Picrasma quassioides leaves: Insights from chemical profiling and bioactivity comparison with stems

In Chinese Pharmacopeia, Picrasma quassioides (PQ) stems and leaves are recorded as Kumu with antimicrobial, anti-cancer, anti-parasitic effects, etc. However, thick stems are predominantly utilized as medicine in many Asian countries, with leaves rarely used. By now, the phytochemistry and bioactivity of PQ leaves are not well investigated.

An Orbitrap Elite mass spectrometer was employed to comprehensively investigate PQ stems and leaves sourced from 7 different locations. Additionally, their bioactivities were evaluated against 5 fungi, 6 Gram-positive bacteria and 9 Gram-negative bacteria, a tumor cell line (A549), a non-tumor cell line (WI-26 VA4) and N₂ wild-type Caenorhabditis elegans.

Bioassay results demonstrated the efficacy of both leaves and stems against tumor cells, several bacteria and fungi, while only leaves exhibited anthelmintic activity against C. elegans. A total of 181 compounds were identified from PQ stems and leaves, including 43 β-carbolines, 20 bis β-carbolines, 8 canthinone alkaloids, 56 quassinoids, 12 triterpenoids, 13 terpenoid derivatives, 11 flavonoids, 7 coumarins, and 11 phenolic derivatives, from which 10 compounds were identified as indicator components for quality evaluation. Most alkaloids and triterpenoids were concentrated in PQ stems, while leaves exhibited higher levels of quassinoids and other carbohydrate (CHO) components.

PQ leaves exhibit distinct chemical profiles and bioactivity with the stems, suggesting their suitability for medicinal purposes. So far, the antibacterial, antifungal, and anthelmintic activities of PQ leaves were first reported here, and considering PQ sustainability, the abundant leaves are recommended for increased utilization, particularly for their rich content of PQ quassinoids.