ReviewPersicaria hydropiper (L.) Delarbre: A review on traditional uses, bioactive chemical constituents and pharmacological and toxicological activities
Graphical abstract
Introduction
Ethnopharmacology, a source of knowledge-driven drug discovery, is playing a significant role in the search of drugs from plants, animals and other natural resources (Cordell and Colvard, 2005; Heinrich, 2010; Heinrich et al., 2009). The 2015 Nobel Prize for the discovery of antimalarial drug from Traditional Chinese Medicine, signifies the exciting and hidden potential of traditional therapies (Efferth et al., 2015). Although about 500,000 plant species are reported in the world, most of them are still to be explored (Mahesh and Satish, 2008). Nearly eighty percent of the world population uses alternative ways for treatment because of being economical, accessible and being relatively safer (Farnsworth et al., 1985). Medicinal plants, therefore, hold potential to fulfil the gap in the current medical practices as it may hold answers to some of the most deadly health issues (Khalil et al., 2014).
Different members of the family Polygonaceae have been widely studied for their pharmacological activities. Polygonaceae represents flowering plants, commonly referred as knotweed and smartweed. The name of the family Polygonaceae, comes from Polygonum genus, first coined by Antoine Laurent, a French botanist. The words “poly” and “gonum” mean “many” and “joints”, respectively. Polygonaceae comprises of about 1300 species distributed in 59 genera (The Plant List, http://www.theplantlist.org/). Members of Polygonaceae are distributed worldwide and represented by various genera including Eriogonum, Rumex, Coccoloba, Polygonum, Persicaria and Calligonum etc. Several species of Polygonaceae are used as ornamental plants while some are considered very important from therapeutic perspective. Among them, Persicaria hydropiper (L.) Delarbre (Synonym: Polygonum hydropiper L.) (Fig. 1) has gained tremendous attention due to its diverse phytochemistry and medicinal uses. P. hydropiper is also known as Water pepper or Smart pepper in English, “Bishkatali” in Bengali and has a cosmopolitan distribution (Oany et al., 2017). A careful review of the ethnomedicinal literature indicated various reported uses of P. hydropiper in epilepsy, edema, inflammation, headache, rheumatoid arthritis, chill, colic pain, fever, joint pain and other infectious diseases. It is also reported for use as central nervous system (CNS) stimulant, diuretic, anthelmintic and in the treatment of kidney diseases, hypertension, hemorrhoids, diarrhea, piles, bleeding, parasitic worms, and angina (Ayaz, Junaid, Ahmed, et al., 2014; Ayaz, Junaid, Subhan, et al., 2014; Kimura et al., 2014; Oany et al., 2017; Said et al., 2015; Xiao et al., 2017a).
Although it is widely used in traditional medicines and studied for chemical constituents and biological activities, the number of comprehensive reviews on P. hydropiper regarding its traditional uses, bioactive compounds and their mechanisms for various pharmacological activities are limited. The main aim of this review was to systematically analyze the reported traditional uses of this plant, bioactive constituents and pharmacological activities with special focus on neurological disorders.
Section snippets
Traditional uses as food and medicine
Analysis of the scientific literature regarding the traditional uses revealed that P. hydropiper is used as a medicine and as a spice in food in various parts of the world. Some of the traditional uses in Asian countries are given in Table 1. Plant as whole or different parts (roots, seeds, and aerial parts) were observed to be used in different traditional medicine systems. Due to its irritant properties, extract obtained from plant is reported to be used medicinally in Europe from centuries
Bioactive chemical constituents
Several classes of phytochemicals have been isolated and identified from different parts of P. hydropiper. The detailed list of these phytochemicals along with their chemical classes is given in Table 2.
Among them, flavonoids are one of the most studied chemical classes (Haraguchi et al., 1992). Persicarin, isolated from P. hydropiper, was the first sulfated flavonoid isolated from natural sources (Kawaguchi and Kim, 1937, 1940). Several other sulfated flavonoids are also reported further. For
Pharmacological studies
Plants belonging to Polygonaceae family have been widely studied for their pharmacological activities. There are many publications related to the different pharmacological activities of P. hydropiper which are mainly related to anti-inflammatory, antioxidant, antinociceptive activities among others. Few studies have also reported its activities related to neuropharmacology. Some of these activities are explained in detail in following sections.
Heavy metals content and phytotoxicity
Ayaz et al. reported contents of the heavy metals including lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn), iron (Fe), nickel (Ni) in crude dried powder of the whole plant, crude methanolic extract, various fractions including n-hexane, chloroform, ethyl acetate, n-butanol and aqueous fractions as well as soil samples via atomic absorption spectrophotometer (Ayaz, Junaid, Subhan, et al., 2014). The heavy metals concentrations were Pb (not detected), Cd (0.35 ± 0.154 ppm), Cu (7.21 ± 0.23 ppm),
Conclusions and future prospects
P. hydropiper is reported to be used as traditional medicine and food from centuries in different parts of the world. Whole plants as well as separate plant parts were found to be utilized for various medicinal purposes. It is also used as spice in many Asian countries. However, due to its irritant properties, P. hydropiper is recommended to be used medicinally with cautions (Mitchell and Dean, 1978). Various compounds including flavonoids, phenyl propanoid derivatives and sesquiterpenoids were
Declaration of competing interest
Authors declare no conflict of interest.
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