Biologically Active Compounds of Knotweed (Reynoutria spp.)

Abstract

Knotweeds (Reynoutria Houtt.) are plants native to the Far East. Japanese knotweed was introduced from Japan to the unsuspecting West by the horticultural activities of Philippe von Siebold via his nursery at Leiden in the 1840s. By 1854, the plant had arrived at the Royal Botanic Gardens in Edinburgh. The plants were then sold by a large number of commercial nursery gardens around the country. Further vegetative spread followed naturally along watercourses. The knotweed is currently extremely persistant invasive plant. There is also an important source of many bioactive substances which could be used in biomedicine. The article discusses biomedically relevant constituents and its pharmacological and toxicological properties.

Full text

Mil. Med. Sci. Lett. (Voj. Zdrav. Listy) 2017, vol. 86(1), p. 17-31
ISSN 0372-7025
REVIEW ARTICLE
BIOLOGICALLY ACTIVE COMPOUNDS OF KNOTWEED
(Reynoutria spp.)
Jiri Patocka 1,2 , Zdenka Navratilova3, Maribel Ovando4
1Institute of Radiology, Toxicology and Civil Protection, Faculty of Health and Social Studies, University of South
Bohemia České Budějovice, České Budějovice, Czech Republic
2Biomedical Research Centre, University Hospital, Hradec Kralove, Czech Republic
3Department of Botany, Faculty of Science, Charles University in Prague
4Department of Scientific and Technological Research DICTUS, University of Sonora, Sonora, Mexico
Received 12th November 2016.
Revised 3rd February 2017.
Published 10th March 2017.
Summary
Knotweeds (Reynoutria Houtt.) are plants native to the Far East. Japanese knotweed was introduced
from Japan to the unsuspecting West by the horticultural activities of Philippe von Siebold via his nursery
at Leiden in the 1840s. By 1854, the plant had arrived at the Royal Botanic Gardens in Edinburgh. The plants
were then sold by a large number of commercial nursery gardens around the country. Further vegetative
spread followed naturally along watercourses. The knotweed is currently extremely persistant invasive plant.
There is also an important source of many bioactive substances which could be used in biomedicine.
The article discusses biomedically relevant constituents and its pharmacological and toxicological properties.
Key words: Knotweed; Reynoutria; Invasive plant; Bioactive compounds; Pharmacology; Toxicology
INTRODUCTION
Knotweed is a common name for plants in several genera in the Polygonaceae family. Knotweed (Reynoutria
Houtt.) are plants native to the Far East (Japan, Sakhalin, Kurile Islands, Taiwan, Korea, northern China). More
than 100 years ago, Japanese knotweed (Reynoutria japonica Houtt.) was introduced to Europe and North America.
Given its capability to grow from rhizome and stem fragments, it persists and spreads locally, forming monotypic
stands. The Japanese knotweed clone originally introduced was a male-sterile female clone; thus, early in the in-
vasion, reproduction from seed was not an issue (Bailey et al., 2009). However, hybridization between Japanese
knotweed and Sakhalin (giant) knotweed (Reynoutria sachalinensis (F. Schmidt Nakai) has been reported, with
the hybrid species, Bohemian knotweed (Reynoutria × bohemica Chrtek & Chrtkova) [1]. This hybride has been first
described in 1983 from a location near the spa Beloves. It spreads faster than the parental species and at this time
forms the majority of knotweed plants in many areas and possessing higher variability than the parent species [2].
Reynoutria elliptica (Koidz.) Migo ex Nakai is a perennial herb originally from China, Korea and Japan. Accepted
name of this plant is Fallopia forbesii (Hance) [3]. Some botanists believe that Fallopia forbesii is conspecific
with Reynoutria japonica. R. elliptica has been used in traditional Korean medicine to promote blood circulation,
relieve pain, increase diuresis, and alleviate respiratory problems, through as yet undefined mechanisms [4].
University of South Bohemia České Budějovice, Faculty of Health and Social Studies, Institute of Radiology,
Toxicology and Civil Protection, Jírovcova 24/1347, 370 04 České Budějovice, Czech Republic
toxicology@toxicology.cz

As temperatures increase, knotweed is predicted to expand its range further north and to higher altitudes [5].
With the ability to regenerate from vegetative fragments, invasive knotweed species are on the move. Knotweed
in the Czech Republic ranks among the invasive plant that spreads uncontrollably outside their original range and
displace native species of plants [2]. The chemical combat is very difficult and economically challenging. An arsenal
of chemical instruments, the ability to shade out competitors, and the ability to adapt rapidly through epigenetic
change makes knotweed a formidable invader.
It is offering a question, however, whether it would be possible to take advantage of the excellent growth
characteristics of Bohemian knotweed for economic purposes [6]. It is known that the knotweeds are the source
of many interesting biologically active compounds and produce large amounts of biomass annually. Biologically
active substances could find application in human and veterinary medicine and biomass could be used as a cheap
source of energy [7, 8]. This review gives an overview of chemical substances that have been isolated from
knotweed, their pharmacological and toxicological properties and their possible use in biomedicine.
BIOLOGY
Knotweeds (Reynoutria Houtt., Polygonaceae) are perennial herbs with thick long branched rhizomes, numerous
high erect stems and large leaves with ovate or broadly elliptic blade. Inflorescences are axillary or terminal
with small white-greenish flowers. Flowers are functionally monosexual, male with long stamens and short pistils,
female with short stamens and distinct pistils. The fruit is a three-sided achene. The genus Reynoutria consists
of approximately 10 species distributed mainly in temperate zone of Asia [9]. Some authors give knotweed
to the genus Fallopia Adans [2].
Reynoutria japonica Houtt. (syn. Fallopia japonica, Polygonum cuspidatum) is distributed in China, Taiwan,
Korea and Japan, R. sachalinensis (F. Schmidt) Nakai (syn. Fallopia sachalinensis) mainly in Japan and Sakhalin.
There is some overlap in distribution areas. Knotweeds were introduced to Europe as ornamental plants
in the 19th century [2].
In the Czech Republic, the genus is represented by R. japonica var. japonica, R. japonica var. compacta,
R. sachalinensis and R. × bohemica, a hybrid between R. sachalinensis and R. japonica described in the Czech
Republic [1]. All of them invade riparian and various human-made habitats. Reynoutria taxa usually reproduce
vegetatively by rhizome and stem fragments. The hybrid has higher invasive potential than parent species [2].
Extensive root system and rhizomes up to 20 m long enables to form thick colonies and shade out native species.
The plants are tolerant of many conditions, including full shade, high temperatures, drought, and floods.
The ecological impact of R. × bohemica on native forbs is not just a result of competition for shared resources, but
it also appears to have a large allelopathic component and inhibit germination of native species. Knotweed removal
is very problematic due to its high regenerative ability. Physical removal is not effective and must be combined
with chemical control. Initial research on biological control of knotweed has been conducted [8, 10, 11]. Knotweed,
especially Reynoutria × bohemica, presents actually one of the most dangerous invasive plants in Europe.
TRADITIONAL MEDICINE
Knotweed rhizomes and young sprouts are used in a traditional Asian medicine as laxatives, and occasionally
as foods. The rhizome and root of R. japonica, also known by its Chinese name Hu Zhang, is officially listed
in the Chinese Pharmacopoeia. In traditional Chinese Medicine, R. japonica was described to be used for treatment
of suppuration, sore throat, toothache, ulcer, hemorrhoids, chronic bronchitis and other ailments. Currently, in China
it is (usually in combination with other herbs) used for treatment of inflammatory diseases (including hepatitis and
suppurative dermatitis) as well as favus, jaundice, skin burns, scald, cough, amenorrhea and hyperlipidemia [12, 13].
Hu Zhang contains resveratrol, polysaccharides, flavonoids, quinones and large amounts of condensed tannins [12, 14].
However, tannins found in members of this genus are known to be carcinogenic [15]. Knotweed is therapeutic
in several different ways. Extracts from R. japonica appear to have antipyretic and analgesic activities. The extracts
appeared to confer protection of the gastric membrane against stress ulcers, slight inhibition of gastric secretion,
Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
18

and no effect on blood pressure [16]. R. japonica also promotes healing of burns by enhancing immune system and
cardiac functions [17]. Leaves of R. sachalinesis are used as desinfectant and as a protective of boils [18].
KNOTWEED AND IMMUNITY
Luo [17] studied the effects of knotweed on the restoration of suppressed cell-mediated, humoral, and non-
specific immune functions in scald mice. Administration of knotweed provided immunomodulating effects
in a dose-dependent fashion [19] showed that knotweed restored impaired functions, such as response to antigen
signal, the proliferative capacity, interleukin II production, and antibody production ability by lymphocytes, in dif-
ferent degrees in severely burned mice. Knotweed promotes healing of burns by enhancing immune system and
cardiac functions. Severely burned animals survived longer while their neutrophil levels and neutrophilic adhesive
rates remained near normal due to treatment with knotweed [20]. In one study, knotweed were administered to rats
at the early stage of burn shock and found that plasma TNF levels remained normal, adhesive leukocytes remained
nearly normal, disturbances in microcirculation were alleviated, and injury to the lung was attenuated [21].
CHEMICAL CONSTITUENTS
Roots and leaves of knotweed contain aromatic hydrocarbons called stilbenes [22, 23] (resveratrols, polydatin),
flavonoids (rutin, apigenin, quercetin, quercitrin, isoquercitrin, hyperosid, reynoutrin, kaempferol), anthraquinones
(emodin, citreorosein, physcion, fallacinol, chrysophanol, phylloquinone B and C) [12, 24], coumarins, essential
oils, and others (lapathoside, 8-hydroxycalamenene, oleanolic acid, chlorogenic acid, protocatechuic acid, gallic
acid, tachioside, β-sitosterol etc.) [12, 25, 26] (Table I). The structures of some of the most important compounds
are shown in Figure 1. and Figure 2.
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Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
I
HO
OH
OH
II
O
O
OH
OH
OH
OH
HO
HO
III
OH OH
OH
O
O
Me
IV
OH OHO
O
Me OMe
V
OH OHO
O
HO
OH
HO
I
O
O
OH
HO
HO
OH
II
OH
Me
I
OH
O
OH
OHOH
OH
OH Me
OH
OMe
OOHOH
OMe
III
O
HO
O
OOHOH
IV
O
OH
V
O
Figure 1. Structures of some important bioactive substances of Knotweed. (I) Resveratrol, (II) Polydatin, (III) Emodin,
(IV) Physcion, (V) Citrorosein.

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Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
O
O
O
O
O
O
O
OH
OOH O
OH
HO
HO
HO
O
OH
OMe
OMe
OH
Me Me
Me
Me
OH
O
HO
OH
OH
O
OH
OH
O
HO
OH
OH
O
OH
VI
VII
VIII
IX
O
O
O
O
O
O
OH
OH
MeMe
Me
VII
O
O
HO
HO
HO
O
O
O
O
O
O
O
O
O
HO
O
OH
O
HO
OHMe
OH
OH
VIII
VII
O
OH
OMe
OMe
OH
VI
OMe OOH
HO
O
OH
VIII
O
OH
OH
IX
OH
OH VI
OOH
Figure 2. Structures of some important bioactive substances of Knotweed. (VI) Lapathoside A, (VII) 8-Hydroxycalamenene,
(VIII) Quercetin, (IX) Kaempferol.
PHARMACOLOGY OF CONSTITUENTS
Recently, the root of the plant has been reported to exhibit several beneficial biological effects. These inhibit
neuraminidases [27] and topoisomerases [28], and have anti-inflammatory [4], anti-oxidant [29], antibacterial [30]
and anti-fungal [31] properties. It also exhibits anti-tumor effect and can modulate multi-drug resistance in case
of chemotherapy failure [32-34]. Specifically, these studies have shown that four active compounds, including
emodin, physcion, omega-hydroxyemodin, and trans-resveratrol, derived from the root, exhibit neuraminidase
inhibitory activity [27] and the hexane fraction of the plant inhibits LPS-induced production of inflammatory
markers by blocking nuclear factor-kappaB (NF-κB) and MAPKs signaling in RAW 264.7 cells [4]. In diabetic
rats, extract of R. japonica help suppress the development of diabetic retinopathy and renal injury [35, 36].
R. japonica has also neuroprotective properties [37, 38].
Among the purified compounds, some showed more potent inhibitory activity against topoisomerase I
(IC50: 4 μM) than camptothecin, as the positive control (IC50: 18 μM). Compounds citreorosein, 3,5-dihy-
droxybenzyl alcohol, cis- and trans-resveratrols, and trans-resveratrol-5-O-β-D-glucopyranoside showed stronger
inhibitory activities toward DNA topoisomerase II (IC50: 0.54, 14, 15, 0.77 and 3 μM, respectively) than
the positive control, etoposide (IC50: 44 μM). Emodin and citreorosein displayed weak cytotoxicities against
human lung cancer (A549), ovarian cancer (SK-OV-3), human liver hepatoblastoma (HepG2) and colon
adenocarcinoma (HT-29) cell lines [28].
Resveratrol and its glucosides
Resveratrol (I) (3,4',5–trihydroxystilbene) is known primarily as a substance present in wine and is responsible
for the so-called "French paradox". Moderate wine drinking is associated with reduced risk of cardiovascular,

cerebrovascular and peripheral vascular disease, and reduced risk of cancer. This phenomenon was observed
for the first time in France – a country famous for its wine production. In the literature, the cardioprotective effect
of wine is very well described and attributed mainly to contained therein resveratrol. Resveratrol is the parent
compound of a family of molecules, including glycosides (piceid) and polymers (viniferins), existing in cis and
trans configurations classified as stilbenes. Recently, it has been demonstrated that resveratrol extends the lifespan
of yeast through activation of the SirT1 longevity gene, which is also responsible for the longevity caused by caloric
restriction [39]. Furthermore, resveratrol exhibits high biological activity, affecting cell structures and contributing
to their protection [40].
Resveratrol demonstrated its ability to be a potential drug candidate for the treatment of various ailments due
to its potent antioxidant properties. To improve the drug stability, increase the bioavailability and minimize side-
effects of resveratrol, novel drug delivery systems have been formulated to bring this potential candidate to the
first line of disease treatment [41-43]. The fact that resveratrol is present in knotweed in large amounts, makes the
plant a source of useful natural substances having a medical use [44].
Resveratrol protects neurons against ischemic injury [45] and attenuates cognitive deficit in aged rats [46] and
in scopolamine-induced memory impairment [47].
Resveratrol inhibits the growth of several bacteria and fungi [48], exhibits cancer chemopreventive activity by
acting as an antioxidant, antimutagen, and anti-inflammatory agent. It also induces human promyelocytic leukemia
cell differentiation (antiprogression activity) and inhibits the development of preneoplastic lesions in mouse
mammary glands [49]. Resveratrol also inhibits protein-tyrosine kinase, which catalyzes the phosphorylation of
tyrosine [50]. This kinase is involved in the regulation of mitogenesis [51].
Resveratrol inhibits lipoxygenase products [52], which are enzymes found in leukocytes, the heart, brain, lung,
and spleen [53]. Resveratrol, and its glucoside precursor, piceid, inhibit the deposition of triglycerides and
cholesterol in the liver of mice [54]. Resveratrol, piceid, and another stilbene compound, reduced the elevation
of aspartate transaminase and alanine transaminase by inhibiting lipid peroxidation in the livers of rats [55]. Analysis
of these two enzymes in blood serum gives good diagnostic information for heart and liver damage [53]. These same
compounds have shown potential as an antithrombotic, thus preventing the formation of blood clots within blood
vessels [56].
Controversial resveratrol
Resveratrol is said to have healing effects on many diseases. The issue is controversial, however, and while
some specialized publications rather deny such effects, others work work with them as a fact and demonstrate
the scientific results [57].
The fact that some research into resveratrol is questionable, is due to now deceased professor Dipak K. Das,
longtime director of the Cardiovascular Research Center at the University of Connecticut Health Center
in Farmington. Das is known for his work on the beneficial properties of resveratrol, but at least twenty of his
research papers have been retracted. Das was a prolific publisher of research. His name appears on over 500 articles,
including 117 articles on resveratrol [58]. The university has notified 11 scientific journals that have published
studies that Das conducted, and the U.S. Office of Research Integrity has launched an independent investigation
of his work.
In January 2012, University of Connecticut officials reported that dismissal proceedings were underway against
Das and declined to accept federal grants awarded to Das’s laboratory. It was reported by the Hartford Courant
in January 2013 that Das wanted to file a $35 million defamation lawsuit against Uiversity of Connectitut, but he
died before the case went to court [59].
Professor Das affair caused damage to the research of natural substances such as resveratrol and brought many
doubts to its usefulness to human health. It will take a long time to bring things into perspective. Until then, it will be
necessary to look at all the scientific results on resveratrol very critically.
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Polydatin
Polydatin (II), also named piceid (3,4',5-trihydroxystilbene-3-β-D-glucoside), is the most known natural
precursor of resveratrol and a type of polyphenolic phytoalexin which has many physiological and pharmacological
effects including anti-inflammatory and anti-oxidative activities [60, 61]. Trans-polydatin is the glucoside formed
with trans-resveratrol, while cis-polydatin is formed with cis-resveratrol. These stilbene compounds isolated from
knotweed protect myocardial cells injured by deprivation of oxygen and glucose. It also inhibits platelet aggregation
after treatment with clonidine, an antihypertensive drug [62, 63]. Wang [64] illustrates that polydatin is the main
substance in serum after intragastric administration with polydatin or resveratrol, and the mutual transformation
between polydatin and resveratrol keeps balance; they both have the ability of antioxidative stress in vivo, and
polydatin has a better effect than resveratrol, which hints that polydatin may be a substitute for resveratrol
as antioxidant for clinical use. Ma et al. [65] demonstrated that polydatin inhibited the oxidative stress-induced
proliferation of vascular smooth muscle cells (VMSCs) by activating the endothelial nitric oxide synthetase
(eNOS/SIRT1) pathway.
Polydatin is a major resveratrol derivative in grape juices [66]. Polydatin has been proved by modern
pharmacological studies to possess extensive cardiovascular pharmacological activity, showing marked effects
on protecting cardio-myocyte, dilating blood vessel, antagonizing platelet aggregation, thrombosis, and
atherosclerosis [67]. Polydatin is an effective candidate drug for the protection of photo-inflammation. Polydatin
exhibits therapeutic potential for vascular dementia, most likely due to its anti-oxidant activity and the direct
protection of neurons [68].
The enumeration of pharmacological effects of polydatin is very long. Polydatin protects bone marrow stem
cells agains oxidative injury and significantly protects bone marrow-derived mesenchymal stem cells (BMSCs )
against apoptosis due to its antioxidative effects and the regulation of Nrf 2/ARE pathway. Therefore polydatin
could be used in combination with BMSCs for the treatment of spinal cord injury by improving the cell survival
and oxidative stress microenvironments [69]. Polydatin upregulated the ratio of osteoprotegerin/receptor activators
of nuclear factor κB ligand (OPG/RANKL) and β‑catenin protein in ST2 cell line [70].
Polydatin supplementation alleviated the hepatic pathological changes, and attenuated the insulin resistance
and also corrected abnormal leptin and adiponectin levels. Specifically, polydatin supplementation enhanced insulin
sensitivity in the liver, as shown by improved insulin receptor substrate 2 expression levels and protein kinase B
(also known as Akt) phosphorylation in the rat liver, following high-fat diet feeding. Polydatin may be an effective
hepatoprotective agent and a potential candidate for the prevention of fatty liver disease and insulin resistance [71].
The results of Hao et al. [72] indicate that polydatin regulates glucose and lipid metabolism in experimental diabetic
models, the underlying mechanism is probably associated with regulating the Akt pathway. The effect of polydatin
on increased Akt phosphorylation is independent of prompting insulin secretion, but dependent of increasing IRS
phosphorylation. The study of Wang et al. [73] indicates that polydatin ameliorates lipid and glucose metabolism
in type 2 diabetes mellitus by downregulating proprotein convertase subtilisin/kexin type 9 (PCSK9). Polydatin
has important therapeutic effects on metabolic syndrome [74].
Polydatin may attenuate ventricular remodeling after myocardial infarction in coronary artery ligation rats through
restricting the excessive activation of the renin-angiotensin-aldosterone system and inhibiting peroxidation [75].
Polydatin exhibits neuroprotective potential for ethanol induced neurotoxicity, both in vivo and in vitro, which
is most likely related to its ability to target cyclin-dependent kinase 5 (Cdk5) in neurons [76]. Polydatin has
a protective effect against learning and memory impairment in neonatal rats with hypoxic-ischemic brain injury
and its protective effect may be mediated through the upregulation of brain-derived neurotrophic factor (BDNF)
[77]. (Sun et al., 2014).
The results of many studies show that polydatin may be a new therapeutic agent against multiorgan dysfunction.
This natural compound improved organ function, prolonged survival time, and reduced multiple-organ dysfunction
syndrom incidence and serum oxidative stress and proinflammatory cytokines. It also decreased apoptosis-related
protein levels and caspase-3 activity and increased B-cell lymphoma-2 (Bcl-2) levels in kidney and liver [76].
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Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)

Anthraquinones
Knotweed also produces anthraquinones, mainly emodin, physcion and citreorosein and their glucopyranoside
derivatives, that have several pharmacological effects. Anthraquinone derivatives are widely used as mild laxatives.
Besides their purgative properties, anthraquinones possess antibacterial, antiviral, antifungal, antioxidant, and
anticancer properties [78, 79].
Emodin (III)
Emodin (III) (6-metyl-1,3,8-trihydroxyanthraquinone) inhibits the motor activity of a parasitic Schistosoma
species [80]. Emodin may also be used in conjunction with known antischistosomal drugs. Second, emodin has
antineoplastic and antimutagenic activities. One study showed that emodin decreased the mutagenicity of a quinoline
product, found in some cooked foods, by direct inhibition of hepatic microsomal activation [81]. Emodin also
inhibits mutagenicity of 1-nitropyrene, a known mutagen, in a dose-dependent fashion by acting as a blocking
and/or suppressing agent to reduce the direct-acting mutagenicity of 1-nitropyrene [82]. Emodin exhibits also
antibacterial and antiviral effect, including anti-MRSA activity [83-85].
Emodin shows cytotoxicity and inhibition precursor incorporation into DNA and RNA activities, which does
not allow expression of genetic information in certain cell lines, in which it has been shown to be an antineoplastic
agent [86, 87]. Emodin is a strong inhibitor of a protein tyrosine kinase [88-90]. Chang et al. [91] isolated three
classes of protein-tyrosine kinase inhibitors, anthraquinone, stilbene, and flavonoid, from R. japonica, and found
that emodin displayed highly selective activities against two different oncogenes, the src-Her-2/neu and ras-
oncogenes.
Perspective is also neuroprotective effect of emodin. Emodin protects neurons against beta-amyloid-induced
neurotoxicity and ischemic injury [92].
Physcion (IV)
Physcion (IV) (1,8-dihydroxy-3-methoxy-6-methylanthraquinone), also known as parietin, is a natural
anthraquinone derivative compound distributed widely in nature from both terrestrial and marine sources [93-95].
In knotweed, physcion is present in the form of its 8-O-β-D-glucopyranoside [24]. Physcion has been reported
previously for a number of biological activities, including anti-microbial [96], anti-inflammatory [97], and
hepatoprotective activities [98].
Physcion 8-O-β-glucopyranoside
Physcion 8-O-β-glucopyranoside (PSG) isolated from knotweed can significantly enhance learning and memory
in Aβ1-40-induced dementia rats, and the mechanisms may be related to increase levels of acetylcholine, serotonin,
noradrenaline, and dopamine, decrease Aβ contents, and up-regulation of dendritic spine protein drebrin [99] (Shim
et al., 2002) in hippocampus [100].
PSG, a major active ingredient from a traditional Chinese herbal medicine Rumex japonicus Houtt, is capable
of preventing human colorectal cancer cells from hypoxia-induced epithelial-mesenchymal transition [101]. Further,
PSG enhances the commitment of mouse mesenchymal progenitors into osteoblasts and their differentiation [102]
and induces mitochondria-dependent apoptosis of human oral squamous carcinoma cells by suppressing protein
survivin expression via miR-21/PTEN/Akt/GSK3β signaling pathway [103].
Citreorosein (V)
Citreorosein (V) is a naturally occurring anthraquinone derivative, first isolated from Penicillium citreoroseum
[104]. Citreorosein inhibits proinflammatory cytokines production through the inhibition of both MAPKs and
AKT-mediated IκB kinase (IKK) phosphorylation and subsequent inhibition of transcription factor NF-κB
activation, thereby attenuating the production of proinflammatory cytokines [105]. This anthraquinone represents
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Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
a potential therapeutic approach for the treatment of inflammatory diseases [106] and would be beneficial for the pre-
vention of allergic inflammation [107].
Other compounds
Sesquiterpene of calamenene type, phenylpropanoides, and polyphenols of flavonoide type were also found in
knotweed.
Lapathosides (VI)
The phenylpropanoid esters of sucrose, lapathosides A, B, C, and D, were first isolated from the aerial parts
of Polygonum lapathifolium [108]. Lapathosides were also found in R. sachalinensis together with other
phenylpropanoids [109]. The primary screening of lapathosides result indicated that these phenylpropanoid sucrose
esters exhibited significant anti-tumor-promoting effects and might be valuable source for new potent anticancer
drug candidates [110].
8-Hydroxycalamenene (VII)
8-hydroxycalamenene (VII) is natural sesquiterpene phenol of cadinane type [111]. This compound shows
not only significant toxicity against fish but also antibacterial activity [112]. Jo et al. [113] showed that 8-hydroxy-
calamenene attenuated the cell death of transformed RGC-5 cells. This compound also produced a dose-dependent
decrease in the expression of apoptotic proteins (cleaved PARP and caspase-3) induced by l-buthionine-(S,R)-
sulfoximine (BSO) plus glutamate and stimulated glutathione and glutathione S-transferase activity.
Quercetin (VIII)
Quercetin (VIII) (2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one) is a flavonol found in many
fruits, vegetables, leaves and grains. It is the aglycone form of a number of other flavonoid glycosides, such as
rutin and quercitrin, found in citrus fruit, buckwheat and onions. It can be used as an ingredient in supplements,
beverages, or foods. Quercetin is one of the most abundant dietary flavonoids with an average daily consumption
of 25–50 mg [114]. It is believed that quercetin is a polyphenol with multifaceted therapeutic applications [115].
There is appreciated particular potential of quercetin in the prevention and treatment of cancers of various
type [116, 117], as an agent against cardiovascular diseases [118], as a preventive molecule for neuropatology
[119], or in the treatment of metabolic syndrome [120-122].
Kaempferol (IX)
Kaempferol (IX) (3,5,7-trihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) is a natural flavonoid, found
in a variety of plants and plant-derived foods. The total average intake of flavonols and flavones in a normal diet
is estimated as 23 mg/day to which kaempferol contributes approximately 17 % [123]. Common foods that contain
kaempferol include: apples, peaches, grapes, green tea, tomatoes, potatoes, broccoli, squash, cucumbers, lettuce,
green beans, blackberries, raspberries, and spinach [124].
Kaempferol acts as an antioxidant by reducing oxidative stress [125-128]. Many studies suggest that consuming
kaempferol may reduce the risk of various cancers [103, 129-131], and it is currently under consideration
as a possible cancer treatment [132, 133].
TOXICOLOGY
Knotweed is considered a non-poisonous plant, however, this does not mean that some of its content substances
cannot be toxic. For example emodin could lead to hepatotoxicity, kidney toxicity and reproductive toxicity,
particularly in high doses and with long-term use [134].

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Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
CONCLUSIONS
Knotweed is widely distributed in the world and has been used as a traditional medicine for a long history
in China. It has been used for treatment of hyperlipidemia, inflammation, infection and cancer, etc. Over 70 com-
pounds including quinones, stilbenes, flavonoids, counmarins and ligans have been isolated and identified
from this plant. Because there is no enough systemic data about the chemical constituents and their pharmacological
effects or toxicities, it is important to investigate the pharmacological effects and molecular mechanisms of this plant
based on modern realization of diseases' pathophysiology. Drug target-guided and bioactivity-guided isolation and
purification of the chemical constituents from this plant and subsequent evaluation of their pharmacologic effects
will promote the development of a new drug and will make sure which chemical constituent or multiple ingredients
contribute to their pharmacological effects. Additionally, chemicals and their pharmacological effects of the other
parts, such as the aerial part of this plant, should be exploited in order to avoid resource waste and to find new
chemical constituents. In the medical literature there are many studies that show the usefulness of knotweed
in human health, although most of them are tested only on laboratory animals. Therefore the information contained
herein is based on published sources, and is made available for academic purposes only.
ACKNOWLEDGMENTS
This work was supported by the Healthy and Happy s.r.o., Slušovice, Czech Republic and by the long-term
organization development plan of University Hospital, Hradec Kralove, Czech Republic.
REFERENCES
1. Chrtek, J.; Chrtkova, A. Reynoutria × bohemica, a new hybrid of Polygonaceae. Cas. Nar. Muz. Ser. Nat. 1983,
152, 120. Czech.
2. Mandak, B.; Pysek, P.; Bimova, K. History of the invasion and distribution of Reynoutria taxa in the Czech
Republic: a hybrid spreading faster than its parents. Preslia. 2004, 76, 15-64.
3. Flora of China Editorial Committee. Flora of China Vol. 5: Ulmaceae through Basellaceae. Missouri Botanical
Garden Press, 2003, p. 506.
4. Lee, G.; Choi, T.W.; Kim, C.; Nam, D.; Lee, S.G.; Jang, H.J.; Lee, J.H.; Um, J.Y.; Jung, S.H.; Shim, B.S.; Ahn,
K.S.; Ahn, K.S. Anti-inflammatory activities of Reynoutria elliptica through suppression of mitogen-activated
protein kinases and nuclear factor-κB activation pathways. Immunopharmacol. Immunotoxicol. 2012, 34, 454-464.
5. Brock, J.H.; Wade, M.; Pyšek, P.; Green, D. Plant Invasions: Studies from North America and Europe, Biol.
Plant. 1997, 41, 95-102.
6. Patocka, J. Knotweed: noxious weeds, or promising material? Vesmír, 2005, 84, 465. Czech.
7. Strasil, Z.; Kara, J. Study of knotweed (Reynoutria) as possible phytomass resource for energy and industrial
utilization. Res. Agricult. Engineering, 2010, 56(3), 85-91.
8. Woodward, S.L.; Quinn, J.A. Encyclopedia of Invasive Species: From Africanized Honey Bees to Zebra
Mussels. Greenwood Press, United States, 2011, p. 387-391.
9. Chrtek J. Reynoutria Houtt. In: Hejný S, Slavík B. (eds.). Flora of the Czech Republic Vol. 2, Academia Praha,
Praha, 1990, p. 362-366. Czech.
10. Moravcova, L.; Pysek, P.; Jarosik, V.; Zakravsky, P. Potential phytotoxic and shading effects of invasive Fallopia
(Polygonaceae) taxa on the germination of dominant native species. NeoBiota. 2011, 9, 31-47.
11. Murrell, C.; Gerber, E.; Krebs, C.; Parepa, M.; Schaffner, U.; Bossdorf, O. Invasive knotweed affects native
plants through allelopathy. Am. J. Bot. 2011, 98, 38-43.
12. Peng, W.; Qin, R.; Li, X.; Zhou, H. Botany, phytochemistry, pharmacology, and potential application of
Polygonum cuspidatum Sieb.et Zucc.: a review. J. Ethnopharmacol. 2013, 148(3), 729-745.
13. Zhang, H.; Li, C.; Kwok, S.T.; Zhang, Q.W.; Chan, S.W. A Review of the Pharmacological Effects of the Dried
Root of Polygonum cuspidatum (Hu Zhang) and Its Constituents. Evid. Based Complement. Alternat. Med.
2013, 2013, 208349.
14. Nosalova, G.; Jurecek, L.; Hromadkova, Z.; Kostalova, Z.; Sadlonova, V. Antioxidant activity of herbal
polysaccharides and cough reflex. In Neurobiology of Respiration. Springer Verlag, Netherlands, 2013, p. 51-57.

26
Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
15. Lewis, W.H.; Elvin-Lewis, M.P.F. 1977. Medical Botany. John Wiley & Sons, Inc., New York, 1997, p. 515.
16. Lin, M.H.; Hsu, S.Y. Studies on pharmacological effects of various extracts of Polygonum cuspidatum S. et Z.
Tai-wan Yao. Hsueh. Tsa. Chih. 1987, 39, 42-53.
17. Luo, Z.H. The use of Chinese traditional medicines to improve impaired immune functions in scald mice. Chung
Hua Cheng Hsing Shao Shang Wai Ko Tsa Chih (China) 1993, 9 (1), 56-58.
18. Quattrocchi, U. CRC World Dictionary of Medicinal and Poisonous Plants: Common Names, Scientific Names,
Eponyms, Synonyms, and Etymology. CRC Press, Boca Raton, Florida, 2012, p. 3960.
19. Lou, Z.; Huang, W.; Liu, J. Effects of Chinese herbs on impaired lymfocyte functions after thermal injury in
mice. Zhonghua Wai Ke Za Zhi. 1995, 33(9), 571-573. Chinese.
20. Wu, X.B.; Zhao, K.S.; Huang, X.L. Changes in adhesion features of leukocytes in rats with severe burns. Chung
Hua I Hsueh Tsa Chih (China) 1994, 74(5), 312-314.
21. Wu, K.; Q. Huang, Q. Relationship between disturbances of microcirculation and TNF during burn shock.
Chung Hua Cheng Hsing Shao Shang Wai Ko Tsa Chih (China) 1996, 12(1), 41-44.
22. Vrchotova, N.; Sera, B.; Triska, J. The stilbene and catechin content of the spring sprouts of Reynoutria species.
Acta Chromatogr. 2007, 19, 21-28.
23. Ivanova, R.; Titei, V. Accumulation of Polyphenolic Substances in Leaves and Flowers of Giant Knotweed
(Polygonum sachalinense) in Republic of Moldova Conditions. Int. J. Second. Met.2014, 1, 11-22.
24. Zhang, X.; Thuong, P.T.; Jin, W.; Su, N.D.; Bae, K.; Kang, S.S. Antioxidant Activity of Anthraquinones and
Flavonoids from Flower of Reynoutria sachalinensis. Arch. Pharm. Res. 2005, 28(1), 22-27.
25. Hegnauer R. Polygonaceae. In: Chemotaxonomie der Pflanzen, Birkhäuser, Basel, 1990, p. 268-285.
26. Hua, Y.; Zhou, J.; Ni, W.; Chen, C. Studies on the constituents of Reynoutria japonica Houtt. Nat. Prod. Res.
Develop. 2000, 13, 16-18.
27. Lee, C.H.; Kim, S.I.; Lee, K.B.; Yoo, Y.C.; Ryu, S.Y.; Song, K.S. Neuraminidase inhibitors from Reynoutria
elliptica. Arch. Pharm. Res. 2003, 26, 367-374.
28. Hwangbo, K.; Zheng, M.S.; Kim, Y.J.; Im, J.Y.; Lee, C.S.; Woo, M.H.; Jahng, Y.; Chang, H.W.; Son, J.K.
Inhibition of DNA topoisomerases I and II of compounds from Reynoutria japonica. Arch. Pharm. Res. 2012,
35, 1583-1589.
29. Hsu, C.Y.; Chan, Y.P.; Chang, J. Antioxidant activity of extract from Polygonum cuspidatum. Biol. Res. 2007,
40, 13-21.
30. Su, P.W.; Yang, C.H.; Yang, J.F.; Su, P.Y.; Chuang, L.Y. Antibacterial Activities and Antibacterial Mechanism
of Polygonum cuspidatum Extracts against Nosocomial Drug-Resistant Pathogens. Molecul. 2015, 20(6), 11119-
11130.
31. Hwang, J.T.; Park, Y.S.; Kim, Y.S.; Kim, J.C.; Lim, C.H. Isolation and identification of antifungal compounds
from Reynoutria elliptica. CNU J. Agricult. Sci. 2012, 39, 583-589.
32. Lin, Y.W.; Yang, F.J.; Chen, C.L.; Lee, W.T.; Chen, R.S. Free radical scavenging activity and antiproliferative
potential of Polygonum cuspidatum root extracts. J. Nat. Med. 2010, 64, 146-152.
33. Lee, C.C.; Chen, Y.T.; Chiu, C.C.; Liao, W.T.; Liu, Y.C.; David Wang, H.M. Polygonum cuspidatum extracts as
bioactive antioxidation, anti-tyrosinase, immune stimulation and anticancer agents. J. Biosci. Bioeng. 2015,
119, 464-469.
34. Eid, S.Y.; El-Readi, M.Z.; Ashour, M.L.; Wink, M. Fallopia japonica, a Natural Modulator, Can Overcome
Multidrug Resistance in Cancer Cells. Evid. Based Complement. Alternat. Med. 2015, 2015: 868424.
35. Sohn, E.; Kim, J.; Kim, C.S.; Jo, K.; Kim, J.S. Extract of Rhizoma Polygonum cuspidatum reduces early renal
podocyte injury in streptozotocin induced diabetic rats and its active compound emodin inhibits methylglyoxal
mediated glycation of proteins. Mol. Med. Rep. 2015, 12(4), 5837-5845.
36. Sohn, E.; Kim, J.; Kim, C.S.; Lee, Y.M.; Kim, J.S. Extract of Polygonum cuspidatum Attenuates Diabetic
Retinopathy by Inhibiting the High-Mobility Group Box-1 (HMGB1) Signaling Pathway in Streptozotocin-
Induced Diabetic Rats. Nutrients. 2016, 8(3), 140.
37. Kim, J.; Kim, M.Y.; Leem, K.H.; Moon, S.; Jamakattel-Pandit, N.; Choi, H.; Kim, H.; Bu, Y. Key compound
groups for the neuroprotective effect of roots of Polygonum cuspidatum on transient middle cerebral artery
occlusion in Sprague-Dawley rats. Nat. Prod. Res. 2010, 24, 1214-1226.
38. Xiao, H.T.; Qi, X.L.; Liang, Y.; Lin, C.Y.; Wang, X.; Guan, Z.Z.; Hao, X.Y. Membrane permeability-guided
identification of neuroprotective components from Polygonum cuspidatum. Pharm. Biol. 2014, 52(3), 356-361.
39. Kuno, A.; Tanno, M.; Horio, Y. The effects of resveratrol and SIRT1 activation on dystrophic cardiomyopathy.
Ann. N Y Acad. Sci. 2015, 1348, 46-54.

27
Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
40. Bavaresco, L.; Lucini, L.; Busconi, M.; Flamini, R.; De Rosso, M. Wine Resveratrol: From the Ground Up.
Nutrients. 2016, 8, E222.
41. Pangeni, R.; Sahni, J.K.; Ali, J.; Sharma, S.; Baboota, S. Resveratrol: review on therapeutic potential and recent
advances in drug delivery. Expert. Opin. Drug Deliv. 2014, 11(8), 1285-1298.
42. Sung, M.M.; Dyck, J.R. Therapeutic potential of resveratrol in heart failure. Ann. N.Y. Acad. Sci. 2015, 1348(1),
32-45.
43. Orsini, F.; Verotta, L.; Klimo, K.; Gerhäuser, C. Synthesis of Resveratrol Derivatives and In Vitro Screening
for Potential Cancer Chemopreventive Activities. Arch. Pharm. (Weinheim). 2016, 349(6), 414-427.
44. Xiang, H.Y.; Zhou, C.S.; Zhong, S.A.; Chen, L.S. Extraction process of resveratrol from Polygonum cuspidatum
Sieb et Zucc. Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and
Technology), 2004, 35(6), 965-969.
45. Yang, H.; Zhang, A.; Zhang, Y.; Ma, S.; Wang, C. Resveratrol Pretreatment Protected against Cerebral
Ischemia/Reperfusion Injury in Rats via Expansion of T Regulatory Cells. J Stroke Cerebrovasc. Dis. 2016,
May 12. [Epub ahead of print]
46. Gocmez, S.S.; Gacar, N.; Utkan, T.; Gacar, G.; Scarpace, P.J.; Tumer, N. Protective effects of resveratrol on
aging-induced cognitive impairment in rats. Neurobiol. Learn. Mem. 2016, 131, 131-136.
47. Gacar, N.; Mutlu, O.; Utkan, T.; Komsuoglu, C.I.; Gocmez S.S.; Ulak, G. Beneficial effects of resveratrol on
scopolamine but not mecamylamine induced memory impairment in the passive avoidance and Morris water
maze tests in rats. Pharmacol Biochem Behav. 2011, 99(3), 316-323.
48. Kubo, M.; Kimura, Y.; Shin, H.; Haneda, T.; Tani, T.; Namba, K. Studies on the antifungal substance of crude
drug: 2. On the roots of Polygonum cuspidatum (Polygonaceae). Shoyakugaku. Zasshi. 1981, 35, 58-61.
49. Jang, M.; Cai, L.; Udeani, G.O. Cancer chemopreventive activity of resveratrol, a natural product derived from
grapes. Science. 1997, 275, 218-220.
50. Jayatilake, G.S.; Jayasuriya, H.; Lee, E.S.; Koonchanok, N.M.; Geahlen, R.L.; Ashendel, C.L.; McLaughlin,
J.L.; Chang, C.J. Kinase inhibitors from Polygonum cuspidatum. J. Nat. Prod. (Lloydia). 1993, 56, 1805-1810.
51. Belsches, A.P.; Haskell, M.D.; Parsons, S.J. Role of c-Src tyrosine kinase in EGF-induced mitogenesis. Front.
Biosci. 1997, 2, d501-d518.
52. Kimura, Y.; Okuda, H.; Kubo, M. Effects of stilbenes isolated from medicinal plants on arachidonate metabolism
and degranulation in human polymorphonuclear leukocytes. J. Ethnopharmacol. 1995, 45, 131-139.
53. Lehninger, A.L.; Nelson, D.L.; Cox, M.M. Principles of Biochemistry, 2nd Ed. Worth Publishers, New York,
1993, p. 1013.
54. Arichi, H.; Kimura, Y.; Okuda, H.; Baba, K.; Kozawa, M.; Arichi, S. Effects of stilbene components of the roots
of Polygonum cuspidatum on lipid metabolism. Chem. Pharm. Bull. (Tokyo) 1982, 30, 1766-1770.
55. Kimura, Y.; Ohminam, H.; Okuda, H.; Baba, K.; Kozawa, M.; Arichi, S. Effects of stilbene components of roots
of Polygonum ssp. on liver injury in peroxidized oil-fed rats. Planta Med. 1983, 49, 51-54.
56. Yuchi, S.; Kimura, J. Patent-Japan Kokai Tokkyo-61 40, 763. Chem. Abstr. 1986, 104, 213296.
57. Oransky, I. Retraction Watch. Tracking retractions as a window into the scientific process. Late resveratrol
researcher Dipak Das up to 20 retractions. 2014. Avalible on: http://retractionwatch.com/2014/03/27/late-
resveratrol-researcher-dipak-das-up-to-20-retractions/
58. Ryan, J. Red wine researcher Dr. Dipak K. Das published fake data: Uconn, 2012, avalible on:
http://www.cbsnews.com/news/red-wine-researcher-dr-dipak-k-das-published-fake-data-uconn/
59. DeFrancesco, C. Scientific Journals Notified Following Research Misconduct Investigation. UConn Today,
January 11, 2012. avalible on: http://today.uconn.edu/2012/01/scientific-journals-notified-following-research-
misconduct-investigation/
60. Du, Q.H.; Peng, C.; Zhang, H. Polydatin: a review of pharmacology and pharmacokinetics. Pharm. Biol. 2013,
51, 1347-1354.
61. Ravagnan, G.; De Filippis, A.; Cartenì, M.; De Maria, S.; Cozza, V.; Petrazzuolo, M.; Tufano, M.A.;
Donnarumma, G. Polydatin, a natural precursor of resveratrol, induces β-defensin production and reduces
inflammatory response. Inflammat. 2013, 36(1), 26-34.
62. Shan, C.W. Effects of polydatin on platelet aggregation of rabbits. Acta. Pharm. Sin. 1988, 23(5), 394-396.
63. Luo, S.F.; Yu, C.L.; Zhang, P.W. Influences of 3,4,5-trihydroxystilbene 3§-mono-D-glucoside on beat rate and
injury of cultured newborn rat myocardial cells. Acta Pharmacol. Sin. 1990, 11(2): 147-150.
64. Wang, H.L.; Gao, J.P.; Han, Y.L.; Xu, X.; Wu, R.; Gao, Y.; Cui, X.H. Comparative studies of polydatin and
resveratrol on mutual transformation and antioxidative effect in vivo. Phytomed. 2015, 22(5), 553-559.

28
Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
65. Ma, Y.; Gong, X.; Mo, Y.; Wu, S. Polydatin inhibits the oxidative stress-induced proliferation of vascular smooth
muscle cells by activating the eNOS/SIRT1 pathway. Int. J. Mol. Med. 2016, 37(6), 1652-1660.
66. Romero-Pérez, A.I.; Ibern-Gómez, M.; Lamuela-Raventós, R.M.; de La Torre-Boronat, M.C. Piceid, the major
resveratrol derivative in grape juices. J. Agric. Food Chem. 1999, 47(4), 1533-1536.
67. Liu, L.T.; Guo, G.; Wu, M.; Zhang, W.G. The progress of the research on cardio-vascular effects and acting
mechanism of polydatin. Chin. J. Integr. Med. 2012, 18(9), 714-719.
68. Li, R.P.; Wang, Z.Z.; Sun, M.X.; Hou, X.L.; Sun, Y.; Deng, Z.F.; Xiao, K. Polydatin protects learning and
memory impairments in a rat model of vascular dementia. Phytomed. 2012, 19, 677-681.
69. Chen, M.; Hou, Y.; Lin, D. Polydatin Protects Bone Marrow Stem Cells against Oxidative Injury: Involvement
of Nrf 2/ARE Pathways. Stem Cells Int. 2016, 2016: 9394150.
70. Zhou, Q.L.; Qin, R.Z.; Yang, Y.X.; Huang, K.B.; Yang, X.W. Polydatin possesses notable anti‑osteoporotic
activity via regulation of OPG, RANKL and β‑catenin. Mol. Med. Rep. 2016, Jun 23. doi:
10.3892/mmr.2016.5432. [Epub ahead of print]
71. Zhang, Q.; Tan, Y.; Zhang, N.; Yao, F. Polydatin supplementation ameliorates diet-induced development of
insulin resistance and hepatic steatosis in rats. Mol. Med. Rep. 2015, 11(1), 603-610.
72. Hao, J.; Chen, C.; Huang, K.; Huang, J.; Li, J.; Liu, P.; Huang, H. Polydatin improves glucose and lipid
metabolism in experimental diabetes through activating the Akt signaling pathway. Eur. J. Pharmacol. 2014,
745, 152-165.
73. Wang, Y.; Ye, J.; Li, J.; Chen, C.; Huang, J.; Liu, P.; Huang, H. Polydatin ameliorates lipid and glucose
metabolism in type 2 diabetes mellitus by downregulating proprotein convertase subtilisin/kexin type 9
(PCSK9). Cardiovasc. Diabetol. 2016, 15, 19.
74. Wu, Y.; Xue, L.; Du, W.; Huang, B.; Tang, C.; Liu, C.; Qiu, H.; Jiang, Q. Polydatin Restores Endothelium-
Dependent Relaxation in Rat Aorta Rings Impaired by High Glucose: A Novel Insight into the PPARβ-NO
Signaling Pathway. PLoS One. 2015, 10(5), e0126249.
75. Gao, Y.; Gao, J.; Chen, C.; Wang, H.; Guo, J.; Wu, R. Cardioprotective effect of polydatin on ventricular
remodeling after myocardial infarction in coronary artery ligation rats. Planta Med.2015, 81, 568-577.
76. Zhang, Y.; Li, S.; Wang, W.; Xu, C.; Liang, S.; Liu, M:; Hao, W.; Zhang R. Beneficial effects of polydatin on
learning and memory in rats with chronic ethanol exposure. Int. J. Clin. Exp. Pathol. 2015, 8(9), 11116-11123.
77. Sun, J.; Qu, Y.; He, H.; Fan, X.; Qin, Y.; Mao, W.; Xu, L. Protective effect of polydatin on learning and memory
impairments in neonatal rats with hypoxic‑ischemic brain injury by up‑regulating brain‑derived neurotrophic
factor. Mol. Med. Rep. 2014, 10(6), 3047-3051.
78. Mueller, S.O.; Schmitt, M.; Dekant, W.; Stopper, H.; Schlatter, J.; Schreier, P.; Lutz, W.K. Occurrence of emodin,
chrysophanol and physcion in vegetables, herbs and liquors. Genotoxicity and anti-genotoxicity of the
anthraquinones and of the whole plants. Food Chem. Toxicol. 1999, 37, 481-491.
79. Kremer, D.; Kosalec, I.; Locatelli, M.; Epifano, F.; Genovese, S.; Carlucci, G.; Koncic, M.Z. Anthraquinone
profiles, antioxidant and antimicrobial properties of Frangula rupestris (Scop.) Schur and Frangula alnus Mill.
Bark Food. Chem. 2012, 131, 1174-1180.
80. Anantaphruti, M.; Terada, M.; Ishii, A.I.; Kino, H.; Sano, M.; Kuroyanagi, M.; Fukushima, S. Chemotherapy
of parasitic helminths: 11. In vitro effects of various drugs on the motor activity of adult Schistosoma japonicum.
JPN J. Parasitol. 1982, 31, 321-328.
81. Lee, H.; Tsai, S.J. Effect of emodin on cooked-food mutagen activation. Food. Chem. Toxicol. 1991, 29, 765-770.
82. Su, H.Y.; Cherng, S.H.; Chen, C.C.; Lee, H. Emodin inhibits the mutagenicity and DNA adducts induced by 1-
nitropyrene. Mutat. Res. 1995, 329(2), 205-212.
83. Cao, F.; Peng, W.; Li, X.; Liu, M.; Li, B.; Qin, R.; Jiang, W.; Cen, Y.; Pan, X.; Yan, Z.; Xiao, K.; Zhou, H.
Emodin is identified as the active component of ether extracts from Rhizoma Polygoni Cuspidati, for anti-
MRSA activity. Can. J. Physiol. Pharmacol. 2015, 93, 485-493.
84. Lin, C.J.; Lin, H.J.; Chen, T.H.; Hsu, Y.A.; Liu, C.S.; Hwang, G.Y.; Wan, L. Polygonum cuspidatum and its
active components inhibit replication of the influenza virus through toll-like receptor 9-induced interferon beta
expression. PLoS One. 2015, 10, e0117602.
85. Li, L.; Song, X.; Yin, Z.; Jia, R.; Li, Z.; Zhou, X.; Zou, Y.; Li, L.; Yin, L.; Yue, G.; Ye, G.; Lv, C.; Shi, W.; Fu,
Y. The antibacterial activity and action mechanism of emodin from Polygonum cuspidatum against Haemophilus
parasuis in vitro. Microbiol. Res. 2016, 186-187, 139-145.
86. Yeh, S.F.; Chou, T.C.; Liu, T.S. Effects of anthraquinones of Polygonum cuspidatum on HL-60 cells. Planta
Med. 1988, 54(5), 413-414.

29
Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
87. Klug, W.S.; Cumming, M.R. Concepts of Genetics, 4th Ed. Prentice Hall, Inc., Englewood Cliffs, NJ, 1994,
p. 779.
88. Jayasuriya, H.; Koonchanok, N.M.; Geahlen, R.L.; McLaughlin, J.L.; Chang C.J. Emodin, a protein tyrosine
kinase inhibitor from Polygonum cuspidatum. J. Nat. Prod. (Lloydia). 1992, 55, 696-698.
89. Chang, C.J. Isolation and structural elucidation of antitumor agents from higher plants. 1997, avalible on:
http://sparky.pharmacy.purdue.edu/mcmp/chang/chang.htm
90. Geahlen, R.L. Protein-tyrosine kinases and signal transduction; Signaling through antigen receptors on immune
cells; Protein acylation; Protein-tyrosine kinase inhibitors. 1997, avalible on:
http://sparky.pharmacy.p.../mcmp/geahlen/geahle.htm
91. Chang, C.J.; Ashendel, C.L.; Geahlen, R.L.; McLaughlin, J.L.; Waters D.J. Oncogene signal transduction
inhibitors from medicinal plants. In Vivo (Greece). 1996, 10, 185-190.
92. Lu, J.S.; Liu, J.X.; Zhang, W.Y.; Liang, S.W.; Wang, D.; Fang, J. Preventive effects of emodin on cerebral
ischemia injury and expression of the inflammatory factors in rats with cerebral ischemia. Zhongguo Zhong
Yao Za Zhi. 2005, 30(24), 1939-1943. Chinese.
93. Agarwal, S.K.; Singh, S.S.; Verma, S.; Kumar, S. Antifungal activity of anthraquinone derivatives from Rheum
emodi. J. Ethnopharmacol. 2000, 72, 43-46.
94. Thiruvengadam, M.; Praveen, N.; Kim, E.H.; Kim, S.H.; Chung, I.M. Production of anthraquinones, phenolic
compounds and biological activities from hairy root cultures of Polygonum multiflorum Thunb. Protoplasma.
2014, 251(3), 555-566.
95. Wijesekara, I.; Zhang, C.; Van Ta, Q.; Vo, T.S.; Li, Y.X.; Kim, S.K. Physcion from marine-derived fungus
Microsporum sp. induces apoptosis in human cervical carcinoma HeLa cells. Microbiol. Res. 2014, 169(4),
255-261.
96. Tamokou, J.D.D.; Tala, M.F.; Wabo, H.K.; Kuiate, J.R.; Tane, P. Antimicrobial activities of methanol extract
and compounds from stem bark of Vismia rubescens. J. Ethnopharmacol. 2009, 124, 571-575.
97. Ghosh, S.; Sarma, M.D.; Patra, A.; Hazra, B. Anti-inflammatory and anticancer compounds isolated from
Ventilago madraspatana Gaertn., Rubia cordifolia Linn. and Lantana camara Linn. J. Pharm. Pharmacol.
2010, 62, 1158-1166.
98. Zhao, Y.L.; Wang, J.B.; Zhou, G.D.; Shan, L.M.; Xiao, X.H. Investigations of free antraquinones from rhubarb
against α-naphthylisothiocyanate-induced cholestatic liver injury in rats. Basic Clin. Pharmacol. Toxicol. 2009,
194, 463-469.
99. Shim, K.S.; Lubec, G. Drebrin, a dendritic spine protein, is manifold decreased in brains of patients with
Alzheimer's disease and Down syndrome. Neurosci. Lett. 2002, 324(3), 209-212.
100. Xu, N.G.; Xiao, Z.J.; Zou, T.; Huang, Z.L. Ameliorative effects of physcion 8-O-β-glucopyranoside isolated
from Polygonum cuspidatum on learning and memory in dementia rats induced by Aβ1-40. Pharm. Biol. 2015,
53(11), 1632-1638.
101. Xie, Q.C.; Yang, Y.P. Anti-proliferative of physcion 8-O-β-glucopyranoside isolated from Rumex japonicus
Houtt. on A549 cell lines via inducing apoptosis and cell cycle arrest. BMC Complement Alternat. Med. 2014,
14(1), 377-381.
102. Lee, S.U.; Choi, Y.H.; Kim, Y.S.; Park, S.J.; Kwak, H.B.; Min, Y.K.; Kim, H.N.; Lim, K.E.; Choi, J.Y.; Rhee,
M.; Kim, S.H. Physcion-8-O-beta-D-glucopyranoside enhances the commitment of mouse mesenchymal
progenitors into osteoblasts and their differentiation: Possible involvement of signaling pathways to activate
BMP gene expression. J. Cell. Biochem. 2010, 109, 1148-1157.
103. Lee, J.; Kim, J.H. Kaempferol Inhibits Pancreatic Cancer Cell Growth and Migration through the Blockade
of EGFR-Related Pathway In Vitro. PLoS One. 2016, 11, e0155264.
104. Karrer W. Anthrachinone (incl. Anthrone u. Anthranole). In: Konstitution und Vorkommen der organischen
Pflanzenstoffe (exclusive Alkaloide). Birkhäuser, Basel, 1976, p. 496-530.
105. Lu, Y.; Suh, S.J.; Li, X.; Liang, J.L.; Chi, M.; Hwangbo, K.; Kwon, O.; Chung, T.W.; Kwak, C.H.; Kwon,
K.M.; Murakami, M.; Jahng, Y.; Kim, C.H.; Son, J.K.; Chang, H.W. Citreorosein inhibic production of
proinflammatory cytokines by blocking mitogen activated protein kinases, nuclear factor-κB and activator
protein-1 activation in mouse bone marrow-derived mast cells. Biol. Pharm. Bull. 2012a, 35(6), 938-945.
106. Lu, Y.; Suh, S.J.; Li, X.; Hwang, S.L.; Li, Y.; Hwangbo, K.; Park, S.J.; Murakami, M.; Lee, S.H.; Jahng, Y.;
Son, J.K.; Kim, C.H.; Chang, H.W. Citreorosein, a naturally occurring anthraquinone derivative isolated from
Polygoni cuspidati radix, attenuates cyclooxygenase-2-dependent prostaglandin D2 generation by blocking Akt
and JNK pathways in mouse bone marrow-derived mast cells. Food Chem. Toxicol. 2012b, 50(3-4), 913-919.

30
Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
107. Lu, Y.; Li, Y.; Jahng, Y.; Son, J.K.; Chang, H.W. Citreorosein inhibits degranulation and leukotriene C4
generation through suppression of Syk pathway in mast cells. Mol Cell. Biochem. 2012c, 365(1-2), 333-341.
108. Takasaki, M.; Kuroki, S.; Kozuka, M.; Konoshima, T. New phenylpropanoid esters of sucrose from Polygonum
lapathifolium. J. Nat. Prod. 2001, 64(10), 1305-1308.
109. Fan, P.; Terrier, L.; Hay, A.E.; Marston, A.; Hostettmann, K. Antioxidant and enzyme inhibition activities and
chemical profiles of Polygonum sachalinensis F. Schmidt ex Maxim (Polygonaceae). Fitoterapia. 2010, 81,
124-131.
110. Panda, P.; Appalashetti, M.; Natarajan, M.; Chan-Park, M.B.; Venkatraman, S.S.; Judeh, Z.M. Synthesis and
antitumor activity of lapathoside D and its analogs. Eur. J. Med. Chem. 2012, 53, 1-12.
111. Serra, S.; Fuganti, C. Aromatic annulation on the p-menthane monoterpenes: enantiospecific synthesis of the
trans and cis isomers of calamenene and 8-hydroxycalamenene. Tetrahedron Lett, 2005, 46(28), 4769-4772.
112. Nishizawa, M.; Inoue, A.; Sastrapradja, S.; Hayashi, Y. (+)-8-Hydroxycalamenene: A fish-poison principle of
Dysoxylum acutangulum and D. alliaceum. Phytochem. 1983, 22(9), 2083-2085.
113. Jo, H.; Lee, H.J.; Kim, C.Y.; Son, J.K.; Jung, S.H. 8-Hydroxycalamenene isolated from the rhizomes of Reynoutria
elliptica exerts neuroptotective effects both in vitro and in vivo. Food. Chem. Toxicol. 2013, 51, 231-241.
114. Formica, J.V.; Regelson, W. Review of the biology of quercetin and related bioflavonoids. Food Chem. Toxicol.
1995, 33, 1061-1080.
115. D'Andrea, G. Quercetin: A flavonol with multifaceted therapeutic applications? Fitoterapia. 2015, 106, 256-271
116. Brito, A.F.; Ribeiro, M.; Abrantes, A.M.; Pires, A.S.; Teixo, R.J.; Tralhão, J.G.; Botelho, M.F. Quercetin in
Cancer Treatment, Alone or in Combination with Conventional Therapeutics? Curr. Med. Chem. 2015, 22,
2025-2039.
117. Yang, F.; Song, L.; Wang, H.; Wang, J.; Xu, Z.; Xing, N. Quercetin in prostate cancer: Chemotherapeutic and
chemopreventive effects, mechanisms and clinical application potential (Review). Oncol. Rep. 2015, 33(6),
2659-2668.
118. Gormaz, J.G.; Quintremil, S.; Rodrigo, R. Cardiovascular Disease: A Target for the Pharmacological Effects
of Quercetin. Curr. Top. Med. Chem. 2015, 15, 1735-1742.
119. Dajas, F.; Abin-Carriquiry, J.A.; Arredondo, F.; Blasina, F.; Echeverry, C.; Martínez, M.; Rivera, F.; Vaamonde,
L. Quercetin in brain diseases: Potential and limits. Neurochem. Int. 2015, 89, 140-148.
120. Cherniack, E.P. Polyphenols: planting the seeds of treatment for the metabolit syndrome. Nutrition. 2011, 27,
617-623.
121. Yan, S.X.; Li, X.; Sun, C.D.; Chen, K.S. Hypoglycemic and hypolipidemic effects of quercetin and its
glycosides. Zhongguo Zhong Yao Za Zhi. 2015, 40(23), 4560-4567. Chinese.
122. Amiot, M.J.; Riva, C.; Vinet A. Effects of dietary polyphenols on metabolit syndrome features in humans: a
systematic review. Obes. Rev. 2016, 17, 573-586.
123. Liu, R.H. Health-promoting components of fruits and vegetables in the diet. Adv. Nutr. 2013, 4(3), 384S-92S.
124. Calderon-Montaño, J.M.; Burgos-Moron, E.; Perez-Guerrero, C.; Lopez-Lazaro, M. A review on the dietary
flavonoid kaempferol. Mini. Rev. Med. Chem. 2011, 11, 298-344.
125. Shakya, G.; Manjini, S.; Hoda, M.; Rajagopalan, R. Hepatoprotective role of kaempferol during alcohol- and
ΔPUFA-induced oxidative stress. J. Basic Clin. Physiol. Pharmacol. 2014, 25 (1),73-79.
126. Al-Numair, K.S.; Chandramohan, G.; Veeramani, C.; Alsaif, M.A. Ameliorative effect of kaempferol, a
flavonoid, on oxidative stress in streptozotocin-induced diabetic rats. Redox Rep. 2015, 20, 198-209.
127. Devi, K.P.; Malar, D.S.; Nabavi, S.F.; Sureda, A.; Xiao, J.; Nabavi, S.M.; Daglia, M. Kaempferol and
inflammation: From chemistry to medicine. Pharmacol. Res. 2015, 99, 1-10.
128. Yang, Q.S.; He, L.P.; Zhou, X.L.; Zhao, Y.; Shen, J.; Xu, P.; Ni, S.Z. Kaempferol pretreatment modulates
systemic inflammation and oxidative stress following hemorrhagic shock in mice. Chin. Med. 2015, 10, 6.
129. Kim, S.H.; Choi, K.C. Anti-cancer Effect and Underlying Mechanism(s) of Kaempferol, a Phytoestrogen, on
the Regulation of Apoptosis in Diverse Cancer Cell Models. Toxicol. Res. 2013, 29, 229-234.
130. Dang, Q.; Song, W.; Xu, D.; Ma, Y.; Li, F.; Zeng, J.; Zhu, G.; Wang, X.; Chang, L.S.; He, D.; Li, L. Kaempferol
suppresses bladder cancer tumor growth by inhibiting cell proliferation and inducing apoptosis. Mol. Carcinog.
2015, 54, 831-840.
131. Song, H.; Bao, J.; Wei, Y.; Chen, Y.; Mao, X.; Li, J.; Yang, Z.; Xue, Y. Kaempferol inhibits gastric cancer
tumor growth: An in vitro and in vivo study. Oncol. Rep. 2015, 33(2), 868-874.
132. Kuo, W.T.; Tsai, Y.C.; Wu, H.C.; Ho, Y.J.; Chen, Y.S.; Yao, C.H.; Yao, C.H. Radiosensitization of non-small
cell lung cancer by kaempferol. Oncol. Rep. 2015, 34, 2351-2356.

31
Patocka et al.: Biologically Active Compounds of Knotweed (Reynoutria spp.)
133. Kim, S.H.; Hwang, K.A.; Choi, K.C. Treatment with kaempferol suppresses breast cancer cell growth caused
by estrogen and triclosan in cellular and xenograft breast cancer models. J. Nutr. Biochem. 2016, 28, 70-82.
134. Dong, X.; Fu, J.; Yin, X.; Cao, S.; Li, X.; Lin, L.; Huyiligeqi, Ni.J. Emodin: A Review of its Pharmacology,
Toxicity and Pharmacokinetics. Phytother. Res. 2016, May 18. Doi: 10.1002/ptr.5631. [Epub ahead of print]
135. Nhiem, N.X.; Van Kiem, P.; Van Minh, C.; Hoai, N.T.; Duc, H.V.; Tai, B.H.; Quang, T.H.; Le Anh, H.T.; Yeo,
S.G.; Song, J.H.; Cheon, D.S.; Park, M.H.; Ko, H.J.; Kim, S.H. Anti-influenza sesquiterpene from the roots
of Reynoutria japonica. Nat. Prod. Commun. 2014, 9(3), 315-318.
136. Hafez, S.L.; S. Al-Rehiayani, M.; Sundararaj, T.P. Differentiation of two geographically isolated populations
of Pratylenchus neglectus based on their parasitism of potato and interaction with Verticillium dahliae.
Nematropica. 1999; 29, 25-36.
137. Wenyi, J.; Na, M.K.; Song, G.Y.; Lee, Y.M.; Bae, K.H. Cytotoxic anthraquinones and stilbenes from Reynoutria
sachalinensis (Fr. Schm.) Nakai. Korean J. Med. Crop Sci. 2005, 13(2), 80-84.
138. Kim, M.H.; Park, J.H.; Won, H.; Park, C.W. Flavonoid chemistry and chromosome numbers of Fallopia section
Pleuropterus (Polygonaceae). Canad. J. Bot. 2000, 78, 1136-1143.
139. Park, J.H.; Moon, H.K.; Park, V.W. Flavonoid chemistry of Fallopia sect. Reynoutria (Polygonaceae) in Korea.
Korea Agricultural Science Digital Library, 2011, avalible on: http://agris.fao.org/agris-
search/search.do?recordID=KR2012001606