Antimycobacterial and cytotoxic activities of compounds isolated from Zanthoxylum flavum subsp. pistaciifolium leaves

Zanthoxylum flavum subsp. pistaciifolium (Griseb). Reynel (Rutaceae) is an endemic Cuban plant traditionally used for respiratory infections. This study evaluates the antimycobacterial and cytotoxic potential of its leaves, leading to the isolation of six known compounds characterized by LC-MS, 1D/2D NMR, and ECD spectra. The crude ethanolic extract ( ZPE ) exhibited moderate activity against M. kansasii (MIC = 31.25 µg/mL), while the hexane-butanone fraction ( A ) was active against M. kansasii and M. tuberculosis H37Ra (MICs of 31.25 and 62.5 µg/mL). From the fraction A , skimmianine ( 1 ), γ -fagarine ( 2 ), ( S )-clausenaside G ( 3 ), ( S )-marmesin ( 4 ) were isolated. Compound 2 was identified as the main bioactive constituent, exhibiting good activity against M. kansasii (MIC = 3.91 µg/mL) and moderate effects against M. tuberculosis H37Ra (MIC = 31.25 µg/mL), M. aurum , and M. avium (MICs = 62.50 µg/mL). In contrast, the fraction ethyl acetate ( B ) and its isolated flavonoid glycosides ( 5 and 6 ) were inactive at the highest concentration tested (MICs ≥ 250 µg/mL). An additive effect was observed when γ -fagarine was combined with rifampicin against M. kansasii using the checkerboard assay, which could be considered as a basis for adjuvant therapy. Molecular docking suggested potential interactions of γ -fagarine with several mycobacterial proteins, particularly DprE1, MmpL3, and DNA gyrase. These computational predictions provide hypotheses for subsequent target-based studies but do not establish direct protein inhibition or a mechanism of antimycobacterial action. Moreover, γ -fagarine exhibited cytotoxicity against the carcinoma cell lines A549, A2780, and MCF‑7 at 10 µM, while no toxicity was observed against MRC-5 (the non-carcinoma cell line of lung fibroblasts). These findings support the traditional medicinal use of this species and highlight its potential as a source of metabolites with dual‑interest scaffolds for antimycobacterial and anticancer drug development.