In vitro erythrocytic membrane effects of dibenzyl trisulfide, a secondary metabolite of Petiveria alliacea

SG1002 and Catenated Divalent Organic Sulfur Compounds as Promising Hydrogen Sulfide Prodrugs

Significance: Sulfur has a critical role in protein structure/function and redox status/signaling in all living organisms. Although hydrogen sulfide (H2S) and sulfane sulfur (SS) are now recognized as central players in physiology and pathophysiology, the full scope and depth of sulfur metabolome's impact on human health and healthy longevity has been vastly underestimated and is only starting to be grasped. Since many pathological conditions have been related to abnormally low levels of H2S/SS in blood and/or tissues, and are amenable to treatment by H2S supplementation, development of safe and efficacious H2S donors deserves to be undertaken with a sense of urgency; these prodrugs also hold the promise of becoming widely used for disease prevention and as antiaging agents. Recent Advances: Supramolecular tuning of the properties of well-known molecules comprising chains of sulfur atoms (diallyl trisulfide [DATS], S8) was shown to lead to improved donors such as DATS-loaded polymeric nanoparticles and SG1002. Encouraging results in animal models have been obtained with SG1002 in heart failure, atherosclerosis, ischemic damage, and Duchenne muscular dystrophy; with TC-2153 in Alzheimer's disease, schizophrenia, age-related memory decline, fragile X syndrome, and cocaine addiction; and with DATS in brain, colon, gastric, and breast cancer. Critical Issues: Mode-of-action studies on allyl polysulfides, benzyl polysulfides, ajoene, and 12 ring-substituted organic disulfides and thiosulfonates led several groups of researchers to conclude that the anticancer effect of these compounds is not mediated by H2S and is only modulated by reactive oxygen species, and that their central model of action is selective protein S-thiolation. Future Directions: SG1002 is likely to emerge as the H2S donor of choice for acquiring knowledge on this gasotransmitter's effects in animal models, on account of its unique ability to efficiently generate H2S without byproducts and in a slow and sustained mode that is dose independent and enzyme independent. Efficient tuning of H2S donation characteristics of DATS, dibenzyl trisulfide, and other hydrophobic H2S prodrugs for both oral and parenteral administration will be achieved not only by conventional structural modification of a lead molecule but also through the new "supramolecular tuning" paradigm.

In vitro effect of dibenzyl trisulfide on the p50 of the oxygen haemoglobin dissociation curve

OBJECTIVES

Dibenzyl trisulfide (DTS) has been reported to have cytotoxic and anti-inflammatory effects. It also affects erythrocyte deformability. We investigated the effects of DTS on the p50 of the oxygen haemoglobin dissociation curve.

METHODS

Blood samples from 10 healthy male volunteers with normal haemoglobin AA were exposed to 50, 100, 200 and 400 ng/mL, respectively, of DTS. A hemox-analyzer was used to obtain the p50 values.

RESULTS

The mean p50 value for the control samples was 25.89 ± 2.18 mm Hg. The values for the samples exposed to 50, 100, 200 and 400 ng/mL were 23.53 ± 1.81 mm Hg, 22.62 ± 1.61 mm Hg, 21.88 ± 1.67 mm Hg and 21.68 ± 1.88 mm Hg, respectively.

CONCLUSIONS

DTS caused a significant (p<0.001) reduction in p50 values indicating a shift of the oxygen- haemoglobin dissociation curve to the left in all the samples compared with control, suggesting that the administration of DTS could result in decrease in oxygen supply to tissues.

Erythrocyte Aggregation and Blood Viscosity is Similar in Homozygous Sickle Cell Disease Patients with and without Leg Ulcers

Background  There is no consensus regarding the role of red blood cell (RBC) aggregation in the pathogenesis of leg ulcers (LUs) in sickle cell disease (SCD). Objectives  We sought to evaluate whether the cross-sectional determination of RBC aggregation and hematological indices were associated with the presence of LU in homozygous SCD. Methods  Twenty-seven patients with LU and 23 with no history of ulceration were recruited into the study. A laser-assisted rotational red cell analyzer (LoRRca) was used in the determination of the aggregation index (AI), aggregation half-time ( t_1/2 ), and the RBC aggregate strength (AMP). Hematological indices were determined using a CELL-DYN Ruby analyzer. Whole blood viscosity (WBV) and plasma viscosity (PV) were measured using a Vilastic bioprofiler. The data were presented as means ± standard deviation or median, interquartile range. Two-sample t -test was used to test for associations between the AIs, WBV, and PV in patients with and without LU. Statistical significance was taken as p  < 0.05. All analyses were conducted using Stata/SE v . 12.1 (StataCorp, College Station, TX). Results  The AI was comparable in the group with and without ulcers (68.6, 16.7 versus 67.7, 16.9; p  = 0.74); t_1/2 (1.7, 1.3 versus 1.8, 1.3; p  = 0.71); AMP (18.8, 14.5 versus 19.1, 13.3; p  = 0.84), WBV (3.8, 1.2 versus 3.8, 0.7; p  = 0.77); and the PV (1.3, 0.08 versus 1.4, 0.1; p  = 0.31) and were also not statistically different between the groups of participants. Conclusion  RBC aggregation and aggregate strength are not associated with leg ulceration in SCD.