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- Saw Palmetto (Serenoa repens, Arecaceae)
- Benign Prostatic Hyperplasia
- Extraction Methods
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Date:
06-30-2015 | HC# 121443-523
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Re: Impact of Extraction Techniques on the Profiles and Efficacy of Saw Palmetto Used to Treat Urinary Tract Symptoms
De Monte C, Carradori S, Granese A, Di Pierro
GB, Leonardo C, De Nunzio C. Modern extraction techniques and their impact on
the pharmacological profile of Serenoa
repens extracts for the treatment of lower urinary tract symptoms. BMC Urol. August 11, 2014;14:63. doi: 10.1186/1471-2490-14-63.
Symptomatic benign prostatic hyperplasia
(BPH), the most common urologic disorder among elderly men, rises in prevalence
with increasing age, and affects about 25% of men in their 50s (50% of those in
their 80s). Slow-progressing BPH may cause bladder prostatic obstruction (BPO) and
lower urinary tract symptoms (LUTS). To manage LUTS, it is desirable to keep
symptoms from worsening by limiting disease progression. Treatment options
include α1-adrenoceptor antagonists, 5α-reductase inhibitors, anti-cholinergic
agents, phosphodiesterase 5 inhibitors, and plant extracts (PEs). The first two
may contribute to sexual dysfunctions. Although use of PEs is rising,
especially noted in Belgium, Hungary, Poland, and France, the European
Association of Urology cannot recommend specific products for LUTS-BPH due to product
heterogeneity and subsequent methodological problems in meta-analysis.
The most popular PEs for BPH are from saw
palmetto (Serenoa repens, Arecaceae),
with constituents found to inhibit 5α-reductase and exert pro-apoptotic, anti-estrogenic, and anti-inflammatory effects. As in many plants, amounts of
therapeutic compounds in saw palmetto are low. Exhaustive extraction provides maximum amounts. Extraction processes should be reproducible, time-saving, and
eco-friendly. Thermolability is an issue with many phytochemicals; hence,
extraction temperatures and other conditions should be optimized. Qualitative
and quantitative variances among BPH saw palmetto products are caused in part
by different extractive processes used in manufacturing and may affect clinical
results. This study aimed to evaluate available evidence on extraction methods
and possible clinical implications for saw palmetto products.
Although pharmacological profiles for saw
palmetto's active compounds are not yet fully described, standard reference
materials (SRMs) for some dietary supplements, prepared by the National
Institutes of Health's Office of Dietary Supplements, the Food and Drug Administration's (FDA) Center for Drug Evaluation and Research, and the National Institute of Standards and Technology (NIST), include two saw palmetto
SRMs. SRM 3250 is ground saw palmetto fruit. SRM 3251 is a supercritical CO2
saw palmetto extract (SPE). Each has certified concentration values (CCVs) for
specific phytosterols and fatty acids, free or as triglycerides; these are
higher in SRM 3251. SRM 3251 also has CCVs for β-carotene and its isomers and
for γ- and δ-tocopherol. The authors extracted SRM 3250 with several extracts
under various conditions, finding that for pressurized fluid extraction (PFE),
the choice of solvent, extraction temperature, and extraction pressure had
little effect on the composition of extracted fractions; for Soxhlet
extraction, solvent choice was of little importance but extraction time (at
least 40 hours) was critical for efficiency. Fatty acids as triglycerides were six
to 25 times higher in SRM 3251 than any SRM 3250 extract. Concentration of each
fatty acid triglyceride was generally higher than its corresponding free fatty acid
extract in either SRM. SRM 3250 had about one-sixth of the linoleic and
α-linolenic acid as SRM 3251; the latter has one of the highest concentrations
of linoleic acid triglycerides of any SRM, including fish oil, and the highest
of α-linolenic acid.
In a database search, the authors found 12 studies
of ten SPE products made with four extraction methods (for two products,
extraction method was not reported), reviewing them for information about bioactive compounds and clinical effects. Two products were multi-herbal. Studies are not described in detail and were not evaluated for quality, and it is
unclear whether all products have been fully characterized. Only one study directly
compared pharmacological profiles associated with different extraction methods —
a hexanic SPE product inhibited MCP-1/CCL2 messenger RNA (mRNA) expression in a
concentration-dependent manner not seen in an SPE made with supercritical CO2
extraction using batches of the same plant. Studies differed markedly in
product or extract type, design, and results reported, making comparison
difficult. One study compared a product's activity in rats with a bovine
prostate peptide complex. While each showed benefits, response to the SPE
product was more targeted. Research on several products is either ongoing or
promising and suggestive of follow-up studies.
The authors describe extraction techniques
that could be used to boost concentrations of active compounds in SPEs; most
have apparently not been used nor evaluated for clinical performance.
These include microwave-assisted extractions of several types, ultrasonic-assisted
extraction, ionic liquid extraction, and enzyme-assisted extraction.
Pressurized liquid/fluid extraction – a novel, eco-friendly method of
phytochemical extraction – is mentioned, but the authors do not state whether
it has been used for SPEs or for any of the products discussed. On the other
hand, one of those products is made with an oily extract; this technique is not
discussed. Of eight products reporting extraction method used, six used solvents,
with five of those using ethanol at different concentrations and one using
hexane; two used supercritical CO2.
While it may be possible, as these authors
have attempted, to compare different plant extracts, link different levels of
bioactive compounds in different extracts to specific effects, and eventually
standardize therapeutic compounds to best address specific conditions, the
research base for this effort does not yet exist for SPEs.
—Mariann
Garner-Wizard
Peer Review Comments:
The
validity of the reviewed results on the product PC-SPES, a blend of eight
herbs, is questionable. Firstly, the original experiments were performed using a
70% ethanol extract of PC-SPES, where the authors claimed this process isolated
saw palmetto from the eight-herb mixture,1 which is physically
impossible and not supported by any chemical analysis. Secondly, batches of PC-SPES had been found to contain pharmaceutical adulterations, and the product
was recalled by the FDA in 2002.2 However, PC-SPES may still be sold
in other countries such as China where the original study was performed in
2007.
References
1Yang Y, Ikezoe T,
Zheng Z, Taguchi H, Koeffler HP, Zhu WG. Saw palmetto induces growth arrest and
apoptosis of androgen-dependent prostate cancer LNCaP cells via inactivation of
STAT 3 and androgen receptor signaling. Int
J Oncol. 2007;31(3):593-600.
2National Cancer
Institute. PC-SPES – for health professionals (PDQ®). Bethesda, MD:
National Cancer Institute. http://www.cancer.gov/cancertopics/pdq/cam/pc-spes/HealthProfessional/page1.
Updated May 22, 2015. Accessed June 18, 2015.
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