Related Experiment Video
Updated: Mar 8, 2026

Chemiluminescence-based Assays for Detection of Nitric Oxide and its Derivatives from Autoxidation and Nitrosated Compounds
Published on: February 16, 2022
Nitric Oxide Production-Inhibitory Activity of Limonoids from Azadirachta indica and Melia azedarach
Toshihiro Akihisa1,2, Yuki Nishimoto3, Eri Ogihara3
1Research Institute for Science & Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan.
Abstract:
Seventy-three limonoids isolated from three Meliaceae plants, Azadirachta indica, A. indica var. siamensis, and Melia azedarach, or semi-synthesized from the Meliaceae limonoids, were evaluated for their inhibitory activity against nitric oxide (NO) production in mouse macrophage RAW 264.7 cells induced by lipopolysaccharide (LPS), as a primary screening test for anti-inflammatory agents. Of the compounds tested, 21 compounds exhibited inhibitory activity (IC50 4.6 - 58.6 μm) without any significant toxicity (IC50 > 100 μm) which were more potent than l-NMMA (NO-production inhibitory activity, IC50 65.6 μm; cytotoxicity, IC50 > 100 μm), and among which, nine compounds, i.e., 17-hydroxy-15-methoxynimbocinol (6), ohchinin (20), 1-cis-cinnamoyl-1-decinnamoylohchinin (24), salannin (27), methyl nimbidate (32), isosalannin (55), nimbolinin D (58), mesendanin E (69), and 7-deacetylgedunin (73) exhibited potent inhibitory activity (IC50 4.6 - 29.3 μm). In particular, compounds 6 (IC50 7.3 μm), an azadirone-type limonoid, and 73 (IC50 4.6 μm), a gedunin-type limonoid, exhibited remarkable activity. Western blot analysis revealed that 27 and 73 reduced the expression levels of the inducible NO synthase and cyclooxygenase-2 proteins in a concentration-dependent manner. These findings suggest that limonoids of A. indica, A. indica var. siamensis, and M. azedarach, and their semi-synthetic derivatives may be effective against inflammation.
Related Concept Videos
Nitric Oxide Signaling Pathway
Preparation of Amines: Reduction of Oximes and Nitro Compounds
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Antihypertensive Drugs: Vasodilators
Antianginal Drugs: Nitrates and β-Blockers
Organic nitrates, such as nitroglycerin, play a pivotal role. Once metabolized, they liberate nitric oxide, a molecular marvel. Nitric oxide triggers guanylyl cyclase and augments cGMP production. This biochemical cascade orchestrates the relaxation of vascular smooth muscles, ushering in vasodilation and enhancing coronary blood flow....
meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H
2° Amines to N-Nitrosamines: Reaction with NaNO2

