Nitric oxide scavenging lignans from Vitex negundo seeds

Area of Science:

• Natural Products Chemistry
• Pharmacology
• Immunology

Background:

• Vitex negundo seeds are a rich source of bioactive compounds.
• Lignans are known for their diverse pharmacological properties.
• Nitric oxide (NO) plays a crucial role in inflammatory processes.

Purpose of the Study:

• To isolate and characterize new lignan compounds from Vitex negundo seeds.
• To evaluate the inhibitory effects of these isolates on nitric oxide production.
• To understand the structure-activity relationship concerning NO inhibition.

Main Methods:

• Isolation of compounds using chromatographic techniques.
• Structure elucidation via Nuclear Magnetic Resonance (NMR), Infrared (IR), and Mass Spectrometry (MS).
• In vitro assessment of nitric oxide production inhibition in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages.

Main Results:

• Ten lignan derivatives were isolated, including four new phenylnaphthalene-type lignans (vitexdoins B-E) and one phenyldihydronaphthalene-type lignan (vitexdoin A).
• Compounds 5, 6, and 9 demonstrated significant inhibition of nitric oxide production with IC(50) values of 0.13, 0.15, and 0.11 microM, respectively.
• The presence of free hydroxyl groups was identified as crucial for potent NO inhibitory activity.

Conclusions:

• Vitex negundo seeds yield novel lignans with promising anti-inflammatory potential.
• Compounds 5, 6, and 9 are potent inhibitors of nitric oxide production.
• Structural features, particularly free hydroxyl groups, are critical for the anti-inflammatory efficacy of these lignans.