Ethnobotanical Characteristics

Description

Annual herb, branched from the base and usually also above, erect, decumbent or prostrate, mostly up to 45 cm. (rarely to 70 cm.). Stem is slender to stout, angular, glabrous or thinly to moderately furnished with short to long, often crisped multicellular hairs which increase upwards, especially in the inflorescence. Leaves glabrous or sometimes sparingly furnished on the lower surface of the principal veins with very short, gland-like hairs, long-petiolate (petiole from 3-4.5 mm, sometimes longer than the lamina), lamina broadly ovate or rhomboid-ovate to narrowly linear-lanceolate or linear, 4-55 x 2-30 mm, acute to obtuse or slightly retuse at the mucronulate tip, cuneate to long-attenuate at the base. 
Inflorescence is an axillary cymose clusters, male and female flowers intermixed, more male flowers is in the upper whorls. Bracts and bracteoles narrowly lanceolate-oblong, pale-membranous, acuminate and with a pale or reddish arista formed by the excurrent green midrib, bracteoles subequal to or usually shorter than the perianth. Perianth segments 3, all 1.5-2 mm; those of the male flowers lanceolate-oblong, acute or subacute, pale-membranous with a narrow green midrib excurrent in a short, pale arista; those of the female flowers lanceolate-oblong to linear-oblong, gradually to abruptly narrowed to a very short to rather long mucronate, the midrib often bordered by a green vitta above and apparently thickened, the margins pale whitish to greenish. Stigmas 3, slender, usually pale, flexuose, 0.5 mm. Capsule sub globose to shortly ovoid, 2-2.25 mm, usually strongly wrinkled throughout with a very short, smooth neck, slightly exceeding the perianth, circumscissile or sometimes not, even on the same plant. Seeds shining, compressed, black, 1-1.25 mm, faintly reticulate especially towards the margin (eFloras, Jongbloed 2003, Mandeville 1990, Miller 1988, 1996).

Habitat and Distribution

Widely dispersed in the drier northern part of the Region, tropical Africa, Europe and Asia. The plant is widespread in U.A.E especially in Coastal areas. 

Part(s) Studied

Whole plant 

Traditional and Medicinal Uses

The plant has edible leaves and is used as a vegetable, and also as a fodder for cattle. Traditional medicine practitioners use the plant as an anti-inflammatory for the treatment of inflammations.  The leaves are used as an emollient; crushed leaves applied to scorpion sting and snake bites and irritating or itchy rashes. The whole plant is used to treat generalized oedema and as a poultice for mastitis. This plant is an astringent and it is used externally as a gargle in ulcerated conditions of the mouth and throat and as a wash and poultice for ulcers and sores (Chopra 1958, Kirtikar 1918, Jayaweera 1981, Jongbloed 2003, Mandaville 1990, Miller 1988, 1996, Ghazanfar 1994).

Pharmacognosy and Phytochemistry

Part(s) studied

Leaf and Stem 

General appearance

The leaf is greyish green in the dried state, and naturally, it is green or reddish-green. The dried leaf is shrunken, reduced in size, twisted to the inside with wavy margins. It is brittle and easily broken. Leaves are found in groups.

Microscopic characteristics

The surface view of the leaf shows that its venation is very intricate and cells embedding the vascular tissues are quite characteristic. They are oblong, of similar sizes and shapes and they are set adjacent in a continual order. These oblong cells are devoid of calcium oxalate crystal cluster. However, other cells isolated by these characteristic oblong cells are rich in these crystals in such a manner that each cell generally contains a comparatively large crystal. Elongated parenchyma cells exist alongside the main veins and other main branches bear uniseriate glandular trichomes with rounded heads. Unicellular covering trichomes are occasional. The ventral surface of the leaf (upper epidermis) contains a number of stomata-like structures whose cells are thicker than normal stomatal guard cells while the dorsal surface (lower epidermis) contains many small anomocytic oval stomata. A sectional view of the leaf exhibits its dorsiventral character. The upper epidermis consists of elongated compressed cells that bulge outwards into angular waves. The elongated epidermal cells at the margins contain smaller cluster crystals of calcium oxalate. The palisade cells underlying the upper epidermis are cylindrical, slender and compactly packed. The spongy mesophyll cells are oblong and they form many layers. The lower epidermal cells are polygonal with wavy cell walls. 
The dried stems and branches are pale yellow in colour with a pinkish tint, glabrous with square cross-sections and prominent two opposite ridges. The branches are brittle and is branching at internodes. 
A transverse section of the stem exhibits its square outline with two prominent opposite ridges. The epidermis consists of elongated parenchyma cells which are tightly packed, bears uniseriate covering trichomes. It is underlain by a layer of oblong cortical yellow-coloured parenchyma cells when viewed through a sectional view of the stem, whereas they appear as square cells on surface view. These are underlain by a circle of nonlignified fibers followed by many layers of compressed parenchyma cells with pitted, thick cell walls which also surround a circle consisting of several layers of lignified yellow-coloured cells separated from the underlying vascular tissues by a few layers of thick-walled polygonal parenchyma cells. The xylem tracheids are narrow, and they have pitted cell walls; the vessels are compactly packed together, and they are mostly spirally thickened while the xylem fibers are long, and all xylem tracheids, vessels and fibers are lignified. Some xylem parenchyma cells contain small crystals of calcium oxalate. The pith is composed of many cells with different shapes but they are mostly rounded and polygonal parenchyma cells. 

Powdered plant materials

Leaf: The material consists of a grayish-green fine powder. It has an unpleasant odour and a sour salty taste. Under the Microscope, the powder shows leaf fragments that have the same characteristics as the cells containing comparatively large rosettes of calcium oxalate, in addition to isolated grayish calcium oxalate rosettes and vascular tissues with conspicuous spirally thickened vessels. Stem: The material consists of a very coarse powder consisting of shredded plant tissues, yellowish-white in color with a straw-like odor and taste. Microscopic observation shows that the powder is comparatively broad semi-square or semi-rectangular parenchyma cells of the cortex which are rich in small (micro sphenoidal) crystals of calcium oxalate that collectively have dark grey colors in addition to fragments of comparatively long vascular tissues with compactly arranged annularly and spirally thickened grayish vessels. 

Parts studied

Leaves and stem

• A. TS of a portion of the leaf showing part of the epidermis, the cylindrical compactly packed palisade cells, the multi-layered spongy mesophyll tissues that are rich in calcium oxalate cluster crystals (dark areas) and the lower epidermis.
• B. Surface view of the stem showing rectangular epidermal cells and some characteristic multicellular covering trichomes. The epidermis exhibits square-shaped outer cortical parenchyma cells. 
• C. TS through a portion of the stem showing from the epidermis inwards: the epidermis with elongated parenchyma cells underlain by a layer of yellow colored cortical parenchyma cells; a circle of non-lignified fibres; compressed parenchyma cells with pitted walls; layers of lignified yellow-colored cells, layers of thick-walled cells; vascular tissues (lignified); then wide pith zone. 

Chemical constituents

The plant contains alkaloids, flavonoids and saponins (Ghazanfar, 1994).Leaves and stems contain alkaloids, glycosides and/or carbohydrates, flavonoids, sterols and tannins (Abu Ziada, 2008).
The following chemical studies have been carried out on the aerial part of the plant Amaranthus graecizans (Evans, (1996) Quality Control methods, 1998; ZCHRTM unpublished work).

Physicochemical constants 

Loss of weight on drying at 105°C:                      9.30
Absolute alcohol solubility:                                  2.00
Water solubility:                                                   20.08

Successive extractives (%)

Petroleum ether (60-80°C) :                                1.30
Chloroform :                                                        1.15 
Absolute alcohol :                                               6.50

pH values (aqueous solution)

1% solution:                                                       6.249
10% solution:                                                     5.504

Ash values (%)

Total ash :                                                       16.33-25.31
Water soluble ash :                                         6.83
Acid insoluble ash (10% HCl) :                       0.68-2.17

Elemental analyses

Ash values (British Herbal Pharmacopeia- Reference)
Assay and identification of elements (AOAC International- Reference)

UV Spectral studies

Chromatographic Studies

Thin layer chromatography (Wagner and Bladt, 1996)

Pharmacological and toxicological studies

Information and reports

Amaranthus graecizans has been reported as antifungal agent (Rivillas, 2007). An antifungal peptide was isolated from Amaranthus hypochondriacus seeds inhibited the growth, at very low doses, of different pathogenic fungi, such as Candida sp., Trichoderma sp., Fusarium solani, Penicillium chrysogenum, Geotrichum candidum, Aspergillus candidus, Aspergillus schraceus, and Alternaria alternate (Rivillas, 2007).  
The anti-diabetic and anti-oxidative effect of amaranth grain may be beneficial for correcting hyperglycemia and preventing diabetic complications (Kim, 2006). 
The plant extract was found to exhibit anti-inflammatory properties (Strzeleckaeta, 2005).It is believed that bioactive compounds from plant foods may have h beneficial effects on health and reduce the risk of chronic inflammatory diseases (Strzeleckaeta; 2005).  
Amaranth oil was found to decrease blood cholesterol levels (Martirosyan, 2007). In rat model experiments, the hypocholesterolemic effect of amaranth oil showed a decrease in the cholesterol level of rat blood which was not accompanied by an increase of cholesterol level in the liver (Kulak ova ,2006). 
Ethanol extract of Amaranthus sp. was investigated for hepatoprotective effect against CCl4-induced liver damage in rats. A significant hepatoprotective effect was observed with a decreased value of the MDA levels (Salwau, 2007).
The plant has also been reported as antioxidant activity as well (Pasko, 2007). Modification of antioxidant activity induced by amaranth oil can maintain oxygen homeostasis, morpho-functional state and inhibit tumor cells proliferation (Lelisieieva, 2006). It is concluded that the consumption of Amaranthus oil at 20% level produces reduction in the hexachloro cyclohexane induced impairment of antioxidant status in rat liver (Anilkumar, 2006). 
The plant pollen grains are known to be highly allergenic and a potential cause of respiratory allergic diseases (Salwau, 2007). An investigation was conducted to record the airborne incidence at different cities of Saudi Arabia (Hasnain, 2007).    
The (grains of )Amaranthus studied was found to be a high oxalate source, however, like most is in the insoluble form, and due to its high calcium and magnesium concentrations, oxalate absorbability could be low (Gelinas , 2007).
The plant extract was screened for antimalarial properties showed significant antimalarial activities in the 4-day suppressive antimalarial assay in mice inoculated with red blood cells parasitized with Plasmodium berghei (Hilou, 2006).
The following pharmacological and safety evaluation studies (Derelanko, 2002; Han, 2003), were carried out on the plant Amaranthus graecizens

1.) Ethanol extract

Summary of the results 

The plant extract exhibited a significant analgesic; antidepressant, strong spasmolytic and anti-spasmodic, antidiarrheal activity, cytoprotective activity tested against necrotizing agents and gastro protective activity against indomethacin. The plant extract on isolated guinea pig tracheal chain caused relaxation indicating broncho dilating activity, positive Uterotropic and anti-stress activity as revealed by the swim endurance test. The plant extract showed no change in blood pressure and heart rate.  
Acute toxicity study of plant extracts (10g/kg, p.o.) did not produce any adverse effect and showed no sign of salivation, nasal discharge, diarrhea or constipation, loss of righting reflex and tremors. The test substance was safe at the dose tested. Repeated dose toxicity revealed that the plant extract at the dose of 1g/kg/day for a period of 14 days showed no signs of abnormalities. 

Antimicrobial activity

The aqueous extract of the whole plant was tested against Mycobacterium smegmatis, C. tropicalis, different strains of Methicillin Resistant Staphylococcus aureus, different strains of ESBL-producing K. pneumonia, E. coli, Pseudomonas aeruginosa and showed no inhibition of growth.

References

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• Abu Ziada, M.E., E.F. El-Halawany, I.A. Mashaly and G.F. Masoud,.Autecology and phytochemistry of genus Amaranthus in the nile delta, Egypt. Asian J. Plant Sci., 2008. 7: 119-129.
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