Rayan P1,2,* and McDonnell PA1
1School of Natural Sciences, Griffith University, Brisbane, Australia.
2Environmental Futures Research Institute, Griffith University, Brisbane, Australia.
Background: Studies have confirmed that dodecanoic acid (DA; C: 12; common name: lauric acid) has anti-giardial properties against G. duodenalis trophozoites in vitro with an LD50 concentration comparable to that of metronidazole, the drug of choice in the treatment of giardiasis. DA appears to induce trophozoite death by accumulating within the parasite cytoplasm resulting in rupture of the trophozoite cell membrane. In this study, the dietary supplementation of dodecanoic acid (and other compounds containing DA) to maternal mice was examined to determine whether such dietary changes could enhance resistance to G.duodenalis infection in suckling neonatal pups. Materials and Methods: Each maternal mouse was offered a dietary supplement of either DA (mean intake of 0.81 and 0.3 gm/day), coconut oil (mean intake of 0.86 gm of dodecanoic acid/day) or Monolaurin™(mean intake of 1.18 gm/day), whereas the negative control maternal mice received normal feed pellets 20 gm/day containing no DA or DA derivatives (no supplementation) for 8 days (3 days ante-partum and then 5 days post-partum).At day 3 of age, all pups from the litters were then orogastrically inoculated with 1×105 G. duodenalis trophozoites. On day 6 post-inoculation, each pup was euthanized and the entire intestinal tract from the pyloric sphincter to the rectum was surgically removed from each necropsied animal. The mean counts of total parasite burdens [trophozoite and cyst] were calculated on the gut washes of each animal. Results: In Trial 1, the pups of the maternal mouse that received a mean intake of 0.81 g ± 0.58 per day of dodecanoic acid were clear of any G. duodenalis trophozoites or cysts. In contrast, the control pups had a mean total parasite burden of 6.2 ± 7.6 x 105. In Trial 2, the pups of the maternal mouse that received a mean intake of 0.30 ± 0.05 g per day of dodecanoic acid were also clear of any G. duodenalis trophozoites or cysts, however the control pups had a mean total parasite burden of 8.6 ± 3.5 x 105. In Trial 3, the pups of the maternal mouse that received a mean intake of 1.72 g ± 0.42 per coconut oil [which gave a calculated average daily intake of 0.86 ± 0.21 g of dodecanoic acid] demonstrated a mean total parasite burden of 5.1 ± 6.3 x 105, (both trophozoites and cysts), whereas the control pups had a mean total parasite burden of 18.2 ± 11.07 x 105. In Trial 4, all pups of the maternal mouse that received a daily mean intake of 1.18g ± 0.32 per day of Monolaurin (dodecanoic monoglyceride) had a mean total of 7.0 ± 4.03 x 105 parasite burden (both trophozoites and cysts) which was similar to the control pups that possessed a mean total parasite burden of 7.75 ± 6.36 x 105. Conclusion: These studies have opened fresh avenues for development of natural drug therapy in which food supplementation may augment, or even replace, some of the standard chemotherapeutic agents presently employed in the treatme of giardiasis and possibly other infectious protozoal intestinal diseases.
Keywords: Dodecanoic Acid, Giardia duodenalis and in vivo trials, metronidazole, coconut oil, lauric acid.