Int J Pharm Pharm Sci, Vol 9, Issue 12, 18-25Review Article


ETHNOMEDICINAL, PHYTOCHEMICAL, AND PHARMACOLOGICAL ASPECTS OF GENUS ACANTHUS

REKHA BORA1, PARTHA PRADIP ADHIKARI2*, AJIT KUMAR DAS1, NANJIAN RAAMAN3, GAURI DUTT SHARMA4

1Laboratory of Ethnobotany and Medicinal Plants Conservation, Department of Ecology and Environmental Science, Assam University, Silchar 788011, India, 2Laboratory of Natural Product and Synthetic Organic Chemistry, Department of Chemistry, Assam University, Silchar 788011, India and Genoine Research Laboratory Pvt. Ltd., Subhash Nagar, Karimganj 788710, Assam, India, 3Center for Advanced Studies in Botany, University of Madras, Guindy Campus, Chennai 600025, India, 4Department of Life Science and Bioinformatics, Assam University, Silchar 788011, India and Bilaspur Vishwavidyalaya, Bilaspur 495001, Chhattisgarh, India
Email: dr.parthaadhikari@gmail.com

Received: 03 Sep 2017 Revised and Accepted: 02 Nov 2017

ABSTRACT

Acanthus (family Acanthaceae) is a genus of the major group angiosperms (flowering plants) comprising more than 29 species widely distributed in the tropical and subtropical region. The aim of this review is to offer thorough scientific information on ethnomedicinal uses, phytochemical, and pharmacological activities of the plant species belonging to the genus Acanthus. Numerous traditional uses of the genus have been supported in this article from the results, and executed by the extracts and/or pure compounds obtained from pharmacological studies will provide a single platform to help future researches on the genus Acanthus. Furthermore, ethnomedicinal evaluation using fractions or isolation of medicinal principles was extensively explored by databases like Google, Google Scholar, and Science Direct at the same time.

Keywords: Acanthus, Acanthaceae, Ethnomedicinal uses, Phytochemistry, Pharmacology, Medicinal principles

© 2017 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
DOI: http://dx.doi.org/10.22159/ijpps.2017v9i12.22386

INTRODUCTION

The word ‘Acanthus’ is originated from the Greek word ‘Acantha’ meaning thorn or thistle signifies sensitive leaves [1]. Most of the species are shrubs or perennial herbs with terminal or axillary, uninterrupted spikes; flower with lower lip only; calyx 4-lobed with larger posterior and anterior lobes; corolla tube short, horny; elongate 3-lobed lip and with 4 exerted stamens, inserted at top of corolla tube [2]. The genus exhibits some mangrove species which are known to survive in the most antagonistic environment which makes this genus as inimitable taxa among all true mangrove genera that represent both terrestrial species and true mangrove. Thus, researchers grow attractive reason to assemble attention for the study of the genus and also to understand the origin and evolution of mangrove species. The distribution of the species of the genus Acanthus has been represented in the fig. 1.

Fig. 1: The distribution of the species of the genus Acanthus (Maps are not to scale)

Description of the genus

The genus Acanthus L. is consist of about 29 representative species geographically distributed mostly in the tropical and subtropical region of the world [3]. Total 28 genera from 20 families represent c. a. 70 true mangroves species among these the genus Acanthus represents five mangrove species e. g. A. ebracteatus, A. illicifolius, A. volubilis, A. latisepalus and A. montanus [4-5]. However, Tomlinson and Yang et al. reported only three mangrove species and c. a. 27 terrestrial species [6-7]. In India, only 6 species of the genus are available; A. ebracteatus Vahl, A. ilicifolius L., A. leucostachyus Wall. ex Nees, A. carduaceus Griff., A. mollis L., A. volubilis Wall. Out of these 6 species A. ilicifolius and A. leucostachyus are extremely medicinal and A. leucostachyus Wall. ex Nees, A. carduaceus Griff., A. mollis L. are terrestrial species [8]. Asia and Australia represent the paramount variety and distribution of mangrove species [1]. Therefore, the genus is unique among all true mangrove genera were both true mangrove and terrestrial members are obtainable. The two sub species A. ebracteatus subsp. ebracteatus and A. ebracteatus subsp. ebarbatus of A. ebracteatus which are endemic to Australia [1]. Moreover, both subspecies are detached by few key morphological features i.e. leaf shape, stem spines, flower color and hairiness etc. [1]. In our previous study, the genus was reported with one known species; A. leucostachyus from North East India which was originally established by Wallich in his Numerical List of Dried Specimens (Cat. No. 2512) on the basis of the collection made by F. De Silva from Sylhet District of Bangladesh [8]. But in the worksheet of [9], higher plant diversity in Pakke Wildlife Sanctuary and Tiger Reserve in East Kameng District of Arunachal Pradesh revealed another member of the genus. A. ilicifolius L., a shrub was available in those areas, medicinal use still unknown and least concern at the international union for conservation of nature (IUCN) status [10]. While in the same checklist A. leucostachys Wall. was mentioned as a herb. Ethnomedicinal uses in cut and wound and anti-inflammatory activity was also revealed and evaluated at IUCN status [10]. A. leucostachyus is a terrestrial species present in the rainforest at 600 to 1200 m above the sea level and bounds to South to Southeast Asia which has the same geographical distribution and same environmental support as the analogous mangrove species. These unique features have made the species more eccentric which have the possibilities to exemplify the phylogenetic aspects of the true mangrove species of the fascinating genus Acanthus [7, 11]. Some of the important species of the genus have described below.

A. leucostachyus Wall. Ex Nees

Common name: Mishisala (Barman); Mussali (Riang); Sam-sikal (Khasi), Sam-Khatchi (Meghalaya). A. leucostachyus is an unbranched herb height reach up to 90 cm, erect; stem brown, ca 4 mm in diam, hairy; abaxially glabrescent or brown pubescent along veins, petiole ~0.8-2.5 cm; leaf blade elliptic, secondary veins ~5-8 on each side of midvein and netted near margin, oblanceolate, or lanceolate, 9-23 × 2-4.5 cm, margin slightly spinose dentate occasionally unnoticeably dentate or irregularly entire, ovate-lanceolate, base rounded to subcordate, adaxially glabrous, tertiary veins inconspicuous, apex acute. Inflorescences fatal thorns, top severe to acuminate; bracteoles lanceolate to oblanceolate, abaxially pubescent, base rounded, palmately veined, apex rounded with a short tip; calyx ca 2 cm, pubescent; corolla white, ca 2.1 cm, villous; lobes orbicular, ca 5 × 5 mm, apex emarginated, margins apically spikey, ca 1-2 × ~0.2-0.4 cm, rachis grayish pubescent; base rounded, margin entire and ciliate. Staminal filaments ca ~8 mm, upper pair curved, glabrous. Ovary ca ~3 mm [8].

Distribution: The plant is distributed in India Bangladesh (Sylhet), China (Yunnan), Myanmar, Laos, Thailand, and Vietnam. Specimen examination, date, and place of collection of the plant in Bhutan and North East India has been enlisted in table 1.

Table 1: List showing the specimens of Acanthus leucostachyus examined in the Bhutan and North East India [8]

Specimen examined by Date of collection Place of collection
U. N. Kanjilal 01.10.1908 Nambor Reserve Forest, Assam
S. R. Sharma 07.03.1932 Nongkhlaw Forest, West Khasi Hills, Meghalaya
N. L. Bor 01.01.1934 Aka Hills, Arunachal Pradesh
S. R. Sharma 23.03.1936 Umsaw, East Khasi Hills, Meghalaya
N. L. Bor March, 1937 Sibsagar, Hollongpar, Assam
G. K. Deka 22.02.1938 Shella, East Khasi hills, Meghalaya
G. K. Deka 03.02.1939 Powai, Tinsukia, Assam
G. Panigrahi 25.05.1957 Garbhanga Reserve Forest, Kamrup, Assam.
R. S. Rao 01.09.1957 Katakhal Reserve Forest, Hailakandi, Assam
G. Panigrahi 22.10.1960 Doomdooma Reserve Forest, Tinsukia, Assam
G. Panigrahi 09.03.1962 Dullong Reserve Forest, Lakhimpur, Assam
D. B. Deb 23.01.1963 Kheitum, Lushai Hills Mizoram,
R. M. Dutta 12.07.1963 Vawmbuk to Thalthlang, Mizoram
N. P. Balakrishnan 14.03.1965 Jashigong to Yangtsi, Eastern Bhutan, Butan
J. Joseph 14.05.1965 Nongpoh,Meghalaya, and Noonmati-Barholng, Assam
D. M. Verma 22.05.1968 Chalohowa, Kananadi, North Lakhimpur, Assam
N. P. Balakrishnan 21.11.1969 Jaintia Hills, 16 km from Khleihriat on road to Sonapur, Meghalaya
A. K. Das 14.02.2002 Goawara forest, Assam
R. Bora and A. K. Das 05.02.2012 Loharbond, Cachar, Assam
J. Sarma and S. Baruah 04.03.2013 Gibbon Wildlife Sanctuary, Jorhat, Assam
J. Sarma and S. Baruah 12.04.2013 Lakhipathar Area of Upper Dihing Reserve Forest under Digboi Forest Division, Assam

Habitat and Ecology: Grow shady places association with other plants like Thottea tomentosa (Blume) Ding Hou and Borreria hispida (L.) K. Schm. etc. [8].

Phenology: March-September

Specimen examined: Specimens of A. leucostachyus Wallich examined in the Bhutan and North East India by various workers in different times [8, 12, 13].

Status: The plant was reported wrongly as endemic to Eastern Himalaya [13-14].

A. ilicifolius L

Common names: Holy leaved acanthus, holy mangrove, holy leaved acanthus and sea holy (Eng.), Harkukanta (Hind.), Harkucha kanta (Beng.), Holechudi (Kan.), Payinachulli (Mal.), Kaludaimulli (Tam.), Alasyakampa, Alchi (Tel.).

The plant is a shrub, height up to 3 m green, light green or purple, stem thick, branched, roots rarely above ground leaves simple, opposite, lanceolate to broadly lanceolate, leaf margin spiny/dentate, leaf tip acute, petiole low length ca 0.5-2 cm long, inflorescences terminal [15].

Distribution: A. ilicifolius true mangrove species distributed in tropical Asia and Africa, through Malaya to Polynesia grown in the many of the foreshore areas [1, 16]. The plant is also reported to grow in Bangladesh [17, 18]. In India, it is reported from the east (the large area of mangrove forest, the Sunderbans) and west seashore and Andamans and a northeastern state, Meghalaya [1, 17].

Habitat and Ecology: Generally it is found on river banks or low marshland areas of mangrove forests and its surroundings above the high tide mark [1].

Phenology: February-May.

Specimen examined: India, Andaman and Nicobar Islands, South Andaman, Shoal Bay Creek (P. Ragavan, PBL 30965 and 30966) [15].

A. ebracteatus Vahl-Vahl

It is a shrub up to 2 m tall, branched, axial spines downward facing, stem thick, grey tint, roots rarely above ground, broadly elliptic to lanceolate, ~10-20 x 3-6 cm, leaves simple, opposite, leaf tip acute to obtuse with or without spiny; petiole length low ca ~0.5-1.5 cm. inflorescence terminal; ovary bilocular; style surrounded by stamens [15].

Distribution: India to tropical Australia, Southeast Asia, and the western Pacific islands. In Southeast Asia plant has found in Cambodia, Myanmar, the Philippines, Vietnam, Malaysia, Singapore, Indonesia and Papua New Guinea; in India, it has recorded in Kerala, Puducherry, and ANI [15].

Habitat and Ecology: Grow in landward ends of mangroves over the high tide mark and in inner mangroves.

Phenology: Throughout the year.

Specimen examined. India, Andaman and Nicobar Islands, South Andaman, Sippighat (P. Ragavan, PBL 30969 and 30970) [15].

Acanthus volubilis wall

Plant is a twisted shrub up to ~2-4 m tall; stem slim, soft, green, branched, axial spines lacking; roots rarely above ground/prop roots on lower parts of reclining stem; leaves simple, opposite, spines absent, juicy, elliptic/oblong-lanceolate, leaf tip acute to obtuse with spin, leaf margin spines lacking, petiole low length ca 0.5-2 cm long, green; inflorescence terminal; style surrounded by stamens; ovary bilocular [15].

Distribution: South to Southeast Asia i.e. Sri Lanka and the Andaman Islands, to Myanmar, Indonesia, Cambodia, Malaysia, Singapore, Thailand and Papua New Guinea. In India, the plant has found in Odisha, ANI, and Sundarbans [15].

Habitat and Ecology: Grown in landward edges of mangroves up to the high tide mark.

Phenology: March-June.

Specimen examined: India, Andaman and Nicobar Islands, South Andaman, Shoal Bay Creek (P. Ragavan, PBL 30969 and 30970) [15].

Acanthus mollis L.

Synonyms: A. Hispanicus Lou., A. latifolius E. Goez., A. longifolius Poir., A. lusitanicus Auct, A. niger Mill., A. platyphyllus Murb., A. spinosissimum Host.

Traditional uses

A. ilicifolius also named as “Holy Mangrove” is used as an ethnomedicinal plant in many countries. In Malaysia the plant leaf used to heal rheumatism, neuralgia and poison arrow wounds; in Bangladesh, leaves are used in the treatment of cancer [18]; in Malaysia, seeds of this plant and A. ebracteatus Vahl. Consumed for curing urolithiasis; in India, the root is utilized to treat coughs and asthma; in Thailand, the fresh bark is applied as an antiseptic [19].

Moreover, the plant is also used in asthma, diabetes, dyspepsia, hepatitis, leprosy, paralysis, ringworm, rheumatism, skin problems, snakebite, leucorrhoea, leukemia etc. [19, 20], dropsy [21]; different plant parts, fruit, leaf, bark, and root are used in healing of asthma, diabetes, hepatitis, inflammation, and rheumatism [22-25]; leaves are applied in snake bite [26], consumed as blood purifier [19]; root used in leucorrhoea [27]; different plant parts useful to treat rheumatism, asthma, paralysis, psoriasis and leucorrhoea [28].

A. leucostachyus is another ethnomedicinal plant belongs to this genus. This plant has also been employed in treatment of various diseases like; the leaves of the plant used in fever and toothache [29]; leaf paste is applied externally in cuts and wounds; pest of leaves are prescribed to be applied externally on cancerous tumor by different tribes of Cachar district of Assam [12, 30]; paste of leaves combined with the extract of tuber of Allium sp. and leaves of Thunbergia sp. is applied externally for swelling, fever, toothache [31]; seed, sap and leaves are used in treatment of allergy, headache, hair tonic, boil, eczema and worms [32]. This plant is also used as traditional medicine by Naga tribe of North East India [33]. Moreover, the plant is used by Derois tribe of India in preparation of Sujen, a rice beer along with other plants like Alpinia malaccensis, Costus speciosus etc. [34].

A. montanus (Nees.) T. Anders leaves are reported to be practiced in curing cough, pneumonia, and fever by Mount Cameroon region, Africa [35]. While, the fruit of A. ebracteatus utilized as a blood purifier, leaf paste is applied in a dressing of burns, roots in snakebite and also used in pain caused by wounds and the seeds are used as anthelminthic [36]. 170 genes of A. ebracteatus are recognized which are engrossed in response to salt stress [37].

Phytochemistry

Investigation phytochemical study of the genus Acanthus indicated that phytochemical study has been extensively done on the true mangrove species; A. ilicifolius, beside this work no phytochemical isolation has been performed on this genus.

Phytochemical screening

Phytochemical study of A. ilicifolius done by Raut and Khan [38] emphasized the presence of some important chemical constituents like triterpenoids, alkaloids, saponins glycosides, flavonoids, steroids etc. Ralf and Gerd [39] study also specify the presence of terpenoids, alkaloids, flavonoids, phenols, coumarins. Flower extracts disclose the occurrence of alkaloids, terpenoids, saponins, phenolics, flavonoids, tannins but the absence of steroids [40]. Other study reveals that the plant possesses alkaloids, steroids, tannins, flavonoids and reducing sugar but saponins and gums are absent in crude methanol extract [27].

Govindasamy and Arulpriya [41] also showed that plant leaves contain with alkaloids, phenol, steroids, protein, resins, steroids, tannins, terpenoids, cardiac glycosides, carbohydrates, saponins, glycosides, sugars, and catechol.

Compound isolation

Wu et al. [42-43] obtained two aliphatic glycosides, ilicifolioside B and ilicifolioside C. Some lignan glycosides, (+)-syringaresinol-O-β-D-glucopyranoside, (+)-lyoniresinol 3α-O-β-D-glucopyranoside, (+)-lyoniresinol 2a-O-α-D-galactopyranosyl-3a-O-β-D-glucopyranoside, (+)-lyoniresinol 3a-O-α-D-galactopyranosyl-(1-6)-β-D-gluco-pyrano-side, (-)-lyoniresinol 3α-O-β-D-glucopyranoside [51, 43, 57]; fatty acid derivatives, β-sitosterol octadecanoate, octadecanoic acid, octacosanol, palmitic acid, stigmasterol octadecanoate, tetracosanol [48]; triterpenoids, lupeol and oleanolic acid and ursolic acid [44-45] were reported from the same species.

Besides these diverse classes of phytochemicals such as alkaloids, fatty acids, glycosides, lignans, triterpenoid, coumaric acid etc. various derivatives have been isolated and characterized from different extracts like Hexane, chloroform, ethanol, methanol of A. ilicifolius, illustrated in table 2 with their structures, pubchem ID’s and relevant citations.

Pharmacology

The pharmacological study has been extensively performed on A. ilicifolius among the species of this genus. This study revealed that A. ilicifolius has significant bioactivities like, antioxidant and cytotoxic activity [26, 55], antinociceptive activity [56], anti-inflammatory activity [23, 26], anti-osteoporotic activity [57], hepatoprotective activity [26, 58], chemopreventive activity [21]; leishmanicidal, tumour reducing and anticancer activities [26, 58, 59, 60]; antileishmanial, antiulcer, antimicrobial, and osteoblastic, activities [26]. Moreover, Firdaus et al. found in their study that flower extract of the plant also has good cytotoxic effects [40]; Smitha et al. showed the anticancer activity of ethyl acetate extract of on two cell lines PA-1 and MCF-7 [61].

Table 2: Compounds isolated from Acanthus ilicifolius

Class of Phyto-chemicals Name of the Phyto-constituents Compound structure PubChem ID References
Alkaloids Acanthicifoline 442503 [46]
Trigonellin 5570 [44]
2-benzoxazolinone 6043 [47, 48]
Benzoxazin-3-one 72757 [49]
5,5’-bis-benzoxazoline-2,2’-dione NF [50]
Benzoxazinoid glucosides NF [51]
4-O-b-D-glucopyranosyl-benzoxazolin-2(3H)-one NF [52]
2-hydroxy-4H-1,4-benzoxazin-3-one 322636 [48]
Flavonoids Quercetin 5280343 [44]
Quercetin-3-O-β-D-glucopyranoside 15959354 [44]
acacetin 7-O-α-L-rhamnopyranosyl-(1"' 6")-O- β-D-glucopyranoside (Linarin) and vitexin

Linarin

Vitexin

 5317025 & 5280441 [53]
Steroids Cholesterol 5997 [49]
campesterol 173183
stigmasterol 5280794
β–sitosterol 222284 [44]
stigmast-7-en-3-β -ol, 441837 [49]
stigmasteryl β -D-glucopyanoside 70699355 [48,49]
28-isofucosterol 5281328 [54]
octacosyl alcohol 68406 [49]
β-sitosterol-3-O-β -D glucopyranoside 70699351 [48]

NF: Not Found

Antioxidant activity

Firdaus et al., [40] have scrutinized the antioxidant properties of A. ilicifolius by the DPPH scavenging assay. The assay was conducted on total five extracts (acetone, methanol, acetone 70%, methanol 80% and water) of flowers and found that methanol extract showed highest antiradical efficiency (141.30%), while water extract of showed lowest (0.0037%) among the extracts. Dey et al. [27] confirmed the antioxidant effects of the methanol extract of the plant. DPPH assay has been adopted for evaluation of the free radical scavenging activity of the extract by preparing ten different concentrations starting from 500 μg/ml to 0.98 μg/ml using serial dilution technique where IC50 was recorded to be 5.1 μg/ml. Moreover, the antioxidant activity of the fractions and isolated compounds of the plant has also been reported [58-60].

Polysaccharides isolated from the plant also showed significant radical scavenging activity [62]; Flavonoids and phenolic compounds of A. ilicifolius displayed their good antioxidant activity on the animal model [63].

Cytotoxic activity

Firdaus et al., [40] analyzed the cytotoxic of the flower extracts of A. ilicifolius on the brine shrimp lethality. The results exhibited methanol extract has lowest LC50 value (22 μg/ml) while water extract showed the highest value at 10 μg/ml among the extracts. Dey et al. [27] have tested the cytotoxic activity of a methanolic crude extract of the plant where it has found that the extract exhibited a significant cytotoxic activity with the LC50 value at 60 μg/ml and LC90 value at 120 μg/ml.

Antimicrobial activity

Antimicrobial activity of alcohol, butanol and chloroform extract (10 mg/ml) of both leaves and roots of the plant exhibited significant activity against all microbes, B. subtilis, P. vulgaris, P. aeruginosa, S. aureus, C. albicans, A. niger, and A. fumigatus. The experiment was followed by agar cup plate method that unveils the leaves were more active than that of roots where ampicillin used as a standard for bacteria and clotrimazole for fungi. Chloroform extract of leaf showed the highest zone of inhibition that was measured ~26 mm against the fungus C. albicans. But butanol extract of leaf extract displayed lowest ~08 mm against the bacterium S. aureus [64].

Govindasamy and Arulpriya [41] studied antimicrobial activity of against seven skin infection causing microbes, methicillin resistance S. aureus (MRSA), L. plantarum, S. pyogenes, S. epidermis, C. albicans, P. aeruginosa, and T. rubrum. In this test four extract of the leaf has been examined where chloroform extract showed the highest activity against all microbes (except S. epidermis and L. plantarum).

Three extracts, ethanol, methanol and aqueous of leaf, stem, and root of the plant has used for the activity. The cub-plate method used to detect the efficiency of the plant against the eleven bacterial strains Escherichia coli, Bacillus, megaterium. Lactobacillus plantarum, Salmonella paratyphi B, Shigella dycentreae, Streptococcus mutans, Klebsiella pneumoniae, Aspergillus flavus, Staphylococcus albus, and Lactobacillus acidophilus and one fungus C. albicans. Ethanol and methanol extract showed more or less same activity and methanol extract indicated significantly more effective than the aqueous extract. Maximum zone of inhibition noticed on aqueous extract of root and methanol extract of the leaf as 17 mm against the same bacterium, S. albus [26].

Rao et al. [65] examined the antimicrobial activity of methanol, ethanol, and ethyl acetate extracts of flower, seed, leaf, and root of the plant by the well-diffusion method. Microbes like Vibrio harveyi, Aeromonas hydrophila, and E. coli were taken for the test, results direct the highest activity observed on ethyl acetate seed extract against V. harveyi. Dey et al. [27] observed the antibacterial activity of a methanolic crude extract of the plant by ten gram-negative and six-gram positive bacteria, unfortunately, no activity was witnessed for the crude methanol extract.

Anticancer activity

Smitha et al. [61] studied the anticancer activity of ethyl acetate extract of leaf and root extract of the plant on two cell lines, MCF-7 and PA-1. The plant is more effective on PA-1 and the result has recommended that at 50 µg/ml ratio is adequate to inhibit the cancer cells. Moreover, the result has also unveiled that the extract is slightly cytotoxic to both of the cell lines. The antimicrobial and antioxidant activity of A. ilicifolius is depicted in table 3.

Table 3: Antimicrobial and antioxidant activity of Acanthus ilicifolius

Plant parts Solvent used for extraction/isolated compound Activity agaist Reference
Leaf and root Hexane, chloroform, and methanol Antibacterial, antifungal [66]
Leaf and root Benzoate and phenylethanoid derivatives Antimicrobial [67]
Leaf and root 2-Benzoxazolinone 4 and benzoxazinium derivatives Antimicrobial, antifungal and insecticidal [22, 43,68]
Leaf and root Methanol Antibacterial [27]
DPPH
Flower Acetone and methanol DPPH [55]

CONCLUSION

The plants from the genus Acanthus are broadly scattered in the tropical and subtropical regions of the world. The systematic pharmacological studies on the genus have given remarkable recognition to their ethnomedicinal uses in health care management. The phytochemical studies of the genus Acanthus revealed, isolation of a total of 21 bioactive compounds from A. ilicifolius and were identified with their structures and their respective PubChem ID’s were mentioned in this review. Hence, the existence of these bioactive compounds may be explored from other sister species and their different pharmacological properties may also be compared. Numerous pharmacological studies using different types of extracts or pure phytochemicals of Acanthus species well justified their practice as an ethnomedicine; for example, antioxidant, antimicrobial, cytotoxic and anticancer activities besides its well-known antinociceptive, hepatoprotective, leishmanicidal and osteoblastic properties. Furthermore, scanty and limited toxicity reports on the animal model are presently available, which suggests that detailed toxicological evaluation is needed for different extracts from the various species. Correspondingly, the biological effectiveness should be carried out for the isolated secondary phytochemicals as well, which would definitely authenticate the medicinal claims of the Acanthus genus.

ACKNOWLEDGMENT

RB is thankful to Assam University, Silchar for institutional fellowship support.

CONFLICTS OF INTERESTS

All authors have no conflicts of interest to declare.

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