Shi, P., et al. Discovery of novel adjuvants: Identification of saponins from Hylomecon japonica (Thunb.) Prantl & Kündig and insights into their in vitro and in vivo activities.

Shi, P., et al. Discovery of novel adjuvants: Identification of saponins from Hylomecon japonica (Thunb.) Prantl & Kündig and insights into their in vitro and in vivo activities.

Bioorg Chem,  2025 Jul 1, 161:108501. PMID: 40318505

• This study isolated fourteen saponins from Hylomecon japonica, including eight novel compounds, with compound HA identified as a potent immune adjuvant. In vitro experiments demonstrated (although the total saponins exhibited superior immune adjuvant activity compared to individual compounds) that HA enhances macrophage activity, promotes lymphocyte proliferation, and stimulates dendritic cell maturation, primarily by activating the TLR4/NF-κB signaling pathway. In vivo, HA improved immune organ development, increased serum antibody levels, and elevated cytokine production, suggesting its potential as a natural immunopotentiator. The findings highlight HA’s capacity to modulate immune responses through multiple cellular targets and signaling mechanisms, offering promising prospects for designing new vaccine adjuvants from natural saponins. 
• The study indicates that among the isolated saponins from Hylomecon japonica, HA exhibited structural similarity to QS-21. While the exact degree of structural similarity to QS-21 is not explicitly detailed in the provided information, the focus on screening compounds based on their structural resemblance to QS-21 suggests that some of these saponins share key features with it, potentially contributing to their immunomodulatory activity.
• While the research indicates that HA exhibits strong immunostimulatory properties, QS-21 is the traditionally considered highly potent saponin. There is no definitive conclusion about QS-21 and HA potency that requires direct head-to-head comparative studies, which are noted as necessary for future research.

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