Separation and determination of strychnine and brucine in Strychnos nux-vomica L. and its preparation by capillary zone electrophoresis

Effect of detoxification (tadbeer) in content of toxic metabolites of Strychnos nux-vomica: A Unani approach for its use in human

Background:

Azaraqi (Strychnos nux-vomica, Loganiaceae) has been the important Unani medicine since long time as a stimulant, anti-inflammatory, and blood purifier. It has been used very frequently by the Unani practitioner. But the Unani system recommends application of azaraqi in medicine only after its detoxification (tadbeer) may be because of the presence of its deadly poisonous alkaloids (strychnine and brucine). In the present investigation, an attempt has been made to quantify the actual content of their toxic alkaloids before and after the tadbeer.

Materials and Methods:

A sensitive high-performance thin layer chromatographic (HPTLC) method has been developed for estimation of strychnine and brucine in different samples of azaraqi before and after tadbeer. Precoated HPTLC silica gel plates were used as stationary phase and (toluene: Ethyl acetate: Dietylamine 7:2:1 v/v/v) was used as mobile phase.

Result:

The R_f value of strychnine and brucine was found as 0.53 and 0.41, respectively. Detection and quantification were performed by densitometry at 270 nm. The calibration plot was linear in the range of 50–1000 ng of strychnine and brucine, respectively, with the correlation coefficient (r²) 0.993 and 0.991 for strychnine and brucine, respectively, which confirms good linearity. The content of strychnine was 0.175, 0.07, 0.18, 0.051, and 0.075% w/w whereas brucine was 0.16, 0.117, 0.061, 0.045, and 0.057 in crude azaraqi, azaraqi without outer cover, azaraqi outer cover only, azaraqi mudabbar and azaraqi mudabbar by fried in ghee, respectively.

Conclusion:

The detoxification results in sharp decrease in content of toxic metabolites. The process by boiling in milk was found much effective but tedious as compare to frying method.

Simultaneous HPTLC determination of strychnine and brucine in strychnos nux-vomica seed

OBJECTIVE

A simple, sensitive, and specific thin layer chromatography (TLC) densitometry method has been developed for the simultaneous quantification of strychnine and brucine in the seeds of Strychnos nux-vomica.

MATERIALS AND METHODS

The method involved simultaneous estimation of strychnine and brucine after resolving it by high performance TLC (HPTLC) on silica gel plate with chloroform-methanol-formic acid (8.5:1.5:0.4 v/v/v) as the mobile phase.

RESULTS

The method was validated as per the ICH guidelines for precision (interday, intraday, intersystem), robustness, accuracy, limit of detection, and limit of quantitation. The relationship between the concentration of standard solutions and the peak response was linear within the concentration range of 50-1000 ng/spot for strychnine and 100-1000 ng/spot for brucine. The method precision was found to be 0.58-2.47 (% relative standard deviation [RSD]) and 0.36-2.22 (% RSD) for strychnine and brucine, respectively. Accuracy of the method was checked by recovery studies conducted at three different concentration levels and the average percentage recovery was found to be 100.75% for strychnine and 100.52% for brucine, respectively.

CONCLUSIONS

The HPTLC method for the simultaneous quantification of strychnine and brucine was found to be simple, precise, specific, sensitive, and accurate and can be used for routine analysis and quality control of raw material of S. nux-vomica and several unani and ayurvedic formulations containing this as an ingredient.

Rapid and sensitive determination of strychnine and brucine in human urine by capillary electrophoresis with field-amplified sample stacking

A simple, rapid, sensitive and low-cost method using capillary electrophoresis (CE) coupled with field-amplified sample stacking (FASS) has been developed and validated for the simultaneous determination of strychnine and brucine residues in human urine. Before sample loading, a water plug (3.5 kPa, 3 s) was injected to contain sample cations and to permit FASS. Electrokinetic injection at a voltage (20 kV, 25 s) was then used to introduce cations. Separation was performed using 20 mM acetate buffer (pH 3.8) with an applied voltage of 20 kV. The calibration curves were linear over a range of 8.00-2.56 infinity 10(2) ng/mL (r = 0.9995) for strychnine and 10.0-3.20 x 10(2) ng/mL (r = 0.9999) for brucine. Extraction recoveries in urine were greater than 79.6 and 82.8% for strychnine and brucine, respectively, with an RSD of less than 4.9%. The detection limits (signal-to-noise ratio 3) for strychnine and brucine were 2.00 and 2.50 ng/mL, respectively. A urine sample from one healthy female volunteer (26 years old, 50 kg) was pretreated and analyzed. Strychnine and brucine levels in urine could be detected 24 h after administration. On these grounds, this method was feasible for application to preliminary screening of trace levels of abused drugs for both doping control and forensic analysis.

Hollow fiber-based liquid-phase microextraction combined with on-line sweeping for trace analysis of Strychnos alkaloids in urine by micellar electrokinetic chromatography

A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextraction (LPME) based on porous polypropylene hollow fibers combined with on-line sweeping in micellar electrokinetic chromatography (MEKC) was developed. Strychnos alkaloids were first extracted from urine sample which was adjusted to alkaline conditions (0.5 mol l(-1) NaOH). The unionized analytes were subsequently extracted into 1-octanol impregnated in the pores of hollow fibers, and then into an acidic acceptor solution (100 mmol l(-1) H3PO4) inside the hollow fiber. The extract was analyzed directly by on-line sweeping in MEKC. In the method, the compound berberine was used as the internal standard (I.S.) for the improvement of the experimental reproducibility. The calibration curve was linear over a range of 20-200 ng ml(-1) for both strychnine and brucine in human urine sample, with a correlation coefficient of 0.996 and 0.997, respectively. The detection limits (S/N=3:1) for strychnine and brucine were 1 and 2 ng ml(-1), respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine sample, indicating that LPME-sweeping-MEKC is a promising combination for analysis of basic drugs present at low levels in some biological matrices.

Optimization of CZE for analysis of phytochemical bioactive compounds

Advantages of CZE such as high efficiency, low cost, short analysis time, and easy implementation result in its wide applications for analysis of phytochemical bioactive compounds (e.g. flavonoids, alkaloids, terpenoids, phenolic acid, saponins, anthraquinones and coumarins). However, several aspects, including sample preparation, separation, and detection have significant effects on CZE analysis. Therefore, optimization of these procedures is necessary for development of the method. In this review, sample preparation such as extraction method and preconcentration, separation factors including buffer type, concentration and pH, additives, voltage and temperature, as well as detection, e.g. direct and indirect UV detection, LIF and MS were discussed for optimization of CZE analysis on phytochemical bioactive compounds. The optimized strategies were also reviewed.

Analysis of Strychnos alkaloids in traditional Chinese medicines with improved sensitivity by sweeping micellar electrokinetic chromatography

The application of an on-line sweeping preconcentration method in micellar electrokinetic chromatography (MEKC) for the determination of Strychnos alkaloids, namely strychnine and brucine, has been investigated in this work. After experimental optimizations, the best separation was achieved in 50 mmol l(-1) H3PO4 (pH 2.0) containing 100 mmol l(-1) SDS and acetonitrile in a ratio of 4:1 (v/v), with an applied voltage of -20 kV at 20 degrees C. The sample matrix consisted of 100 mmol l(-1) H3PO4 (pH 2.0), and sample introduction was performed at 0.5 psi for 270 s, with photodiode array detection at 203 nm. Compared with the conventional MEKC injection method, up to 100-fold improvement in concentration sensitivity was achieved in terms of peak height by using this sweeping injection technique. In the method, the compound berberine was used as the internal standard for the improvement of the experimental reproducibility. The calibration curve was linear over a range of 0.5-15 microg ml(-1) for both strychnine and brucine, with a correlation coefficient of 0.998 and 0.997, respectively. The detection limits (S/N=3:1) for strychnine and brucine were 0.05 and 0.07 microg ml(-1), respectively. The sweeping-MEKC method has been successfully applied to the analysis of strychnine and brucine in Strychnos nux-vomica L. and its Chinese medicinal preparations.

Separation and determination of strychnine and brucine in Strychnos nux-vomica L. and its preparation by nonaqueous capillary electrophoresis

An easy, rapid method for simultaneous determination of strychnine and brucine in Strychnos nux-vomica L. and its preparation was developed by nonaqueous capillary electrophoresis (NACE) without pretreatment for the first time. Optimum separation was achieved with a fused-silica capillary column (50 cmx75 microm i.d.) and a running buffer containing 30 mM ammonium acetate, 1.0% acetic acid and 15% acetonitrile (ACN) in methanol medium. The applied voltage was 30.0 kV. The analytes were detected by UV at 214 nm. The effects of concentration of ammonium acetate, acetic acid and organic modifier on electrophoretic behavior of the analytes were studied. The established method with sophoridine as internal standard was linear in the range of 5-1000 mg/mL for both strychnine and brucine. The extracts of Strychnos nux-vomica and its preparation could be directly injected for determination with recoveries ranging from 94.5 to 104%.

Rapid separation of strychnine and brucine on a dynamically modified poly(dimethylsiloxane) microchip followed by electrochemical detection

A method has been developed for rapidly separating and detecting strychnine and brucine using a poly(dimethysiloxane) (PDMS) microchip and electrochemical (EC) detection. PDMS microchannels dynamically modified by Brij35 are shown to be more efficient than native ones. The two analytes are well separated within 90 s in 70 mmol/L acetate buffer (pH 5.5) containing 0.01% (v/v) Brij35. Detection limits were found to be 1.0 micromol/L for strychnine and 0.2 micromol/L for brucine at S/N = 3. The method was used to determine trace strychnine and brucine in rat serum, and the results obtained correlate well with those obtained via high-performance liquid chromatography (HPLC).

Capillary electrophoresis with field-enhanced stacking for rapid and sensitive determination of strychnine and brucine

A new capillary electrophoresis procedure with field-enhanced stacking concentration for the analysis of strychnine and brucine is established. After optimization of the separation and concentration conditions, the two alkaloids can be separated within 5 min and quantified with high sensitivity (The detection limits were 1.0 ng mL(-1) for strychnine and 1.4 ng mL(-1) for brucine). The method was useful for qualitative and quantitative analysis of strychnine and brucine in Strychnos nux-vomica L with recovery of 105.1% for strychnine and 98.4% for brucine.

Determination of five toxic alkaloids in two common herbal medicines with capillary electrophoresis

A method was developed for the determination of five highly toxic alkaloids in two commonly used herbal medicines by capillary electrophoresis, which had not been applied to the determination of Aconitum alkaloids before. The buffer contained 40 mM ammonium acetate and 0.1% acetic acid in 80% methanol. Five alkaloids can be determined in 15 min by a single run. The calibration curves showed a linear range from 2 to 200 mg/l for these alkaloids with correlation coefficients (R2) between 0.9988 and 0.9999. Detection limits (SIN = 3) varied from 0.85 to 1.90 mg/l. Recoveries ranged from 95 to 108.8%. The method can provide an effective tool for the strict control of these fetal herbal medicine components.