Hernandez-Cruz et al. 2024 - Sulforaphane protection against cadmium toxicity in C. elegans

Hernandez-Cruz and colleagues tested whether sulforaphane pre-exposure reduces cadmium chloride toxicity and mitochondrial dysfunction in the nematode Caenorhabditis elegans. This is primary health/toxicology mechanism evidence, not food, ingredient, or product occurrence evidence. The source’s routeable metal facts are experimental CdCl2 exposure doses: a 300-6000 uM survival screen and a selected 4600 uM CdCl2 challenge for the remaining toxicity, mitochondrial, oxidative-stress, and IIS-pathway assays.

Key numbers

Exposure concentrations and survival

The authors exposed L1-stage C. elegans to CdCl2 concentrations from 300 to 6000 uM for 24 hours. The 300 uM CdCl2 dose decreased survival by 7%, while 6000 uM decreased survival by 73%. Two LC50 calculations were reported: 4858 uM with a 95% confidence interval of 4707-5019 uM by simple logistic regression in Prism 10, and 4857 uM with a 95% confidence interval of 4719-4996 uM by Probit analysis. The 4600 uM CdCl2 dose, described as close to the lower LC50 limit, was selected for the remaining experiments.

Sulforaphane alone was tested at 25, 50, 100, and 200 uM for 48 hours and did not significantly affect survival. In the combined protocol, nematodes received sulforaphane for 24 hours followed by sulforaphane plus 4600 uM CdCl2 for 24 hours. Pre-exposure to 50 and 100 uM sulforaphane increased survival by 27.45% and 34.01%, respectively, versus CdCl2 alone; 100 uM sulforaphane achieved 90.5% survival and was used for subsequent assays.

Lifespan and organism-level toxicity

Table 2 reports lifespan outcomes:

Compared with CdCl2 alone, sulforaphane plus CdCl2 increased mean lifespan by 42.9%, prevented Cd-induced lipofuscin accumulation by 21.1%, increased body length by 34.5%, and increased body bends by 33%. Sulforaphane alone reduced lipofuscin by 52.51% versus the DMSO group.

Mitochondrial and oxidative-stress endpoints

At 4600 uM CdCl2, mitochondrial membrane potential decreased by 69.67% versus control. Sulforaphane plus CdCl2 increased membrane potential by 62.65% versus CdCl2 alone. CdCl2 decreased mitochondrial oxygen consumption by 79.11% versus control; sulforaphane plus CdCl2 increased oxygen consumption by 78.29% versus CdCl2 alone.

CdCl2 decreased total and intestinal mitochondrial mass. Sulforaphane plus CdCl2 increased mitochondrial mass by 24.39% using MitoTracker Green and by 44.04% using the SJ4143 intestinal mitochondrial GFP reporter strain, both compared with CdCl2 alone. Sulforaphane alone increased mitochondrial mass by 19% with MitoTracker Green and 26% with the SJ4143 reporter.

For ROS, CdCl2 increased intracellular ROS by 10.4% versus control; sulforaphane plus CdCl2 trended lower but was not statistically significant. CdCl2 increased mitochondrial ROS by 59.2%, while sulforaphane plus CdCl2 decreased mitochondrial ROS by 20.11% versus CdCl2 alone. In mev-1 mutant worms, CdCl2 hypersensitivity was not attenuated by sulforaphane, suggesting a mev-1-dependent component of protection.

Cadmium-response and IIS-pathway genes

The mtl-2 and cdr-2 mutant assays showed that sulforaphane still protected both mutant strains from CdCl2-induced death, but cdr-2 loss reduced protection by 7.49% versus wild type. CdCl2 alone reduced DAF-2 expression by 44% versus control; sulforaphane plus CdCl2 reduced DAF-2 expression by 50.72% versus DMSO and 32.82% versus CdCl2 alone. In age-1 mutants, sulforaphane protection persisted and survival reached almost 90%, while CdCl2-only survival increased versus wild type.

The skn-1c mutant lost sulforaphane protection: protection decreased from 34.01% in wild type to -3.604% in skn-1c mutants. skn-1a deletion did not remove sulforaphane protection. daf-16 mutant worms remained partly protected, with sulforaphane before CdCl2 increasing survival by 19.61% versus CdCl2 alone, but protection was lower than in wild type. The authors also report greater DAF-16 nuclear translocation in the sulforaphane plus CdCl2 group than in the CdCl2-only group.

Methods (brief)

The authors cultured C. elegans on nematode growth medium with E. coli OP50-1 and synchronized worms before L1-stage exposures in K medium or on plates depending on endpoint. Treatment groups included untreated control, DMSO vehicle, CdCl2, sulforaphane plus CdCl2, and sulforaphane alone. Endpoints included survival, lifespan, lipofuscin, body length, body bends, mitochondrial-associated oxygen consumption by Oroboros Oxygraph 2K, mitochondrial membrane potential by JC-1, mitochondrial mass by MitoTracker Green and GFP reporter strains, intracellular and mitochondrial ROS by H2DCFDA and MitoSOX Red, DAF-2 expression, DAF-16 nuclear localization, and mutant-strain survival assays. LC50 was calculated by logistic regression and Probit analysis.

Implications

Certification: This source does not support food or product concentration thresholds. It is mechanistic evidence for Cd toxicity, mitochondrial dysfunction, and antioxidant-mediated protection in an animal model.

Courses: Useful for teaching the difference between exposure-dose toxicology and occurrence evidence. It also gives a compact model for Cd-driven mitochondrial membrane-potential loss, oxygen-consumption loss, mitochondrial ROS, and IIS-pathway involvement.

App: Keep as cadmium health/toxicology context. Do not route to broccoli, cabbage, or other cruciferous-food pages merely because sulforaphane is a cruciferous-derived compound; no food matrix was measured.

Wiki pages this source may touch

• cadmium
• index

Verification notes

The PDF has author attribution and DOI 10.3390/antiox13050584; no DOI conflict was observed. The source reports experimental CdCl2 treatment concentrations, not environmental, dietary, food, or product cadmium occurrence. Brand and supplier names for reagents and instruments are omitted except where the method class is necessary to understand the assay.

Merge-enhance 2026-06-02 (Claude Opus 4.7): corrected the first LC50 95% confidence interval from “4707-4019 uM” to “4707-5019 uM” — verified against Figure 2A inset in the PDF, which prints “Confidence intervals 95%: 4707 to 5019 µM” for the simple-logistic-regression LC50 of 4858 uM. The prior page text described this interval as “internally reversed or otherwise inconsistent,” but the source is consistent (4858 uM falls inside 4707-5019 uM); the inconsistency was a transcription error in the prior ingest. Also trimmed two invented matrix slugs (cadmium-chloride-exposure, sulforaphane-pre-exposure) — those describe experimental treatments, not biological sample matrices — and added mechanistic-toxicology to align with the convention used in balali-mood2021-toxic-mechanisms-five-heavy-metals.

Matrix-slug convention used here for non-food mechanistic toxicology in model organisms: caenorhabditis-elegans (specific model), nematode-model (broader class), mechanistic-toxicology (study-type descriptor). The standard food-matrices vocabulary (rice, infant-formula, fish, etc.) does not apply because no food, ingredient, or product was measured. The routing layer correctly treats empty products/ingredients as advisory not blocking for this source class.

Fresh-context audit subagent (2026-06-02, Agent tool, general-purpose): verdict PROMOTE. All numerical, methodological, brand-firewall, and Part 2 firewall checks were independently confirmed against the PDF including the corrected LC50 interval. Two advisory concerns raised: (a) the model-organism matrix slugs above, addressed in this verification note; (b) the [[health/index]] link — verified post-audit to exist at wiki/health/index.md, so this was an audit false positive (the snapshot the subagent consulted does not list the health/ namespace).

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.