It has been shown that a lipophilic CO₂-extract prepared from the leaves of Petasites hybridus (Ze 339) inhibited leukotriene synthesis in vitro and ex vivo. The inhibition of the leukotriene synthesis was solely attributed to the sum of the petasins, namely petasin and its isomers isopetasin and neopetasin. To further investigate the influence of the extract matrix on leukotriene synthesis inhibition, we compared twelve selected batches of Ze 339 that differed significantly in the composition of the extract matrix. Quantitative analysis of the twelve extract batches revealed high contents of petasins [28.8-41.9%], fatty acids [17.1-27.2%] and crude oil and fat [17.7-44.2%]. The amount of sterols ranged between 3.0 and 4.9% and that of essential oils between 1.3 and 10.5%. Based on the quantitative analysis, 97-100% of the extract mass could be attributed to the above mentioned groups of ingredients. Despite significant differences in extract matrix composition, only the content of petasins was critical for the dose-dependent inhibition of leukotriene synthesis. However, at equal concentrations of petasins, no significant differences in 5-LOX, LTC4 synthase and LTA4 hydrolase inhibition were detected between the selected extract batches, despite differences in the composition of the petasin isomers. Our data suggest that the extract matrix of Ze 339 has no effect on leukotriene inhibitory effects of the petasins.

Cucurbita pepo (CP) seeds are traditionally used to alleviate lower urinary tract symptoms associated with benign prostatic hyperplasia and overactive bladder. While these effects are often attributed to lipophilic constituents, recent studies have highlighted the therapeutic potential of oil-free hydroethanolic extracts. However, their composition remains insufficiently characterized, considering the species’ significant phenotypic and phytochemical variability. This study aimed to characterize the phytochemical profile of hydrophilic hydroethanolic seed extracts from ten CP cultivars originating from different European regions, with a focus on compositional variability. The elemental composition, along with primary and secondary metabolites, was analyzed using established spectroscopic and chromatographic methods. The extracts showed considerable variation in protein (45.39 to 114.58 mg/g dw) and free amino acid content (46.51 to 111.10 mg/g dw), as well as differences in elemental composition. Principal component analysis revealed distinct clustering patterns, with several samples displaying metabolite profiles comparable to the Cucurbita pepo var. styriaca variety currently recommended by the European Pharmacopoeia (Ph. Eur.) and the Committee on Herbal Medicinal Products (HMPC). These findings open the possibility of using other CP varieties as alternative sources for extract preparation and offer novel insights into the composition of less explored hydrophilic extracts derived from CP seeds.

The use of herbal medicines containing Petasites hybridus extracts has a long history in the treatment of various ailments. The observed effects are primarily due to pharmacologically active compounds such as petasin, isopetasin, and neopetasin. In evidence-based phytotherapy, extracts from leaves and rhizomes are applied for different indications. While leaf extracts are administered to treat allergic rhinitis symptoms, rhizome extracts are utilized among others in the management of gastrointestinal spasms and migraines. The quality and source of plants are critical for producing authorized herbal medicinal products. Although the preparation of P. hybridus leaf extracts from cultivated plant material is already established, the rhizomes used for preparing extracts are still derived from commercial wild collections. However, switching to cultivation is desirable to ensure consistent quality and availability. For regulatory purposes, comparative pharmacological studies are needed to assess the bioactivity of plant material from different sources. Therefore, this study analyzed rhizome extracts from wild harvesting and cultivation for their petasin composition (i.e., isopetasin, neopetasin, petasin) and spasmolytic effects on Ca²⁺-dependent precontracted guinea pig ileum ex vivo. The results confirm petasins as active compounds of P. hybridus rhizome extracts. Moreover, they demonstrate that the total content of petasins determines the spasmolytic effects, regardless of the individual composition of the different petasins. No significant differences in efficacy were found between cultivated and wild-collected rhizomes, demonstrating that cultivated material is a reliable, consistent, and sustainable alternative for P. hybridus rhizome extract production.

Actaea racemosa L. (syn. Cimicifuga racemosa (L.) Nutt., black cohosh) rhizomes contain triterpene glycosides (TTGs) that serve as principal quality markers in the European Pharmacopoeia (Ph. Eur.) monograph. However, discrepancies between chromatographic profiles of the plant material and the herbal reference standard (HRS) dry extract complicate quality assessment. This study elucidated the chemical origin of these discrepancies and evaluated whether the extract-based HRS can represent the analytical fingerprint of the plant material. Thirteen TTGs were identified and characterized within the official Ph. Eur. HPLC–ELSD method using centrifugal partition chromatography, semi-preparative UPLC, HRMS, GC–MS and NMR spectroscopy, employing reference standards and isolated compounds. Three malonylated TTGs (8a, 9a, 10a) were detected in wild and cultivated rhizomes but were absent from the A. racemosa dry extract HRS and other dry extracts. Quantitative analysis revealed that cultivated plants contained an insufficient amount of TTGs; however, after extraction, both the amount and the profile aligned with the Ph. Eur. requirements. This behavior is explained by the degradation and rearrangement pathways of the TTGs. Overall, these findings clarify the origin of chemical variability between plant and extract fingerprints and support the inclusion of malonylated TTGs in the quantitative determination of A. racemosa triterpene glycosides in the Ph. Eur.

Hydroethanolic Cucurbita pepo seed extracts are traditionally used for alleviating lower urinary tract symptoms (LUTS), yet their mechanisms remain unclear. Adenosine, a purine nucleoside involved in neuromodulation and smooth muscle relaxation, was recently identified in C. pepo seeds. Since A₁ adenosine receptors (A₁AR) suppress parasympathetic bladder overactivity by inhibiting acetylcholine (ACh) release, we investigated to which extent purines from pumpkin seed extracts contribute to A₁AR activation. Complementary antioxidant capacity was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Three hydrophilic seed extracts containing different adenosine levels (0.60–1.18 mg/g dw) were evaluated for agonist activity using a cAMP inhibition assay. The most active extract showed an EC₅₀ of 40.22 µg/mL. Selective removal of adenosine shifted the dose–response curve rightward, while further elimination of an adenosine derivative increased the EC₅₀ to 212.10 µg/mL, confirming adenosine as the principal active compound. Guanosine and inosine did not exhibit A₁AR agonist or allosteric effects. All samples exhibited measurable but weak antioxidant activity (IC₅₀ = 1.02–4.19 mg/mL), consistent with their low total phenolic content. These findings underscore the importance of accounting for naturally occurring agonists in plant extracts to avoid overestimating receptor-mediated effects in vitro which are not translatable in vivo.