Abstract :
[en] Analytical aspects of marinobufagenin and its applications in the diagnostic of preeclampsia
C. Lenaerts1, B. Blankert1
1 Laboratory of Pharmaceutical Analysis, Faculty of medicine and pharmacy, University of Mons, place du parc 20, 7000 Mons, Belgium. E-mail: charline.lenaerts@umons.ac.be
The bufadienolides are a group of steroid compouds containing a 6-membered lactone ring in the C17 position, and that belong to the cardiac glycosides class like the cardenolides. Bufadienolides are present in humans as well as in some plants and animals, but the principal source for these compounds is the skin and venom of some toad species, notably Bufo Marinus species of which the major cardiotonic steroid venom component is marinobufagenin.
Marinobufagenin (MBG), an endogenous mammalian cardiotonic bufadienolide with vasoconstrictive activities, is a selective inhibitor of the a1 subunit of Na+,K+-ATPase making it implicated in series of pathophysiological circumstances and leading to hypertension and natriuresis. Indeed, increased plasma MBG has been observed in dogs[1], rats [2] and patients [3] presenting volume-expansion, especially when it is associated with fluid retention, like in the preeclampsia syndrome.
Preeclampsia (PE) is a pregnancy-related disorder that consists in the development of hypertension and proteinuria after 20 weeks of gestation. In an animal model of PE, some authors have demonstrated that the urinary excretion of the circulating cardiotonic steroid MBG is elevated prior the development of hypertension and proteinuria [4]. The enhanced production of MBG in preeclampsia compared to normal pregnancy has even been confirmed in human patients [5] [6], leading us to consider MBG as a biomarker for PE.
This consideration implicates an efficient, accuracy and sensitive analytical method of MBG plasma levels in order to further investigate the implications of MBG in volume expansion-mediated hypertensive states, and to establish a diagnosis for preeclampsia.
Given that no standard compound of MBG already exists, we have developed a successful extraction method of MBG from the crystallized venom of Bufo Marinus.
In order to quantify MBG levels, a pre-extraction step from rat and human plasma has been carried out through a solid phase extraction (SPE) HLB (hydrophilic lipophilic balanced) cartridge with an extraction yield of 88%.
The reversed-phase LC-UV method to allow quantifications of MBG in the nanomolar range is under development.
References:
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2. Bagrov, A. Y., et al., Clinical and Experimental Hypertension, 1998. 20(5-6): p. 581-591.
3. Bagrov, A.Y., et al., Hypertension, 1995. 26(5): p. 781-788.
4. Vu, H.V., et al., American Journal of Nephrology, 2005. 25(5): p. 520-528.
5. Agunanne, E., et al., Amer J Perinatol, 2011. 28(EFirst): p. 509-514.
6. Lopatin, D.A., et al., Journal of Hypertension, 1999. 17(8): p. 1179-1187.
