A number of interesting compounds were identified in all extracts displaying antigiardial activity that were also absent in the inactive hexane extract. Purine (Fig. 4a) was putatively identified in all of the inhibitory extracts. Numerous studies have reported that Giardia lamblia are unable to synthesise their own purine or pyrimidine nucleotides. Instead, G.lamblia are reliant on salvage pathways to supply them with nucleotides for nucleic acid synthesis. These studies also reported that G. lamblia are incapable of interconversion between purine nucleotides. Furthermore, purine analogues have been reported to inhibit the growth of G.lamblia and have been proposed as potential chemotherapeutic agents to treat giardisis.It is therefore possible that the G.duodenalis examined in our studies may incorporate the purine analogue identified in the inhibitory extracts into their nucleic acids during replication, causing DNA mismatches and blocking giardial proliferation