Comment: 7a-Acetoxydihydronomilin and mexicanolide: limonoids from Xylocarpus gralzatum (Koenig)

ANG S. NG Department of Chemistry, Natzyang Unicersity, Singapore 22

AND

ALEX G. FALLIS Department of Chetnistry, Menlorial Uni~.rrsit). of Ner+fiundland, St . John's, N f l t f . , Cannda A l B 3x7

Received September 7. 1979

ANG S. NG and ALEX G. FALLIS. Can. J. Chem. 57,3088 (1979). A recent report by the present authors (Can. J. Chem. 56, 1020 (1978)) of the isolation of

7a-acetoxydihydronomilin from the seeds of Uncaria gambia (Roxb.) contains a taxonomic error. The seeds were in fact from Xylocarpus granatum (Koenig).

ANG S. NG et ALEX G. FALLIS. Can. J. Chem. 57,3088 (1979). Une erreur taxonomique s'est glissee dans notre recente publication concernant l'isolation

de la 7cc-acCtoxydihydronomiline (Can. J. Chem. 56, 1020 (1978)). Le produit est extrait de semence de Xylocarpus granatum (Koenig) et non de semence de Uncaria gambia (Roxb.).

[Traduit par le journal]

In Malaysia extracts of at least two different plant species are used as tanning agents called Gambir. We recently reported (la, see also ref. I b) the isolation and structure elucidation of 7u-acetoxydihydronomilin (1) from the seeds of one such species Uncaria gambia (Roxb.), a member of the Rubiaceae family.' This appeared to be the first example of a limonoid from Rubiaceae and as such, was unexpected as previously limonoids had only been found in the related families Rutaceae, Meliaceae, and Cneora- ceae.

We wish to point out that the seeds we extracted were misidentified and are in fact from Xylocarpus granatum (Koenig), a mangrove of the Meliaceae family,' an assignment in keeping with their terpene content. In addition to 1 we have isolated (2) the known limonoid mexicanolide (2) (3) from these seeds. Earlier Okorie and Taylor (4) identified the structurally related compounds gedunin (3), xylo- carpin (4), and the corresponding A8 olefin from the petroleum ether extracts of Xylocarpus granatum (Koenig) seed. Subsequently, examination of unripe seed (originally reported (5) to be Xylocarpus molluscensis but established since (6) as Xylocarpus

17cc-Acetoxydihydronomilin has also been isolated from Cneorum tricoccon (Linne).

ZThe fruit of X. granatunz are large, round, and often referred to as "cannon balls." In our sample the largest was similar in size to a soccer ball. One or more tightly packed seeds are contained within this shell or husk. These seeds are easily crushed when fresh but harden and darken upon standing. The dry seeds have a wrinkled appearance and resemble dried prunes in size.

granatum (Koenig)) afforded the bitter principle xylomollin as unusual monoterpenoid secoiridoid possessing hemiacetal and acetal functions.

Acknowledgements We are grateful to Professor D. A. M. Taylor for

drawing this taxonomic error to our attention and for a fruitful exchange of correspondence. In addition the National Research Council of Canada is thanked for financial support.

0008-4042/79/233088-02$0 1 .00/0 01979 National Research Council of Canada/Conseil national de recherches du Canada

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1. (a) F. R. AHMED, A. S. NG. and A. G. FALLIS. Can. J . ADESOGAN and D. A. H. TAYLOR. J . Chem. Soc. C, 1974 Chem. 56, 1020 (1978); (b ) B. EPE and A. M O ~ D O N . Tet- (1968). rahedron Lett. 2015 (1979). 4. D. A. OKORIE and D. A. H. TAYLOR. J . Chem. Soc. C, 21 1

2. A. S. NG and A. G. FALLIS. Occasional Paper No. 40. (1970). Faculty of Graduate Studies, Nanyang University. Singa- 5. I. KUBO, I. MIURA, and K. NAKAKISHI. J . Am. Chem. Soc. pore. September, 1978. 98,6704 (1976).

3. J . D. C O N ~ O L L Y . R. MCCRINDLE, and K. H. OVER-ION. 6. D. A. H. TAYLOR. Personal communication. Tetrahedron. 24, 1489 (1968); 24, 1497 (1968); E. K.

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