Local production of 5-HTP from the seeds of griffonia simplicifolia
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Date
2009-07-12
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Abstract
Griffonia simplicifolia is a stout, woody, climbing shrub growing to about 3m with
greenish flowers and inflated black pods. The seeds contain substantial quantities of the
amino acid, 5-hydroxytryptophan (5-HTP). Today, the seed of this climbing shrub is used
in the treatment of fibromyalgia, headaches, insomnia, depression and stomach
problems.
Griffonia seeds continue to be exported from Ghana. Therefore it was considered prudent
to develop a simple method of production of 5-HTP from the seeds of Griffonia in
reasonable purity prior to export. This will add value to the export.
This project, is to develop enhanced extraction and purification methods in the
production of 5-HTP from the seeds of Griffonia simplicifolia. In addition, the kinetics of
the degradation of the 5-HTP obtained was studied in order to predict the most the stable
conditions of storage prior to export.
Griffonia seeds that had been harvested and stored for 10 months were used for the
project. The solvent system used for all extractions was water- methanol (50-50). This
has been determined to be the optimum solvent for the extraction (Lemaire and Adosraku
2002).
The amount of 5-HTP present in the seeds was determined by High Pressure Liquid
Chromatography. Using the HPLC method for the direct assay of 5-HTP from the seeds
of Griffonia developed by Lemaire and Adosraku, the content of the seeds was found to
be 6.37 %w/w. However, a modified method which employs the use of solvent at 80 °C
gave 5-HTP content of 8.98 %w/w.
The effect of varying conditions on the extraction of 5-HTP from the seeds was
investigated. The conditions investigated were temperature of extracting solvent, volume
of extracting solvent and the particle size of the powdered seeds. In all instances, the
amount of 5-HTP extracted was determined by HPLC using pure 5-HTP as reference.
Generally it was observed that an increase in the temperature and volume of solvent
provided an increase in yield of 5-HTP extracted. A reduction in particle size of the
powdered seeds by crushing the seeds, also increases the amount of 5-HTP extracted. A
combination of the effects of the above factors was found to yield the highest amount of
5-HTP.
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The optimum solvent composition for the recrystallisation of the extracted 5-HTP
crystals was also investigated. The limitation here is that the solvents used must nontoxic
and readily available in Ghana. Thus, various compositions of water and ethanol
were used to recrystallise the 5-HTP. The composition found to be useful was waterethanol
(20-80). Using this solvent mixture, 5-HTP was obtained as approximately 92%
pure. The percentage yield of 5-HTP(92% pure) was 6.14 %w/w of seed taken.
The purified 5-HTP crystals were subjected to stability studies, assuming first order
kinetics. The rate constant for the degradation was 1.059 E-03 day-1 at refrigerator
temperature (approx. 5°C) as compared to 1.195 E-03 day-1 for that kept at room
temperature. The t90 values for refrigerator temperature and room temperature were 99.62
days and 88.28 days respectively. The difference in shelf life was thus 11 days. This is
considered economically not significant considering the cost of refrigeration.
The ether insoluble constituents of the aqueous- methanolic seed extract were separated
using preparative thin layer chromatography and studied. Two constituents apart from 5-
HTP were isolated. One of the constituents is postulated to be amino methoxy indole-3-
acetic acid from the spectroscopic data obtained. The other constituent could not be
identified with certainty and further work will have to be done.