Powdered Saw Palmetto
DEFINITION
Powdered Saw Palmetto is Saw Palmetto reduced to a fine or a very fine powder. It contains NLT 2% (v/w) of volatile oil, NLT 7% of lipophilic extract, and NLT 9.0% of total fatty acids.
IDENTIFICATION
• A. Thin-Layer Chromatographic Identification Test
[Note—Perform the following test under subdued light. ]
Reagent solution:
3.7 mg/mL of 4-bromomethyl-7-methoxycoumarin in acetone. Store this solution in a dark place.
Standard solution:
5.0 g of magnesium stearate in a 100-mL round-bottom flask fitted with a reflux condenser. Add 50 mL of ether, 20 mL of 12.5% nitric acid, and 20 mL of water, and heat until solution is complete. Cool, transfer the contents of the flask to a separatory funnel, and withdraw the lower aqueous phase. Extract the ether phase twice, each time using 4 mL of water, separating the aqueous phases. Extract the combined aqueous phases with 15 mL of ether, combining the ether extracts. Evaporate to dryness, and dry the residue at 105
. Transfer 1 mg of the residue to an amber glass vial fitted with a metal-clamped rubber cap. Add 10 mg of lithium carbonate, 3 µL of tris-[2-(2-methoxyethoxy)ethyl]amine, and 1.0 mg of the Reagent solution. Replace the metal-clamped rubber cap, dry at 105 for 2 h, and cool.
. Transfer 1 mg of the residue to an amber glass vial fitted with a metal-clamped rubber cap. Add 10 mg of lithium carbonate, 3 µL of tris-[2-(2-methoxyethoxy)ethyl]amine, and 1.0 mg of the Reagent solution. Replace the metal-clamped rubber cap, dry at 105 for 2 h, and cool.
Sample solution:
10.0 g of Powdered Saw Palmetto in a 250-mL round-bottom flask fitted with a reflux condenser. Add 150 mL of alcohol, and heat under a reflux condenser on a steam bath for 1 h. Cool, filter, wash the residue with alcohol, and dilute the combined washings and filtrate with alcohol to 200.0 mL. Transfer 0.6 mL of this solution to a suitable flask, and evaporate to dryness. To the residue add 1.0 mL of the Reagent solution. Transfer this solution with the aid of a pipet to an amber glass vial fitted with a metal-clamped rubber cap. Add 3 µL of tris-[2-(2-methoxyethoxy)ethyl]amine and 10 mg of lithium carbonate to the vial. Replace the metal-clamped rubber cap, dry at 105 for 2 h, and cool. Use the cooled solution.
for 2 h, and cool. Use the cooled solution.
Blank solution:
To 10 mg of lithium carbonate in an amber glass vial fitted with a metal-clamped rubber cap, add 3 µL of tris-[2-(2-methoxyethoxy)ethyl]amine and 1.0 mL of the Reagent solution. Replace the metal-clamped rubber cap, dry at 105 for 2 h, and cool.
for 2 h, and cool.
Chromatographic system
Absorbent:
0.25-mm layer of chromatographic silica gel mixture, typically 20 cm in length (TLC plates)
Application volume:
2 µL
Developing solvent system:
Cyclohexane, ethyl acetate, and acetic acid (70:30:1)
Analysis
Samples:
Standard solution, Sample solution, and Blank solution
Develop the chromatograms in the solvent system until the solvent front has moved three-fourths of the length of the plate. Remove the plate from the chromatographic chamber, mark the solvent front, and allow the plate to air-dry. Examine the plate under long-wavelength UV light.
Acceptance criteria:
The chromatogram of the Sample solution exhibits at least two zones of blue fluorescence corresponding in RF values to similar zones exhibited in the Standard solution. The blue fluorescent zones from the Sample solution appear above the blue fluorescent zones exhibited in the Blank solution.
COMPOSITION
• Articles of Botanical Origin, Volatile Oil Determination 
561
:
NLT 2 mL/100 g of an oil that solidifies to a white solid at room temperature
561:
NLT 2 mL/100 g of an oil that solidifies to a white solid at room temperature
• Content of Lipophilic Extract
Analysis:
Transfer 10 g of Powdered Saw Palmetto to a 250-mL round-bottom flask fitted with a reflux condenser, and add 150 mL of alcohol. Heat the flask on a boiling water bath under reflux for 1 h. Cool, filter, and wash the residue with small portions of alcohol. Collect the filtrate and washings in a 200-mL volumetric flask, and dilute with alcohol to volume. Evaporate 100.0 mL of this solution to dryness in a rotary evaporator under vacuum. Add 40 mL of n-hexane to the residue, stir for 5 min, filter, and collect the filtrate in a round-bottom flask. Repeat the above operation of washing with n-hexane two more times, and collect all of the filtrates in the same flask. Using a rotary evaporator, evaporate off the organic solvent to dryness. Dry the residue obtained at 105 for 2 h.
for 2 h.
Acceptance criteria:
The weight of the residue is NLT 0.35 g (NLT 7%).
• Content of Fatty Acids
Internal standard solution:
12 mg/mL of nonadecane in hexanes.
Standard stock solution:
Dissolve quantities of USP Methyl Laurate RS, USP Methyl Oleate RS, USP Methyl Myristate RS, USP Methyl Palmitate RS, USP Methyl Linoleate RS, USP Methyl Caproate RS, USP Methyl Caprylate RS, USP Methyl Caprate RS, USP Methyl Palmitoleate RS, USP Methyl Stearate RS, and USP Methyl Linolenate RS in hexanes to obtain concentrations of each methyl ester as given in the Table 1.
Table 1
| Methyl Ester | Concentration (mg/mL) |
|---|---|
| Methyl laurate | 5 |
| Methyl oleate | 5 |
| Methyl myristate | 2 |
| Methyl palmitate | 2 |
| Methyl linoleate | 1 |
| Methyl caproate | 0.4 |
| Methyl caprylate | 0.4 |
| Methyl caprate | 0.4 |
| Methyl palmitoleate | 0.4 |
| Methyl stearate | 0.4 |
| Methyl linolenate | 0.4 |
Standard solution:
Transfer 1.0 mL of Internal standard solution to 5.0 mL of Standard stock solution.
Sample solution:
Transfer 1 g of Powdered Saw Palmetto to a 100-mL round-bottom flask fitted with a water-cooled reflux condenser and a magnetic bar. Add 10 mL of 0.5 N methanolic sodium hydroxide solution (20 mg/mL of sodium hydroxide in methanol), and heat the flask with stirring under reflux conditions for 15 min. Pipet 5 mL of a solution of boron trifluoride in methanol (140 mg/mL of boron trifluoride in methanol) through the reflux condenser into the flask, and continue boiling for 2 more min. Add 5.0 mL of hexanes through the condenser, and continue boiling for an additional 1 min. Cool the flask, remove the condenser, add 15 mL of saturated sodium chloride solution, and add 1.0 mL of the Internal standard solution. While the solution is still tepid, insert a stopper into the flask, and shake vigorously. Pipet 1.0 mL of the upper hexanes layer into a glass-stoppered test tube containing a small quantity of anhydrous sodium sulfate. Filter the solution, and, if necessary, dilute a volume of the filtrate with hexanes to obtain a known volume. [Note—Store this solution in a refrigerator until just before use. ]
Chromatographic system
Mode:
GC
Detector:
Flame ionization
Column:
0.25-mm × 30-m fused silica capillary; 0.25-µm film of phase G16 coating
Temperature
Injector:
250
Detector:
300
Column:
See Table 2.
Table 2
| Initial Temperature ( ) |
Temperature Ramp ( /min) |
Final Temperature ( ) |
Hold Time at Final Temperature (min) |
|---|---|---|---|
| 120 | 0 | 120 | 3 |
| 120 | 50 | 220 | 12 |
Carrier gas:
Helium
Flow rate:
1 mL/min
Injection size:
1 µL
System suitability
Sample:
Standard solution
[Note—See Table 3 for the relative retention times. ]
Table 3
| Methyl Ester | Relative Retention Time |
|---|---|
| Methyl caproate | 0.39 |
| Methyl caprylate | 0.56 |
| Methyl caprate | 0.76 |
| Methyl laurate | 0.94 |
| Nonadecane (internal standard) | 1.0 |
| Methyl myristate | 1.1 |
| Methyl palmitate | 1.3 |
| Methyl palmitoleate | 1.35 |
| Methyl stearate | 1.65 |
| Methyl oleate | 1.7 |
| Methyl linoleate | 1.8 |
| Methyl linolenate | 2.0 |
Suitability requirements
Resolution:
NLT 1.5 between methyl stearate and methyl oleate
Tailing factor:
NMT 2.0 for each of the methyl ester peaks
Relative standard deviation:
NMT 5.0% for each of the methyl ester peaks
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of each fatty acid in the portion of the Powdered Saw Palmetto taken:
Result = (RU/RS) × (CS × V) × (1/W ) × (Mr1/Mr2) × 100
| RU | = | = peak response ratio of the relevant methyl ester to the internal standard obtained from the Sample solution |
| RS | = | = peak response ratio of the relevant methyl ester to the internal standard obtained from the Standard solution |
| CS | = | = concentration of the respective methyl ester in the Standard stock solution (mg/mL) |
| V | = | = volume of the Standard stock solution used to prepare the Standard solution (mL) |
| W | = | = weight of Powdered Saw Palmetto taken to prepare the Sample solution (mg) |
| Mr1 | = | = molecular weight of the relevant fatty acid |
| Mr2 | = | = molecular weight of the methyl ester of the relevant fatty acid |
Acceptance criteria:
NLT 9.0% for the sum of the percentages of all the fatty acids. See Table 4 for individual fatty acids.
Table 4
| Individual Fatty Acids |
Percentages (%) |
|---|---|
| Oleic acid | NLT 3.0 |
| Lauric acid | NLT 2.0 |
| Myristic acid | NLT 1.2 |
| Palmitic acid | NLT 1.0 |
| Linoleic acid | NLT 0.4 |
| Caproic acid | NLT 0.2 |
| Caprylic acid | NLT 0.2 |
| Capric acid | NLT 0.2 |
| Stearic acid | NLT 0.1 |
| Linolenic acid | NLT 0.05 |
| Palmitoleic acid | NLT 0.01 |
CONTAMINANTS
• Heavy Metals 231:
NMT 10 µg/g
231:
NMT 10 µg/g
• Articles of Botanical Origin, Pesticide Residues 561:
Meets the requirements
561:
Meets the requirements
• Microbial Enumeration Tests 2021:
The total bacterial count does not exceed 104 cfu/g, and the total combined molds and yeasts count does not exceed 102 cfu/g.
2021:
The total bacterial count does not exceed 104 cfu/g, and the total combined molds and yeasts count does not exceed 102 cfu/g.
• Absence of Specified Microorganisms 2022:
It meets the requirements of the test for absence of Salmonella species and Escherichia coli and for absence of Staphylococcus aureus.
2022:
It meets the requirements of the test for absence of Salmonella species and Escherichia coli and for absence of Staphylococcus aureus.
SPECIFIC TESTS
• Loss on Drying 731:
Dry 1.0 g of Powdered Saw Palmetto at 105 for 2 h: it loses NMT 12.0% of its weight.
731:
Dry 1.0 g of Powdered Saw Palmetto at 105 for 2 h: it loses NMT 12.0% of its weight.
• Articles of Botanical Origin, Total Ash 561:
NMT 5.0%, determined on 1.0 g of Powdered Saw Palmetto
561:
NMT 5.0%, determined on 1.0 g of Powdered Saw Palmetto
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers, protected from light.
• Labeling:
The label states the Latin binomial and, following the official name, the part of the plant source from which the article was derived.
• USP Reference Standards 11
11
USP Methyl Caprate RS
USP Methyl Caproate RS
USP Methyl Caprylate RS
USP Methyl Laurate RS
USP Methyl Linoleate RS
USP Methyl Linolenate RS
USP Methyl Myristate RS
USP Methyl Oleate RS
USP Methyl Palmitate RS
USP Methyl Palmitoleate RS
USP Methyl Stearate RS
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Maged H. Sharaf, Ph.D.
Principal Scientific Liaison 1-301-816-8318 |
(DS2010) Monographs - Dietary Supplements |
| 2021 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison 1-301-816-8339 |
(GCM2010) General Chapters - Microbiology |
| 2022 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison 1-301-816-8339 |
(GCM2010) General Chapters - Microbiology |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 1433