Biomedical Applications of Humic Substances: From Natural Biopolymers to Therapeutic Agents
Key Findings
- HS scavenge reactive oxygen species and modulate cytokine production
- HS inhibit viral fusion and promote wound healing
- HS enhance gut microbiota balance
- HA and FA exhibit anticancer activity by inducing apoptosis in tumor cells while protecting healthy tissues
- Chelating capacity underlies detoxifying activity and heavy metal binding
- HS have antioxidant, anti-inflammatory, antimicrobial, antiviral, and immunomodulatory properties
- FA fraction is more bioavailable due to lower molecular weight and higher carboxyl group density
- Hymatomelanic acids (ethanol-soluble HA fraction) identified as distinct subclass
A comprehensive 2025 review of humic substance biomedical applications, published in the MDPI journal Antioxidants and funded by EU NextGenerationEU. This is the most current broad-scope synthesis of humic and fulvic acid pharmacology in the knowledge graph, updating and extending earlier reviews like Klöcking 2005 and Wollina 2009 with two decades of additional research.
Scope of Activities Covered
The review maps eight categories of biological activity:
Antioxidant — humic substances scavenge reactive oxygen species (ROS) and modulate cytokine production, reducing oxidative stress. The FA fraction is identified as more bioavailable than HA due to lower molecular weight and higher carboxyl group density.
Anti-inflammatory — cytokine suppression (TNF-α, IL-1β, IL-6) and pathway-level modulation, consistent with prior reviews.
Antimicrobial — broad-spectrum activity against bacteria and fungi, building on the Ansorg 1978 foundational work.
Antiviral — HS inhibit viral fusion by blocking surface glycoproteins, preventing cell entry. Mechanism identified across multiple viral types.
Immunomodulatory — regulatory rather than merely suppressive; immune cell population shifts toward homeostasis.
Anticancer — FA induces apoptosis in tumor cells while protecting healthy tissues in vitro. This finding requires independent confirmation before clinical interpretation.
Wound healing — pro-regenerative effects through fibroblast stimulation and Nrf2 pathway activation.
Gut microbiota — selective stimulation of beneficial bacterial populations. An emerging and novel area for HS research.
The HMA Note
The review specifically identifies hymatomelanic acids (HMA) as a distinct bioactive subclass of humic substances — the ethanol-soluble fraction — reinforcing the importance of fractionation in understanding peat’s full biological activity. HMA content is highest in Estonian peat (19.3% dry weight, from Orru 2011).