Identification of cytotoxic compounds from several selected plants belonging to the Myrtaceae and Asteraceae families.

Theoretical results:
- Sampling was conducted and 5 plant samples were collected for the study, including: aerial parts of Syzygium cinerum (Synonyms: Syzygium borneense); leaves, flowers and stems of Syzygium fruticosum (Synonyms: Syzygium cumini); branches and leaves of Syzygium aff rubicundum; leaves and flowers of Tithonia diversifolia; aerial parts of Xanthium inaequilaterum.
- From 5 selected plants, 132 pure compounds (87 different compounds) were isolated and structurally elucidated, including: 7 new compounds (SC1, SC2, SC3, SC4, TD1, TD2, and XI5) and 3 compounds isolated from nature for the first time (SCT1, SAR-10, FTD12). 
- Among 87 isolated compounds, 35 compounds were selected and evaluated for their cytotoxicity against four human cancer cell lines (KB, HepG2, A549, MCF7). The cytotoxicity assay results showed that 12/35 compounds exhibited moderate to strong activity. Of them, 7 compounds (SC6, TD1, TD2, TD3, TD4, TD5, TD6) strongly inhibited the growth of cancer cells with IC50 values < 10 µM. 
- Two new compounds, TD1 and TD2, were further investigated for their effects on cell cycle analysis and induction of apoptosis in KB cancer cells. The results showed that compound TD1 exhibited an induction of apoptosis in KB cells at a concentration of 2x IC50 (equivalent to 7.26 µM) and showed an effect of arresting the KB cell cycle at the S phase at a concentration of 2xIC50 (equivalent to 7.26 µM).

- The research results revealed new findings on the chemical composition and biological activities of five Vietnamese plant species: Syzygium cinerum (Synonyms: Syzygium borneense), Syzygium fruticosum (Synonyms: Syzygium cumini), Syzygium aff rubicundum, Tithonia diversifolia, and Xanthium inaequilaterum. Seven new compounds were discovered, among which two exhibited potent cytotoxicity against cancer cells.
- Seven compounds with potent cytotoxicity against cancer cells were identified, with IC50 values comparable to or even lower than the reference compound, ellipticine.
- Our findings highlight the potential of these plants as a source of new anticancer agents and contribute to the ongoing search for natural products with therapeutic applications. 

Additional research is required to further explore the potential of certain compounds with anticancer activity (SC6, TD3-TD6) and to assess their suitability for pharmaceutical applications, along with the potential medicinal uses of the studied plant species.