The chemical constituents and biological activities of the young fruits of Naringi crenulata
(Roxb.) Nicolson (Rutaceae) remain poorly investigated. This study aimed to isolate secondary
metabolites from the young fruits and evaluate the in vitro cytotoxicity and relative selectivity of
the extracts and the isolated compounds. The plant material was sequentially extracted with
hexane, CH2Cl2, acetone, and MeOH, and cytotoxicity was evaluated against KB, MCF-7, and
Vero cells using the MTT assay. Of these extracts, CH2Cl2 was the most active against KB and
MCF-7 cells, with IC50 values of 15.08 and 27.92 µg/mL, respectively, and showed lower
cytotoxicity toward Vero cells (IC50 = 169.65 µg/mL), corresponding to selectivity indices (SI) of
11.25 and 6.07. Three known prenylated benzoyltyramine alkaloids, acidissimin (1), acidissiminin
epoxide (2), and acidissiminol (3), were isolated. Their structures were assigned from
spectroscopic data acquired in this study and compared with published values. Compound 3 was
the most active against KB and MCF-7 cells (IC50 = 0.79 and 0.87 µg/mL; SI = 6.10 and 5.54) but
also showed appreciable cytotoxicity toward Vero cells (IC50 = 4.82 µg/mL). Compound 2 was
selectively cytotoxic toward KB cells (IC50 = 6.11 µg/mL; SI >16.37), whereas compound 1 was
less active. This is the first report of compounds 1–3 from N. crenulata and their preliminary
evaluation in these cell models.