Eg Valentin F. Cracan (@VFCracan) / X
https://cracanlab.com/
Um this WAS what jesse pogalnick (and even gladyshev) used to be into
DJ-1 does not have one clean enzymatic job like “breaks down dopamine.” It acts more like a redox-sensitive molecular switch/protector .
The central event is:
[ \boxed{\mathrm{Cys106\ gets\ oxidized}} ]
When ROS or electrophilic stress rises, DJ-1’s Cys106 changes oxidation state. That changes DJ-1’s structure, localization, and which proteins it interacts with.
The downstream consequences are roughly:
- Mitochondria: helps preserve mitochondrial respiration, membrane potential, and quality control.
- Antioxidant response: promotes/stabilizes stress-response pathways including NRF2-related signaling.
- Cell-death signaling: restrains some pro-apoptotic stress pathways such as ASK1.
- Protein protection/chaperone-like effects: helps limit aggregation/damage under oxidative stress.
- Reactive dopamine chemistry: DJ-1 cysteines can be modified by dopamine quinones, so it directly encounters the kind of electrophilic chemistry produced by oxidized dopamine.
So the most concrete cartoon is:
[ \text{oxidative/electrophilic stress} \rightarrow \boxed{\text{DJ-1 oxidation}} \rightarrow \begin{cases} \text{mitochondrial protection}\ \text{antioxidant signaling}\ \text{less stress-induced cell death} \end{cases} ]
And if PARK7/DJ-1 is lost , cells become much more vulnerable to oxidative and mitochondrial stress. That is why biallelic PARK7 loss can cause early-onset parkinsonism.
The part worth memorizing is:
[ \boxed{\text{DJ-1 = Cys106 redox sensor that helps mitochondria survive oxidative stress}} ]
not “DJ-1 is a dopamine receptor” or “DJ-1 metabolizes dopamine.”
Yes. I’d split mixed tocopherols and mixed tocotrienols into separate rows because they behave similarly but not identically.
Compound Main redox action PRDX / H₂O₂ signaling KEAP1→NRF2 GSH/GRX/Trx lipid-peroxide signaling mitochondrial redox Vitamin C aqueous radical reductant ↔ / mild ↓ mild indirect ↓ ↔ indirect ↓ mild ↓ α-Tocopherol lipid-radical chain breaker ↔ indirect ↓ ↔ ↓↓↓ membrane ↓ Mixed tocopherols broader vitamin-E family; lipid radical + reactive nitrogen/electrophile trapping ↔ ± indirect ↔ ↓↓↓ membrane ↓ Mixed tocotrienols vitamin-E family with unsaturated tail; rapid membrane distribution, lipid-chain termination ↔ / mild ↓ indirect ± / often ↑ NRF2 experimentally indirect ↓↓↓ ↓ to ↓↓ NAC cysteine/GSH precursor, thiol reductant ↓ indirectly ± ↓↓↓ / strong shift ↓ ↓ GSH GPX substrate + thiol redox currency ↓ via GPX indirect ↓ central system ↓ via GPX4 ↓ Melatonin mitochondrial/redox modulator + scavenging ↓ often ↑ ↑ defenses ↓ ↓↓ Sulforaphane electrophile / hormetic signal later ↓ ↑↑↑ directly later ↑ later ↓ indirect Astaxanthin membrane carotenoid antioxidant little direct often ↑ indirect ↓↓ ↓ CoQ10 / ubiquinol ETC carrier + lipid antioxidant indirect weak/variable indirect ↓↓ central The useful distinction inside mixed tocopherols is that α-tocopherol is the classic lipid-peroxyl-radical chain breaker, while γ-tocopherol and related forms can handle some chemistry α-tocopherol is less good at, particularly reactive nitrogen/electrophilic species. So a mixed preparation is chemically broader than pure α-tocopherol.
For tocotrienols, the chromanol “antioxidant head” is basically vitamin-E chemistry, but the tail has three double bonds rather than being saturated. That changes membrane mobility and distribution. Tocotrienols can be very effective at interrupting lipid-peroxidation chains and, in experimental systems, can also activate NRF2 and other adaptive stress pathways. So they are not merely stronger α-tocopherol.
The compact memory map is:
[
\boxed{
\text{tocopherols}
\approx
\text{membrane lipid-peroxidation brakes}
}
]while
[
\boxed{
\text{tocotrienols}
\approx
\text{membrane lipid-peroxidation brakes}
+
\text{some stronger signaling effects}
}
]and neither is particularly good at directly erasing the PRDX-H₂O₂ signaling channel. They mostly operate in the lipid compartment, which is a very different redox universe from NAC/GSH.
Yes. The map gets much clearer if you distinguish what chemical species each “antioxidant” actually intercepts . They are not interchangeable.
Legend: ↓ likely dampens that redox signal, ↑ activates it, ↔ little direct effect, ± context-dependent.
Compound Main redox action PRDX / H₂O₂ signaling KEAP1→NRF2 GSH/GRX/Trx lipid-peroxide signaling mitochondrial redox Vitamin C aqueous radical reductant ↔ / mild ↓ mild indirect ↓ ↔ indirect ↓ mild ↓ Vitamin E lipid-radical chain breaker ↔ indirect ↓ ↔ ↓↓↓ membrane ↓ NAC cysteine/GSH precursor, thiol reductant ↓ indirectly ± ↓↓↓ / shifts strongly ↓ ↓ GSH GPX substrate + thiol redox currency ↓ via GPX indirect ↓ central system ↓ via GPX4 ↓ Melatonin mitochondrial/redox modulator + radical scavenging ↓ often ↑ NRF2 ↑ defenses ↓ ↓↓ Sulforaphane electrophile , not ordinary scavenger later ↓ ↑↑↑ directly later ↑ GSH later ↓ indirect Astaxanthin membrane carotenoid antioxidant little direct often ↑ NRF2 indirect ↓↓ ↓ CoQ10/ubiquinol ETC carrier + membrane antioxidant indirect weak/variable indirect ↓↓ central The individual stories are more interesting than the table.
Vitamin C: much less of an H₂O₂ sponge than people imagine
Ascorbate is excellent against various radicals such as hydroxyl-derived radicals and can contribute to superoxide handling. But mammalian vitamin C reacts very slowly with H₂O₂ compared with peroxiredoxins, catalase and glutathione peroxidases. PubMed Central (PMC)
So:
[ H_2O_2 \xrightarrow{\text{PRDX/GPX}} H_2O ]
dominates enormously over
[ H_2O_2+\text{vitamin C}. ]
That means vitamin C does not automatically erase PRDX-mediated peroxide signaling .
It can, however, reduce upstream or downstream radical chemistry, potentially lowering the amount of oxidative signal that eventually reaches things such as KEAP1, ATM or DJ-1.
There is also the famous flip side: in the presence of accessible Fe/Cu, ascorbate can reduce the metal and promote Fenton chemistry. Under normal physiology free transition-metal availability is tightly restricted, so that doesn’t mean normal dietary vitamin C is generally pro-oxidant. PubMed Central (PMC)
Vitamin E: think membrane firebreak
Vitamin E is much more specialized.
[ L^\bullet + O_2\rightarrow LOO^\bullet ]
normally gives a propagating lipid-peroxidation chain:
[ LOO^\bullet + LH \rightarrow LOOH + L^\bullet. ]
α-Tocopherol intercepts the lipid peroxyl radical and breaks that chain. PubMed
So vitamin E is particularly good at reducing:
[ \boxed{\text{lipid peroxyl radicals}} ]
and downstream electrophiles such as lipid-peroxidation products.
That could indirectly mean less activation of electrophile-sensitive proteins such as KEAP1 and TRPA1.
But vitamin E does not efficiently mop up cellular H₂O₂ . Hence:
[ \boxed{\text{vitamin E is far more relevant to lipid redox signaling than PRDX-H}_2O_2\text{ signaling}.} ]
This is also why vitamin E is connected to ferroptosis , whose defining chemistry is runaway membrane lipid peroxidation. PubMed
NAC: probably the strongest general perturbation of thiol-redox signaling on your list
N-acetylcysteine mainly works by supplying:
[ NAC\rightarrow\text{cysteine}\rightarrow GSH. ]
Increasing GSH supports glutathione peroxidases:
[ 2GSH+H_2O_2 \xrightarrow{GPX} GSSG+2H_2O. ]
Thus NAC can indirectly reduce peroxide availability and alter the
[ GSH/GSSG ]
environment. PubMed Central (PMC)
That means it can affect:
- protein S-glutathionylation
- glutaredoxin signaling
- thioredoxin-linked pathways
- redox-sensitive transcription factors
- downstream H₂O₂-sensitive switches.
So of these compounds, NAC is one of the ones for which “could blunt some physiological redox signaling” is most chemically plausible , particularly when it appreciably alters intracellular thiol status.
But even NAC isn’t:
[ \text{ROS}\rightarrow0. ]
Local PRDX-mediated signaling can survive substantial global reducing capacity.
GSH is different: it’s part of the signaling machinery itself
Calling glutathione merely an antioxidant misses half the story.
It participates in:
[ Protein-SH \rightleftarrows Protein-S-SG. ]
That’s S-glutathionylation .
It can protect a cysteine from irreversible oxidation while simultaneously altering the protein’s function. Glutaredoxins then remove the GSH modification. PubMed Central (PMC)
So:
[ \boxed{ GSH\text{ isn’t just noise suppression; it’s part of the redox signaling language.} } ]
Increasing GSH can therefore change signaling rather than simply suppress it.
And GPX4 uses GSH to eliminate lipid hydroperoxides, making the GSH system central to suppression of lipid-peroxide cascades and ferroptosis.
Melatonin: disproportionately mitochondrial
Melatonin is more complicated because it has both receptor-mediated effects and redox effects.
There is experimental literature supporting:
- mitochondrial accumulation,
- direct scavenging by melatonin and metabolites,
- increased antioxidant-enzyme activity,
- NRF2/SIRT3-related responses,
- reduced mitochondrial electron leakage and oxidative stress. PubMed Central (PMC)
So you might get:
[ \text{melatonin} \rightarrow \downarrow mitochondrial\ ROS ]
which could indirectly reduce oxidation of:
[ PRDX3,\quad DJ!-!1,\quad mitochondrial\ Trx2/Grx2,\quad etc. ]
But I would put an asterisk beside claims that ordinary systemic melatonin works primarily by stoichiometrically scavenging every ROS molecule . Its regulatory and mitochondrial effects may be at least as important, and some mechanistic literature remains debated. PubMed Central (PMC)
Sulforaphane is the glorious opposite
Sulforaphane gets sold under the word “antioxidant,” yet chemically it does this:
[ \boxed{\text{sulforaphane is an electrophile}} ]
It deliberately reacts with sensor cysteines.
Most famously:
[ SFN + KEAP1-C151 \rightarrow KEAP1_{\rm modified}. ]
Then:
[ KEAP1\downarrow \rightarrow NRF2\uparrow \rightarrow GSH,\ NQO1,\ HO!-!1,\ GST,\ldots\uparrow. ]
This is exceptionally well established. PubMed Central (PMC)
So its time course looks almost paradoxical:
[ \boxed{ \text{mild electrophilic insult NOW} \rightarrow \text{stronger antioxidant capacity LATER}. } ]
It activates the redox alarm system rather than silencing it .
This is hormesis in a rather literal molecular form.
Astaxanthin: mostly membrane protection + indirect signaling
Astaxanthin is a lipophilic carotenoid that embeds in lipid structures and can reduce lipid oxidative chemistry.
Experimental models also repeatedly report:
[ \text{astaxanthin} \rightarrow NRF2\uparrow ]
and
[ NF\kappa B\downarrow. ]
But much of the mechanistic evidence here is preclinical, so I’d be less confident assigning a specific KEAP1 cysteine mechanism than with sulforaphane. PubMed Central (PMC)
Think:
[ \boxed{\text{astaxanthin primarily changes the membrane/lipid oxidative environment}} ]
rather than directly sitting on PRDX and stopping peroxide sensing.
CoQ10: especially interesting because it is part of the redox machine
CoQ isn’t merely an antioxidant added from the outside.
Mitochondria already depend on:
[ CoQ\rightleftarrows CoQH_2 ]
to shuttle electrons through the respiratory chain.
Reduced CoQ, ubiquinol , is also a powerful lipid-phase chain-breaking antioxidant and can regenerate vitamin E. PubMed
Thus its strongest redox territory is:
[ \boxed{ \text{mitochondrial inner membrane} + \text{lipid peroxidation}. } ]
Changing CoQ status could therefore alter mitochondrial ROS production upstream of sensors such as PRDX3 and DJ-1.
But there is a lovely Janus face here too:
[ CoQ\rightarrow CoQ^{\bullet-}\rightarrow CoQH_2 ]
contains a semiquinone radical intermediate .
So the CoQ pool can participate in ROS generation as well as ROS suppression. PubMed
It isn’t a simple sponge.
If your question is specifically “which ones would most suppress physiological redox signaling?”
Very approximately:
[ \boxed{ \text{NAC/GSH manipulation} } ]
has the most direct potential to broadly alter thiol-redox circuitry ,
while
[ \boxed{\text{vitamin E / astaxanthin / CoQ}} ]
are much more weighted toward lipid and membrane redox chemistry ,
and
[ \boxed{\text{vitamin C}} ]
hits selected soluble radicals much more effectively than H₂O₂ itself.
Meanwhile:
[ \boxed{\text{sulforaphane}} ]
is almost the conceptual inverse. It trips KEAP1’s redox alarm on purpose and thereby increases the cell’s endogenous defenses. PubMed Central (PMC)
And this is why “total antioxidant capacity” is such a lousy mental model. The cell has multiple redox channels:
[ \begin{array}{c} H_2O_2\ \text{lipid-OOH}\ \text{electrophiles}\ NO\ O_2^{\bullet-}\ GSH/GSSG\ Trx_{red}/Trx_{ox}\ CoQ/CoQH_2 \end{array} ]
and each of these compounds moves a different subset of those channels , sometimes in opposite directions.