Ruta chalepensis is an herb used to treat various ailments, and its potential cytotoxic effects on different tumor cell lines have been extensively studied. The present study aimed to evaluate the cytotoxic activity of R. chalepensis methanol extract (RCME), sub-partitions obtained from solvents of increasing polarity, and major compounds, as well as their hemolytic, anti-hemolytic, and antioxidant potential. The in vitro cytotoxic activity against the human hepatocarcinoma (HEP-G2) and the murine lymphoma cell line (L5178Y-R) was evaluated using the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay, whereas selectivity indices (SIs) were determined by comparing cytotoxicity against normal African green monkey kidney cells (VERO) and human peripheral blood mononuclear cells (PBMC). Hemolytic and anti-hemolytic activities were evaluated on human erythrocytes. The most effective cytotoxic treatment was evaluated for nitric oxide release by J774A.1 macrophages. Antioxidant activity of R. chalepensis material was also determined. Results showed that RCME produced significant (p < 0.05) cytotoxicity in HEP-G2 (IC50 = 1.79 µg/mL) and L5178Y-R (IC50 = 1.60 µg/mL) cells and exhibited high SIs (291.50 and 114.80, respectively). In addition, the n-hexane fraction (RCHF) showed an IC50 of 18.31 µg/mL in HEP-G2 cells and an SI of 9.48 in VERO cells, whereas the chloroform fraction (RCCF) evidenced an IC50 of 1.60 µg/mL in L5178Y-R cells and an SI of 34.27 in PBMC cells. Chalepensin (CHL), rutamarin (RTM), and graveolin (GRV), which are major components of R. chalepensis, showed high activity against L5178Y-R cells, with IC50 of 9.15, 15.13 and SI of 45.08 µg/mL, respectively. In addition, CHL, RTM, and GRV showed SIs of 24.76, 9.98, and 3.52, respectively, when compared with PBMC cells. RCME at concentrations of 125 µg/mL and 250 µg/mL, significantly (p < 0.05) decreased nitrite production in J774A.1 cells, when exposed to lipopolysaccharide. This study demonstrated that RCME showed significant cytotoxic activity against HEP-G2 and L5178Y-R cells, without affecting normal VERO, PBMC, and J774A.1 cells.

Graveoline is a biologically active ingredient extracted from Ruta graveolens. Current work aimed at investigating in vitro metabolism of graveoline using rat or human liver microsomes and hepatocytes. Graveoline (20 μM) was incubated with nicotinamide adenine dinucleotide phosphate-supplemented rat and human liver microsomes as well as hepatocytes. LC coupled to a photo diode array detector and quadrupole/time-of-flight tandem mass spectrometry was used to detect and identify the metabolites. The structures of the metabolites were identified by accurate mass, elemental composition, and indicative fragment ions. A total of 12 metabolites, comprising 6 phase I and 6 phase II metabolites, were obtained. The metabolic pathways included demethylenation, demethylation, hydroxylation, glucuronidation, and glutathion conjugation. The metabolite (M10) produced by opening the ring of the methylenedioxyphenyl moiety was detected as the most abundant in both liver microsomes and hepatocytes, mainly catalyzed by CYP1A2, 2C8, 2C9, 2C19, 2D6, 3A4, and 3A5. This study provides valuable information on the in vitro metabolism of graveoline, which is indispensable for further development and safety evaluation of this compound.