Determination of Triterpenes in Centella asiatica (Gotu Kola) by HPLC-CAD

Significance of the Topic

Centella asiatica, commonly known as gotu kola, contains ursane- and oleanane-type triterpenes with reported memory, circulatory and wound-healing benefits. Reliable quantitation of these nonchromophoric analytes in herbal extracts is essential for quality control and standardization in pharmaceutical and nutraceutical applications.

Objectives and Study Overview

This work compares low-wavelength UV and charged aerosol detection (CAD) for triterpene analysis by reversed-phase HPLC. The study aims to demonstrate CAD’s improved baseline stability and reduced coelution interferences, and to apply the method for quantifying six key triterpenes in a gotu kola extract.

Methodology and Instrumentation

The HPLC method employs a Fused-Core C18 column (3.0×100 mm, 2.7 μm) and a gradient of 0.1% formic acid in water (A) and acetonitrile (B). Key parameters:

• System: Thermo Scientific Dionex Summit (P680 pump, ASI-100 autosampler, TCC-100 compartment) or UltiMate 3000 equivalent
• Detector: Thermo Scientific Corona CAD
• Gradient: 18%–22% B (0–8 min), 22%–45% B (8–17 min), 45%–80% B (17–23 min)
• Flow rate: 0.64 mL/min; column temp: 35 °C; injection: 5 µL
• Sample prep: ~250 mg extract in 100 mL methanol, sonicate, filter (0.2 µm PTFE)
• Calibration: six serial dilutions of triterpene standards in methanol, with quadratic fits; cross-quantitation for coeluting pairs

Main Results and Discussion

CAD provided a flat, stable baseline and resolved major triterpenes without UV-absorbance interferences. Overlayed chromatograms show that UV detection suffered from rising baselines and coelution of UV-active impurities, particularly around high-polarity glycosides. CAD calibration showed excellent linearity and reproducibility. Quantified triterpene content in the extract:

• Asiaticoside B: 5.67 %
• Madecassoside: 13.4 %
• Asiaticoside: 10.7 %
• Madecassic acid: 1.147 %
• Terminolic acid: 0.744 %
• Asiatic acid: 0.908 %
• Total triterpenes: 32.6 %

Benefits and Practical Applications

Charged aerosol detection enhances quantitation of nonchromophoric compounds by eliminating low-wavelength UV limitations. The method supports robust quality control of herbal preparations, standardization of bioactive triterpene levels, and routine compliance testing in pharmaceutical and nutraceutical industries.

Future Trends and Potential Uses

Further integration of CAD with mass spectrometry could expand compound identification and trace-level detection. Advances in column technologies and green solvents will streamline workflows. Automation and chemometric data processing promise faster method development and real-time quality monitoring in process analytical technology (PAT).

Conclusion

The HPLC-CAD approach offers superior baseline stability and reduced interferences compared to UV detection for triterpene analysis in Centella asiatica. This reliable, quantitative method delivers accurate profiling of bioactive triterpenes, facilitating quality assurance in natural product research and manufacturing.