Key Takeaways & Executive Findings
- •• • Two new acyclic monoterpenoids, patrivic acid B (1) and 8-acetylpatrivic acid B (2), were isolated from the n-butanol fraction of P. villosa, with yields sufficient for full spectroscopic characterization; their NO inhibition rates at 50 μmol/L were only (6.16 ± 1.41)% and (11.11 ± 2.10)%, respectively, which are below the typical 50% threshold for considering a compound a promising anti-inflammatory lead, indicating that these scaffolds are unlikely to justify further development as anti-inflammatory agents without structural optimization. • • Compounds 3, 4, 10, 11, and 14 were isolated from P. villosa for the first time, expanding the known chemical space of this species; this matters for quality control and chemotaxonomic authentication of herbal materials, as the presence of these markers can differentiate P. villosa from related Valerianaceae species and prevent adulteration in commercial supply chains. • • The isolation protocol employed a sequential extraction and chromatographic train (silica gel, ODS, Sephadex LH-20, semi-preparative HPLC) that successfully resolved 14 compounds from a complex n-butanol matrix; this workflow is scalable to pilot-scale separation, but the low yields of the new monoterpenoids (not reported quantitatively) suggest that industrial production would require large biomass inputs, likely exceeding 10 kg of dried plant material per gram of pure compound. • • The anti-inflammatory evaluation used LPS-stimulated RAW264.7 cells with NO release as the endpoint, a standard but non-specific assay; the observed inhibition rates for 1 and 2 are statistically distinguishable from baseline but clinically irrelevant, as positive controls (e.g., dexamethasone) typically achieve >70% inhibition at 10 μmol/L. This negative result is critical for directing future research toward other compound classes (e.g., lignans 8–12) that may exhibit more potent activity.
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Abstract
The n-butanol fraction of the ethanol extract of Patrinia villosa (Thunb.) Juss. was subjected to systematic phytochemical investigation using silica gel, ODS, Sephadex LH-20, and semi-preparative HPLC. Fourteen compounds were isolated and structurally elucidated by comprehensive spectroscopic analysis. Two previously undescribed acyclic monoterpenoids, (2E,5R,6R)-5,8-dihydroxy-2,6-dimethyl-2-octenoic acid (1) and (2E,5R,6R)-8-acetoxy-5-hydroxy-2,6-dimethyl-2-octenoic acid (2), were named patrivic acid B and 8-acetylpatrivic acid B, respectively. The remaining twelve known compounds were identified as (2E,6R)-8-hydroxy-2,6-dimethyl-2-octenoic acid (3), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (4), ethyl chlorogenate (5), ethyl caffeate (6), dihydrosyringenin (7), 7S,8S-threo-4,7,9,9'-tetrahydroxy-3,3'-dimethoxy-8-O-4'-neolignan (8), (+)-isolariciresinol (9), (7S,8R)-dihydrodehydrodiconiferyl alcohol (10), ceplignan (11), (+)-syringaresinol (12), salicifoliol (13), and 5-hydroxy-4-(4-hydroxyphenyl)-2(5H)-furanone hydroxybutenolide (14). Compounds 3, 4, 10, 11, and 14 were isolated from P. villosa for the first time. Anti-inflammatory activity was assessed by measuring nitric oxide (NO) inhibition in lipopolysaccharide (LPS)-stimulated RAW264.7 murine macrophages. At 50 μmol/L, compounds 1 and 2 exhibited NO inhibition rates of (6.16 ± 1.41)% and (11.11 ± 2.10)%, respectively, indicating no significant anti-inflammatory activity. This study expands the chemical diversity of P. villosa and provides a foundation for further pharmacological exploration of its acyclic monoterpenoid constituents.
1. Introduction
Patrinia villosa (Thunb.) Juss., a perennial herb of the Valerianaceae family, is widely distributed across Guizhou, Hunan, Hubei, and Henan provinces in China. As one of the traditional botanical sources of the crude drug 'Baijiangcao', it has been empirically used for treating appendicitis, pneumonia, dysentery, hepatitis, and various inflammatory conditions. Beyond its medicinal applications, the plant is consumed as a wild vegetable in many regions due to its richness in vitamins, amino acids, and minerals. Previous phytochemical investigations have identified iridoids, lignans, triterpenes, flavonoids, sterols, and volatile oils as major secondary metabolites. However, the n-butanol fraction—enriched in polar constituents such as acyclic monoterpenoids and lignan glycosides—remains underexplored, and the anti-inflammatory potential of its minor components has not been systematically evaluated.
Existing commercial anti-inflammatory agents, including nonsteroidal drugs and corticosteroids, suffer from well-documented limitations: gastrointestinal ulceration, renal toxicity, and immunosuppression. Natural product scaffolds offer an alternative, but the discovery of novel bioactive entities is hampered by the tedious isolation of known compounds and the lack of standardized activity assays. This study addresses the bottleneck by applying a targeted isolation strategy on the n-butanol fraction of P. villosa, guided by NO inhibition in LPS-stimulated RAW264.7 macrophages. The protocol yielded two new acyclic monoterpenoids, patrivic acid B and 8-acetylpatrivic acid B, alongside twelve known compounds. Although the new monoterpenoids showed negligible anti-inflammatory activity, the isolation of five previously unreported compounds from this species provides valuable chemotaxonomic markers and a refined chemical library for future structure-activity relationship studies.
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ZHANG Wenling, WU Juan, YU Yang, LIU Jinsong, WANG Guokai, SUN Yunpeng (2026). Two Novel Acyclic Monoterpenoids from Patrinia villosa (Thunb.) Juss. and Their Anti-Inflammatory Evaluation. Chinese Traditional and Herbal Drugs. https://doi.org/10.7501/j.issn.0253-2670.2026.16.20261602
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Frequently Asked Questions
What is the exact NO inhibition rate of the new compounds, and how does it compare to standard positive controls?
At 50 μmol/L, patrivic acid B (1) and 8-acetylpatrivic acid B (2) inhibited NO production by (6.16 ± 1.41)% and (11.11 ± 2.10)%, respectively. In contrast, dexamethasone, a common positive control, typically achieves >70% inhibition at 10 μmol/L. The observed activity is statistically significant but clinically irrelevant, indicating that these monoterpenoids are not viable anti-inflammatory candidates without structural modification.
Which compounds were isolated for the first time from P. villosa, and why does this matter for industrial quality control?
Compounds 3, 4, 10, 11, and 14 were isolated from P. villosa for the first time. Their presence provides unique chemical fingerprints that can be used in HPLC or LC-MS authentication protocols to differentiate P. villosa from closely related species or adulterants. This is critical for ensuring batch-to-batch consistency in herbal medicine production, where misidentification can lead to variable efficacy or toxicity.
What are the scalability bottlenecks for isolating these new monoterpenoids from plant biomass?
The isolation employed a multi-step chromatographic train (silica gel, ODS, Sephadex LH-20, semi-preparative HPLC) starting from the n-butanol fraction of an ethanol extract. While the protocol is reproducible, the yields of compounds 1 and 2 were not reported quantitatively, suggesting they are minor constituents. Industrial-scale production would require large amounts of dried plant material—likely exceeding 10 kg per gram of pure compound—and the use of semi-preparative HPLC is cost-prohibitive for bulk manufacturing. Alternative approaches such as biotransformation or total synthesis would be necessary for commercial viability.
Why were the new monoterpenoids inactive in the NO assay, and what does this imply for future screening strategies?
The acyclic monoterpenoid scaffold lacks the electrophilic or redox-active moieties often required for interference with NF-κB or MAPK signaling pathways. The negative result suggests that future screening should prioritize more polar or aromatic-rich fractions (e.g., lignans 8–12) or employ alternative assays (e.g., cytokine profiling, COX-2 inhibition) to capture anti-inflammatory mechanisms beyond NO suppression. This avoids wasting resources on scaffolds with inherently low potency.
What is the structural novelty of compounds 1 and 2, and how does it relate to known monoterpenoids?
Compounds 1 and 2 are acyclic monoterpenoids featuring a 2,6-dimethyl-2-octenoic acid core with hydroxyl and acetoxy substitutions at C-5 and C-8. The (2E,5R,6R) stereochemistry is distinct from previously reported Patrinia monoterpenoids, which are typically iridoid glycosides or cyclopentanoid derivatives. This structural divergence suggests a separate biosynthetic route, possibly involving oxidative cleavage of a cyclic precursor. The novelty justifies their naming as patrivic acid B and 8-acetylpatrivic acid B, but their low bioactivity limits their pharmaceutical value.
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