HO........,OH.... OH-'.OH.... OH L A,~H OH

Abstract: The isolation from Casuarina equisetifolia L. (Casuarinaceae) bark of casuarine 1, (1R,2R,3R,6S,7S,7aR)-3-(hydroxymethyl)-l,2,6,7-tetrahydroxypyrrolizidine is reported. Both natural 1and synthetic mono- and bi-cyclic nitrogen analogues of carbohydrates have potential as chemotherapeutic agents, 2 both as free bases 3 and as alkaloidal glycosides.4, 5 Alexine 26 and australine 37 were the first pyrrolizidine alkaloids to be isolated with a carbon substituent a C-3, rather than the more usual C-1 substituents. 8 Further stereoisomers of alexine and the related amino acid 7a-epialexaflorine 4, found in Alexa grandiflora., 9 have also been isolated The alexines and castanospermine 5 occur in all species of the genus Alexa and also in the related species Castanospermum australe; 5 is a potent glucosidase inhibitor 10 some of its derivatives may have potential for the treatment ofpatients with HIV. 11 Because of the reported antiviral properties of some of the alexines 1Z13 and other potential applications, 14 there has been considerable interest in the synthesis of the natural products and of synthetic analogues. 1