Saw Palmetto
»Saw Palmetto consists of partially dried,ripe fruit of Serenoa repens(Bartram)Small (Fam.Arecaceae)[Serenoa serrulatumSchultes;Sabal serrulata(Michaux)Nichols].
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 contained in the article.
Botanic characteristics—
Macroscopic— Subspherical to ovoid drupes,about 2to 3cm in length and about 1.5cm thick,dark brown to black with a smooth,dull surface and with large,irregular depressions and ridges caused by shrinkage on drying;remains of style at the summit;base bearing a small depression with the scar of the stalk;epicarp and underlying sarcocarp forming a fragile layer that partially peels off,revealing the hard,pale brown layer of endocarp surrounding the seed.Seed irregularly spherical to ovoid,up to about 1.2cm in length and 1cm in width,hard,surface finely pitted and reddish brown with a paler,raised and membranous area over the raphe and micropyle;when cut transversely,it shows a thin testa,a narrow perisperm,and a large area of dense,horny,grayish-white endosperm.
Microscopic— The pulp is covered by a small-celled,thin-walled epidermis and consists chiefly of a very large-celled,mostly thin-walled parenchyma.The outermost layers contain brown substances;farther inside,single cells only with brown contents are scattered in the tissue;occasional large,thick-walled,rather punctate stone cells with a wide lumen are also found.The vascular bundles are accompanied by fibers with cover cells (stigmata)containing siliceous solids attached.The innermost layers of the pulp wall consist of almost completely thickened,rather punctate,quite irregularly shaped stone cells (astrosclereids).The outer layers of the seed coat are large-celled,the cells are coarse-walled;the middle layers are thin-walled,the cells are smaller;the innermost layers are small-celled,flattened.All cells are filled with a brown substance.On the outside,the endosperm exhibits radial elongated,nonpunctate,coarse-walled cells;in the deeper layers,the cells are larger,thick-walled,rather coarse punctate.The middle lamella is fairly recognizable.Aleurone with protein crystalloids is present in the cell contents.
Identification— [NOTE—Perform the following test under subdued light.]
Reagent solution— Transfer 37.0mg of 4-bromomethyl-7-methoxycoumarin to a 10-mLvolumetric flask,dissolve in and dilute with acetone to volume,and mix.Store this solution in a dark place.
Test solution— Transfer 10.0g of finely powdered Saw Palmetto to a 250-mLround-bottom flask fitted with a reflux condenser.Add 150mLof alcohol,and heat under a reflux condenser on a steam bath for 1hour.Cool,filter,wash the residue with alcohol,and dilute the combined washings and filtrate with alcohol to 200.0mL.Transfer 0.6mLof this solution to a suitable flask,and evaporate to dryness.To the residue add 1.0mLof the Reagent solution,and mix.Transfer this solution with the aid of a pipet to an amber glass vial fitted with a metal-clamped rubber cap.Add 3µLof tris-[2-(2-methoxyethoxy)ethyl]amine and 10mg of lithium carbonate to the vial,replace the metal-clamped rubber cap,and dry at 105for 2hours.Cool,and use the cooled solution as the test solution.
Standard solution— Transfer 5.0g of magnesium stearate to a 100-mLround-bottom flask fitted with a reflux condenser.Add 50mLof ether,20mLof 12.5%nitric acid,and 20mLof 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 4mLof water,separating the aqueous phases.Extract the combined aqueous phases with 15mLof ether,combining the ether extracts.Evaporate to dryness,and dry the residue at 105.Transfer 1mg of the residue to an amber glass vial fitted with a metal-clamped rubber cap.Add 10mg of lithium carbonate,3µLof tris-[2-(2-methoxyethoxy)ethyl]amine,and 1.0mg of the Reagent solution,replace the metal-clamped rubber cap,dry at 105for 2hours,and cool.
Blank solution— To 10mg of lithium carbonate in an amber glass vial fitted with a metal-clamped rubber cap,add 3µLof tris-[2-(2-methoxyethoxy)ethyl]amine and 1.0mLof the Reagent solution,replace the metal-clamped rubber cap,dry at 105for 2hours,and cool.
Procedure— Separately apply 2µLeach of the Test solution,the Standard solution,and the Blank solutionto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture,and allow the spots to dry.Develop the chromatograms in a solvent system consisting of a mixture of cyclohexane,ethyl acetate,and acetic acid (70:30:1)until the solvent front has moved about 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 UVlight.The chromatogram of the Test solutionexhibits at least two zones of blue fluorescence corresponding in RFvalues to similar zones exhibited in the chromatogram of the Standard solution.The blue fluorescent zones from the Test solutionappear above the blue fluorescent zones exhibited in the chromatogram of the Blank solution.
Foreign organic matter á561ñ: not more than 2.0%.
Loss on drying á731ñ Dry 1.0g of finely powdered Saw Palmetto at 105for 2hours:it loses not more than 12.0%of its weight.
Total ash á561ñ: not more than 5.0%,determined on 1.0g of finely powdered Saw Palmetto.
Acid-insoluble ash á561ñ: not more than 1.0%.
Heavy metals á231ñ: not more than 0.001%.
Volatile oil content á561ñ: not less than 2mLper 100g of fruits of an oil that solidifies to a white solid at room temperature is obtained.
Pesticide residues á561ñ: meets the requirements.
Microbial enumeration á2021ñ The total bacterial count does not exceed 104cfu per g,the total combined molds and yeasts count does not exceed 100cfu per g,and it meets the requirements of the test for absence of Salmonellaspecies and Escherichia coliand for absence of Staphylococcus aureus.
Content of lipophilic extract— Pulverize about 100g of Saw Palmetto,and transfer 10g,accurately weighed,to a 250-mLround-bottom flask fitted with a reflux condenser,add 150mLof alcohol,and mix.Heat the flask on a boiling water bath under reflux for 1hour.Cool,filter,and wash the residue with small portions of alcohol.Collect the filtrate and washings in a 200-mLvolumetric flask,dilute with alcohol to volume,and mix.Evaporate 100.0mLof this solution to dryness in a rotary evaporator under vacuum.Add 40mLof n-hexane to the residue,stir for 5minutes,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 105for 2hours:the weight of the residue is not less than 0.35g (7%).
Content of fatty acids—
Internal standard solution— Dissolve an accurately weighed quantity of nonadecane in hexanes to obtain a solution having a known concentration of about 12mg per mL.
Standard solution— Dissolve accurately weighed 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 RSin hexanes to obtain a solution having a known concentration of each methyl ester as given below.Transfer 1.0mLof Internal standard solutionto 5.0mLof this solution,and mix.
Methyl ester Concentration (in mg per 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
Test solution— Pulverize about 50g of dried Saw Palmetto to a moderately coarse powder.Transfer an accurately weighed quantity of about 1g of the pulverized powder to a 100-mLround-bottom flask fitted with a water-cooled reflux condenser and a magnetic bar.Add 10mLof 0.5Nmethanolic sodium hydroxide solution (prepared by dissolving 0.2g of sodium hydroxide in 10mLof methanol),and heat the flask with stirring under reflux conditions for 15minutes.Pipet 5mLof a solution of boron trifluoride in methanol (prepared by dissolving 1.4g of boron trifluoride in 10mLof methanol)through the reflux condenser into the flask,and continue boiling for 2more minutes.Add 5.0mLof hexanes through the condenser,and continue boiling for an additional 1minute.Cool the flask,remove the condenser,add about 15mLof saturated sodium chloride solution,and add 1.0mLof the Internal standard solution.While the solution is still tepid,insert a stopper into the flask,and shake vigorously.Pipet 1.0mLof 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 an accurately measured volume of the filtrate with hexanes to obtain a known volume.Store this solution in a refrigerator until just prior to use.
Chromatographic system (see Chromatography á621ñ)—The gas chromatograph is equipped with a flame-ionization detector maintained at 300and a 0.25-mm ×30-m fused silica capillary column coated with a 0.25-µm film of phase G16.The injection port is maintained at 250.The column temperature is initially held at 120for 3minutes,then programmed to rise to 220at the rate of 50per minute,where it is maintained for an additional 12minutes.The carrier gas is helium flowing at a rate of about 1mLper minute.Chromatograph the Standard solution,and record the responses as directed for Procedure:the relative retention times are about 0.39for methyl caproate,0.56for methyl caprylate,0.76for methyl caprate,0.94for methyl laurate,1.0for nonadecane (internal standard),1.1for methyl myristate,1.3for methyl palmitate,1.35for methyl palmitoleate,1.65for methyl stearate,1.7for methyl oleate,1.8for methyl linoleate,and 2.0for methyl linolenate;the resolution,R,between the methyl stearate and methyl oleate peaks is not less than 1.5;the tailing factor for each of the methyl ester peaks in the Standard solutionis not greater than 2.0,and the relative standard deviation for replicate injections for each of the methyl ester peaks is not more than 5.0%.
Procedure— Separately inject equal volumes (about 1µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the peak responses of the fatty acid esters.Calculate the percentage of each fatty acid in the portion of the Saw Palmetto taken by the formula:
in which Cis the concentration,in mg per mL,of the respective methyl ester in the Standard solution,Wis the weight,in mg,of pulverized Saw Palmetto taken to prepare the Test solution,RUand RSare the ratios of the responses of the relevant methyl ester peak and the internal standard peak obtained from the Test solutionand the Standard solution,respectively,andMAandMEare the molecular weights of the relevant fatty acid and its methyl ester,respectively:the percentages of individual fatty acids obtained are not less than 3.0%of oleic and 2.0%of lauric acid,1.2%of myristic acid,1.0%of palmitic acid,0.4%of linoleic acid,0.2%each of caproic acid,caprylic acid,and capric acid,0.1%of stearic acid,0.5%of linolenic acid,and 0.01%of palmitoleic acid.The sum of the percentages of all the fatty acids is not less than 9.0%.
Auxiliary Information— Staff Liaison:Gabriel I.Giancaspro,Ph.D.,Senior Scientist and Latin American Specialist
Expert Committee:(DSB)Dietary Supplements:Botanicals
USP28–NF23Page 2126
Phone Number:1-301-816-8343