Therapeutic potential of a polyherbal extract against COVID-19 and associated inflammation and mucormycosis: In vitro characterization and in vivo validation in a human coronavirus 229E-infected mouse model.

The rise of viral infections has been accompanied by an increased incidence of secondary opportunistic infections, such as mucormycosis, highlighting the urgent need for broad-spectrum therapeutics capable of targeting multiple pathological pathways. This study evaluates the antiviral, antioxidant, anti-inflammatory, and antifungal potential of a polyherbal extract (PHE) and its optimized self-nanoemulsifying intravenous formulation (PH-SNEDDS). PHE displayed strong free-radical-scavenging activity (DPPH, IC50: 21.99μg/mL; ABTS, IC50: 58.97μg/mL) and significantly downregulated pro-inflammatory mediators in LPS-stimulated THP-1 and RAW 264.7 cells, reducing TNF-α and iNOS gene expression by 4.04-fold and 4.91-fold, respectively. The extract also exhibited potent antifungal activity against Apophysomyces elegans (MIC: 1μg/mL) and Rhizopus oryzae (MIC: 0.5μg/mL). In A549 lung epithelial cells, PHE effectively inhibited HCoV-229E replication with minimal cytotoxicity. The PH-SNEDDS formulation demonstrated optimal physicochemical properties, including a particle size of 146±2.9nm and zeta potential of -41.1±2.7mV. In HCoV-229E-infected BALB/c mice, PH-SNEDDS significantly reduced pulmonary viral load, mitigated histopathological damage, and suppressed viral RNA and protein expression. Immunological profiling revealed a shift toward protective immune responses, with an increased Th1/Th2 ratio (1.37±0.06), decreased Th17/Treg ratio (1.97±0.08), and elevated B cell (3.31±0.18) and NK cell (2.57±0.08) populations, along with markedly lower serum levels of IL-6 (59.62±5.03pg/mL) and TNF-α (121.75±5.83pg/mL). Collectively, these findings demonstrate the strong antiviral, anti-inflammatory, and antifungal efficacy of PH-SNEDDS, supporting its potential as a promising multifunctional therapeutic candidate for coronavirus infections and their associated inflammatory or fungal complications.