Arundo donax L.: An overview on its traditional and ethnomedicinal importance, phytochemistry and pharmacological aspects

Introduction Arundo donax L. (Giant reed) is a perennial and rhizomatous plant that belongs to the Poaceae family and one of the most widespread species of the genus Arundo. The plant is of general occurrence across the globe. It has been included amongst the worst invasive species of the world because it displaces the native flora and deteriorates the ecological state of lands wherever it grows (1). The plant also possesses several medicinal properties, and therefore, has traditionally been used by several ethnic groups across the world to cure various ailments. According to the World Health Organization (WHO), almost 80% of the world’s population relies on indigenous medicinal plants to cure diseases (2,3). With the immense existing potential and rich knowledge about medicinal plants at the ethnic level, the ethnomedicinal system has reinforced the discovery of several therapeutically important drugs such as Quinine and Artemisinin from the Amazon and China, respectively (4). This traditional system of medicine has provided A. donax L. in Ayurvedic texts i.e., Charak Saṁhitā, Suśruta Saṁhitā and Mādhava Chikitsā for the treatment of urinary disorders such as Mūtrakṛcchra, in medical terminology called as Dysuria (5). A large group of people belonging to different ethnic groups and tribes uses this plant for treating fever, urinary disorders, bone fracture, menstrual disorders, and organ http://www.herbmedpharmacol.com doi: 10.34172/jhp.2021.31

In India, the plant is used in several traditional formulations as a vasopressor, uterine stimulator, hypotensive and antispasmodic agent (7). A decoction of its rhizome acts as an emollient, diuretic, galactagogue (for enhancing lactation) and menstrual stimulator (8).
Local Amchi people (herbalist) in the Kinnaur district of Himachal Pradesh use a decoction of the roots to cure cancer (9). In Chinese folk herbal medicine, the rhizome of Giant reed has been using to treat toothache, swollen gums, vomiting and knee osteoarthritis (10). In Manipur (north-eastern) India, the steam of boiled leaves is used to cure chronic haemorrhoids (11). Ethnic Albanian people in Italy use the internal stem membrane of this plant to arrest bleeding (12,13). The roots are diaphoretic, diuretic, emollient (14,15) and used by local peoples to treat cancer in Pakistan (16,17). Apart from this, the plant also possesses socio-economic importance as different ethnic groups use its strong stem and leaf to make rooftops, thatches, basket, and ropes (6). The stem is also used to make musical instruments and fishing nets (6,14). Phytochemical studies have revealed that the plant contains fatty acids, sterols, and secondary metabolites such as alkaloids (tryptamine, bufotenidine, gramine, and arundamine), terpenes, carotenoids and phenols (8).
Bioactive compounds are shown to have remarkable pharmacological properties such as anti-microbial, anti-oxidant, anti-pyretic (18) and anti-tumorous activities (19). Various types of tryptamines viz. N, N-dimethyltryptamine, 5-methoxy-N, Ndimethyltryptamine, bufotenine, etc., have been isolated from the rhizome, which possesses mild psychedelic effects (20,21). A lectin isolated from the rhizome of Giant reed is reported to have anti-tumorous properties (19). Despite having immense ethnomedicinal importance, there is a lack of systematic account of the literature on Giant reed. To the best of our knowledge, no review article published till date highlighting its ethnomedicinal values and therapeutic potential. Thus, the present study aimed to summarize the existing knowledge of ethnomedicinal uses, phytochemistry, and pharmacological aspects of A. donax L. This review hopefully will provide baseline information for other researchers who intend to work on this plant.

Methods
To get comprehensive and systematic information on its traditional and ethnomedicinal uses, as well as phytochemistry and pharmacological aspects of this plant, we carried out an extensive survey of literature through available search engines like Scopus, Web of Science, Science Direct, Google Scholar, and PubMed by using keywords such as Arundo donax, Arundo benghalensis, Giant reed, and Spanish reed. We found a total of 95 articles through a search made in the available databases. But we retained 82 articles for the preparation of the present review based on the suitability of the study. Chemical structures of the isolated phytoconstituents were drawn using software ChemDraw Pro 12.0 from Cambridgesoft. All figures were prepared through SigmaPlot 12.0 version software.

Vernacular names
In India, at the regional and state level, the plant is known by various vernacular names such as Giant reed, River reed, Wild cane, Spanish cane in English; Naal, Baranal, Narasal, Naade in Hindi; Kasa, Dhamana, Potagala, Sunyamadhya in Sanskrit; Noljora, Nol, Gabnol in Assamese; Caravanam, Mudampul, Nanalpul, Velam in Tamil, Yachi in local dialects of Arunachal Pradesh; Nolkhagra in Bengali; Yenthou in Manipuri; Nard, Naal, Narsaal, Naur in local dialects in Jammu; Ama in Malayalam; and Peepalu, Paatuveduru in Telegu. In Ayurveda (The traditional system of medicine in India), the plant is known by various names such as Poṭgala, Śunayāmadhayā, Dhaman, Devanala. In the Siddha (Tamil) system of medicine, it is known as Korukkai.

Botanical description and ecological distribution
It is one of the largest members of the genus (Arundo), which attains a luxurious growth with a height of 6-8 m (22). It has a very strong root architecture that penetrates deep into the soil and gives rise to fleshy tuberous rhizomes, which spreads horizontally and forms large thickets. Each stem is hollow, cane-like, divided into distinct nodes and internodes. Leaf-blades are large, somewhat bamboolike, pale to blue-green, distichous, linear to lanceolate, rounded or cordate with a tuft of hairs at base, 30-60 cm long and 3-5 cm wide tightly clasped around the stem. The inflorescence is panicle-like 30-60 cm long with the onset of flowering from June-December (23).
It is thought to be native of South Asia (India, China, Bhutan, Afghanistan, Myanmar, and Thailand) and the Mediterranean region. It moderately grows in several climates across the world and, therefore, has become a naturalised invasive plant species in most of the countries of the European continent, South America, South Africa, Mexico, and the pacific islands (24). Giant reed commonly found along river beds, ditches, and roadsides reproduce through vegetative means by spreading its canes through floodwater and quickly encompass the entire landscape by outcompeting the native vegetation (1). In India, its distribution range generally varies from subtropical low lying Himalayan hills at 600 m to 2400 m. Morphological attributes and habitats of Giant reed are depicted in Figure 1.

Socio-economic importance
The Giant reed is a source of livelihood for people of the Meitei community in Manipur, North-East India.
The plant is commonly used in daily household stuff, life-fencing, soil binder, firewood, and cage for livestock rearing. Thrashing mat made from the stem of this plant costs around 2200-3000 ₹ per piece in the market of Manipur, India (6). Generally, the stem and leaves of the A. donax L. are used to make baskets, mats, ropes, and thatching of huts in Garhwal Himalaya (25). Terminal panicles of A. donax L. are also used to make brooms in other parts of India like Uttar Pradesh and Garhwal Himalaya (14,25). Local people from the Mishing tribe in Brahmaputra valley of Assam use the whole plant to keep their rice stock (26). Fumigants after burning of dried leaves of A. donax L. are used as mosquito repellents by tribals of Senapati district, Manipur (27).
The stem of the plant is used as a building material, fencing, and supporter for climbing crops and an important source of firewood for local people in Yangzhou, East China, and Manipur, India (6,28). The Tharu tribe of Katarniaghat Wildlife Sanctuary, Uttar Pradesh uses its stem to make fishing rods and walking sticks (14). It is also used in rituals, ceremonies for prayer to forefathers and deities (Apokpa Khurumba) by Chothe tribes in Manipur (29). The stem of Giant reed has been used for making musical instruments or woodwind such as flutes since ancient times (6,30). Besides, it is also used in the paper and pulp industry, source of fuel and phytoremediation of heavy metals (23). Various experimental studies have shown that the roots of this plant accumulate significant concentration of trace elements in sediments and water, and can be used as a promising tool for biomonitoring campaigns of wetlands (31).

Traditional and ethnomedicinal uses
Different parts of the plant, such as leaves, stem, roots, and rhizome are used in traditional and ethnic formulations to cure a broad spectrum of diseases ( Table 1). The plant is well explored in folk medicines as a diuretic, emollient, and to treat skin disorders. An ancient Indian text (in Sushruta) states that if decoction of Arundo donax L.

Circulatory disorders
Haemostatic The dividing membrane of nodes or internal membrane of stem is used as a plaster for wounds to prevent infections and induce cicatrisation.

Menolipsis in humans Root
Aqueous decoction of fresh root (ca. 10 mL) with 7 long pepper (Piper longum) paste is given to women at early morning in empty stomach to cure menolipsis. The drug is given for successive 3 days just after completion of menstrual cycle by the Lodhas.

Root
Root decoction along with Jaggery is taken orally as an abortifacient.  along with Salix alba L. is given, it can cure chronic fever (7). It has been widely used by local people of Sardinia, Italy for vulnerary (healing of wounds), emmenagogue (stimulation of menstrual discharge), galactagogue (promote lactation), haemostatic (arrest of bleeding), diuretic, diaphoretic, anti-inflammatory and anti-septic purposes (32)(33)(34). Furthermore, about 100-250 g of fresh leaves of Arundo donax L. are given orally to cure worm infestation of cattle in the Jhang district, Pakistan (35). In Ayurvedic formulations, Trinpanchmula kwath Giant reed is used to treat fever, rabies, retention of urine, and erysipelas (36). Roots and rhizome are consumed in 56% of all ethnomedicinal practices, followed by stem (21%), leaves (17%), and whole plant (7%), as shown in Figure 2. Furthermore, the use of Giant reed to cure reproductive disorders is most cited (18.18%), followed by dermatological (14.28%) and inflammatory diseases (12.98%) (Figure 3). Out of all the documented ethnomedicinal uses, the plant has been extensively used as a diuretic, followed by emmenagogue, haemostatic, diaphoretic, and antipyretic agents.
A recent phytochemical investigation, through acid  Staphylococcus aureus, Micrococcus luteus, Klebsiella, Escherichia coli, and Pseudomonas aeruginosa. The aqueous extract of the stem node exhibited anti-bacterial activity against methicillin-resistant Staphylococcus aureus at a concentration of 128 μg/mL (73). Moreover, in another study Sharma et al demonstrated that the methanolic root extract showed high efficacy against bacterial strains; P. aeruginosa with inhibition zone diameter (15.0 ± 2.8) followed by Klebsiella pneumoniae (14.0 ± 2.08) and Streptococcus aureus (14.0 ± 6.0) at an inhibitory concentration of 40.0 μg/mL. While in methanolic leaf extract, high efficacy was observed against Streptococcus aureus only, with maximum inhibition zone (7.3 ± 3.7) at the same concentration. However, a low activity was observed against K. pneumoniae (6.6 ± 3.5) at the same concentration (74).
In another study, Pansuksan et al observed that the dichloromethane (DCM) rhizome extract exhibited strong anti-bacterial activity against Bacillus subtilis and Bacillus cereus with inhibition zone 18.0 mm and 17.8 mm, respectively. However, hexane, ethyl acetate, and methanolic extract showed lower efficacy against B.  subtilis. No prohibitory effect was found against E. coli, S. aureus, and Candida albicans (67). The specific bioactive compounds responsible for anti-bacterial activities of Giant reed are not discussed in most of the studies. Therefore, future studies must focus on identifying the bioactive molecules and their mode of action. Furthermore, to elicit the anti-bacterial activities of Giant reed, more pathogenic strains are needed to be tested using different extraction solvents.
Anti-oxidant activity In recent times much attention has been paid to natural anti-oxidants and their therapeutic potential for the cure of many complex disorders. The human body, due to metabolic and biochemical processes, produce several metabolic by-products called free radicals, which can damage cells, tissues, DNA, and promote aging. Antioxidants act as reducing agents that can quench the free radicals by donating hydrogen atoms and slow down the oxidation process, therefore protect cells and tissues from their deteriorating effects (4). A phytochemical investigation conducted by Sağir et al using leaf extract of the Giant reed reported a total anti-oxidant capacity of 3.4 ± 0.58 mg/g FW and total superoxide dismutase activity of 234.0 ± 74 units/g FW (72). The Giant reed is a rich source of secondary metabolites and derivatives of total phenols, non-tannic phenols, flavonoids, and tannins, which impart anti-oxidant properties (75). In another study, free radical scavenging activity of five percent aqueous extract of roots of Giant reed was investigated using 2,2-diphenyl-2-picrylhydrazyl (DPPH) and Phosphomolybdenum complex. The DPPH free radical scavenging activity was 399.10 μg/mL and 0.98 for phosphomolybdenum complex (76). Phenolic compounds contribute significantly to anti-oxidant activity, and it is well evidenced in Piluzza and Bullitta (75), where they found the total anti-oxidant activity of acetone leaf extract ranged 6.64±0.13 and 7.03±0.59 mmol/100 g/DW against DPPH and ABTS free radical ions. All of the above-cited anti-oxidant studies have been conducted using total anti-oxidant capacity, DPPH, and ABTS free radical scavenging assays in vitro conditions, which may or may not produce similar results in vivo conditions. Therefore, animal systems must be taken into consideration for free radical scavenging assays for the reliability of results.
Anti-algal and anti-fungal properties Bloom forming algae (algal blooms) may pose a severe threat to water bodies, and underlying aquatic life primarily promotes fish mortality due to depletion of dissolved oxygen in the water and releasing harmful toxins (28). Therefore, the use of allelochemicals from aquatic plants to control algal blooms is a hot topic of research. A study conducted by Hong et al reported that methanolic shoot extract of Giant reed inhibited the growth of bloom-forming cyanobacterium Microcystis aeruginosa (77). They fractioned the methanolic extract into acidic and neutral fractions, of which the neutral fraction had higher inhibitory growth than the acidic fraction. They accredited it to the presence of allelochemical gramine and proved to be one of the most effective anti-algal compounds known in aquatic plants.
Other allelochemicals isolated from methanolic shoot extract of Giant reed were 3-methyl-indole (Skatone), 2,4,6-trimethyl-benzonitrile, and 6,10, 14-trimethyl-2-pentadecanone (also called Phytone), 3,7,11,15-tetramethyl-2-hexadecan-1-ol (phytol), and 4,8,12,16-tetramethyl heptadecan-4-olide, which speculated to possess anti-algal properties (78). Pyrolytic vinegar or bio-oil from Giant reed is shown to have algicidal properties and inhibit red tide dinoflagellate Karenia brevis, which may cause neurotoxic poisoning to the marine organisms. The pyrolytic vinegar was predominantly composed of acetic acid, phenol, aldehyde, ketones, and ester, which could render antialgal properties (28). In another study, it was found that a neutral fraction of methanolic extract of Giant reed was able to suppress the growth of harmful golden alga Prymnesium parvum and the maximum algicidal activity was observed at 50 mg/L (79). Likewise in the case of Microcystis aeruginosa, gramine was proved to be the most potent growth suppressing compound in golden alga as well. Another indole compound skatole was also found to suppress the growth of golden alga; however, its algicidal activity was less potent than gramine. Since synthetic anti-algal compounds are toxic to aquatic life and suppress the growth of non-harmful algae as well, therefore, the algicidal activity of giant reed extract proved to be a promising tool for control of harmful algal blooms in water bodies. Gramine is also reported to suppress the growth of freshwater algae Desmodesmus armatus (80) and marine Chattonella marina (81). Information about the antifungal activity of Arundo donax L. is very sparse in the literature. However, its efficacy has been reported against few basidiomycetes i.e., Trametes versicolor, Coniophora puteana, Gloeophyllum trabeum, and Postia placenta (22).

Anti-parasitic and anthelmintic uses
Badar et al studied the anti-parasitic and anthelmintic potential of Giant reed leaves. Crude aqueous methanolic extract of leaves was used to study in vitro (adult motility assay and egg hatch test) and in vivo (faecal egg count reduction test) anthelmintic activity against Haemonchus contortus. In adult motility assay, 56.7% mortality of H. contortus was observed by 10 hours post-exposure with the extract at 50 mg/mL. In egg hatch test, A. donax L. exhibited ovicidal activity with LC 50 = 200.1 μg/mL; whereas, crude powder of A. donax resulted in 50.5% reduction in egg per gram of faeces in sheep, naturally infected with gastrointestinal nematodes (36). Anthelmintic activity of giant reed was also observed against cattle worms, such as Ascaris sp., Oesophagostomum sp., and Paramphistomum sp. (82,83). In Sardinia, Italy, the leaves of Giant reed are used to cure coughs and intestinal worms in horses (33,75).
Anti-cancerous properties People in Calabria, Southern Italy, use a mixture of Arundo donax L. with Spartium junceum L. and Cynodon dactylon L. (Pers.) to treat tumors (the type of tumor is not specified) (84). Roots and leaves of Giant reed are used to treat cancer by local people in Bahawalpur, Pakistan (17). Root and stem powder with honey is given to cure cancer in Muzaffarabad, Pakistan (55). All the reports of anti-cancerous uses of this plant are restricted to the ethnic and local level. There is no scientific validation of the anti-cancerous properties of this plant so far. Although in 2005, a specific lectin named N-acetyl-Dglucosamine isolated from the rhizome of Giant reed was found to possess anti-proliferative properties towards human cancer cell lines and mitogenic towards human peripheral blood mononuclear cells (19). Of the several human cancer cell lines studied, the lectin at the highest concentration of 50 μg/mL showed the maximum effect of 62% against ovarian cell line (OVCAR-5) followed by SKN-N-MC (CNS), Hep-2 (Liver), SW-620 (Colon), and SK-N-SH (CNS) cell lines, with 59%, 53%, 51% and 45% growth inhibition, respectively.
Further studies are required to unravel the molecular mechanisms for the anti-proliferative properties of this plant. Therefore, traditional formulations and medicinal plants used for the ethnic cure of diseases must be screened pharmaceutically to pass ethnic knowledge to the modern system of medicine for the betterment of humankind.
Effect on skeletal and smooth muscle Defatted ethanolic extract from rhizome of Giant reed is proved to hypotensive and antispasmodic against histamine, serotonin, and acetylcholine-induced spasms. Several pharmacological aspects of rhizomatous alkaloid bufotenidine have been studied on smooth muscles such as the intestinal loop of guinea pig, dog's intestine, the uterus of albino rats and guinea pigs, and dog's tracheal chain (8). A muscular spasm was observed after injection of alkaloid, and repeated doses followed tachyphylaxis in dog's intestine. In the isolated loop of the intestine, the alkaloid initially relaxes the muscle but when administered in doses above 20 mg/kg it alters the spasmodic effects of histamine, acetylcholine.
A muscular spasm was observed in isolated guinea pig uterus and rat uterus at an initial concentration of alkaloid (20 μg/mL and 10 μg/mL, respectively). However, at higher doses, the drug blocked acetylcholine-induced spasm. This might be the reason behind the stimulatory action of rhizome extract against menstrual discharge in traditional formulations (8). In contrast, there was no effect of alkaloid's higher doses on dog's tracheal chain, nor it influenced the acetylcholine-induced spasm. Surprisingly, there was no such kind of study conducted on human beings yet.

Toxicological aspects
The first toxicological report about Giant reed was published in 1969, where a rhizomatous extract was reported to be toxic towards albino mice and rats (8). The chief alkaloid responsible for toxicity was bufotenidine. When the alkaloid was administered to albino mice and rats at a dose of 10 mg/kg, the sudden death of all five mice and ataxia in all ten rats was observed. Besides, the alkaloid produced head drop followed by death in rabbits in 5-6 mg/kg dose given against 0.3-0.5 mg/kg dose of alkaloid d-tubocurarine. The alkaloid bufotenidine acts as a neuromuscular blocking agent, which is mainly a toad poison. However, no toxicological aspects of Giant reed have been studied concerning human beings so far.

Other uses
Ethanolic rhizome extract from Giant reed has antipyretic properties due to the prevalence of bis-tryptamine alkaloid donasine (18). A significant reduction in the rat anal temperature was observed in donasine infused rats. Bioactive compounds in Giant reed are reported to show antifeedant activity against cotton boll weevil (Anthonomus grand). The strong inhibitory effect against cotton boll weevil is due to the presence of alkaloid N-(4'bromophenyl) 2,2-diphenylacetanilide in A. donax L. (85).
The Giant reed is a rich source of indole bases (gramine, N, N dimethyltryptamine, 5-methoxy-Nmethyltryptamine, 5-methoxy-N,N-dimethyltryptamine, bufotenine, bufotenidine, dehydrobufotenine, Nb-Methyltetrahydroharman) and tetrahydro-p-carbolines. These alkaloids at low concentrations produce fine tremors, salivation, and hypermotility in mice and rats. However, a higher dose of alkaloids resulted in jumping movements, rapid tapping of the forelimbs, and paralysis of hindlimbs, convulsions, and respiratory arrest and completely antagonised the pre-treatment effect of the drug chlorpromazine (20). Therefore, the psychedelic effects of indole compounds and other phytoconstituents from giant reed should be screened at broad-spectrum while considering humans as well.

Conclusion
The present study summarised information about ethnomedicinal values, isolated chief phytoconstituents, and pharmacological aspects such as anti-bacterial, antioxidant, anti-proliferative, anthelmintic, and toxicological properties. Although all components of the plant are used to cure health ailments, chiefly rhizomes and roots find their mention across all formulations. In traditional healthcare practices, the plant has been extensively used in the treatment of skin disorders, urinary diseases, menstrual problems, diarrhoea, respiratory problems, and complex diseases such as cancer. However, the mode of consumption and administration is not mentioned in several studies. The scientific plausibility of cured ailments is also lacking. Yet, the plant has invaded several parts of Africa, America, and Mexico and has acquired the status of the worst invasive weed. Nonetheless, in European countries and the Indian subcontinent, the plant has been used in rural areas as a source of livelihood, medicines, substitute of firewood for locals. Therefore, further cultivation of Giant reed is recommended to generate income and livelihood resources for the local communities. Future ethnobotanical studies must focus on validating the reliability of formulations and modes of administration. Apart from this, the plant must be screened pharmaceutically for the isolation of bioactive molecules and the development of drug discovery and therapeutic potential.