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Planta Med 2013; 79(12): 1081-1083
DOI: 10.1055/s-0032-1328713
Analytical Studies
Letters
Georg Thieme Verlag KG Stuttgart · New York

Trace Metals Accumulation in Bacopa monnieri and Their Bioaccessibility

Rama Venkata Srikanth Lavu
1   Laboratory of Analytical Chemistry and Applied Ecochemistry, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
,
Majeti Narasimha Vara Prasad
2   Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, India
,
Varalakshmi Lalithya Pratti
1   Laboratory of Analytical Chemistry and Applied Ecochemistry, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
5   Laboratory of Microbial Ecology and Technology, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
,
Ralph Meißner
3   UFZ – Helmholtz Centre for Environmental Research, Department of Soil Physics, Lysimeter Station, Falkenberg, Germany
,
Jörg Rinklebe
4   Institute for Soil Engineering, Water- and Waste-Management, Department D, Civil Engineering, University of Wuppertal, Wuppertal, Germany
,
Tom Van De Wiele
5   Laboratory of Microbial Ecology and Technology, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
,
Filip Tack
1   Laboratory of Analytical Chemistry and Applied Ecochemistry, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
,
Gijs Du Laing
1   Laboratory of Analytical Chemistry and Applied Ecochemistry, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
› Author Affiliations
Further Information

Correspondence

Rama Venkata Srikanth Lavu
Laboratory of Analytical Chemistry and Applied Ecochemistry, Faculty of Bioscience Engineering, Ghent University
Coupure Links 653
9000 Gent
Belgium
Phone: +32 92 64 59 95   
Fax: +32 32 92 64 62 32   

Publication History

received 11 November 2012
revised 29 May 2013

accepted 30 May 2013

Publication Date:
03 July 2013 (online)

Also available at
 
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Abstract

Bacopa monnieri is commonly known as “Brahmi” or “Water hyssop” and is a source of nootropic drugs. Aboveground parts of plant samples collected from peri-urban Indian areas were analysed for total trace metal concentrations. Subsequently, three samples with high concentrations of Cd and Pb were subjected to in vitro gastrointestinal digestion to assess the bioaccessibility of the trace metals in these plants. The total concentrations of trace metals on a dry weight basis were 1.3 to 6.7 mg · kg−1 Cd, 1.5 to 22 mg · kg−1 Pb, 36 to 237 mg · kg−1 Cu, and 78 to 186 mg · kg−1 Zn. The majority of Bacopa monnieri samples exceeded threshold limits of Cd, Pb, Cu, and Zn for use as raw medicinal plant material or direct consumption. Therefore, it is necessary to evaluate Bacopa monnieri collected in nature for their trace metal content prior to human consumption and preparation of herbal formulations.


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Key words

Bacopa monnieri - Scrophulariaceae - bioaccessibility - brain tonic - herbal drug - toxic metals

Bacopa monnieri (BM) Scrophulariaceae (water hyssop, water purslane) has drawn attention in various national and international markets as a raw material for nootropics. It has also been used for its anticonvulsant and antihyperglycaemic activity, and antioxidants that are effective for irritable bowel [1], [2], [3]. It grows in the wild preferentially on wet or marshy lands, on the margins of dirty drainage channels or sewage pools, and is reported to accumulate from low to high levels of toxic metals [4], [5]. Metals in food crops and medicinal products may affect the health of humans consuming them when exceeding their limits [6], [7]. However, the toxicity of trace metals in food and herbal medicines in humans depends not only on their total concentrations, but also on their bioaccessibility, i.e., their release from their matrix into the gastrointestinal tract during digestion [8]. Therefore, the objective of our study was to investigate samples of BM for their trace metal content in the aboveground plant part and to assess the bioaccessibility of the trace metals in these samples.

The plants markedly differed in total metal content depending on the sampling location ([Table 1]). All BM samples for Cd (0.3 mg · kg−1) and two samples for Pb (10 mg · kg−1) in raw medicinal plant material concentrations were above the permissible limit [9]. Notably, in all BM samples, the concentrations of Zn and Cu exceeded the permissible levels for herbal products (50 and 20 mg · kg−1, respectively) [10]. The concentration of Fe ranged between 153 and 1863 mg · kg−1 and Mn ranged between < 16 and 115 mg · kg−1 ([Table 1]). Only three BM samples had Mn concentrations above the detection limit of ICP-OES. However, the tolerable daily intake of Cd (60 µg/day) and Pb (250 µg/day) was not exceeded in any of the samples if a dose of 5 g BM per day would be consumed ([Table 2]) [11], [12].

Table 1 Trace metal content in BM samples collected from 13 locations (expressed in mg · kg−1 dry weight).

Sample ID

Cu

Fe

Mn

Zn

Cd

Pb

1

36.1

228

< 16

82.6

1.8

4.3

2

57.2

387

< 16

100.7

2.3

5.0

3

63.4

384

< 16

90.4

2.3

5.2

4

237.1

1863

115.20

186.2

6.7

21.7

5

103.8

842

76.46

126.0

3.4

10.8

6

42.1

157

< 16

92.6

1.8

1.5

7

63.7

401

68.15

93.3

2.5

6.4

8

50.1

256

< 16

78.0

2.1

4.5

9

38.0

153

< 16

91.9

1.3

2.0

10

46.4

243

< 16

102.9

2.0

2.6

11

48.5

270

< 16

107.5

1.7

2.6

12

59.9

333

< 16

108.0

2.4

3.3

13

53.0

295

< 16

120.3

1.8

3.8

Table 2 Calculated intake of trace metals through the consumption of a dose of 5 g dry BM powder per day (µg/day).

Sample ID

Intake (µg/day)

Cu

Fe

Mn

Zn

Cd

Pb

1

181

1140

< 80

413

9.0

21.5

2

286

1933

< 80

503

11.5

25.0

3

317

1919

< 80

452

11.5

26.0

4

1186

9313

576

931

33.5

108.5

5

519

4209

382

630

17.0

54.0

6

210

782

< 80

463

9.0

7.5

7

319

2004

341

467

12.5

32.0

8

251

1280

< 80

390

10.5

22.5

9

190

764

< 80

460

6.5

10.0

10

232

1215

< 80

515

10.0

13.0

11

243

1352

< 80

538

8.5

13.0

12

299

1666

< 80

540

12.0

16.5

13

265

1475

< 80

601

9.0

19.0

The bioaccessibility of Cd and Pb was found to be lower compared to other herbal medicinal plants which were reported earlier [8]. Remarkably, the bioaccessibility of Cd and Pb was found to be lower in the intestinal phase compared to the gastric phase ([Table 3]). Similar trends were observed for Amaranthus spinosus (ASL), and spruce needle and sea lettuce reference materials ([Table 3]). In the gastric phase, the bioaccessibility of Cu was found to be lower compared to the bioaccessibility of Zn ([Table 3]). However, a significant increase of Cu bioaccessibility was observed in the small intestine, whereas it decreased for Zn. This may be due to precipitation or readsorption reactions that may occur with increasing pH in the intestinal phase. Similar bioaccessibilities were observed for Zn and Cu in the reference material and ASL. However, the bioaccessibility of these trace metals could differ in the presence of other food matrices [13], [14]. Among the analysed trace metals assessed for bioaccessibility, Fe was found to be lower compared to the other trace metals ([Table 3]). Manganese showed a higher bioaccessibility in BM (up to 82.3 ± 2.6 % in the gastric phase) compared to its bioaccessibility in ASL (62.3 ± 1.1 % in the gastric phase) and other trace metals in BM, but lower compared to spruce needles reference material (92.2 ± 1.3 % in the gastric phase) ([Table 3]).

Table 3 Bioaccessibility of trace metals in gastric and small intestine phases (% of total).

Digestion phase

Sample

Cu

Fe

Mn

Zn

Cd

Pb

S.I.: small intestine, BM: Bacopa monnieri, ASL: Amaranthous spinosus, SL: sea lettuce BCR (279), SN: spurce needles BCR (101), NR: reference material not validated for this element, NS: not quantified; data represented are mean ± SD (n = 3)

Gastric

BM1

16.4 ± 1.2

8.8 ± 0.5

NS

40.2 ± 0.6

39.3 ± 2.3

16.9 ± 1.0

BM 2

15.7 ± 0.2

3.8 ± 0.0

68.7 ± 0.1

27.0 ± 0.4

35.4 ± 0.2

10.5 ± 0.1

BM 3

19.7 ± 1.5

5.8 ± 0.3

82.3 ± 2.6

33.4 ± 0.2

38.5 ± 2.0

12.1 ± 0.5

ASL1

28.1 ± 0.8

11.0 ± 0.3

55.1 ± 0.6

56.7 ± 0.6

24.6 ± 0.3

9.5 ± 0.3

ASL 2

11.3 ± 1.0

7.0 ± 0.2

61.0 ± 1.3

74.9 ± 6.4

27.2 ± 1.1

6.7 ± 0.1

ASL 3

22.1 ± 0.6

10.5 ± 0.3

62.3 ± 1.1

61.2 ± 1.0

29.4 ± 1.3

12.0 ± 0.5

SL

42.5 ± 0.3

NR

NR

56.9 ± 0.8

47.7 ± 0.5

1.1 ± 0.2

SN

NR

NR

92.2 ± 1.3

< 21

NR

NR

S. I.

BM1

39.9 ± 4.5

ND

NS

17.4 ± 1.0

23.0 ± 1.9

9.9 ± 0.5

BM 2

42.7 ± 1.9

2.9 ± 0.2

28.9 ± 0.1

7.8 ± 0.4

17.3 ± 2.6

5.3 ± 0.9

BM 3

51.6 ± 5.4

2.6 ± 0.2

31.4 ± 0.2

11.0 ± 0.4

19.7 ± 1.3

6.4 ± 0.5

ASL1

44.7 ± 0.5

7.0 ± 0.2

38.3 ± 1.2

21.4 ± 0.3

17.8 ± 0.4

7.1 ± 0.1

ASL 2

14.7 ± 1.7

3.7 ± 0.1

33.8 ± 1.2

< 21

13.7 ± 1.4

3.4 ± 0.4

ASL 3

33.8 ± 3.7

6.7 ± 0.4

41.9 ± 0.4

21.8 ± 1.5

19.7 ± 0.9

8.4 ± 0.6

SL

45.7 ± 23.1

NR

NR

< 21

22.6 ± 8.2

0.6 ± 0.5

SN

NR

NR

42.5 ± 0.2

< 21

NR

NR

Materials and Methods

Samples were collected from the wild from 13 different locations in the Krishna District, Andhra Pradesh, India. The plants were identified by Prof. M. N. V. Prasad with the help of available literature and herbaria. A voucher specimen (UH62011) is kept in the University of Hyderabad Herbarium (Acronym – “UH”), which is recognised by Kew (UK) and New York (US) Botanic Gardens. The locations were selected on the basis of relative abundance of the plants and easy accessibility of the location (Fig. 1S a–c in Supporting Information). For determination of total trace metals in the BM samples, the plant parts were pooled and air-dried. A subsample of 0.5 g was weighed and transferred to Teflon tubes and digested with 10 mL ultrapure 65 % HNO3 in a microwave digestion system (Mars). The temperature was raised to 165 °C for 15 min at 1200 Watts and 60 % power with pressure maintained at 85 psi. Afterwards, the temperature was kept at 195 °C for 20 min at 1200 Watts and 70 % power with pressure maintained at 120 psi. The digests were then transferred into a 100-mL volumetric flask and diluted to the mark with deionised water. Microwave digestion was previously found to be efficient in extracting trace metals from botanical and dietary supplements. For validation of the microwave digestion procedure, certified reference plant material BCR-CRM 279 and 101 (sea lettuce and spruce needles) were digested using the same procedure. The accuracy of the analytical method for Fe was checked by spiking a known amount of Fe to the samples with an obtained recovery of 96 ± 3 %. For assessment of the bioaccessibility, a powdered sample (0.5 g) was transferred into 100 mL amber coloured bottles (n = 3) and introduced into 30 mL simulated gastric juice. After 1 h, 5 mL was sampled with a syringe. This sample is considered to represent the gastric phase. Afterwards, 12.5 mL of small intestine fluid was added and the mixture was shaken in the incubator again for 2 h. After 2 h, 5 mL of sample, representing the small intestine, was sampled. The procedure was optimised from the bioaccessibility approach reported earlier [15]. However, similar concentrations of gastric and small intestine fluids were used in this study. A similar procedure was performed on BCR reference material (spruce needles and sea lettuce) and other wildly collected Amaranthus spinosus plant leaf material.

In all extracts, Fe, Al, Cu, Cr, Zn, Ni, and Mn contents were determined by inductively coupled plasma optical emission spectrometry (ICP-OES, Varian Vista MPX; Varian), and Cd and Pb contents were determined by inductively coupled plasma mass spectrometry (ICP-MS; PerkinElmer DRC-e). For ICP-MS determination, gallium was added to a concentration of 10 µg · L−1 as an internal standard. The isotope 111Cd was selected to be determined rather than 114Cd because of the isobaric interference of Sn (114Sn), and for Pb, the most abundant isotope, 208Pb, was analysed. This isotope also experienced less matrix interferences compared to 206Pb and 207Pb.

Supporting information

A picture of Bacopa monnieri growing under natural conditions at the sampling sites and percentage recovery in reference materials used for quality control are available as Supporting Information.


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Acknowledgements

M. N. V. P. thankfully acknowledges the Visiting Foreign Researcher Fellowship awarded by the Special Research Fund of Ghent University.


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Conflict of Interest

The authors declare no competing financial interest.

Supporting Information

  • References

  • 1 Mathew J, Paul J, Nandhu M, Paulose C. Bacopa monnieri and Bacoside-A for ameliorating epilepsy associated behavioral deficits. Fitoterapia 2010; 81: 315-322
    CrossrefPubMedSearch in Google Scholar
  • 2 Singh H. Brain enhancing ingredients from Āyurvedic medicine: quintessential example of Bacopa monnieri, a narrative review. Nutrients 2013; 5: 478-497
    CrossrefPubMedSearch in Google Scholar
  • 3 Ghosh T, Maity TK, Singh J. Antihyperglycemic activity of bacosine, a triterpene from Bacopa monnieri, in alloxan-induced diabetic rats. Planta Med 2011; 77: 804-808
    Thieme ConnectPubMedSearch in Google Scholar
  • 4 Lenka M, Panda KK, Panda BB. Monitoring and assessment of mercury pollution in the vicinity of a chloralkali plant. IV. Bioconcentration of mercury in in situ aquatic and terrestrial plants at Ganjam, India. Arch Environ Contam Toxicol 1992; 22: 195-202
    CrossrefPubMedSearch in Google Scholar
  • 5 Shukla OP, Dubey S, Rai UN. Preferential accumulation of cadmium and chromium: toxicity in Bacopa monnieri L. under mixed metal treatments. Bull Environ Contam Toxicol 2007; 78: 252-257
    CrossrefPubMedSearch in Google Scholar
  • 6 Jalili M, Azizkhani R. Lead toxicity resulting from chronic ingestion of opium. West J Emerg Med 2009; 10: 244-246
    PubMedSearch in Google Scholar
  • 7 Brewer GJ. Copper toxicity in the general population. Clin Neurophysiol 2010; 121: 459-460
    CrossrefPubMedSearch in Google Scholar
  • 8 Jayawardene I, Saper R, Lupoli N, Sehgal A, Wright RO, Amarasiriwardena C. Determination of in vitro bioaccessibility of Pb, As, Cd and Hg in selected traditional Indian medicines. J Anal At Spectrom 2010; 25: 1275-1282
    CrossrefPubMedSearch in Google Scholar
  • 9 World Health Organization (WHO). WHO guidelines on good agricultural and field collection practices (GACP) for medicinal plants. Geneva: WHO; 2003
    CrossrefSearch in Google Scholar
  • 10 FAO/WHO. Contaminants. In: WHO, editors. Codex Alimentarius, Volume 17. 1st edition.. Geneva: WHO; 1984
    Search in Google Scholar
  • 11 World Health Organization (WHO). Environmental health criteria 134 – Cadmium International Programme on Chemical Safety (IPCS) Monograph. Geneva: WHO; 1992
    CrossrefSearch in Google Scholar
  • 12 FAO/WHO. Codex Alimentarious Commission. Draft maximum levels for lead. CX/FAC 00/24. Joint FAO/WHO food standards programme codex committee on food additives and contaminants. Geneva: WHO; 1999
    CrossrefSearch in Google Scholar
  • 13 Gautam S, Platel K, Srinivasan K. Higher bioaccessibility of iron and zinc from food grains in the presence of garlic and onion. J Agric Food Chem 2010; 58: 8426-8429
    CrossrefPubMedSearch in Google Scholar
  • 14 Gillooly M, Bothwell T, Torrance J, MacPhail A, Derman D, Bezwoda W, Mills W, Charlton R, Mayet F. The effect of organic acids, phytates and polyphenols on the absorption of iron from vegetables. Br J Nutr 1983; 49: 331-336
    CrossrefPubMedSearch in Google Scholar
  • 15 Lavu RV, Du Laing G, Van de Wiele T, Pratti VL, Willekens K, Vandecasteele B, Tack F. Fertilizing soil with selenium fertilizers: impact on concentration, speciation, and bioaccessibility of selenium in leek (Allium ampeloprasum). J Agric Food Chem 2012; 60: 10930-10935
    CrossrefPubMedSearch in Google Scholar

Correspondence

Rama Venkata Srikanth Lavu
Laboratory of Analytical Chemistry and Applied Ecochemistry, Faculty of Bioscience Engineering, Ghent University
Coupure Links 653
9000 Gent
Belgium
Phone: +32 92 64 59 95   
Fax: +32 32 92 64 62 32   

  • References

  • 1 Mathew J, Paul J, Nandhu M, Paulose C. Bacopa monnieri and Bacoside-A for ameliorating epilepsy associated behavioral deficits. Fitoterapia 2010; 81: 315-322
    CrossrefPubMedSearch in Google Scholar
  • 2 Singh H. Brain enhancing ingredients from Āyurvedic medicine: quintessential example of Bacopa monnieri, a narrative review. Nutrients 2013; 5: 478-497
    CrossrefPubMedSearch in Google Scholar
  • 3 Ghosh T, Maity TK, Singh J. Antihyperglycemic activity of bacosine, a triterpene from Bacopa monnieri, in alloxan-induced diabetic rats. Planta Med 2011; 77: 804-808
    Thieme ConnectPubMedSearch in Google Scholar
  • 4 Lenka M, Panda KK, Panda BB. Monitoring and assessment of mercury pollution in the vicinity of a chloralkali plant. IV. Bioconcentration of mercury in in situ aquatic and terrestrial plants at Ganjam, India. Arch Environ Contam Toxicol 1992; 22: 195-202
    CrossrefPubMedSearch in Google Scholar
  • 5 Shukla OP, Dubey S, Rai UN. Preferential accumulation of cadmium and chromium: toxicity in Bacopa monnieri L. under mixed metal treatments. Bull Environ Contam Toxicol 2007; 78: 252-257
    CrossrefPubMedSearch in Google Scholar
  • 6 Jalili M, Azizkhani R. Lead toxicity resulting from chronic ingestion of opium. West J Emerg Med 2009; 10: 244-246
    PubMedSearch in Google Scholar
  • 7 Brewer GJ. Copper toxicity in the general population. Clin Neurophysiol 2010; 121: 459-460
    CrossrefPubMedSearch in Google Scholar
  • 8 Jayawardene I, Saper R, Lupoli N, Sehgal A, Wright RO, Amarasiriwardena C. Determination of in vitro bioaccessibility of Pb, As, Cd and Hg in selected traditional Indian medicines. J Anal At Spectrom 2010; 25: 1275-1282
    CrossrefPubMedSearch in Google Scholar
  • 9 World Health Organization (WHO). WHO guidelines on good agricultural and field collection practices (GACP) for medicinal plants. Geneva: WHO; 2003
    CrossrefSearch in Google Scholar
  • 10 FAO/WHO. Contaminants. In: WHO, editors. Codex Alimentarius, Volume 17. 1st edition.. Geneva: WHO; 1984
    Search in Google Scholar
  • 11 World Health Organization (WHO). Environmental health criteria 134 – Cadmium International Programme on Chemical Safety (IPCS) Monograph. Geneva: WHO; 1992
    CrossrefSearch in Google Scholar
  • 12 FAO/WHO. Codex Alimentarious Commission. Draft maximum levels for lead. CX/FAC 00/24. Joint FAO/WHO food standards programme codex committee on food additives and contaminants. Geneva: WHO; 1999
    CrossrefSearch in Google Scholar
  • 13 Gautam S, Platel K, Srinivasan K. Higher bioaccessibility of iron and zinc from food grains in the presence of garlic and onion. J Agric Food Chem 2010; 58: 8426-8429
    CrossrefPubMedSearch in Google Scholar
  • 14 Gillooly M, Bothwell T, Torrance J, MacPhail A, Derman D, Bezwoda W, Mills W, Charlton R, Mayet F. The effect of organic acids, phytates and polyphenols on the absorption of iron from vegetables. Br J Nutr 1983; 49: 331-336
    CrossrefPubMedSearch in Google Scholar
  • 15 Lavu RV, Du Laing G, Van de Wiele T, Pratti VL, Willekens K, Vandecasteele B, Tack F. Fertilizing soil with selenium fertilizers: impact on concentration, speciation, and bioaccessibility of selenium in leek (Allium ampeloprasum). J Agric Food Chem 2012; 60: 10930-10935
    CrossrefPubMedSearch in Google Scholar

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