Bioactive 5/5/5/6 Four-Ring System Iridoids from Plumeria alba L

Area of Science:

• Phytochemistry
• Natural Products Chemistry
• Pharmacology

Background:

• Plumeria alba is a plant species known for its potential medicinal properties.
• Iridoids are a class of natural compounds with diverse biological activities.
• Nitric oxide (NO) plays a role in inflammation and cancer progression.

Purpose of the Study:

• To isolate and characterize novel iridoid compounds from Plumeria alba.
• To evaluate the inhibitory effects of isolated compounds on nitric oxide production.
• To assess the in vitro cytotoxic activities of these compounds against human cancer cell lines.

Main Methods:

• Isolation of compounds using chromatographic techniques.
• Structure elucidation through comprehensive spectroscopic analyses (NMR, MS).
• X-ray crystallographic analysis for absolute configuration determination.
• In vitro assays to measure nitric oxide production inhibition.
• In vitro cytotoxicity assays against A549, Hela, and MCF-7 cancer cell lines.

Main Results:

• Two new iridoid derivatives, allamancins A and B, and one known derivative, 3-O-methyallamancin, were isolated.
• Allamancin A and 3-O-methyallamancin exhibited significant inhibition of nitric oxide production with IC50 values of 18.3±0.12 μM and 22.1±0.14 μM, respectively.
• Compounds 1-3 displayed moderate inhibitory activity against A549, Hela, and MCF-7 cancer cell lines.

Conclusions:

• Plumeria alba flowers are a source of rare, structurally unique iridoid compounds.
• Allamancins A and 3-O-methyallamancin possess anti-inflammatory potential via NO inhibition.
• The isolated iridoids demonstrate potential as cytotoxic agents against various cancer cell lines, warranting further investigation.