Hypotaurine

Placenta. 2015 Jun;36(6):693-8.

Protective effect of hypotaurine against oxidative stress-induced cytotoxicity in rat placental trophoblasts.[Pubmed: 25801460]

Hypotaurine is a precursor of taurine and an antioxidant, and is concentrated in fetal plasma compared to maternal plasma. Hypotaurine is significantly decreased in fetal plasma of ezrin (Vil2) knock-out mice, and fetuses show intrauterine growth retardation. The aim of this study was to characterize the mechanism through which cellular Hypotaurine level is maintained in placental trophoblasts, and the effect of Hypotaurine on oxidative stress induced by hydrogen peroxide (H2O2).
METHODS AND RESULTS:
Hypotaurine transfer from extracellular fluid and antioxidant effect of Hypotaurine were analyzed in rat placental trophoblast TR-TBT 18d-1 cells. We found that Hypotaurine is concentrated into rat placental trophoblast TR-TBT 18d-1 cells, and the level of Hypotaurine was markedly reduced by culture in medium supplemented with dialyzed fetal bovine serum (FBS) instead of normal FBS. The Hypotaurine level recovered almost completely when Hypotaurine was added to the culture medium, indicating that intracellular Hypotaurine is predominantly supplied by transport across the plasma membrane from extracellular fluid rather than by biosynthesis. Hypotaurine showed a cytoprotective effect against H2O2-induced oxidative damage in TR-TBT 18d-1 cells. Hypotaurine treatment of TR-TBT 18d-1 cells increased antioxidant capacity against hydroxyl radical and peroxyl radical. The concentration of intracellular hydroxyl radical induced by H2O2 in TR-TBT 18d-1 cells was significantly reduced by Hypotaurine treatment.
CONCLUSIONS:
These results indicate that intracellular Hypotaurine is mainly supplied to placental trophoblasts by transfer from extracellular fluid across the plasma membrane, and may play a role in cell protection by scavenging reactive oxygen species.

Amino Acids. 2015 Jun;47(6):1215-23.

Propargylglycine inhibits hypotaurine/taurine synthesis and elevates cystathionine and homocysteine concentrations in primary mouse hepatocytes.[Pubmed: 25772816 ]

Hypotaurine and cysteine sulfinic acid are known to be readily oxidized to the respective sulfonates, taurine and cysteic acid, by several oxidative agents that may be present in biological systems.
METHODS AND RESULTS:
In this work, the relevance of both the carbonate anion and nitrogen dioxide radicals in the oxidation of Hypotaurine and cysteine sulfinic acid has been explored by the peroxidase activity of Cu,Zn superoxide dismutase (SOD) and by pulse radiolysis. The extent of sulfinate oxidation induced by the system SOD/H2O2 in the presence of bicarbonate (CO3(•-) generation), or nitrite ((•)NO2 generation) has been evaluated. Hypotaurine is efficiently oxidized by the carbonate radical anion generated by the peroxidase activity of Cu,Zn SOD. Pulse radiolysis studies have shown that the carbonate radical anion reacts with Hypotaurine more rapidly (k = 1.1 × 10(9) M(-1)s(-1)) than nitrogen dioxide (k = 1.6 × 10(7) M(-1)s(-1)). Regarding cysteine sulfinic acid, it is less reactive with the carbonate radical anion (k = 5.5 × 10(7) M(-1)s(-1)) than Hypotaurine.
CONCLUSIONS:
The protective effect exerted by Hypotaurine and cysteine sulfinate on the carbonate radical anion-mediated tyrosine dimerization indicates that both sulfinates have scavenging activity towards the carbonate radical anion.

Free Radic Res. 2014 Nov;48(11):1300-10.

Reactivity of hypotaurine and cysteine sulfinic acid toward carbonate radical anion and nitrogen dioxide as explored by the peroxidase activity of Cu,Zn superoxide dismutase and by pulse radiolysis.[Pubmed: 25156684 ]

Hypotaurine and cysteine sulfinic acid are known to be readily oxidized to the respective sulfonates, taurine and cysteic acid, by several oxidative agents that may be present in biological systems.
METHODS AND RESULTS:
In this work, the relevance of both the carbonate anion and nitrogen dioxide radicals in the oxidation of Hypotaurine and cysteine sulfinic acid has been explored by the peroxidase activity of Cu,Zn superoxide dismutase (SOD) and by pulse radiolysis. The extent of sulfinate oxidation induced by the system SOD/H2O2 in the presence of bicarbonate (CO3(•-) generation), or nitrite ((•)NO2 generation) has been evaluated. Hypotaurine is efficiently oxidized by the carbonate radical anion generated by the peroxidase activity of Cu,Zn SOD. Pulse radiolysis studies have shown that the carbonate radical anion reacts with Hypotaurine more rapidly (k = 1.1 × 10(9) M(-1)s(-1)) than nitrogen dioxide (k = 1.6 × 10(7) M(-1)s(-1)). Regarding cysteine sulfinic acid, it is less reactive with the carbonate radical anion (k = 5.5 × 10(7) M(-1)s(-1)) than Hypotaurine. It has also been observed that the one-electron transfer oxidation of both sulfinates by the radicals is accompanied by the generation of transient sulfonyl radicals (RSO2(•)).
CONCLUSIONS:
Considering that the carbonate radical anion could be formed in vivo at high level from bicarbonate, this radical can be included in the oxidants capable of performing the last metabolic step of taurine biosynthesis. Moreover, the protective effect exerted by Hypotaurine and cysteine sulfinate on the carbonate radical anion-mediated tyrosine dimerization indicates that both sulfinates have scavenging activity towards the carbonate radical anion. However, the formation of transient reactive intermediates during sulfinate oxidation by carbonate anion and nitrogen dioxide radical may at the same time promote oxidative reactions.

Cryobiology. 2013 Aug;67(1):34-9.

Raffinose and hypotaurine improve the post-thawed Merino ram sperm parameters.[Pubmed: 23644017]

The aim of this study was to determine the effects of raffinose and Hypotaurine on sperm parameters after the freeze-thawing of Merino ram sperm.
METHODS AND RESULTS:
Raffinose and Hypotaurine led to higher viability (40.8 ± 4.68%, 40.8 ± 4.7%), high sperm mitochondrial activity (29.5 ± 5.4%, 27.3 ± 4.9%) and acrosome integrity (50.8 ± 8.1, 50.7 ± 4.4) percentages, compared to control groups (31.5 ± 3.5%, 9.5 ± 8.2%, 42.8 ± 7.3%, P<0.05). H+R group only led to high sperm mitochondrial activity when compared to control group. In the comet test, raffinose and Hypotaurine resulted in lower sperm with damaged DNA (6.2% and 3.9%) than that of control (9.1%), reducing the DNA damage. For TUNEL assay, The TUNEL-positive cell was distinguished by distinct nuclear staining. Raffinose and H+R groups resulted in lower sperm with TUNEL-positive cell (1.5 ± 1.2% and 2.1 ± 0.9%) than that of control (4.9 ± 2.5%) (P<0.05).
CONCLUSIONS:
In conclusion, findings of this study showed that raffinose and Hypotaurine supplementation in semen extenders provided a better protection of sperm parameters against cryopreservation injury, in comparison to the control groups.

Amino Acids. 2012 Jul;43(1):397-404.

Antinociceptive effect of intrathecal administration of hypotaurine in rat models of inflammatory and neuropathic pain.[Pubmed: 21971909]

Hypotaurine is an intermediate in taurine biosynthesis from cysteine in astrocytes. Although Hypotaurine functions as an antioxidant and organic osmolyte, its physiological role in the central nervous system remains unclear. This study used behavioral assessments to determine whether Hypotaurine influenced nociceptive transmission in acute, inflammatory, and neuropathic pain.
METHODS AND RESULTS:
The tail flick, paw pressure, and formalin tests were performed in male Sprague-Dawley rats to examine the effects of the intrathecal administration of Hypotaurine (100, 200, 400, 600 μg) on thermal, mechanical, and chemical nociception. Chronic constriction injury (CCI) to the sciatic nerve was induced in the rats, and the electronic von Frey test and plantar test were performed to assess the effects on neuropathic pain. To determine which neurotransmitter pathway(s) was involved in the action of Hypotaurine, in this study, we examined how the antagonists of spinal pain processing receptors altered the effect of 600 μg Hypotaurine. To explore whether Hypotaurine affected motor performance, the Rotarod test was conducted. Hypotaurine had antinociceptive effects on thermal, mechanical, and chemical nociception in the spinal cord. In CCI rats, Hypotaurine alleviated mechanical allodynia and thermal hyperalgesia. These effects were reversed completely by pretreatment with an intrathecal injection of strychnine, a glycine receptor antagonist. Conversely, Hypotaurine did not affect motor performance.
CONCLUSIONS:
This study demonstrated that intrathecal Hypotaurine suppressed acute, inflammatory, and neuropathic pain. Hypotaurine may regulate nociceptive transmission physiologically by activating glycinergic neurons in the spinal cord, and it is a promising candidate for treating various pain states.