Ethnobotanical Characteristics

Description

Twining shrub with milky juice, branches covered with dense ash-colored pubescence. Leaves 1.5-3.5 x 1-3 cm, cordate, pubescent to sub-glabrous above, pubescent or velvety below, petiole 4-12 mm long. Flowers in umbellate cymes; peduncle 1-2 cm long, solitary at nodes, between the petioles. Pedicel 1.0-2.5 cm long. Sepals 2.5-3.5 mm long, pubescent, glandular within. Corolla dull white tinged with pink, 7.5-10 mm long, tube 2.5 mm long, lobes 7 mm long, hairy outside. Follicles 5-7.5 x 1.2-1.3 cm, tapering towards the apex softly echinulate (Jongbloed. 2003; e-Floras).

Habitat and Distribution

Throughout Arabia, in drier areas, climbing over trees and shrubs. Also distributed in North Africa, Pakistan, Iran and Afghanistan (Ghazanfar, 1994).

Part(s) Used

Whole plant

Traditional and Medicinal Uses

The plant is used for treating skin problems, as an expectorant and as a purgative. The latex is applied to skin sores and other skin disorders. Extract of the plant is used as a purgative and as an expectorant (Ghazanfar, 1994). The stems and shoots were used to loosen the hair from hides so that it could be scraped off before the hide was tanned. The latex was also used medicinally to treat skin diseases, especially the circular skin sores, often very itchy, that were a common problem in Dhofar. However, this treatment was usually only given to adults or livestock, as it was very painful. If the latex touches broken skin, alarming swelling and discoloration occur, and if a drop falls in the eye, or the eyes are rubbed with fingers stained with the latex, pain, and inflammation can result.   Elsewhere in the Middle East, the plant is also used as a depilatory, and as a purgative and vermifuge. It is also taken as an abortifacient, and used to treat a variety of skin conditions (Miller, 1988)

Pharmacognosy and Phytochemistry

General appearance

Leaves and Stem

The leaf is broad with a palmate structure, petiolate with a wavy margin. The colour of the ventral side is pale yellow colour with a green tint. Both sides are tough and tomentose. The leaf is brittle and the venation is prominent on the dorsal side. The stem and branches are pale green. The branch is cylindrical and the surface is slightly tough. Branches get thinner from the base to the top and dried branches are usually devoid of leaves. Larger branches are brittle but young slender branches do not break easily.

Plant material studied

dried stem and branches

Microscopic characteristics

The surface view of both epidermises shows that they are covered with numerous short unicellular conical covering trichomes, but comparatively longer trichomes also exist. The leaf shows a net of the intricate vein system. In the sectional view, the leaf exhibits a dorsiventral character, and both epidermal layers consist of small oblong cells covered with thin cuticle. Beneath the upper epidermis is a layer of loosely packed cylindrical palisade cells. The spongy mesophyll cells contain small masses. The spongy mesophyll cells imbed many vascular tissues, the vessels of which are annularly thickened in general.A cross-section of the stem shows its circular outline. The epidermal layers consist of compactly arranged longitudinal cells that bear many covering trichomes, similar in shape to those of the leaf, but also few multi cellular trichomes are detected. The cortex consists of many layers of small polygonal parenchyma cells intersperced with isolated groups of unlignified fibers. The cortical parenchyma adjacent to the stele is compressed, and the stele is composed of a wide circle of compactly packed, heavily lignified vascular tissues whose vessels are generally annularly thickened. The pith occupies a wide central zone. It consists of compressed parenchyma cells with thick cell walls, which are distorted in shape; these cells contain different small masses and particles.

Parts studied

stem and branches

• A. TS of a portion of the leaf showing both epidermises bearing dense short and long conical covering trichomes. Also shown is the palisade layer underlain by the spongy mesophyll tissue imbedding many vascular tissues (dark area).
• B. A TS of a portion of the stem near the periphery showing the epidermis that bear numerous covering trichomes: unicellular and multicellular; the cortical layers interrupted by isolated groups of unlignified fibers. The cortex is underlain by heavily lignified vascular tissues. 
• C. A T.S. of a portion of the stem at its central part showing part of the lignified vascular tissues (dark area), part of the pith and the central hollow zone. 

Chemical constituents

The five cardenolide glycosides, 3'-O-beta-D-glucopyranosylcalactin, 2-dehydroxyghalakinoside and 6'-dehydroxyghalakinoside, ghalakinoside and calactin, were isolated from the roots of Pergularia   tomentosa (Mansour, 1988; Rastogi, 1995). 
The phytochemical analysis of the plant Pergularia tomentosa (Syn. Daemia cordata) revealed the presence of cardiac glycosides, flavonoids, tannins, and sterols and /or triterpenes, cardenolides A, B, C, D, and E as coroglaucigenin (Al-Yahya,1990).
The following chemical studies have been carried out on the aerial part of the plant Pergularia tomentosa (Quality Control methods, 1998; Evans, 1996; ZCHRTM unpublished work) .

Physicochemical parameters 

Loss of weight in drying at 105°C :                                             8.70
Absolute alcohol solubility              :                                           5.60
Water solubility : 20.40

Successive extractives (%)

Petroleum ether (60-80) °C :                                                      4.15
Chloroform :                                                                                1.90
Absolute alcohol :                                                                       11.00
Distilled water :                                                                           17.10

Ash values (%)

Total ash :                                                                                   9.17
Water soluble ash :                                                                    4.33
Acid insoluble ash (10% HCl) :                                                   Nil 

pH values (aqueous solution)

pH of 1% solution :                                                                   5.656-5.667
pH of 10% solution :                                                                 5.175-5.177

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 about the plant:
 The observation of animals, injected intraperitoneally with the ethanolic extract and chloroform extracts, showed that both extracts produced rapid respiration, piloerection and lowered body temperature. The group of animals administered ethanol extract also showed urination and the constriction of the pupil (Al-Yahya, 1990). The isolated cardenolides caused apoptotic cell death of Kaposi's sarcoma cells (Hamed, 2006).
Abiola, (1993) reported that a large number of ruminants are often lost in Niger due to poisoning caused by Pergularia tomentosa L. The effect of this plant, traditionally used to tan skin, was experienced in goats. The symptoms observed the post-mortem findings, and the search for toxic compounds suggest that P. tomentosa contains tannins. Also, this plant most likely also includes substances with cardiac effects.
Pergularia tomentosa did not show hypoglycemic activity in fasting alloxan-induced diabetic rats (Shabana, 1990).
Biochemical studies on ghalakinoside, a possible antitumor agent from Pergularia tomentosa was carried out (Al-Said, 1989).
The molluscicidal activity of a cardenolide (cardiac glycoside) extract from Pergularia tomentosa (L.) (Asclepiadaceae), methomyl, and methiocarb were evaluated against the land snail Monacha obstructa (Ferussac). Cardiac glycosides from P. tomentosa, was found to have a strong antifeedant effect against land snails (Hussein, 1999). 
Both extracts produced contractions in the isolated guinea pig ileum. The ethanol extract was more active.  The contraction induced by ethanol extract was partially blocked by atropine and completely blocked by antihistamine suggesting combined parasympathomimetic and histaminic activity of the extract (Al-Yahiya, 1990).
The chloroform extract induced contraction that were completely blocked by atropine, indicating a cholinomimetic activity. Both ethanol and chloroform extracts failed to produce any effect per se on the isolated muscle of frog rectus abdominis, but they modified the acetylcholine-induced contraction of the preparation (Al-Yahiya, 1990).
The ethanol extract produced a positive inotropic effect in isolated rabbit heart. However, no significant changes in the force of contraction were produced by the chloroform extract. The ethanol extract significantly lowered the blood pressure of the anaesthetized rabbit, and the reduction was partially blocked by atropine, corroborating the effect of the extracts on smooth muscles. However, a decrease in the blood pressure was produced by the chloroform extract, which was blocked by atropine.
The biochemical studies in rats revealed that the serum glucose level significantly decreased in the chloroform extract treated group. However, no significant changes in the cholesterol level were observed in both treated groups. The serum electrolyte estimation revealed a significant increase in potassium level in both treated groups. However, the sodium content remained unchanged in the treated groups. Hematological studies showed a significant decrease in the RBC count and hemoglobin level in the chloroform extract treated group. The WBC count did not reveal any appreciable changes as compared to the control groups. Blood coagulation studies revealed no influence of both extract on prothrombin time PT (Al-Yahya, 1990).
The following pharmacological and safety evaluation studies were carried out on the plant extract of Pergularia tomentosa (Derelanko 2002; Han, 2003).

Summary of results 

The plant Pergularia tomentosa showed positive Anti-inflammatory, Antidepressant, Antithrombotic, Guinea pig tracheal chain (Anti-histaminic) activities. The plants of this species also showed the presence of moderate antispasmodic activity, mild antidiarrheal activity; and mild antinociceptive activity. Hepatoprotective studies showed decreased bilirubin. No change was observed in the rabbit corpus cavernous strip. Evaluation of single dose acute toxicity was safe at the dose tested; No mortality recorded. 

Antimicrobial activity

The aqueous extract of the whole plant was tested against Mycobacterium smegmatis, C. tropicalis, different strains of Staphylococcus aureus (Including ATCC 257), 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 weak antimicrobial activity against Mycobacterium smegmatis only.

References

• Abiola FA, Alogninouwa T, el Bahri L, Ali M, Kaboret , Fayomi B. Experimental study of poisoning of goats with Pergularia tomentosa L. Rev Elev Med Vet Pays Trop, 1993, 46:591-595. 
• Al- Yahya MA, Al- Meshal IA, Mossa JS, Al- Badr AA, Tariq M. Saudi Plants: A Phytochemical and Biological Approach. king abdulaziz city for science and technology,1990. P.315
• Al-Said MS, Abu-Jayyab A, Hifnawy MS. Biochemical studies on ghalakinoside, a possible antitumor agent from Pergularia tomentosa. J Ethnopharmacol, 1989, 27:235-240.
• Al-Yahya, M.A., I.A. Al-Meshal, J.S. Mossa, A.A. Al-Badr and M. Tariq, 1990. Saudi Plants: A Phytochemical and Biological Approach. 1st Edn. King Saud University Press, Riyadh, Saudi Arabia, pp: 142-144..
• El-Ghonemy, A. A. (1993). Encyclopedia of Medicinal plants of the United Emirates. 1st Edition. University of U.A.E.
• Fawzi, M. K. (1995). Weeds in the United Arab Emirates. University of U.A.E.
• Hamed AI, Plaza A, Balestrieri ML, Mahalel UA, Springuel IV, Oleszek W, Pizza C, Piacente S. Cardenolide glycosides from Pergularia tomentosa and their proapoptotic activity in Kaposi's sarcoma cells. J Nat Prod, 2006, 69:1319-1322.
• Hussein H. I.; Al-Rajhy D.; El-Shahawi F. I.; Hashem S. M. Molluscicidal activity of Pergularia tomentosa (L.), methomyl and methiocarb, against land snails.    International Journal of Pest Management, 1999, 45: 211- 213.  
• Jonbloed, M. V., Feulner, G. R., Boer, B. & Western, A. R. (2003). The comprehensive Guide to the Wild Flowers of the United Arab Emirates, Erwda, Abu Dhabi, U.A.E. 
• Mandaville, J. P. (1990). Flora of Eastern Saudi Arabia. Kegan Paul International, Riyadh, Saudi Arabia.
• Mansour S. Al-Said, Mohamed S. Hifnawy, Andrew T. McPhail and Donald R. McPhail. Ghalakinoside, a cytotoxic cardiac glycoside from Pergularia tomentosa. Phytochemistry , Volume 27, Issue 10, 1988, Pages 3245-3250
• Miller, A. G.  and M. Morris . 1988. Plants of Dhofar, The Southern Region of Oman. Traditional Economic and Medicinal Uses. Diwan of Royal Court Sultanate of Oman—Holmes MC Dougall, Edinburgh, Scotland.
• Rastogi & Mehrotra, Compendium of Indian medicinal plants : vol. 4, PID, New Delhi,1995, p.543
• S.W. Hassan, R.A. Umar, M.J. Ladan, P. Nyemike, R.S.U. Wasagu, M. Lawal and A.A. Ebbo Nutritive Value, Phytochemical and Antifungal Properties of Pergularia tomentosa L. (Asclepiadaceae) International Journal of Pharmacology, 2007,  3 : 334-340.
• Shabana MM, Mirhom YW, Genenah AA, Aboutabl EA, Amer HA Study into wild Egyptian plants of potential medicinal activity. Ninth communication: hypoglycaemic activity of some selected plants in normal fasting and alloxanised rats.  Arch Exp Veterinarmed., 1990, 4:389-394.
• Shahina A.Gazanfar. Handbook of Arabian medicinal plants, CRC Press, USA, p.35, 1994.
• Western, A. R. (1986).  The Flora of United Arab Emirates. An introduction. Al Ain.
• Western, A. R. (1989). The Flora of United Arab Emirates. An introduction. Publications of the U.A.E. University.