Aloe vera

Aloe vera
Aloe vera plant with flower detail inset
Scientific classification
Kingdom:Plantae
Clade:Angiosperms
Clade:Monocots
Order:Asparagales
Family:Asphodelaceae
Subfamily:Asphodeloideae
Genus:Aloe
Species: A. vera
Binomial name
Aloe vera
Synonyms[1][2]
  • Aloe barbadensis Mill.
  • Aloe barbadensis var. chinensis Haw.
  • Aloe chinensis (Haw.) Baker
  • Aloe elongata Murray
  • Aloe flava Pers.
  • Aloe indica Royle
  • Aloe lanzae Tod.
  • Aloe maculata Forssk. (illegitimate)
  • Aloe perfoliata var. vera L.
  • Aloe rubescens DC.
  • Aloe variegata Forssk. (illegitimate)
  • Aloe vera Mill. (illegitimate)
  • Aloe vera var. chinensis (Haw.) A. Berger
  • Aloe vera var. lanzae Baker
  • Aloe vera var. littoralis J.Koenig ex Baker
  • Aloe vulgaris Lam.
Aloe vera - Muséum de Toulouse (MHNT)

Aloe vera (/ˈæloʊiː/ or /ˈæloʊ/) is a succulent plant species of the genus Aloe. An evergreen perennial, it originates from the Arabian Peninsula but grows wild in tropical climates around the world and is cultivated for agricultural and medicinal uses. The species is also used for decorative purposes and grows successfully indoors as a potted plant.[3]

It is found in many consumer products including beverages, skin lotion, cosmetics, or ointments for minor burns and sunburns. There is little scientific evidence of the effectiveness or safety of Aloe vera extracts for either cosmetic or medicinal purposes. Studies finding positive evidence are frequently contradicted by other studies.

Description

Aloe vera is a stemless or very short-stemmed plant growing to 60–100 cm (24–39 in) tall, spreading by offsets. The leaves are thick and fleshy, green to grey-green, with some varieties showing white flecks on their upper and lower stem surfaces.[4] The margin of the leaf is serrated and has small white teeth. The flowers are produced in summer on a spike up to 90 cm (35 in) tall, each flower being pendulous, with a yellow tubular corolla 2–3 cm (0.8–1.2 in) long.[4][5] Like other Aloe species, Aloe vera forms arbuscular mycorrhiza, a symbiosis that allows the plant better access to mineral nutrients in soil.[6]

Aloe vera leaves contain phytochemicals under study for possible bioactivity, such as acetylated mannans, polymannans, anthraquinone C-glycosides, anthrones, other anthraquinones, such as emodin and various lectins.[7][8]

Taxonomy and etymology

Spotted forms of Aloe vera, also named Aloe vera var. chinensis
Historical image of aloe from Acta Eruditorum, 1688

The species has a number of synonyms: A. barbadensis Mill., Aloe indica Royle, Aloe perfoliata L. var. vera and A. vulgaris Lam.[9][10] Common names include Chinese Aloe, Indian Aloe, True Aloe, Barbados Aloe, Burn Aloe, First Aid Plant.[5][11][12][13][14] The species epithet vera means "true" or "genuine".[11] Some literature identifies the white-spotted form of Aloe vera as Aloe vera var. chinensis;[15][16] however, the species varies widely with regard to leaf spots[17] and it has been suggested that the spotted form of Aloe vera may be conspecific with A. massawana.[18] The species was first described by Carl Linnaeus in 1753 as Aloe perfoliata var. vera,[19] and was described again in 1768 by Nicolaas Laurens Burman as Aloe vera in Flora Indica on 6 April and by Philip Miller as Aloe barbadensis some ten days after Burman in the Gardener's Dictionary.[20]

Techniques based on DNA comparison suggest Aloe vera is relatively closely related to Aloe perryi, a species endemic to Yemen.[21] Similar techniques, using chloroplast DNA sequence comparison and ISSR profiling have also suggested it is closely related to Aloe forbesii, Aloe inermis, Aloe scobinifolia, Aloe sinkatana, and Aloe striata.[22] With the exception of the South African species A. striata, these Aloe species are native to Socotra (Yemen), Somalia, and Sudan.[22] The lack of obvious natural populations of the species has led some authors to suggest Aloe vera may be of hybrid origin.[23]

Distribution

A. vera is considered to be native only to the south-west Arabian Peninsula.[24] However, it has been widely cultivated around the world, and has become naturalized in North Africa, as well as Sudan and neighboring countries, along with the Canary Islands, Cape Verde, and Madeira Islands.[9] It is also naturalized in wild areas across southern Spain, especially in the region of Murcia, being the only place in Europe where it has been found naturalized.[25]

The species was introduced to China and various parts of southern Europe in the 17th century.[26] It is widely naturalized elsewhere, occurring in temperate and tropical regions of Australia, South America, Mexico, the Caribbean and southeastern US states.[24][27] The current distribution may be the result of human cultivation.[18][28]

Cultivation

Aloe vera as an ornamental plant

Aloe vera has been widely grown as an ornamental plant. The species is popular with modern gardeners as a putatively medicinal plant and for its interesting flowers, form, and succulence. This succulence enables the species to survive in areas of low natural rainfall, making it ideal for rockeries and other low water-use gardens.[4] The species is hardy in zones 8–11, and is intolerant of heavy frost and snow.[5][29] The species is relatively resistant to most insect pests, though spider mites, mealy bugs, scale insects, and aphid species may cause a decline in plant health.[30][31] This plant has gained the Royal Horticultural Society's Award of Garden Merit.[32]

In pots, the species requires well-drained, sandy potting soil and bright, sunny conditions. Aloe plants can burn under too much sun or shrivel when the pot does not drain water. The use of a good-quality commercial propagation mix or packaged "cacti and succulent mix" is recommended, as they allow good drainage.[33] Terra cotta pots are preferable as they are porous.[33] Potted plants should be allowed to completely dry before rewatering. When potted, aloes can become crowded with "pups" growing from the sides of the "mother plant". Plants that have become crowded should be divided and repotted to allow room for further growth and help prevent pest infestations. During winter, Aloe vera may become dormant, during which little moisture is required. In areas that receive frost or snow, the species is best kept indoors or in heated glasshouses.[5]

There is large-scale agricultural production of Aloe vera in Australia,[34] Bangladesh, Cuba,[35] the Dominican Republic, China, Mexico,[36] India,[37] Jamaica,[38] Spain, where it grows even well inland,[39] Kenya, Tanzania and South Africa,[40] along with the USA[41] to supply the cosmetics industry.

Uses

Research

Although there is little scientific evidence of the effectiveness or safety of Aloe vera extracts for either cosmetic or medicinal purposes, the cosmetic and alternative medicine industries regularly make claims regarding the soothing, moisturizing, and healing properties of aloe vera.[42] There is no good evidence aloe vera is of use in treating wounds or burns,[43] nor that topical application is effective for treating genital herpes or psoriasis.[44] A 2014 Cochrane review found insufficient evidence for using aloe vera topically to treat or prevent phlebitis caused by intravenous infusion.[45]

Aloe vera gel is used commercially as an ingredient in yogurts, beverages, and some desserts,[46] but at certain high doses, its toxic properties could be severe when taken orally.[42][47]

Dietary supplement

Aloin, a compound found in the exudate of some Aloe species, was the common ingredient in over-the-counter (OTC) laxative products in the United States until 2002 when the Food and Drug Administration banned it because the companies manufacturing it failed to provide the necessary safety data.[48][49] Aloe vera has potential toxicity, with side effects occurring at some dose levels both when ingested or applied topically.[42][47] Although toxicity may be less when aloin is removed by processing, Aloe vera that contains aloin in excess amounts may induce side effects.[50]

Aloe vera juice is marketed to support the health of the digestive system, but there is neither scientific evidence nor regulatory approval to support this claim.[51] The extracts and quantities typically used for such purposes appear to be dose-dependent for toxic effects.[47]

Traditional medicine

Aloe vera is used in traditional medicine as a skin treatment. In Ayurvedic medicine it is called kathalai, as are extracts from agave.[52]:196 for aloe:117 for agave Early records of Aloe vera use appear in the Ebers Papyrus from the 16th century BC,[14]:18 and in Dioscorides' De Materia Medica and Pliny the Elder's Natural History – both written in the mid-first century AD.[14]:20 It is also written of in the Juliana Anicia Codex of 512 AD.[46]:9

Commodities

Aloe vera is used on facial tissues where it is promoted as a moisturizer and anti-irritant to reduce chafing of the nose. Cosmetic companies commonly add sap or other derivatives from Aloe vera to products such as makeup, tissues, moisturizers, soaps, sunscreens, incense, shaving cream, or shampoos.[46] A review of academic literature notes that its inclusion in many hygiene products is due to its "moisturizing emollient effect".[8]

Other potential uses for extracts of Aloe vera include the dilution of semen for the artificial fertilization of sheep,[53] as a fresh food preservative,[54] or for water conservation in small farms.[55] It has also been suggested that biofuels could be obtained from Aloe vera seeds.[56]

Toxicity

Under the guidelines of California Proposition 65, orally ingested non-decolorized aloe vera leaf extract has been listed by the OEHHA, along with goldenseal, among "chemicals known to the state to cause cancer or reproductive toxicity".[57]

Use of topical aloe vera is not associated with significant side effects.[48] Oral ingestion of aloe vera, however, is potentially toxic,[42] and may cause abdominal cramps and diarrhea which in turn can decrease the absorption of drugs.[48] IARC studies have found ingested non-decolorized liquid aloe vera[58] is a possible carcinogen when eaten or ingested by humans.[59]

See also

References

  1. ↑ Aloe vera (L.) Burm. f. Tropicos.org
  2. ↑ Aloe vera (L.) Burm.f. is an accepted name . theplantlist.org
  3. ↑ Perkins, Cyndi. "Is Aloe a Tropical Plant?". SFgate.com. Retrieved 13 February 2016.
  4. 1 2 3 Yates A. (2002) Yates Garden Guide. Harper Collins Australia
  5. 1 2 3 4 Random House Australia Botanica's Pocket Gardening Encyclopedia for Australian Gardeners Random House Publishers, Australia
  6. ↑ Gong M, Wang F, Chen Y (2002). "[Study on application of arbuscular-mycorrhizas in growing seedings of Aloe vera]". Zhong Yao Cai (in Chinese). 25 (1): 1–3. PMID 12583231.
  7. ↑ King GK, Yates KM, Greenlee PG, Pierce KR, Ford CR, McAnalley BH, Tizard IR (1995). "The effect of Acemannan Immunostimulant in combination with surgery and radiation therapy on spontaneous canine and feline fibrosarcomas". J Am Anim Hosp Assoc. 31 (5): 439–47. doi:10.5326/15473317-31-5-439. PMID 8542364.
  8. 1 2 Eshun K, He Q (2004). "Aloe vera: a valuable ingredient for the food, pharmaceutical and cosmetic industries--a review". Critical Reviews in Food Science and Nutrition. 44 (2): 91–6. doi:10.1080/10408690490424694. PMID 15116756.
  9. 1 2 "Aloe vera, African flowering plants database". Conservatoire et Jardin botaniques de la Ville de Genève. Retrieved 19 November 2017.
  10. ↑ "Taxon: Aloe vera (L.) Burm. f." Germplasm Resources Information Network, United States Department of Agriculture. Archived from the original on 24 September 2015. Retrieved 16 July 2008.
  11. 1 2 Ombrello, T. "Aloe vera". Archived from the original on 5 July 2008. Retrieved 21 June 2008.
  12. ↑ Liao Z, Chen M, Tan F, Sun X, Tang K (2004). "Microprogagation of endangered Chinese aloe". Plant Cell, Tissue and Organ Culture. 76 (1): 83–86. doi:10.1023/a:1025868515705.
  13. ↑ Jamir TT, Sharma HK, Dolui AK (1999). "Folklore medicinal plants of Nagaland, India". Fitoterapia. 70 (1): 395–401. doi:10.1016/S0367-326X(99)00063-5.
  14. 1 2 3 Barcroft, A. and Myskja, A. (2003) Aloe Vera: Nature's Silent Healer. BAAM, USA. ISBN 0-9545071-0-X
  15. ↑ Wang H, Li F, Wang T, Li J, Li J, Yang X, Li J (2004). "[Determination of aloin content in callus of Aloe vera var. chinensis]". Zhong Yao Cai (in Chinese). 27 (9): 627–8. PMID 15704580.
  16. ↑ Gao W, Xiao P (1997). "[Peroxidase and soluble protein in the leaves of Aloe vera L. var. chinensis (Haw.)Berger]". Zhongguo Zhong Yao Za Zhi (in Chinese). 22 (11): 653–4, 702. PMID 11243179.
  17. ↑ Akinyele BO, Odiyi AC (2007). "Comparative study of the vegetative morphology and the existing taxonomic status of Aloe vera L.". Journal of Plant Sciences. 2 (5): 558–563. doi:10.3923/jps.2007.558.563.
  18. 1 2 Lyons G. "The Definitive Aloe vera, vera?". Huntington Botanic Gardens. Archived from the original on 25 July 2008. Retrieved 11 July 2008.
  19. ↑ Linnaeus, C. (1753). Species plantarum, exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. Vol. 2 pp. [i], 561–1200, [1–30, index], [i, err.]. Holmiae [Stockholm]: Impensis Laurentii Salvii.
  20. ↑ Newton LE (1979). "In defense of the name Aloe vera". The Cactus and Succulent Journal of Great Britain. 41: 29–30.
  21. ↑ Darokar MP, Rai R, Gupta AK, Shasany AK, Rajkumar S, Sunderasan V, Khanuja SP (2003). "Molecular assessment of germplasm diversity in Aloe spp. using RAPD and AFLP analysis". J Med. Arom. Plant Sci. 25 (2): 354–361.
  22. 1 2 Treutlein J, Smith GF, van Wyk BE, Wink W (2003). "Phylogenetic relationships in Asphodelaceae (Alooideae) inferred from chloroplast DNA sequences (rbcl, matK) and from genomic finger-printing (ISSR)". Taxon. 52 (2): 193. doi:10.2307/3647389. JSTOR 3647389.
  23. ↑ Jones WD, Sacamano C. (2000) Landscape Plants for Dry Regions: More Than 600 Species from Around the World. California Bill's Automotive Publishers. USA.
  24. 1 2 "Aloe vera". World Checklist of Selected Plant Families. Royal Botanic Gardens, Kew. Retrieved 19 November 2017.
  25. ↑ "Aloe Vera Cultivation in Murcia".
  26. ↑ Farooqi, A. A. and Sreeramu, B. S. (2001) Cultivation of Medicinal and Aromatic Crops. Orient Longman, India. ISBN 8173712514. p. 25.
  27. ↑ "Aloe vera". Royal Botanic Gardens, Kew. 2016. Retrieved 10 August 2016.
  28. ↑ "Aloe vera (Linnaeus) Burman f., Fl. Indica. 83. 1768." in Flora of North America Vol. 26, p. 411
  29. ↑ "BBC Gardening, Aloe vera". British Broadcasting Corporation. Retrieved 11 July 2008.
  30. ↑ "Pest Alert: Aloe vera aphid Aloephagus myersi Essi". Florida Department of Agriculture and Consumer Services. Archived from the original on 12 June 2008. Retrieved 11 July 2008.
  31. ↑ "Kemper Center for Home Gardening: Aloe vera". Missouri Botanic Gardens, USA. Retrieved 11 July 2008.
  32. ↑ "RHS Plant Selector Aloe vera AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 9 November 2012.
  33. 1 2 Coleby-Williams, J. "Fact Sheet: Aloes". Gardening Australia, Australian Broadcasting Corporation. Archived from the original on 6 July 2008. Retrieved 8 July 2008.
  34. ↑ "Aloe vera producer signs $3m China deal". Australian Broadcasting Corporation. 6 December 2005.
  35. ↑ "More Medicinal Plants Grow in Ciego de Ávila". invasor.cu. Retrieved 25 June 2008.
  36. ↑ "Korea interested in Dominican 'aloe vera'". DominicanToday.com—The Dominican Republic News Source in English. 7 July 2006. Archived from the original on 6 December 2008.
  37. ↑ Varma, Vaibhav (11 December 2005). "India experiments with farming medicinal plants". channelnewsasia.com.
  38. ↑ "Harnessing the potential of our aloe". Jamaica Gleaner, jamaica-gleaner.com. Archived from the original on 24 March 2008. Retrieved 19 July 2008.
  39. ↑ http://sevilla.abc.es/andalucia/cordoba/20150824/sevi-aloe-vera-cordoba-201508232056.html
  40. ↑ Mburu, Solomon (2 August 2007). "Kenya: Imported Gel Hurts Aloe Vera Market". allafrica.com.
  41. ↑ "US Farms, Inc. – A Different Kind of Natural Resource Company". resourceinvestor.com. Archived from the original on 17 September 2008. Retrieved 19 July 2008.
  42. 1 2 3 4 "Aloe". Drugs.com. 18 September 2017. Retrieved 8 September 2018.
  43. ↑ Dat AD, Poon F, Pham KB, Doust J (2012). "Aloe vera for treating acute and chronic wounds". Cochrane Database Syst Rev (Systematic review) (2): CD008762. doi:10.1002/14651858.CD008762.pub2. PMID 22336851.
  44. ↑ Deng S, May BH, Zhang AL, Lu C, Xue CC (2013). "Plant extracts for the topical management of psoriasis: a systematic review and meta-analysis". Br. J. Dermatol. 169 (4): 769–82. doi:10.1111/bjd.12557. PMID 23909714.
  45. ↑ Zheng GH, Yang L, Chen HY, Chu JF, Mei L (2014). "Aloe vera for prevention and treatment of infusion phlebitis". Cochrane Database Syst Rev. John Wiley & Sons. 6 (6): CD009162. doi:10.1002/14651858.CD009162.pub2. PMID 24895299.
  46. 1 2 3 Reynolds, Tom (Ed.) (2004) Aloes: The genus Aloe (Medicinal and Aromatic Plants - Industrial Profiles. CRC Press. ISBN 978-0415306720
  47. 1 2 3 Cosmetic Ingredient Review Expert Panel (2007). "Final Report on the Safety Assessment of Aloe Andongensis Extract, Aloe Andongensis Leaf Juice, Aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice, Aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract" (PDF). Int. J. Toxicol. 26 (Suppl 2): 1–50. doi:10.1080/10915810701351186. PMID 17613130.
  48. 1 2 3 "Aloe Vera : Science and Safety | NCCIH". Nccih.nih.gov. Retrieved 31 January 2014.
  49. ↑ Food Drug Administration, HHS (2002). "Status of certain additional over-the-counter drug category II and III active ingredients. Final rule". Fed Regist. 67 (90): 31125–7. PMID 12001972.
  50. ↑ Bottenberg MM, Wall GC, Harvey RL, Habib S (2007). "Oral aloe vera-induced hepatitis". Ann Pharmacother. 41 (10): 1740–3. doi:10.1345/aph.1K132. PMID 17726067.
  51. ↑ "Aloe (Aloe vera)". MayoClinic.com. 1 September 2012. Retrieved 9 November 2012.
  52. ↑ Quattrocchi, Umberto (2012) CRC World Dictionary of Medicinal and Poisonous Plants: Common Names, Scientific Names, Eponyms, Synonyms, and Etymology (5 Volume Set) CRC Press. ISBN 978-1420080445
  53. ↑ Rodriguez F, Baldassarre H, Simonetti J, Aste F, Ruttle JL (1988). "Cervical versus intrauterine insemination of ewes using fresh or frozen semen diluted with aloe vera gel". Theriogenology. 30 (5): 843–54. doi:10.1016/S0093-691X(88)80046-3. PMID 16726526.
  54. ↑ Serrano M, Valverde JM, Guillén F, Castillo S, Martínez-Romero D, Valero D (2006). "Use of Aloe vera gel coating preserves the functional properties of table grapes". J. Agric. Food Chem. 54 (11): 3882–6. doi:10.1021/jf060168p. PMID 16719510.
  55. ↑ "Water conservation". Chennai, India: The Hindu. 10 July 2008. Archived from the original on 2 August 2008. Retrieved 14 July 2008.
  56. ↑ Shukla, S. "Aloe Vera has biodiesel potential, reveals MSU study". The Indian Express. Archived from the original on 14 January 2009. Retrieved 21 June 2008.
  57. ↑ Proposition 65. Chemicals Listed Effective December 4, 2015, as Known to the State of California to Cause Cancer: Aloe Vera, Non-Decolorized Whole Leaf Extract, and Goldenseal Root Powder. U.S. Office of Environmental Health Hazard Assessment (4 December 2015)
  58. ↑ "Aloe Vera | NCCIH". NCCIH. Retrieved 1 March 2016.
  59. ↑ Preamble in IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. International Agency for Research on Cancer, Lyon, France (2006)

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