Comparative analysis of phytochemical profile and antioxidant and anti-inflammatory activity of four Gentiana species from the Qinghai-Tibet Plateau

ETHNOPHARMACOLOGICAL RELEVANCE

Gentiana species, known as the traditional Tibetan medicine "Bangjian," have been integral to clinical practice for millennia. Despite their longstanding use, our understanding of the variation in chemical constituents and bioactive effects among different species is limited.

AIM OF THE STUDY

In the present study, we aimed to assess the differences in chemical profiles and bioactivities among four Gentiana species (G. veitchiorum, G. trichotoma, G. crassuloides, and G. squarrosa) and explore potential bioactive markers.

MATERIALS AND METHODS

The chemical composition of the four Gentiana species was analyzed using UPLC-QE-Orbitrap-MS. The antioxidant activity of the extracts was compared through DPPH, ABTS, and reducing power assays. The anti-inflammatory activity was evaluated by measuring the inhibitory effects on lipopolysaccharide-induced secretion of nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) by RAW264.7 macrophages. Additionally, compounds strongly correlated with anti-inflammatory and antioxidant activities were identified through spectrum-effect relationship analysis.

RESULTS

A total of 50 compounds were identified across the four Gentiana species. In vitro antioxidant assays demonstrated DPPH and ABTS scavenging abilities and reducing power within the concentration range of 62.5-2000 μg/mL. All four species inhibited the production of NO, IL-6, and TNF-α in RAW264.7 cells. Spectrum-effect relationship analysis revealed that gentiascabraside A, gentiatibetine, tachioside, lutonarin, and isotachioside were associated with the highest antioxidant activity; and swertiamarin, tarennoside, eleganoside C, and alpigenoside were associated with the highest anti-inflammatory activity.

CONCLUSIONS

This study presents, for the first time, the chemical profiles and bioactivities of G. trichotoma, G. crassuloides, and G. squarrosa, which were comprehensively compared with those of G. veitchiorum. The findings provide novel insights to understand the traditional use and/or expand the current use of Gentiana species. Additionally, this research highlights the potential of Gentiana species as natural sources of antioxidants and anti-inflammatory agents, suggesting promising applications in tea production or medicinal contexts in the near future.

Melanin biosynthesis inhibitory activity of a compound isolated from young green barley (Hordeum vulgare L.) in B16 melanoma cells

In the course to find compounds that inhibit melanin biosynthesis (i.e., whitening agents), we evaluated the effects of the methanol-soluble fraction (i.e., the water-soluble portion of methanol extracts-CHP20P-MeOH eluted fraction) from young green barley leaves on melanin production in B16 melanoma cells. Activity-guided fractionation led to an isolate called tricin (compound 1) as an inhibitory compound of melanin production in B16 melanoma cells. Furthermore, tricin analogs such as tricetin, tricetin trimethyl ether, luteolin, and apigenin were used for analyzing the structure-activity relationships (SAR) of 5,7-dihydroxyflavones studies. Tricin demonstrated stronger inhibitory activity compared to three other compounds. The results suggest that a hydroxyl group at the C-4' position and methoxy groups at the C-3',5' positions of the tricin skeleton may have important roles in this inhibitory activity in B16 melanoma cells. Our results suggest that tricin inhibits melanin biosynthesis with higher efficacy than arbutin, and it could be used as a whitening agent.