Using the natural rotenoids rotenone, amorphigenin, deguelin, rotenonic acid, dalpanol and munduserone as examples, their phytochemical biosynthesis has been examined in
Derris elliptica, Amorpha ...fruticosa and
Tephrosia vogelii. The rotenoids are advanced isoflavonoids, and construction of their angular A⧹B⧹C⧹D-ring systems has been studied experimentally starting out from simple primary metabolites and passing through a series of mainly oxidative phases. The oxidative reactions of rot-2′-enonic acid which biosynthetically form the E-rings of rotenone, amorphigenin, dalpanol and deguelin have been studied in both chemical and stereochemical detail using seedling preparations and the enzyme deguelin cyclase. This investigation has extensively employed substrates isotopically labelled with
14C,
13C,
2H and
3H and, particularly in connection with E-ring biosynthesis, required new approaches to the demanding chemical and stereochemical requirements of the experimentation.
Ralph Alexander Raphael was born in Croydon on 1 January 1921, the eldest child of Jack Raphael and his wife Lily (née Woolf); there were also three daughters. The paternal family hailed from Poland; ...Ralph's grandfather, Solomon Raphael, was born in Klatchova. At the age of sixteen, in 1864, he had emigrated via Hamburg and Grimsby to avoid being pressed into the Russian army, and then proceeded to London. There, in 1875, he married Sarah Berg, also from Poland, and they formed a well-balanced pair, as a remarkable photograph reveals. Solomon was a fiery-tempered, soft-hearted and very orthodox Jew: Sarah was calm, efficient, humorous, and a legendary cook. Ralph's father, Jack, was one of their thirteen children.
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