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Vegetational variation of phenoliccompounds in Epilobium angustifoliumSiiri Jürgenson a , Vallo Matto a & Ain Raal aa Department of Pharmacy, University of Tartu, Nooruse 1, Tartu50411, EstoniaVersion of record first published: 09 Dec 2011.

To cite this article: Siiri Jürgenson , Vallo Matto & Ain Raal (2012): Vegetational variation ofphenolic compounds in Epilobium angustifolium , Natural Product Research: Formerly NaturalProduct Letters, 26:20, 1951-1953

To link to this article: http://dx.doi.org/10.1080/14786419.2011.643310

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Natural Product ResearchVol. 26, No. 20, October 2012, 1951–1953

SHORT COMMUNICATION

Vegetational variation of phenolic compounds in Epilobium angustifolium

Siiri Jurgenson, Vallo Matto* and Ain Raal

Department of Pharmacy, University of Tartu, Nooruse 1, Tartu 50411, Estonia

(Received 8 August 2011; final version received 7 September 2011)

Epilobium angustifolium L. herbs are used in ethnomedicine to treat benignprostate hyperplasia. The aim of the study was to investigate the phenoliccontents in distinct E. angustifolium organs during the whole vegetational periodfrom May to October. The plants were obtained from a remote habitat in Estoniaand spectrophotometrically analysed for the total polyphenol, tannin, andflavonoid contents. The total polyphenol content was the highest in roots(85mg g�1) and stems (67mg g�1) in July. The total flavonoid content wasthe highest in leaves (2.36mg g�1) and flowers (2.09mg g�1) and it remainedrelatively stable during the summer months. The highest tannin content wasfound in small growing plants in May; in older ones it declined, whereas theabsolute yield per plant was greater. In sum, the aerial organs without stemscollected in July–August are the best choice to get E. angustifolium plant materialwith stable high phenolic content.

Keywords: Epilobium angustifolium L.; vegetational variation; polyphenols;tannins; flavonoids; medicinal plant; Estonia

1. Introduction

Epilobium angustifolium L. (commonly known as fireweed or rosebay willowherb) is themost prevalent species of the genus Epilobium L. (Onagraceae) in Estonia (Kukk & Kull,2005). The contemporary major indication for the use of E. angustifolium is benignprostatic hyperplasia since the E. angustifolium extracts specifically inhibit tissueproliferation (Vitalone, Guizzetti, Costa, & Tita, 2003). Though extensively studied, theabsolute values of the biologically active compounds and their ratios of Epilobium plantsvary among the studies (Hevesi Toth, Blazics, & Kery, 2009; Raal, Remmel, Vares, Toom,& Jurgenson, 2010).

The E. angustifolium plants are traditionally collected during the whole vegetationperiod but the impact of the collection time is poorly understood. Therefore, this studyinvestigated the vegetational variation of the biologically active phenolics inE. angustifolium.

2. Results and discussion

The collected plants were carefully identified using the Taxonomic Guide of EstonianPlants (Krall et al., 1999). The voucher specimens are stored at the Department ofPharmacy (No Onagraceae/Epi6), University of Tartu, Tartu, Estonia.

*Corresponding author. Email: vallo.matto@ut.ee

ISSN 1478–6419 print/ISSN 1478–6427 online

� 2012 Taylor & Francis

http://dx.doi.org/10.1080/14786419.2011.643310

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The therapeutic effect and efficacy (Ennajar et al., 2010) of medicinal plants coulddepend on the seasonal and organ variations of the contents of the biologically activecompounds. Herewith, we report for the first time that all E. angustifolium organs collectedfrom Southern Estonia contained polyphenols, tannins and flavonoids during the wholevegetation period in remarkable amounts (Table 1).

The contents of tannins in E. angustifolium collected from Estonia were much higherthan those of polyphenols or flavonoids. This is an important finding since the dimerichydrolysable tannin, the oenothein B, has been evidenced to be the major biologicallyactive compound modulating the proliferative processes (Kiss, Kowalski, & Melzig, 2006).The moderately fluctuating total polyphenol content of E. angustifolium was higher inroots and stems. It is notable that in the study of Shikov et al. (2006), the total phenolcontent in five commercially available herbal preparations of E. angustifolium marketed inRussian Federation contained up to 30% of the different amounts of phenols, which maybe due to the vegetational variation of the content of E. angustifolium and, alternatively,due to the distinct aerial organs’ ratios among the herbal preparations. The total flavonoidcontent in our study was the highest in E. angustifolium leaves and flowers in summer butthe absolute values of flavonoids’ content were rather low. Since the inter- or intra-populational variation of flavonoid content in various Epilobium plants per se is very low(Bohm, 1987), the flavonoid fluctuations reported herewith can be clearly attributedto vegetational rather than taxonomic variability. The content of total tannins inE. angustifolium was the highest in May but since May is the beginning of theE. angustifolium vegetation and the plants are quite small, the absolute yield of gross plantorgan mass per single individual plant is substantially lower, too. This finding is in good

Table 1. Vegetational variations of the contents of total polyphenols, tannins and flavonoids(mg g�1) in E. angustifolium collected from Estonia.

Month Organ Polyphenols Tannins Flavonoids

May Roots 62.1 162.8 b.d.l.Stems 77.5 149.9 0.06Leaves 63.8 414.2 1.63

June Roots 40.6 126.1 0.17Stems 66.7 54.0 0.21Leaves 32.2 186.4 1.88

July Roots 85.0 107.7 0.05Stems 67.4 27.3 0.07Leaves 27.6 160.6 2.35Floral meristems 34.7 361.5 1.55Flowers 34.1 279.0 2.09Fruits 35.4 202.1 0.89

August Roots 75.6 77.2 0.17Stems 83.3 55.2 0.17Leaves 44.4 169.3 2.19Fruits 46.7 175.4 1.22

September Roots 70.8 89.2 0.16Stems 55.9 60.4 0.19Viable coloured leaves 41.1 180.2 2.17Dried brownish leaves 43.1 191.5 1.13Fruits 45.5 199.6 0.68

October Roots 79.4 106.4 0.19Aerial organs 27.0 83.8 0.30

Note: b.d.l., below spectrophotometric detection limit.

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agreement with the recent study of Shikov et al. (2010), who found high content of thehydrolysable tannin oenothein B in budding E. angustifolium with subsequent decline overthe vegetational period. Further, as a general limitation of the study, one has to rememberthat the seasonal or vegetational changes of the total phenolics in plants are onlyindicative, while it is known that the individual compounds and/or their ratios may beseasonally or vegetationally variable by the fairly stable total phenolic content (Salminenet al., 2004) and from therapeutic point of view, the bioequivalence has to be evaluated(Loew & Kaszkin, 2002).

3. Conclusions

This study concludes that the most optimal, although not exclusive, collection time of E.angustifolium in temperate climate zone is July–August (the summer). Since the phenoliccontent of stems is much lower than that in other aerial organs, the use of the stems forherbal preparations is not recommended.

Supplementary material

Experimental details of the study are available online.

References

Bohm, B.A. (1987). Intraspecific flavonoid variation. The Botanical Review, 53, 197–279.

Ennajar, M., Bouajila, J., Lebrihi, A., Mathieu, F., Savagnac, A., Abderraba, M., . . . , Romdhane, M. (2010).

The influence of organ, season and drying method on chemical composition and antioxidant and

antimicrobial activities of Juniperus phoenicea L. essential oils. Journal of Agricultural and Food Chemistry,

90, 462–470.

Hevesi Toth, B., Blazics, B., & Kery, A. (2009). Polyphenol composition and antioxidant capacity of Epilobium

species. Journal of Pharmaceutical and Biomedical Analysis, 49, 26–31.

Kiss, A., Kowalski, J., & Melzig, M.F. (2006). Induction of neutral endopeptidase activity in PC-3 cells by an

aqueous extract of Epilobium angustifolium L. and oenothein B. Phytomedicine, 13, 284–289.

Krall, H., Kukk, T., Kull, T., Kuusk, V., Leht, M., Oja, T., . . . , Tuulik, T. (1999). Taxonomic guide of Estonian

plants. Tartu, Estonia: Eesti Loodusfoto Press (in Estonian).

Kukk, T., & Kull, T. (2005). Atlas of the Estonian flora. Tartu, Estonia: The Estonian University of Agriculture

Press (in Estonian).

Loew, D., & Kaszkin, M. (2002). Approaching the problem of bioequivalence of herbal medicinal products.

Phytotherapy Research, 16, 705–711.

Raal, A., Remmel, I., Vares, L., Toom, L., & Jurgenson, S. (2010). Content of total polyphenols, tannins and

flavonoids in Epilobium species growing in Estonia. Planta Medica, 76, 1224.

Salminen, J.P., Roslin, T., Karonen, M., Sinkkonen, J., Pihlaja, K., & Pulkkinen, P. (2004). Seasonal variation in

the content of hydrolyzable tannins, flavonoid glycosides, and proanthocyanidins in oak leaves. Journal of

Chemical Ecology, 30, 1693–1711.

Shikov, A.N., Poltanov, E.A., Dorman, H.J., Makarov, V.G., Tikhonov, V.P., & Hiltunen, R. (2006). Chemical

composition and in vitro antioxidant evaluation of commercial water-soluble willow herb (Epilobium

angustifolium L.) extracts. Journal of Agricultural and Food Chemistry, 54, 3617–3624.

Shikov, A.N., Pozharitskaya, O.N., Ivanova, S.A., Makarov, V.G., Tikhonov, V.P., & Galambosi, B. (2010).

Improved and validated HPTLC method for quantification of oenothein B and its use for analysis of

Epilobium angustifolium L. JPC – Journal of Planar Chromatography – Modern TLC, 23, 70–74.

Vitalone, A., Guizzetti, M., Costa, L.G., & Tita, B. (2003). Extracts of various species of Epilobium inhibit

proliferation of human prostate cells. The Journal of Pharmacy and Pharmacology, 55, 683–690.

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