Vanillin, a potential agent for the treatment of sickle cell anemia
DJ Abraham, AS Mehanna, FC Wireko, J Whitney, RP Thomas and EP Orringer
Department of Medicinal Chemistry, Medical College of Virginia/Virginia
Commonwealth University, Richmond 23298-0581.
Vanillin, a food additive, has been evaluated as a potential agent to treat
sickle cell anemia. Earlier studies indicated that vanillin had moderate
antisickling activity when compared with other aldehydes. We have
determined by high performance liquid chromatography that vanillin reacts
covalently with sickle hemoglobin (HbS) both in solution and in intact red
blood cells. Hemoscan oxygen equilibrium curves show a dose- dependent left
shift, particularly at low oxygen tensions. Rheologic evaluation (pO2 scan
Ektacytometry) of vanillin-reacted HbS erythrocytes shows a dose-dependent
inhibition of deoxygenation-induced cell sickling. Ektacytometry also
suggests that vanillin may have a direct inhibitory effect on HbS polymer
formation. Vanillin has no adverse effects on cell ion or water content.
X-ray crystallographic studies with deoxyhemoglobin (HbA)-vanillin
demonstrate that vanillin binds near His 103 alpha, Cys 104 alpha, and Gln
131 beta in the central water cavity. A secondary binding site is located
between His 116 beta and His 117 beta. His 116 beta has been implicated as
a polymer contact residue. Oxygen equilibrium, ektacytometry, and x-ray
studies indicate that vanillin may be acting to decrease HbS polymerization
by a dual mechanism of action; allosteric modulation to a high-affinity HbS
molecule and by stereospecific inhibition of T state HbS polymerization.
Because vanillin is a food additive on the GRAS (generally regarded as
safe) list, and because it has little or no adverse effects at high dosages
in animals, vanillin is a candidate for further evaluation as an agent for
the treatment of sickle cell disease.
Volume 77,
Issue 6,
pp. 1334-1341,
03/15/1991
Copyright © 1991 by The American Society of Hematology