Biological Evaluation of (Mbberellins 519 



The ;7-alkyl esters (methyl to /?-decyl) of gibberellin A3 were not 

 active in promoting growth of bean epicotyls or tomato ovaries. Let- 

 tuce seed germination, however, was enhanced by the methyl, ethyl, 

 n-propyl, ?2-butyl, n-amyl, 72-hexyl, and n-heptyl gibberellates. 



The presence or absence of biological activity of several other de- 

 rivatives of gibberellins Aj, A3, and A4 showed that intact A and D 

 rings and a reactive carboxyl group were essential. 



As of publication date, five additional gibberellins (A5, A„, A-, A,, and A,) have 

 been isolated and characterized — A-„ Ae, and A, from immature seeds of the 'Scarlet 

 Runner' bean and A.- and A9 froin the fungus GibbereUa fujikuroi. No data are 

 available on their comparative biological activity. Also, a revised structure for A;, 

 has been proposed in -which the lactone of ring A is attached to carbons 1 and 1 1 . 

 (See Cross et al. Proc. Chem. Soc. p. 302. 1959.) 



LITERATURE CITED 



1. Brian, P. W. Effects of gibberellins on plant growth and development. Biol. 

 Rev. 34: 37-84. 1959. 



2. , Grove, J. F., Hemming, H. G., MulhoUand, T. P. C., and Radley M. 



Gibberellic acid, part VI. The biological activity of a/Zogibberic acid and its 

 identity with gibberellin B. Plant Physiol. 33: 329-333. 1958. 



3. Bukovac, M. J., and Wittwer, S. H. Comparative biological effectiveness of the 

 gibberellins. Nature. 181: 1484. 1958. 



4. , Wittwer, S. H., and Gaur, B. K. Some factors influencing the response 



of the bean {Phaseolus vulgaris L.) to gibberellin. Mich. Agr. Exp. Sta. 

 Quart. Bui. 41: 296-302. 1958. 



5. Cathey, H. M. Growth evaluations of four gibberellins and several derivatives. 

 Plant Physiol. 33 (suppl.): xliii. 1958. 



6. Cross, B. E. Gibberellic acid. Part I. Jour. Chem. Soc. pp. 4670-1676. 1954. 



7. Curtis, P. J., and Cross, B. E. Gibberellic acid. A new metabolite from the 

 culture filtrates of GibbereUa fujikuroi. Chem. and Ind. (London) p. 1066. 

 1954. 



8. Gerzon, K., Bird, H. L., Jr., and Woolf, D. O., Jr. Gibberellenic acid, a by- 

 product of gibberellic acid fermentation. Experientia. 13: 487-489. 1957. 



9. Imamura, S., Ogawa, Y., Okuda, M., and Hirono, Y. Bioassay of gibberellin 

 with a dwarf mutant of Japanese morning glory, Pharbitis Nil Chois. Abst. 

 2nd Meeting Japan Gibberellin Res. Assoc. Tokyo, Japan, p. 69. 1958. 



10. Imperial Chemicals Industries Limited. New organic compounds. Accepted 

 patent application No. 10190-1955. Commonwealth of Australia. 1955. 



11. MacMillan, J., and Suter, P. J. The occurrence of gibberellin Ai in higher 

 plants: isolation from the seed of runner bean (Phaseolus multiflorus). Natur- 

 wis. 45: 46. 1958. 



12. Phinney, B. O., and Neely, P. M. Differential biological properties of gib- 

 berellin-like factors isolated from beans and peas. Plant Physiol. 33 (suppl.): 

 xxxviii. 1958. 



13. Sell, H. M., Rafos, S., Bukovac, M. J., and Wittwer, S. H. Characterization of 

 several n-alkyl esters of gibberellin A3 and their comparative biological activity. 

 Jour. Org. Chem. 24: 1822, 1823. 1959. 



14. Stodola, F. H., Raper, K. B., Fennell, D. I., Conway, H. F., Sohns, V. E., Lang- 

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