Ethnobotanical Characteristics

Description

It is an annual or biennial, prostrate, densely appressed whitish silky pubescent herb. Stem hirsute to sericeous, branches spreading. Leaves paripinnate, 2.5-5 cm long; stipules lanceolate to falcate, 3-5 mm long; leaflets (4-) 5-6(-8) pairs ovate to elliptic-oblong, 5-10(-12) mm long, 3-8 mm broad, inequilateral, acute. Flowers are yellow, 1-1.5 cm across; pedicel up to 1.5(-2) cm long. Sepals ovate-lanceolate, 5-6 mm long, c. 3 mm broad, acute. Petals obovate, 6-8 mm long, 3-4 mm broad, obtuse. Stamens 10, filamentous c. 3-5 mm long, anthers versatile. Ovary ovoid, hirsute; style c. 1.5 mm long, stigmas decurrent. Fruit up to c. 1 cm in diameter, 4-8 mm long, mericarps densely crested and tuberculate on the dorsal side, densely hairy to glabrescent, with two long patent and two short downwardly directed spines (rarely all or lower 2 reduced to tubercles). (Jongbloed 2003, Flora of Pakistan).

Habitat and Distribution

Tropical and subtropical countries in Asia, Africa, S. Europe, and North Australia and introduced in new world tropics. In the UAE, it is common and widespread in urban areas, roadsides and depressions. (Mandaville, 1990).

Part(s) Used

Whole plant

Traditional and Medicinal Uses

In the UAE, the plant is used by some healers as an aphrodisiac, diuretic and hypotensive and to treat dysuria. It is soothing, analgesic, diuretic, tonic, and acts against colic. The leaves of the plant are used to treat enlarged spleen, puerperal fever, sores, diarrhea, nervous exhaustion and cramps.

Pharmacognosy and Phytochemistry

Plant material Studied

Dried leaflet

General appearance

The leaflet is small in size (up to 12 mm long and 5 mm wide) and grayish green. It shrinks when dried, exposing the lower epidermis outwards. It is brittle and easily broken.

Microscopic characteristics

Leaflet: Both surfaces are covered with dense covering trichomes of different sizes and lengths, which are generally one-celled, conical and tapering. Some of the trichomes have blunt ends, but all have thick cell walls and wide lumens. No glandular trichomes have been detected. In surface view, the cells of both epidermises are observed to be distinctly polygonal and have thick walls; the most characteristic epidermal cells are the basal cells that surround the cicatrices of detached covering trichomes. The oval and anomocytic stomata are equally distributed on both epidermises. The leaflet is unilateral, having one layer of palisade tissues with tightly packed cells underneath the upper epidermis. The spongy mesophyll cells are irregularly shaped and they are tightly packed. Also, the spongy mesophyll contains individual cells with thick cell walls and significant polygonal structures that surround the vascular tissues, of which the most significant are the spirally thickened vessels. Some spongy parenchyma cells contain individual cluster crystals of calcium oxalate with varying sizes; such kinds of cells are generally found near to the vascular tissues. Both palisade and spongy mesophyll cells are rich in tiny coloured particles, and those of the spongy mesophyll contain club-shaped masses.

Plant material Studied

Dried stem and branches

General appearance

The stem and the branches are light grayish-green with a pinkish tint. Branches are thin (1-2 mm in diameter), almost cylindrical in outline but not straight as they change their growing directions in a zigzag form at nodes. They are coarse tomentose touch. They are brittle and tare easily broken. A transverse section of the stem from the periphery to the pith shows the following: an epidermal layer consisting of small ovoid cells with thick cell walls, and the epidermis is covered with thick cuticle. Attached to the epidermis are numerous one-celled covering trichomes that have comparatively wide lumens and thick cell walls. The epidermis encircles several layers of cortical collenchyma (about 6-7 layers); the inner layers enclose groups of lignified fibers that have thick cell walls and narrow lumens. The cortex encircles phloem tissues, heavily lignified xylem tissues (vessels, tracheids and fibers) ,and at the center are the nearly rounded parenchyma cells of the pith, which occupy a wide zone.

Parts studied

leaf and stem

• A. Leaf: Detailed transverse section at the midrib region covering and glandular trichomes on the upper epidermis, palisade (one layer) spongy tissues, vascular tissues, lower epidermis (less covering trichomes) colored particles (in palisade and spongy parenchyma cells). Vascular elements are surrounded by characteristic cells with thick cell walls and wide lumens. 
• B. TS of stem: From outside to inside; covering trichomes, epidermal layer (small globular cells covered with a thick cuticle), several layers of cortical collenchyma, groups of lignified fibers of the cortex (purple in colour), phloem tissues, heavily lignified xylem tissues; vessels, tracheids, fibers (dark violet) and at the center the parenchyma cells of the pith. 
• C. TS of stem: From outside to inside; Epidermal layer (small ovoid cells with thick cell walls) bearing covering trichomes, cortical collenchyma with thick cells, groups of lignified fibers with thick cell walls and narrow lumens, phloem tissues, vessels, tracheids and xylem fibers (heavily lignified). 

Chemical constituents

Alkaloids, fixed and volatile oils, saponins, diosgenin, ruscogenin, resin and sapogenin. (El-Ghonemy, 1993).
 Dried fruits contain terrestribisamide, 25R-spirost-4-en-3,12-dione, tribulusterine, N-p-coumaroyltyramine, terrestriamide, hecogenin, aurantiamide acetate, xanthosine, fatty acid ester, ferulic acid, vanillin, p-hydroxybenzoic acid, β-sitosterol, terrestroside A, tribufurosides I and J (Tian-Shung, 1999; Yuan Wei-Huae, 2008; Tunhai, 2009).
The steroidal saponins: protodioscin, prototribestin, pseudoprotodioscin, dioscin, tribestin and tribulosin. The flavonoid rutin (Dragomir, 2008). Furostanol saponin (tribol), and sitosterol glucoside (J. Conrad, 2004). β-sitosterol-D-glucoside and a spirostanol type steroidal saponins: Tribulosin (M. Deepak, 2002). It also contains the steroidal saponin: protodioscin. (Gauthaman, 2002). Steroidal saponins in the aerial parts: Protodioscin, neoprotodioscin and prototribestin (De Combarieu, 2003).
Aerial parts: flavonoids, tannins, sterols and/or triterpenes and volatile oils. leaves and fruits: flavonoids kaempferol, kamferl 3-glucoside, kaempferol 3-rutinoside and tribloside. steroidal saponins, diosgenin. Chlorogenin and gitogenin, ruscogenin, hecogenin, neotigogenin, and 3-deoxy D3-diosgenin, b-sitosterol and stigmasterol. Steroid glycoside dioscin, trillin, diosgenin-D-glycoside and gracillin in addition to Harman and harmine alkaloids. The aerial parts also contain steroidal saponins main furostanol bisglycosides (Al-Yahya, 1990). The flowers contain sterols; stigmasterol, campesterol and b-sitosterol, sapogenins; diosgenin, gitogenin, and neogitogenin, flavonoidal aglycons; Kaempferol and quercetin and reducing sugars; D-glucose, D-arabinose and L-rhamnose).
The following chemical studies have been carried out on the plant Tribals terrestris (Quality Control methods, 1998; Evans, 1996, ZCHRTM unpublished work) 

Physicochemical constituents 

Loss of weight in drying at 105°C :                          7.09
Absolute alcohol solubility             :                         3.20
Water solubility :                                                     21.20

Successive extractives (%)

Petroleum ether 60-80°C :                                       1.75
Chloroform :                                                             1.55
Absolute alcohol :                                                     5.70
Distilled water :                                                        18.00

Ash values (%)

Total ash :                                                                 10.60
Water soluble ash :                                                   3.60
Acid insoluble ash (10% HCl) :                                 1.30

pH values (aqueous solution)

pH of 1% solution :                                                   5.98-6.05
pH of 10% solution :                                                 5.47-5.48

Elemental analyses

Ash values (British Herbal Pharmacopeia)
Assay and identification of element (AOAC International)

UV Spectral studies

Chromatographical Studies

Thin layer chromatography (TLC): Wagner and Bladt, 1996

TLC fingerprint of Petroleum ether 60-80°C (track 1) and MeOH extract (track 2)

Pharmacological and toxicological studies

Information reported in the Literature about the plant: The important pharmacological and toxicological activities of the plant Tribulus terrestris reported in various scientific journals have been presented in the present brief review:
A mixture of 9 oriental herbs were given including Tribulus terrestris showed an increase in the copulatory behavior parameters in rats, improved the sexual activity and erectile function.
The effects of methanolic and aqueous extracts of Tribulus terrestris on rat blood pressure (BP) and the perfusion of mesenteric vascular bed were investigated and found to possess significant antihypertensive activity in spontaneously hypertensive rats (Phillips et. al., 2006). Effect of Saponins from Tribulus terrestris (STT) on the renal carcinoma cell (786-0) in-vitro and inhibitory mechanisms studied significantly inhibited the growth of 786-0 in-vitro, partially, by apoptosis (Yang, 2005).
Tribulus is a genus of plants found in many warm regions. The best-known member is T. terrestris (Puncture Vine), a widespread weed and also the source of a dietary supplement claimed to increase the body's natural testosterone levels and thereby improve male sexual performance and help build muscle. T. terrestris has consistently failed to increase testosterone levels in controlled studies. (Brown, 2000; Brown, 2001 and Neychev, 2005). It has also failed to demonstrate strength-enhancing properties (Rogerson, 2007). Tribulus has been shown to enhance sexual behavior in an animal model. It appears to do so by stimulating androgen receptors in the brain (Gauthaman, 2002). Jameel, 2004 reported a case of a young weight-trainer who developed gynecomastia due to oral intake of a herbal tablet, which he used as a steroid alternative for body-building.
The aqueous extract of Tribulus terrestris can significantly increase melanocyte-stimulating hormone (MSH) expression in the hair follicle melanocytes by activating tyrosinase activity and promoting melanocyte proliferation, melanine synthesis, and epidermal migration of dormant melanocytes (Yang, 2006).
Tribulus terrestris showed protective effect for STZ-induced diabetic rats may be mediated by inhibiting oxidative stress (Amin, 2006).
Sharifi, 2003 investigated the antihypertensive mechanism of Tribulus in 2K1C hypertensive rats by measurement of circulatory and local ACE activity in aorta, heart, kidney and lung. The ACE activity in all tissues of Tribulus fed hypertensive rats was significantly lower than that of hypertensive rats, which was more pronounced in kidney. These results indicated that there is a negative correlation between consumption of Tribulus and ACE activity in serum and different tissues in 2K1C rats.
Oludotun, 2005 reported the effects of methanolic and aqueous extracts of Tribulus terrestris on rat blood pressure (BP) and the perfused mesenteric vascular bed were investigated. The extracts dose-dependently reduced BP in spontaneously hypertensive rats (SHRs) with the aqueous fraction being more potent than the methanolic fraction at all doses tested. In vitro, the methanolic but not aqueous extract produced a dose-dependent increase in perfusion pressure of the mesenteric vascular bed. When perfusion pressure was raised with phenylephrine, the aqueous extract produced a dose-dependent reduction in perfusion. It was concluded that methanolic and aqueous extracts of Tribulus terrestris possess significant antihypertensive activity in spontaneously hypertensive rats. The antihypertensive effects appeared to result from a direct arterial smooth muscle relaxation possibly involving nitric oxide release and membrane hyperpolarization.
The inhibitory effect of saponins from Tribulus terrestris (STT) on Bcap-37 breast cancer cell line were determined by cell growth curve, MTT assay, protein content assay and morphological observation showed that STT had potent inhibitory effect on Bcap-37 cell line in a concentration-dependent manner (Sun, 2003).
The results of pharmacological and toxicological studies carried out at ZCHRTM on the 70% alcoholic extract of the plant (Derelanko 2002; Han, 2003) have been given below:

Summary of Results

The oral administration of the plant extract was non-toxic up to the dose of 10 g/kg b.wt., p.o. These acute studies demonstrated that the plant extract is safe and did not cause any detrimental effects in vivo under the conditions investigated in this study.
The LD₅₀ of plant extract was found to be >10 g/kg when administered once via gastric intubation to rats. Plant extract produced a mild relaxation in phenylephrine pre-contracted corpus cavernous tissue.

Antimicrobial activity

The aqueous extract of the whole plant was tested against Mycobacterium smegmatis, C. tropicalis, different strains of Staphylococcus aureus (Including ATCC 257) as well as strains of Methicillin Resistant Staphylococcus aureus, strains of E. coli (Including ATCC UN 109), different strains of ESBL-producing K. pneumonia, E. coli, Pseudomonas aeruginosa. The extract showed strong antibacterial activity against S. aureus only.

References

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