TITLE:
Pressurized Hot Water Extraction of Alkaloids in Goldenseal
AUTHORS:
Janes Mokgadi, Charlotta Turner, Nelson Torto
KEYWORDS:
Subcritical Water Extraction; Extraction Yields; Degradation; Hydrastine; Berberine
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.4 No.8,
August
9,
2013
ABSTRACT: A quick, efficient and environmentally beneficial
approach for the extraction of alkaloids in goldenseal based on pressurized hot
water extraction (PHWE) is presented. PHWE was evaluated following the
extraction of hydrastine and berberine which are the two main alkaloids of
goldenseal. The effects of temperature and other parameters on extraction
yields were monitored by high performance liquid chromatography coupled to
diode array detector (HPLC-DAD). The extraction yields
were compared to those achieved through reflux and
ultrasonic extraction methods. PHWE employed hot water at an optimal
temperature of 140℃, a pressure of 50 bars and flow rate of 1 mL.min-1 for
extraction experiments conducted in the dynamic mode. Both PHWE and
conventional methods achieved comparable extraction yields. Reflux and
ultrasonic extractions had procedures that were slower (over 6 h) and
employed large quantities (200 mL) of organic solvents. The PHWE method
was simple and relatively fast as extraction was achieved in 15 min. At 95% confidence
level (n = 3), reflux and ultrasonic methods recorded extraction
yields that were not significantly different from that of PHWE. Moreover,
PHWE employed a more readily available “green” solvent, (water) to achieve comparable results to those of conventional methods
which utilized organic solvents. The percentage relative standard deviations
(%RSD) for the extraction yields were less than 3% in all cases indicating the high
reproducibility of the method. However, when using PHWE to extract thermally labile
analytes like alkaloids, degradation effects also occurred. Increasing the
temperatures certainly achieved higher extraction yields but also led to
degradation of these thermally labile compounds indicating a necessity for
optimization.