Source and Occurrence
Artemisinin is a sesquiterpene lactone containing a peroxide bridge, isolated from the sweet wormwood plant (Artemisia annua).
It is renowned for its potent antimalarial properties.
Isolation of Artemisinin
Extraction:
Solvent Extraction: Dried and powdered Artemisia annua leaves are subjected to extraction using solvents like ethanol or dichloromethane.
Purification:
Liquid-Liquid Extraction: Separates artemisinin from other components based on solubility differences.
Chromatography:
Column Chromatography: Utilizing silica gel or reverse-phase columns to isolate artemisinin.
High-Performance Liquid Chromatography (HPLC): For higher purity levels.
Crystallization:
Precipitation of artemisinin by altering solvent conditions, followed by filtration and drying.
Identification
Physical Properties:
Appearance: White crystalline solid.
Melting Point: Decomposes before melting.
Solubility: Soluble in chloroform, ether, and other organic solvents; insoluble in water.
Spectroscopic Techniques:
IR Spectroscopy: Detects functional groups, especially the characteristic peroxide bridge (~800 cm⁻¹).
NMR Spectroscopy:
¹H NMR: Confirms the presence of specific hydrogen environments.
¹³C NMR: Provides detailed carbon framework information.
Mass Spectrometry: Molecular ion peak at m/z 282.4.
Chromatographic Techniques:
HPLC: Confirms purity and quantifies artemisinin content.
GC-MS: Sometimes used but can cause decomposition due to high temperatures.
Analysis
Quantitative Analysis:
HPLC with UV Detection: Standard method for quantifying artemisinin levels.
Spectrophotometry: Less common due to specificity issues.
Quality Control:
Ensuring the absence of impurities that could affect efficacy.
Verifying structural integrity via spectroscopic data.
Applications and Significance
Artemisinin is a cornerstone in antimalarial therapy, especially against Plasmodium falciparum.
Its derivatives, such as artesunate and artemether, are critical in combination therapies to prevent resistance.