were investigated
as the free acids, which possessed considerable solu-
bility in water.
In the present work, a number of p-substituted
(phenylthio)- (IIa_e) and (phenylsulphonyl)aceto-
hydroxamic acids (Ilf_j), as well as a-(III) and
ß-(phenylthio) propionyl hydroxamic acids (IV)
1
S. M. A. D. Z a yed , a . F. a bouleZZ, a . M. S alama and W . S.
e l-hamouly, J. Pharmacy Pharmacol. 17, 809 [1965].
3 C. h . F awcett, D. M. S pencer and R. L. w a in , Ann. appl.
Biol. 43, 553 [1955].
2 C. h . F awcett, D. M. S pencer and R. L.
Biol. 45,158 [1957].
w a in , Ann. appl.
Unauthenticated
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