Phytochemistry and Biological Properties of Burnet Weed ( Sanguisorba spp . ) : A Review

Great burnet (Sanguisorba officinalis L.) and small burnet (Sansguisorba minor Scop.) are edible, perennial weeds widely distributed in the world. These are the most widespread Sanguisorba species. The bioactive components of Sanguisorba plants include phenolics (phenolic acids, flavonoids and neolignans) and terpenoids. Large potential exists to use burnets as medicinal plants. Sanguisorba species are known to show anticancer properties, antioxidative, antimicrobial and antiviral activities. Also, Sanguisorba extracts show anti-Alzheimer and antiinflammatory properties. Small burnet extracts could also be a useful alternative to synthetic fungicides for crop production. This review focuses on biological activities of Sanguisorba extracts and emphasizing their potential applications in pharmaceutical areas.

Large potential exists to cultivate burnet as medicinal plant.Moreover, small burnet has good forage quality (Elgersma et al., 2013a).Burnet plants are very good cold tolerant.A limiting factor in burnet production is weed competition.There is a report that small burnet can tolerate bromoxynil, clethodim, clopyralid, dimethenamid-P, metribuzin, pendimethalin andquincloracherbicides (Nelson et al., 2014).The aim of this paper is to review the existing literature and explore the potential of burnet plants for medicinal properties.

Botanical-morphological description
Burnet (Sanguisorba spp.) is a member of the Rosaceaee family.Great burnet (Sanguisorba officinalis L.) and small burnet (Sansguisorba minor Scop.(synonym Poterium sanguisorba L.)) are the most widespread Sanguisorba species.Burnets are perennial herbs widely distributed throughout Europe, Asia and other parts of the world.
Burnets plants have pinnate leaves (Fig. 1).Leaflets are in pairs placed opposite or alternative.Inflorescences appear at the end of stems.The flowers have four sepals and no petals (Sutton, 2007;Andrabi et al., 2012).The seeds are achenes.The weight of 1000 burnet seeds is 10 g.
S. minor is a drought tolerant species (Koukoura et al., 2007).Douglas et al. (1994) reported that S. minor plants in the dry regime had soluble sugar levels of 1.4 -1.7 times higher than those watered adequately, which suggested that plants adjusted to water depletion.
Sanguisorba plants can be propagated from seeds.Seeds of Sanguisorba spp.germinated most rapidly at 24 to 25 °C constant temperatures, following 6 months of dry storage at 4 °C.Presence or absence of light does not affect germination percentages (Holloway and Matheke, 2003).

Burnets and human health
S. officinalis leaves can be used in salads or for various extracts or specialized preparations.Several studies have recently confirmed the anticancer properties of burnet plants (Goun et al., 2002).According to Wang et al. (2012) and Shin et al. (2012) S. officinalis inhibited the growth of breast and oral cancer.Choi et al. (2012a) also observed that extracts of S. officinalis could be used for treatment of prostate cancer.
Furthermore, Sanguisorba species are known to show antioxidative activities.Menkovic et al. (2007) reported that S. minor and S. officinalis extracts showed strong antioxidant activity.There was a correlation between the phenolic content and antioxidant activity.Moreover, Choi et al. (2012b) reported that ZYM-201 sodium succinate (salt form) can be used for the treatment of atherosclerosis and vascular diseases.ZYM-201 (methyl ester of a triterpenoid glycoside) is isolated from S. officinalis (Choi et al., 2006).
Burnet plants also show antiviral and antimicrobial activities.According to Bedoya et al. (2001) and Abad et al. (2000) the aqueous extracts of S. minor showed inhibitory effects against human immunodeficiency virus type 1 (HIV-1), herpes simplex virus type I (HSV-1) and vesicular stomatitis virus (VSV).Furthermore, Moreira et al. (2011) reported that the S. hybrida extracts showed high antibacterial activity against Staphylococcus aureus.
Moreover, Sanguisorba extracts show anti-Alzheimer activities.Sanguisorba spp.extracts inhibited the glycogen synthase kinase 3β (Kaufmann et al., 2009).Glycogen synthase kinase 3 has been shown to play an important role in Alzheimer's disease (Anand and Singh, 2013;Kaufmann et al., 2009).Moreover, it has been reported that acetylcholinesterase enzyme inhibitors are approved for Alzheimer management (Tabet, 2006).Ferreira et al. (2006) found that S. minor showed the best inhibition of acetylcholinesterase enzyme.These findings indicate that Sanguisorba extracts could be used against Alzheimer's disease.Anti-inflammatory properties of S. officinalis have been the subject of several studies.Lee et al. (2010) observed that S. officinalis ethanol extract has therapeutic potential against bronchial asthma associated with allergic diseases.Yu et al. (2011) also found that burnet extracts can be effectively applied as a therapeutic agents and anti-inflammatory herbal medicines.
Furthermore, Chapman (2013) reported that the S. officinalis treatment significantly reduced hair loss and significantly reduced the telogen/anagen ratio.S. minor is also used to treat bites of the most venomous snakes in southern Europe (i.e.Bosnia and Herzegovina), such as Vipera berus and Vipera ammodytes (Redzic, 2010).

Small burnet and other uses
Small burnet extracts could be a useful alternative to synthetic fungicides in the management of postharvest fungal pathogens (Gatto et al., 2011).The authors reported that the extracts from small burnet completely inhibited in vitro spore germination of Monilnialaxa, Penicilliumdigitatum, Pencilliumitalicum and Aspergilusniger, while it significantly reduced those of Botrytis cinerea and Pencilliumexpansum.Askarne et al. (2012) also observed that the powder of Sanguisorba minor was effective against P. italicum.Kokubun et al. (1994) found that the root tissue of S. minor produced the phenolic compound 2΄6΄-dihydroxy-4΄methoxyacetophenone as a phytoalexin after fungal inoculation with Botrytis cinerea.
Moreover, the dry powder of small burnet leaves could be used to enrich vegetable oils with low content of natural antioxidant, such as sunflower and corn oil (Romojaro et al., 2013).Finally, the addition of S. minor (leaves and stems) increased the content of phenolic compounds and antioxidant capacity in orange and kiwifruit juices in more than 30% (Sanchez-Bel et al. 2014).

Conclusions
Burnets are perennial herbs widely distributed throughout Europe, Asia and other parts of the world.Burnets are rich in bioactive compounds.Great burnet (Sanguisorba officinalis L.) and small burnet (Sansguisorba minor Scop.) plants show anticancer, antioxidative, antiviral and antimicrobial activities.Furthermore, Sanguisorba extracts could be used against Alzheimer's disease.Their pharmacological properties are due to the presence of phenolics and terpenoids as active constituents.