BACKGROUND : Limonoids are highly oxygenated compounds with a prototypical structure. Their occurrence in the
plant kingdom is mainly confined to plant families of Meliaceae and Rutaceae. Owing to their wide range of pharmacological
and therapeutic properties, this study was aimed at investigating the potential nitric oxide (NO) and
acetylcholinesterase (AChE) inhibitory activity and the cytotoxicity of three limonoids: trichilia lactone D5 (1), rohituka
3 (2) and dregeanin DM4 (3), isolated from Trichilia welwitschii C.DC.
RESULTS : Results indicated that the three limonoids had low cytotoxicity towards Vero cells with LC50 values ranging
from 89.17 to 75.82 μg/mL. Compounds (2) and (3) had lower cytotoxicity compared to puromycin and doxorubicin
used as reference cytotoxic compounds. Compound (1) (LC50 of 23.55 μg/mL) had good antiproliferative activity
against RAW 264.7 cancer cells. At the lowest concentration tested (0.5 μg/mL), compound (2) and (3) released the
lowest amount of nitric oxide (2.97 and 2.93 μM, respectively). The three limonoids had anti-AChE activity with IC50
values ranged of 19.13 μg/mL for (1), 34.15 μg/mL for (2) and 45.66 μg/mL for (3), compared to galantamine (IC50 of
8.22 μg/mL) used as positive control.
CONCLUSION: The limonoid compounds studied in this work inhibited nitric oxide production in LPS-stimulated
macrophages and had anti-AChE activity. Trichilia lactone D5 had potential antiproliferative activity against RAW 264.7
cancer cells. The limonoids had low cytotoxicity towards Vero cells lines. This study provided further examples of the
importance of limonoids compounds as potential AChE inhibitors and anti-inflammatory agents targeting the inhibition
of NO production.