Improvisation of a spectrophotometric method to quantify hydroxycitric acid.

Area of Science:

• Analytical Chemistry
• Biochemistry

Background:

• The existing spectrophotometric method for hydroxycitric acid (HCA) quantification is limited by the poor stability of the HCA-metavanadate complex.
• Hydroxycitric acid (HCA) is a valuable compound, and efficient methods for its quantification are needed, particularly for screening microbial producers.

Purpose of the Study:

• To improve the stability and reliability of the spectrophotometric method for HCA quantification.
• To adapt the method for high-throughput screening of microorganisms that produce HCA.

Main Methods:

• The HCA-metavanadate assay system was modified by adding 1 M NaOH to neutralize acidity, enhancing complex stability.
• The Beer-Lambert law was validated for the modified assay within a concentration range of 33–677 μg/ml, with a coefficient of determination (R² = 0.998).
• Interference from tartrate was addressed by establishing a correction factor.

Main Results:

• The modified HCA-metavanadate complex exhibited enhanced stability, retaining up to 70% absorbance after 60 minutes.
• The optimized method demonstrated a linear calibration curve and was suitable for high-throughput screening.
• HCA levels measured in bacterial culture supernatant using the proposed method closely matched those determined by HPLC.

Conclusions:

• The revised spectrophotometric procedure offers a convenient, sensitive, accurate, and high-throughput method for primary screening of HCA-producing microbes.
• This optimized method provides an efficient way to identify microbial sources of optically pure hydroxycitric acid.