Aloe vera- A Review

 

P. Srujana*,V. Sai Kishore, K. Srikanth and  P.Y. Shanmukha

Bapatla College of Pharmacy, Bapatla-522101, Andhra Pradesh,  India.

 

ABSTRACT:

Aloe vera is a perennial, drought-resisting, succulent plant belonging to the Liliaceae family which, historically has been used for a variety of medicinal purposes. It has a vast traditional role in indigenous system of medicine like ayurveda, siddha, unani and homoeopathy. As a result of its use as folk medicine, it is claimed that aloe vera has wound and burn healing properties, antifungal activity, hypoglycemic or antidiabetic effects anti-inflammatory, anticancer, immunomodulatory and gastroprotective properties. Aloe vera is used in a variety of commercial products because of these therapeutic properties.  The known biological activities of A. vera were briefly discussed and also further highlighted recently discovered effects and applications of the leaf gel. The present review is therefore, an effort to give a detailed survey of the literature on its traditional, phytochemical and pharmacological properties, Industrial processing technique and   Industrial uses. With technological developments in the field of analytical chemistry it has become easier to isolate and characterise the chemical components of the leaf gel and it is expected that more information in this regard will become available in the future at a faster rate. More applications are discovered as research from different viewpoints is conducted on this versatile plant to provide a better understanding of its composition and effects. Further research needs to be done to unravel the myth surrounding the biological activity and the exploitation of aloe constituents.

 

KEY WORDS: Aloe vera, phytochemical, pharmacological, cosmetic, pharmaceutical, food industries.

 

INTRODUCTION:

Aloe vera (Aloe barbadensis Miller) is a perennial succulent belonging to the Liliacea family,and is called the healing plant or the silent healer1. It is commonly called aloe, burn plant, lily of the desert, elephant’s gall. The name, aloe, is derived from the Arabic "alloeh" or Hebrew "halal" meaning bitter shiny substance. It is present in the arid regions of India and in temperate and sub tropical parts of the world. Aloe vera has been used therapeutically for many centuries and is of particular interest due to its lengthy historic reputation as a curative agent and its widespread use in supplementary therapies. It has a vast traditional role in indigenous system of medicine like ayurveda, siddha, unani and homoeopathy2.

 

History of Aloevera as a popular folk medicine:

Aloe vera is as old civilisation and throughout history it has been used as a popular folk medicine. Aloe was cultivated in Egypt thousands of years ago and was used by the people of the Mediterranean at least 400 years before Christ. Aloe is also mentioned in the Bible's New Testament.  Aloe vera was well known not only to the Egyptians, but also the Roman, Greek, Arab and Indian cultures. In fact, many famous physicians of those times, including Dioscorides, Pliny the EIder and Galen considered to be the father of modern medicine, included aloe vera in their therapeutic armouries Myths and legends surrounding the use of aloe vera in ancient times suggest that it was an important part of the beauty regime of the Egyptian queens, Nefertiti and Cleopatra. Legend has it that, in 333 BC, Alexander the Great was persuaded by his mentor Aristotle to capture the island of Socotra in the Indian Ocean, famed for its supply of aloe which he needed to heal his wounded soldiers.

 

The Egyptians referred to aloe as the "plant of immortality" and included it among the funerary gifts buried with the pharaohs. The healing benefits of aloe were recognized in the ancient Indian, Chinese, Greek, and Roman civilizations3.

 

Phyto chemical composition:

 It is one to two feet tall and its leaves are succulent, broad at the base and pointed at the tips, with spines along the edges. Each leaf consists of two parts, an outer green rind and an inner clear pulp4. The pulp, the major part of the leaf by volume, appears to be clear and mucilaginous. The pulp is part of plant that has been most widely used for therapeutic purposes. The chemical composition of the pulp has been described in numerous reports.  Chemical analysis has revealed that this clear pulp contains vitamins, enzymes, proteins, amino acids, minerals, polysaccharides and biological stimulators. Aloe pulp also contains lignans, saponins, salicylic acid, sterols, triterpenoids, and the minerals 5-6. The fresh gel contains glutathione peroxidase, isoenzymes of superoxide dismutase, and the proteolytic enzyme carboxypeptidase 7-8. It has been hypothesized that this heterogeneous composition of the Aloe vera pulp may contribute to the diverse pharmacological and therapeutic activities which have been observed for aloe gel products.

 

Phytopharmacological properties:

1) Anti-diabetic effects: It lowers glucose and tri-glyceride levels in diabetic patients. Effects can be seen from the second week of the treatment. 16

 

2) Immunomodulatory effects:

A number of studies indicated immunomodulating activities of the polysaccharides in A. vera gel, and suggested that these effects occur via activation of macrophage cells to generate nitric oxide, secrete cytokines (e.g. tumour necrosis factor-alpha or TNF-α, interleukin-1 or IL-1, interleukin-6 or IL-6 and interferon-γ or INF-γ) and present cell surface markers.17

 

3)Anti-inflammatory activity: Aloe gel reduces inflammation that is induced by agents via promotion of prostaglandin synthesis as well as increased infiltration of leucocytes.18

 

4) Anti-oxidant effects: Glutathione peroxidise activity, superoxide dismutase enzymes and a phenolic antioxidant were found to be present in A. vera gel, which may be responsible for these anti-oxidant effects.19

 

5) Anti-cancer effects: The two fractions from aloes that are claimed to have anti-cancer effects include glycoproteins (lectins) and polysaccharides . One mechanism of action that was proposed for these anti-cancer effects of aloe polysaccharides is stimulation of the immune response.20

 

6) Skin hydration effects: It was proposed that the A. vera gel containing products improved skin hydration possibly by means of a humectant mechanism.21

 

7) Hepatoprotective activities: Histopathological studies confirmed the curative efficacy of the water extract of A. vera against carbon tetrachloride induced liver damage as indicated by reversal of centrilobular necrosis, macro-vascular fatty changes and scattered lymphomononuclear cell infiltrate in hepatic parenchyma.22

 

8) Antimicrobial activities: Anthraquinones isolated from the exudate of A. vera have shown wide antimicrobial activity. The antibacterial activity of emodin against Escherichia coli was proposed to be mediated through inhibition of solute transport in membranes. Many anthraquinones have shown antiviral and/or virucidal effects on enveloped viruses.23

 

9) Wound healing activity: Aloe vera stimulate wound healing by means of growth factors such as gibberllin, auxin and mannose phosphate.24

Table 1. Summary of the chemical composition of A. vera leaf pulp and exudate 9-15

Class

Compounds

Vitamins

B1, B2, B6, C, β-carotene, choline, folic acid,α-tocopherol.

Enzymes

Alkaline phosphatase, amylase,carboxy peptidase,cyclooxidase,cyclooxygenase, lipase,oxidase,phosphoenolpyruvate carboxylase, superoxide dismutase

Proteins

Lectins, lectin-like substance.

Amino acids

Alanine, arginine, aspartic acid, glutamic acid, glycine, histidine,hydroxyproline, isoleucine, leucine, lysine, methionine, phenylalanine,proline, threonine, tyrosine, valine

Carbohydrates

Pure mannan, acetylated mannan, acetylated glucomannan, glucogalactomannan, galactan, galactogalacturan, arabinogalactan, galactoglucoarabinomannan, pectic substance, xylan, cellulose

Saccharides

Mannose, glucose, L-rhamnose, aldopentose

Anthraquinones/anthrones

Aloe-emodin, aloetic-acid, anthranol, aloin A and B (or collectively known as barbaloin), isobarbaloin, emodin, ester of cinnamic acid

Chromones

8-C-glucosyl-(2’-O-cinnamoyl)-7-O-methylaloediol A, 8-C-glucosyl-(S)-aloesol, 8-C-glucosyl-7-O-methyl-(S)-aloesol, 8-C-glucosyl-7-O-methylaloediol,8-C-glucosyl-noreugenin, isoaloeresin D, isorabaichromone,neoaloesin A.

Sterols

Campesterol, Sitosterol , Lupeol

Minerals(Inorganiccompoun)

Calcium, chlorine, chromium, copper, iron, magnesium, manganese,potassium, phosphorous, sodium, zinc

Miscellaneous including

organic compounds and

lipids

Arachidonic acid, γ-linolenic acid, steroids (campestrol, cholesterol, β-sitosterol), triglicerides, triterpenoid, gibberillin, lignins, potassium sorbate, salicylic acid, uric acid

10) Anti-ulcer Activity: It stops bleeding, damage and leakage of intestine walls and rebuilds protective mucosa lining.25

 

11. Gastroprotective activity: The plant was more active as a gastroprotective agent at lower concentration against mucosal injury. Aloe vera acts as a healing agent inside the digestive tract. It encourages the release of pepsin a gastric enzyme necessary for digestive process. 25

 

12) Atherosclerosis and coronary heart disease : The ingestion of aloe gel may have beneficial effect by lowering serum cholesterol, serum triglycerides and serum phospholipids, which when elevated ,seem to accelerate the deposition of fatty material in the large and medium sized arteries, including the coronary arteries ,including the coronary arteries of theheart.26

 

13) Hypolipidemic activity: The administration of   Processed Aloe vera  gel  lowered triacylglyceride levels in liver and plasma. Aloe vera gel helps rebalance the blood chemistry in a way that it lowers cholesterol naturally.2

 

14) Antifungal activity: Leaf pulp and liquid fraction of Aloe vera act against plant pathogenic fungi.28

 

15) External Skin Care: Aloe vera heals the  skin in several ways.29

 

Cures cuts: It promotes healthy healing of minor cuts, scrapes, scratches and wounds. It seals off the injury and helps the formation of new skin cells.

 

Heals burns: It helps the formation of new skin cells and hastens healing. It promotes healthy tissue growth by reducing inflammation and killing bacteria that thrive on damaged skin cells. Its cooling effects offer instant relief from burns and prevent blistering.

 

Alleviates Allergy: It is proven that the pulp of aloe vera relieves itching due to allergies and insect bites as well as aids in healing. Aloe vera is used on blisters, sores, rashes, fungal infections etc.

 

Skin disease treatment: Aloe vera is reputed to be effective in the treatment of seborrhea, herpes, red spot, eczema, psoriasis, warts etc.

 

Reduces stretch marks: Pregnant women use aloe vera gel and lotion to make stretch marks disappear.

 

Enhances beauty: It gives a glowing effect to dry skin. It reduces acne and sunburn. It lessens wrinkles and overall

gives the skin a healthy touch.

 

Scalp and hair care:

Aloe vera is good for hair and scalp acting as a natural hair conditioner. It makes the root of the hair stronger and reduces hair-fall. It revitalizes dull hair, giving them a natural sheen.

Industrial  processing  of aloe vera leaf gel:

Industrial processing  of Aloe vera leaf gel includes the following steps.30

 

Reception of raw materials: The Aloe vera leaves after harvesting were preferably transported in refrigerated vans from the field to the processing place. The leaves should be sound, undamaged, mold/rot free and matured (3-4 years) in order to keep all the active ingredients in full concentration1. However, the composition of these active ingredients are subtly affected by seasonal, climatic and soil variations. One important factor that must be considered is the handling/treatment of the leaves after its harvesting because the decomposition of the gel matrix occurs on cutting due to natural enzymatic reactions and the activity of bacteria that are normally present on the leaves. This degradative process can adversely affect the quality of the end product. Therefore, there is a need to carefully work towards refrigerating the freshly removed leaves within 4-6 h or get the raw material directly into production.

 

Filleting operation: The losses of biological activity appeared to be the result of enzymatic activity after the aloe leaf was removed from the plant. In fact, it was shown that the aloe gel, once extracted from the leaf, had greater stability than the gel left in the leaf. In order to avoid the decomposition of the biological activity, the filleting operation must be completed within 36 h of harvesting the leaves. In the other hand, the anthraquinone was one important factor leading to nonenzymatic browning in aloe

gel product.

 

Grinding/homogenization: The major steps in this process include crushing or grinding. The aloe gel fillets should be crushed and homogenized using a commercial high speed tissue crusher at room temperature (25ºC). Due to the reaction of enzymatic browning, the longer the crushing/grinding time, the higher the browning index in Aloe vera gel juice. Therefore, crushing or grinding should be shortened within 10-20 min in order to avoid the enzymatic browning reaction of Aloe vera gel.

 

Addition of pectolytic enzyme:

Enzymatic treatment of Aloe vera gel for a long duration prior to processing is detrimental to biologically active compound such as polysaccharide which is the single most important constituent in aloe. Many researches have been done on the polysaccharides. It has been reported that the enzyme treatment at 50°C and within 20 min did not induce the loss of biological activity of polysaccharide in Aloe vera gel.

 

Filtration: This operation influences on the stability of Aloe vera gel juice. For example, the product showed the sedimentation of particles as the filtration operation lost its control.

 

Addition of vitamin C and citric acid: The unpasteurized aloe gel juice was fortified with vitamin C and citric acid to avoid browning reaction, to improve the flavor of Aloe vera gel juice and to stabilize the juice. The pH of aloe gel juice was adjusted between 3.0 and 3.5 by adding citric acid to improve the flavour of Aloe vera gel juice.

 

Dearation: The aim of dearation step is to avoid the oxidation of ascorbic acid , which eventually improves the shelf life of the Aloe vera gel juice.

 

Pasteurization: Like the process of other vegetable juice, this step may affect the taste, appearance and the content of biological activity of aloe gel product. HTST (High Temperature Shot Time) treatment (at 85-95°C for 1-2 min) is an effective method to avoid the bad flavour and the loss of biological activity of the Aloe vera gel .

 

Flash cooling: After pasteurization, the juice is flash cooled to 5°C or below within 10-15 sec. This is a crucial step to preserve biological activity of the Aloe vera gel.

 

Concentration: The gel obtained using the pasteurization and flash cooling methods can be concentrated under vacuum without the loss of biological activity. The concentration operation must be conducted under 125 mm mercury vacuum at temperature below 50°C and must not exceed 2 min. Higher vacuum and temperature will cause activity loss, as will extend concentration times.

 

Freeze or spray drying: The concentrated product can then be freeze-dried at temperature between -45 and 30°C or can be spray dried with product temperature below 60°C without the loss in biological activity.

 

Storage: Relative humidity and temperature are two most important environmental parameters that affect product quality. Those two parameters can also affect the amount of the volatile substances of the juice absorbed by the packaging material and consequently, affect the shelf-life of the product.

 

Quality of  aloevera  products

 Aloe is not just aloe because the manufacturer says so. To assure that an aloe product at a price worth paying and to achieve the desired results, it is recommended to look for International Aloe Science Council (IASC) certification seal on literature and packaging. Another way to ascertain whether an  Aloe Vera product has a high healing capacity is to find out the number of mucopolysaccharides (MPS) present. This is sometimes included on the labeling. The highest therapeutic value is found in product containing between 10,000 and 20,000 MPS per liter.31

 

Industrial uses:

1.Food Industry:

In the food industry, Aloe vera has been utilized as a resource of functional food, especially for the preparation of health food drinks and other beverages, including tea.32-33

 

2. Cosmetic and Toiletry Industries:

Aloe vera gel also finds its application in the cosmetic and toiletry industries, where it is used as a base for the preparation of creams, lotions, soaps, shampoos and facial cleaners. Aloe Vera also used as moisturizer, skin caring product and  healing agent in cosmetics. 34-35

 

3. Pharmaceutical industry

In the pharmaceutical industry, it has been used for the manufacture of topical products such as ointments and gel preparations, as well as in the production of tablets and capsules36. Important pharmaceutical properties that have recently been discovered for both the A. vera gel and whole leaf extract include the ability to improve the bioavailability of co-administered vitamins in human subjects37. Due to its absorption enhancing effects, A. vera gel may be employed to effectively deliver poorly absorbable drugs through the oral route of drug administration. Furthermore, the dried powder obtained from A. vera gel was successfully used to manufacture directly compressible matrix type tablets. These matrix type tablets slowly released a model compound over an extended period of time and thereby showing potential to be used as an excipient in modified release dosage forms 38. Aloe vera also used in the preparation of nutraceuticals39 and  OTC drugs40.

 

4. Textile industry:

With the price of yarn increasing, weavers in Tamil Nadu using the aloe vera natural fibre to make colourful sarees.

 

Aloe In Global Market:

Aloe Vera being a medicinal plant and due to its  extensive medicinal, nutraceutical and other uses its enjoy a great demand in the market across the globe. The major markets for Aloe Vera and its extracts are Australia, US and the entire Europe. Given the exponentially growing demand for it in the international market, Aloe Vera presents the finest commercial opportunity among the various medicinal plants. India is one  among the few countries gifted with the unique geographical features essential for cultivation of Aloe Vera and other high potential medicinal plants.

The International Aloe Science Council is a non-profit trade organization for the Aloe Vera Industry world-wide. Aloe growers, processors, finished goods, manufactures, marketing companies, insurance companies, equipment suppliers, printers, sales organizations, physicians, scientists and researchers are all eligible for and compromise membership. The common bond between the diverse group of individuals and companies is an interest in promoting Aloe Vera use in skin care products, beverages, pharmaceuticals and a wide variety of other products.

 

CONCLUSION:

A review on Aloe vera plant  has revealed  that  Aloe vera is a highly potential functional and valuable ingredient and exhibits relatively impressive biological functions of great interest in cosmetic, pharmaceutical and food industries. More applications are discovered as research from different viewpoints is conducted on this versatile plant to provide a better understanding of its composition and effects. Further research needs to be done to unravel the myth surrounding the biological activity and the exploitation of aloe constituents.

REFERENCES:

1.        Dagne E, Bisrat, D, Viljoen A and Van Wyk  BE. Chemistry of Aloe species. Curr. Org. Chem. 2000; 4: 1055-1078.

2.        Singh S, Sharma P K, Kumar N and Dudhe R. Biological activities of aloe vera. International Journal Of Pharmacy and Technology.2010;2(3):259-280.

3.        Baby Joseph and Justin Raj S. Pharmacognostic and phytochemical properties of aloe vera linn –An overview.2010 ;4(2):106-110.

4.        Grindlay D and Reynolds T. The Aloe vera phenomenon: A review of the properties and modern uses of the leaf parenchyma gel. J Ethnopharmacol.1986; 116:117-151.

5.        Shelton RM. Aloe vera: Its chemical and therapeutic properties. Int J Dermatol 1991; 30:679-83.

6.        Yamaguchi I, Mega N and Sanada H. Components of the gel of Aloe vera (L.) burm. Biosci Biotechnol Biochem. 1993; 57: 1350-52.

7.        Klein AD and  Penneys NS. Aloe vera. J Am Academy Dermat 1988; 18: 714-20.

8.        8. Sabeh F, Wright T and Norton SJ. Purification and characterization of  a   glutathione  peroxidase  from  the  Aloe vera plant. Enzyme Protein 1993; 47: 92-98.

9.        Ni Y,Turner D, Yates KM and Tizard I.Isolation and characterisation of structural components of Aloe vera L. leaf pulp. Int. Immunopharmacol. 2004; 4: 1745-1755.

10.     Femenia A, Sanchez E S and Imal S.compositional features of polysacchaides from Aloe vera (Aloe barbadensis Miller) plant tissues. Carbohydr. Polym. 1999; 39 :109-117.

11.     Choi S, Son BW and Son YS. The wound-healing effect of a glycoprotein fraction isolated from aloe vera. Br J Derm. 2001; 145:535-545.

12.     Steenkamp, V.; Stewart, M.J. Medicinal applications and toxicological activities of Aloe products. Pharm. Biol. 2007, 45, 411-420.

13.     Choi S, Chung M H. A review on the relationship between Aloe vera components and their biologic effects. Semin. Integr. Med. 2003; 1: 53-62.

14.     Mckeown E, Anthraquinones and anthracenic derivatives absorb UV light. Cosmetics and toiletries.1987;102: 64-65.

15.     Boudreau M.D and  Beland F A. An evaluation of the biological and toxicological properties of Aloe Barbadensis (Miller), Aloe vera. J. Environ. Sci. Health C. 2006; 24: 103-154.

16.     16.Bunyapraphatsara,N.,Yongchaiyudha,S.,Rungpitarangsi,V.,Chokechaijaroenporn,O.,.Antidiabeticactivityof Aloe vera L. juice. II. Clinicaltrial in diabetes mellitus patients in combination with glibenclamide. Phytomedicine 1996;3: 245–248.

17.     17.S-A. Im,. S-T. Oh, S-T. Song, S, M-R. Kim, M-R. Kim, S-S, Woo,T.H. Jo, Y.I. Park, C-K. Lee, identification of optimal molecular size of modified Aloe polysaccharides with immunomodulatory activity. Int. Immunopharmacol. 2005; 5:271-279.

18.     18.B. Vazquez, G. Avila, D. Segura, B. Escalante, . Antiinflammatory activity of extracts from Aloe vera gel. J. Ethnopharmacol. 1996, Vol 55, pp 69-75.

19.     19.El-Shemy HA, Aboul-Soud MA, Nassr-Allah AA, Aboul-Enein KM, Kabash A, Yagi A. Antitumor properties and modulation of antioxidant enzymes' activity by Aloe vera leaf active principles isolated via supercritical carbon dioxide extraction. Curr Med Chem.17(2)2010,129-38.

20.     Steenkamp V, Stewart M J . Medicinal applications and toxicological activities of Aloe products. Pharm. Biol. 2007; 45: 411-420.

21.     Vogler B.K  and  Enst E.  Aloe vera a systemic review of south Africa plants used for medicinal purposes. Journal of Ethnopharmacology 1997 ; 56(1) : 81-87.

22.     Alves D S, Pérez-Fons L , Estepa A and Micol V. Membrane-related effects underlying thebiological activity of the anthraquinones emodin and barbaloin. Biochem. Pharmacol. 2004;68:549-561.

23.     Stuart RW, Lefkowitz DL and Lincoln JA. Upregulation of phagocytosis and candidicidal activity of macrophages exposedto the immunostimulant acemannan. Int J Immunopharmacol 1997;19:75-82.

24.     E. E. Galal, A. Kandil, R. Hegazy, M. Ghoroury, W. Gobran, Aloe vera and gastrogenic ulceration. J Res.1975 ;7:73-77.

25.     Sadiq Yusuf, Abdulkarim Agunu and Mshelia, The effect of Aloe vera A. Berger (Liliaceae) on gastric acid secretion and acute gastric mucosal injury in rats, Journal of Ethno pharmacology2004;93 (1):33-37.

26.     O. P. Agarwal, prevention of arthamatous heart diseases. Angiology 1985; 36:485-492.

27.     Kim K, Kim H, Kwon J, Lee S, Kong H, Im SA, Lee YH, Lee YR, Oh ST, Jo TH, Park YI, Lee CK, Kim K. Hypoglycemic and hypolipidemic effects of processed Aloe vera gel in a mouse model of noninsulin-dependent diabetes mellitus. Phytomedicine.2009;16(9) : 856-63.

28.     Jasso de Rodríguez, , Hernández Castillo D, Rodríguez García R and  Angulo Sanchez J. L. Antifungal activity in vitro of Aloe vera pulp and liquid fraction against plant pathogenic fungi. Industrial Crops and Products. 2005;21(1):81-87.

29.     Danof IE and McAnalley W. Stabilised Aloe vera: Effect on human skin cells. Drug and Cosmetic Industry.1983; 133:105-106.

30.     Ramachandra  CT , Srinivasa Rao P. Processing of Aloe Vera Leaf Gel. A Review. Am. J. Agril. and Biol. Sci. 2008; 3 (2): 502-510.

31.     He, Q.; Changhong, L.; Kojo, E.; Tian, Z. Quality and safety assurance in the processing of Aloe vera gel juice. Food Control. 2005; 16: 95-104.

32.     Atherton P. Aloe vera: magic or medicine?. Nurs Stand.1998 ; 41: 49-54.

33.     Vogler B K and Ernst E. Aloe vera: a systematic review of its clinical effectiveness. Br J Gen Pract. 1999; 49 :823-828.

34.     Reynolds T and Dweck AC. Aloe vera leaf gel: a review update. J Ethnopharmacol.1999; 68 : 3-37.

35.     Kaufman T, Kalderon N, Ullman Y and Berger J. Aloe vera gel hindered wound healing of experimental second degree burns: a quantitative controlled study. J. Burn Care Rehabil .1988;9:156-159.

36.     Eshun, K.; He, Q. Aloe vera: A valuable ingredient for the food, pharmaceutical and cosmetic industries – A review. Crit. Rev. Food Sci. Nutr. 2004;44: 91-96.

37.     Vinson J A, Al Kharrat H and Andreoli L. Effect of Aloe vera preparations on the human bioavailability of vitamins C and E. Phytomedicine 2005; 12: 760-765.

38.     Jani, G.K.; Shah, D.P.; Jain, V.C.; Patel, M.J.; Vithalan, D.A. Evaluating mucilage from Aloe Barbadensis Miller as a pharmaceutical excipient for sustained-release matrix tablets. Pharm.Technol. 2007; 31: 90-98.

39.     Gordon MC, David JN. Natural product drug discovery in the next millennium. Pharm Biol 2001;39: 8-17.

40.     Shelton RM. Aloe vera. Its chemical and therapeutic properties. Int J Dermatol, 1991; 30: 679-683.

 

 

Received on 12.11.2011

Modified on 11.12.2011

Accepted on 24.12.2011

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Research Journal of Pharmacognosy  and Phytochemistry. 4(2): March-April  2012, 119-123