N,N'bis-(2-mercaptoethyl) isophthalamide (NBMI) exerts neuroprotection against lead-induced toxicity in U-87 MG cells.
Level 5 - mechanism / opinion, no new human data
In vitro bench study using human glioblastoma cell line (no animal or human subjects)
PubMed 34165617 · doi:10.1007/s00204-021-03103-2
What was done
Investigators tested the neuroprotective activity of the lipophilic heavy metal chelator N,N'-bis(2-mercaptoethyl)isophthalamide (NBMI) compared to dimercaptosuccinic acid (DMSA) in U-87 MG cells. Cells were pretreated with NBMI or DMSA for 24 hours prior to a 48-hour exposure to 250 µM lead acetate (PbAc). The study evaluated cell death pathways, intracellular glutathione (GSH) levels, neuroinflammatory markers (IL-1β and GFAP), and the metal efflux transporter ferroportin.
What was found
Exposure to 250 µM Pb induced 55% cell death (p < 0.0001) and reduced intracellular GSH levels (0.70-fold, p < 0.005). Pretreatment with NBMI at concentrations as low as 10 µM significantly attenuated cell death and GSH depletion, whereas DMSA was ineffective. NBMI reduced Pb-induced IL-1β (0.59-fold, p < 0.05) and GFAP expression. NBMI alone increased ferroportin expression (1.97-fold, p < 0.05). Pb-induced cell death was necrotic with no apoptotic pathway response.
Why it matters
NBMI demonstrated in vitro neuroprotective and antioxidant efficacy against lead toxicity, showing activity in cell culture where the standard chelator DMSA was ineffective.
Limits
The experiment was conducted exclusively in an immortalized cell line (U-87 MG) in vitro, so in vivo efficacy, safety, and pharmacokinetics remain unknown. Sample size (replicates) and exact numerical change for GFAP were not reported in the abstract. NBMI was applied as a pretreatment rather than a post-exposure rescue intervention.
Cited by
- supports DMSA is an FDA-approved drug for chelation that binds heavy metals for urinary excretion.