RP-HPLC Analysis of Derivatized Sapogenin of Asparagus)

Full Length Research Paper

High performance liquid chromatographic analysis of derivatized sapogenin of Asparagus (RP-HPLC analysis of derivatized sapogenin of Asparagus)

Jagmohan S. Negi 1*, Pramod Singh 2, Geeta Joshi nee Pant 2 and M. S. M. Rawat 2

1Herbal Research and Development Institute, Mandal-Gopeshwar (Chamoli)-246401, Uttarakhand, India 2Department of Chemistry, HNB Garhwal University, Srinagar (Garhwal)-246 174, Uttarakhand, India.

Accepted 28 September, 2010

RP-HPLC method on C 8 column was investigated for derivatized sapogenin, the marker in Asparagus species using water and acetonitrile as mobile phase in isocratic manner at a flow rate of 0.5 ml/min. The method is sensitive (LOD = 2.02 µg), accurate (average recovery was 98.97%) and precise (intra day variation of RT<0.398, inter day variation of RT<0.982). Quantification was done by UV absorption at 210 nm. Rhizome has maximum concentration of bioactive ranging in between 0.10 to 3.72.

Key words: Asparagus racemosus, A. curillus , RP-HPLC, sarsasapogenin, acetyl sarsasapogenin, quantification.

INTRODUCTION

Asparagus racemosus and A. curillus (family liliacae) Sarsasapogenin, a saturated steroidal genin does not commonly known as Shatavari or Jhirna are wild growing absorb in the λ range 200 to 210 nm, hence this is the first shrubs cultivated in some nurseries of India. These are report of HPLC study of variation of sarsasaoigenin as its distributed in the tropical and subtropical regions and are acetyl derivative in A. racemosus and A. curillus leaves used as aphrodisiac, antiseptic and refrigerant. A. and roots extracts to determine the optimum harvesting racemosus has been reported as antioxidant (Velavan et period. However, HPLC-UV methods for saponins bearing al., 2007; Kamat et al., 2000), immunostimulant, unsaturation have been published using methanol as antihepatotoxic (Muruganandan et al., 2001), antibacterial mobile phase with or without addition of acid or buffer. (Mandal et al., 2000), antioxytocic (Sekine et al., 1997) and HPLC-ELSD (evaporative light scattering detection), reproductive agent (Arora et al., 2005) mainly due to the HPLC-MS (mass spectrometry), and HPLC-RI (refractive presence of steroidal saponins and sapogenins. index) methods have been developed for overcoming the Sarsasapogenin and saponins have been isolated from the detection problem of saponins by UV absorbance. HPLC- aerial part, root and fruits of A. racemosus (Ravikumar et MS and HPLC-ELSD have been largely used for the al., 1987; Ahmad et al., 1991; Sharma et al., 1981), from analysis of saponins in medicinally important plant extracts fruits of A. curillus (Sharma et al., 1982) and A. officinalis such as sarsasapogenin in A. racemosus (Patricia et al., (Pant et al., 1988) and this justifies the interest of 2006) and steroidal saponins in A. officinalis (Kite et al., quantification. Saponins of Asparagus species are usually 2007). Saponins were successfully separated on difficult to be detected by HPLC-UV (accessible UV) due to Spherisorb ODS2, C 18 column in MeCN-H2O gradient lack of strong chromophores and are monitored at lower (Oleszek and Bialy, 2006), C 8, Zorbax carbohydrate, ODS5 UV wavelengths (Kite et al., 2007). column in CH 3CN-H2O isocratic mobile phase and quantified using calibration curves, with detection limits of 50 ng (Gnoatto et al., 2005). This paper reports the concentration level of sarsasapogenin studied in A. *Correspondingauthor. E-mail: [email protected], racemosus and A. curillus in order to bring to focus the [email protected]. quality of crude drug shatavari. Although, HPLC-UV Negi et al. 1901

O O

Acetic anhydride O HO Pyridine H3C C O

Sarsasapogenin Acetyl sarsasapogenin

Figure 1. Preparation of acetyl sarsasapogenin.

determination of benzoyl derivatives of sarsasapogenin in indicator as the stationary phase and hexane: ethylacetate (9:1) as the mobile phase. Sarsasapogenin acetate was crystallized in hexane Rhizoma anemarrhenae have been established (Ying et - - al., 2008) but the acetylation was less time consuming and mp 144-145˚C, IR (cm ) 2929, 2850, 1739, 1460 and 1262; [IR (cm ) 2937, 2919, 2862, 1737, 1467, 1448 and 1227 Lit.] (Askew et al., simple. 1936). The reputed Ayurvedic drug “Shatavari” is prepared from A. racemosus , used in variety of diseases. The potential activities of drug mainly depend on the concentration of Preparation of samples particular component present in it. Therefore, the aim of All dried plant materials were extracted through soxhlet in methanol. this study was to develop a novel HPLC method for the The -OH group of sarsasapogenin is converted into -OCOCH 3 by the determination of sarsasapogenin as its acetylated reaction of dried extracts (5 g) with acetic anhydride (0.025 ml) and derivative in A. racemosus and A. curillus grown in different pyridine (0.201 ml) for six hours at 40°C and the crude extract was altitudes of Uttarakhand, India. dried by rotary evaporator (Kumar et al., 1987). 10 mg dry acetylated extract was dissolved in 10 ml extraction solvent to get 1 mg/ml solution, filtered through 0.25 m syringe filter and injected to Waters HPLC system. MATERIALS AND METHODS

Plant materials RP-HPLC conditions

Aerial parts and roots of A. racemosus and A. curillus were collected HPLC analysis was carried out on Waters 600E, a rheodyne 7725i in four different seasons e.g. April, June, August and October 2008, injection valve with a 20 µl loop, a 486 UV variable wavelength from six different altitudes such as Mandal, cultivated (2000 m), detector (set at 210 nm) sensitivity was 0.001 AUFS using Bondapak Mandal, wild (2200 m), Kasturivihar, cultivated (2500 m), Pokhari, ® 5 µm C (150 × 3.9 mm i.d.) column. The analytes were eluted wild (2200 m), Khirshu, wild (1800 m) and Ukhimatha, wild (1500 m) 8 isocratically at a flow rate of 0.5 ml/min. Chromatograms were of Uttarakhand, India. Authentication was done by Prof. RD Gaur, generated on Empower-2 software. The HPLC instrument was Department of Botany, HNB Garhwal University. operated at room temperature (23 ± 2°C). Each diluted extract 20 µl

was injected in to the HPLC three times and the average peak area

was reported and used for quantification. Chemicals and reagent

Acetonitrile (HPLC grade) was obtained from Merck, deionised water Calibration (Millipore Milli-Q) was produced in laboratory. Sarsasapogenin was isolated from A. officinalis which was characterized previously (Pant The standard solutions of acetyl sarsasapogenin containing 1 to 100 et al., 1988) and was derivatized to acetyl sarsasapogenin. µg/ml were prepared and injected in triplicate into the HPLC reverse

phase column, calibration curves were constructed and their linear

ranges determined. Calibration curves were plotted by the peak area Preparation of standard against concentration of each analytes. The linearity was evaluated

by linear regression analysis. The calibration curve was in good linear 250 mg shatavarin-IV (sarsasapogenin triglycoside) was refluxed with correlation with correlation coefficient 0.9997. The limit of detection 50 ml 2N HCl-MeOH (1:1) on water bath for 5 h, neutralized with (LOD), defined as the lowest detectable amount of analyte was Ag O, filtered. Filtrate was concentrated in vacuo , diluted with water 2 calculated by using the formula, LOD = (b+3 σ )/a where a is the slope and extracted with ethylacetate to afford the aglycone b of the calibration curve, b is intercept and σ is the standard deviation (sarsasapogenin) structure of which was confirmed by Co-TLC, mp b associated with the intercept (Fernand et al., 2008). and IR with standard [mp 200˚C, IR 3400 (OH) 2925 (C-H) 1150 (C- O)]. Acetyl derivative of sarsasapogenin (Figure 1) was prepared by the reaction of sarsasapogenin and acetic anhydride in equimolar ratio in the presence of pyridine, the completion of reaction was Validation monitored by TLC. The product was purified (as it had slight impurity of the parent) by radial chromatography (chromatotron) containing 2 Standard stock solution (100 g/ml) was diluted with extraction mm thick Silica gel, TLC standard grade Silica gel G with fluorescent solvent (water: acetonitrile) to give different concentrations (1, 5, 10, 1902 J. Med. Plant. Res.

Table 1. Linearity study of acetyl sarsasapogenin.

Calibration curve equation Slope Intercept R2 LOD µg RT (RSD %) PA (RSD %) Y=23092x+40362 23092 40362 0.9997 Intra day Y=23722x+42344 23722 42344 0.9997 2.026 0.3984 1.5071 Y=23456x+44492 23456 44492 0.9997

Y=24315x+34548 24315 34548 0.9998 Inter day Y=24317x+42365 24317 42365 0.9995 1.995 0.9821 0.8761 Y=23649x+34923 23649 34923 0.9997

RT=Retention time, PA= Peak area and LOD= Limit of detection.

Table 2. Concentration (in %) of sarsasapogenin in A. racemosus and A. curillus.

Samples I Collection (April) II Collection (June) III Collection (August) IV Collection (October) ArMD (Roots, Cultivated) 1.33 0.62 0.21 0.61 ArMD (Leaves, Cultivated) 0.31 0.36 0.35 0.22 Ar KV (Roots, Cultivated) 1.62 0.19 0.93 1.43 Ar KV (Leaves, Cultivated) 0.54 0.58 0.31 0.42 ArNP (Roots, Wild) 2.96 0.32 0.47 0.44 ArNP (Leaves, Wild) 1.48 2.55 0.1 0.1 ArUM (Roots, Wild) 1.83 2.11 0.67 0.5 ArUM (Leaves, Wild) 1.87 0.84 0.37 0.36 AcKS (Roots, Wild) 1.53 0.39 0.57 1.27 AcKS (Leaves, Wild) 0.56 0.85 0.42 0.98 AcNP (Roots, Wild) 2.55 3.72 0.83 1.3 AcNP (Leaves, Wild) 0.91 0.21 0.57 0.83 AcMD (Roots, Wild) 2.06 0.39 0.84 3.7 AcMD (Leaves, Wild) 0.51 0.38 0.68 0.84

Ar= Asparagus racemosus , Ac= Asparagus curillus MD=Mandal (2000-2250 m), KV=Kasturivihar (2500 m), NP=Nagnath-Pokhari (2200 m), UM=Ukhimatha (1500 m), KS=Khirshu (1800 m).

15, 20 ppm). Intra day (injecting each concentration three times within Several preliminary experiments were conducted to 24 h) and inter day analysis (injecting each concentration three times develop RP-HPLC method for the separation of derivatized over 3 days with each injection separated by at least 24 h) were run sapogenin in Asparagus species by adjusting water, to check reproducibility. The standard deviation (SD) and relative standard deviation (RSD) were calculated shown in Table 1. acetonitrile and λmax to obtain better resolution and Recovery test was used to evaluate the accuracy of the method. detection. Chromatograms were achieved within 15 min for Accurate amounts of acetylsarsasapogenin was added to 10 mg standard and 30 min for Asparagus roots and leaves MeOH extract of Asparagus species and then analysed as samples. extracts by use of mobile phase water: acetonitrile (30:70 The percentage recoveries were determined by the equation [(C3- v/v) at 210 nm. Identification was confirmed by comparison C2)/C1] ×100 where C1 represents the amounts of standard spiked, C2 represents the original amount of marker in extracts and C3 of retention time and quantification by linear regression represents the total (observed) amount of marker in extracts. RSD equation (y=mx+c). Derivatized sarsasapogenin was eluted was determined by the formula, % RSD = (SD/mean) × 100. at 5.2 min. Data obtained on the concentration of bioactive is shown in Table 2. The chromatograms of standard, A. racemosus and A. curillus are shown in Figure 2. RESULTS AND DISCUSSION The LOD obtained for analyte was 2.02 ppm for intra day and 1.99 ppm for inter day analysis. RP-HPLC method was Chromatographic behaviour of acetylated sapogenin of validated by determining relative standard deviation (RSD) Asparagus species in extracts was analyzed by HPLC-UV of inter and intra day analysis. The RSD value for retention on C 8 stationary phase using water: acetonitrile in 30: 70 time and peak areas were 0.398 and 1.50 and 0.982 and (v/v) ratios as mobile phase in isocratic mode. The purpose 0.876 for intra day and inter day analysis, respectively of derivatization of sarsasapogenin to acetyl (Table 1). The recovery test was used to evaluate the sarsasapogenin was to overcome the detection problem. accuracy of the developed method. The recovery of the Negi et al. 1903

0.060

0.050

0.040

AU 0.030

0.020

0.010

0.000

0.10

0.08

0.06 AU

0.04

0.02

0.00

Figure 2. Chromatograms of (a) Standard, (b) A. racemosus and (c) A . curillus root extract.

Table 3. Recovery study of acetyl sarsasapogenin.

Samples Original Spiked Observed Recovery Mean RSD (%) (µg) (µg) (µg) (%) (%) 700 1482 98 796 500 1294 99.6 98.97 0.707 300 1094 99.33

analysis is shown in Table 3. The average recovery % is percentage of bioactive than leaves. Maximum greater than 98% and concentration of acetyl concentration was found in A. curillus (wild) rhizomes sarsasapogenin was in the range of 0.1 to 3.72% in collected from Nagnath-Pokhari (2200 m). Highest Asparagus species (Table 1). The concentration of concentrations of sarsasapogenin in most of the sarsasapogenin varies from site to site and season to Asparagus samples were found in those samples which season. In the samples studied, roots had higher are collected from Mandal (2000 to 2200 m) in June, which 1904 J. Med. Plant. Res.

seems to be appropriate altitude for cultivation and proper Kamat JP, Boloor KK, Devasagayam TPA, Venkatachalam SR (2000). harvesting period is June. Antioxidant properties of Asparagus racemosus against damage induced by gamma-radiation in rat liver mitochondria. J. Ethnopharmacol., 71(3): 425-435. Kite GC, Porter EA, Simmonds MSJ (2007). Chromatographic behaviour Conclusion of steroidal saponins studied by high-performance liquid chromatography-mass spectrometry. J. Chromatogr., A 1148: 177-183. Kumar P, Suman R, Chetty GL, Pandey RC, Sukhdev (1987). Chemistry The analytical method described in this paper is accurate of Aurvedic crude drugs: Part VI a-(Shatavari-I): Structure of Shatavarin- and precise for qualitative and quantitative determination of IV b,c . Indian J. Chem., 26(6): 1012-1017. sarsasapogenin as acetyl sarsasapogenin in Asparagus Mandal SC, Nandy A, Pal M, Saha BP (2000). Evaluation of antibacterial species. This method is accurate, precise and it activity of Asparagus racemosus willd. root. Phytother. Res., 14(2): 118-119. successfully analyzed the crude acetylated extract of Muruganandan S, Garg H, Lal J, Suresh C, Dinesh K (2001). Studies on Asparagus species. Roots had higher concentration of the immunostimulant and anti-hepatotoxic activities of Asparagus bioactive in those samples which were collected in June. racemosus root extracts. J. Med. Arom. Pl. Sci., 22(4A): 49-52. This period seems to be proper harvesting period of Oleszek W, Bialy Z (2006). Chromatographic determination of plant saponins-An update (2002–2005). J. Chromatogr., A 1112(12): 78-91. Asparagus species and proper altitude for cultivation is Pant G, Panwar MS, Negi DS, Rawat MSM, Morris GA (1988). 2000 to 2200 m. Spirostanol glycoside from fruits of Asparagus officinalis . Phytochem., 27: 3324-3325. Patricia YH, Aisyah HJ, Reg L, Kerry P, William K, James JDV (2006). Structure revision of shatavarins I and IV, The major components from ACKNOWLEDGEMENTS the roots of Asparagus racemosus . Tetrahed. Lett., 47: 6965-6969. Ravikumar PR, Soman R, Chetty GL, Sukhdev (1987). Chemistry of The authors are grateful to UCOST Dehradun for providing Ayurvedic crude drugs: Part VI-(Shatavari-I). Structure of Shatavarin- fund (Grant No. UCS&T/R&D/CHEM-05/06-07). Thanks IV. Ind. J. Chem., 26B: 1012-1017. Sekine T, Fukasawa N, Murakoshi I, Ruangrungsi N (1997). A 9,10- are also due to DST New Delhi to provide HPLC facility to dihydrophenanthrene from Asparagus racemosus . Phytochem., 44(4): the department under the FIST programme. 763-764. Sharma SC, Sati OP, Chand R (1981). Constituents of the fruits of Asparagus racemosus Willd. Pharmazie, 36: 709-710. Sharma SC, Sati OP, Chand R (1982). Steroidal constituents of different REFERENCES parts of Asparagus curillus Buch.-Ham. Curr. Sci., 51(6): 280-281.

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