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. 2021 May 17;10(5):789. doi: 10.3390/antiox10050789

Table 2.

HO-1 inhibitory tools.

Pharmacological Inhibitors Benefits Drawbacks Ref.
Porphyrin-Based Compounds
Metalloporphyrins
  • -

    Zinc II protoporphyrin IX (ZnPPIX)

  • -

    Tin protoporphyrin IX (SnPPIX)

  • -

    Tin mesoporphyrin IX (SnMPIX)
  • -

    Competitive inhibitors

  • -

    Well proved activity in vitro and in vivo
  • -

    Non selective on HO-1 isoform

  • -

    Active on other heme-dependent

  • -

    enzymes (NOS, sGC, and CYP)

  • -

    HO-1 inducers

  • -

    Photo reactive

  • -

    Poor soluble

 [196,201,202]
Modified protoporphyrins
  • -

    Polyethylene-glycol (PEG-ZnPPIX)

  • -

    Amphiphilic styrene-maleic acid copolymer (SMA-ZnPPIX)
  • -

    Water-soluble

 [206,207,208,209,210]
Imidazole-based compounds
  • -

    Azalanstat

  • -

    Other imidazole-derived compounds

  • -

    (OB-24)
  • -

    Non competitive inhibitors

  • -

    Selective on HO-1 isoforms

  • -

    Limited inhibitory activity on NOS, sGC, and CYP

  • -

    Water-soluble
  • -

    Not well studied and not tested in clinical trials

 [211,212]
Genetic tools
Small interfering RNA and short hairpin RNA
  • -

    Specific targeting HO-1 mRNA
  • -

    Limited therapeutic application

(delivery methods) 		[195]
CRISPR/Cas9
  • -

    Genetic ablation of HO-1 gene

  • -

    Stable knock-down

  • -

    High efficiency of HO-1 inhibition
  • -

    Limited therapeutic application

(delivery methods) 		[195]