Elsevier

Journal of Ethnopharmacology

Volume 102, Issue 2, 14 November 2005, Pages 197-201
Journal of Ethnopharmacology

Assessment of Aloe vera (L.) genotoxic potential on Escherichia coli and plasmid DNA

https://doi.org/10.1016/j.jep.2005.06.013Get rights and content

Abstract

Aloe vera is a tropical plant, known in Brazil as babosa and several reputable suppliers produce a stabilized aloe gel for topic use. Since people use Aloe vera topically, they could be exposed to solar ultraviolet light in addition and it might cause a cross damage effect between these agents. The aim of this work was to investigate the biological effects of Aloe vera pulp extract, associated or not to UVA radiation, on Escherichia coli-deficient repair mutants and plasmid DNA, in order to test its genotoxic potential. Data obtained from analysis of survival fractions, bacterial transformation and agarose gel electrophoresis suggest that Aloe vera has genotoxic properties, but it seems not to be able to damage the cell membrane.

Introduction

The use of phytotherapeutic products by the world population has greatly increased in the last decades (Briskin, 2000, Ang-Lee et al., 2001, Chan, 2003). As they used to be generally classified as “natural”, these products are considered to be harmless. However, several studies show that many of those products present undesirable action when ingested or applied on the skin (Joshi and Kaul, 2001, Chan, 2003, Gilbert and Alves, 2003).

The Aloe vera (L.) Burm.f., popularly known in Brazil as babosa, is a tropical or sub-tropical plant from North Africa, with turgid lace-shaped green leaves with jagged edges and sharp points (Okiar et al., 2001). The plant is a member of the lily family (Liliaceae), not the cactus family, as many would believe from the rosette-like arrangement of the long, spiked leaves on the central stem (Grindlay and Reynolds, 1986). Historically, Muslims considered it as a sacred plant, which could keep malignant influences away from home (Zeilmann et al., 2003). There are over 300 species of Aloe known, but Aloe vera L. is recognized as the “true Aloe vera” for its widespread use and purported healing powers.

It has been demonstrated that a large part of the pharmacological activity of this plant is due to polysaccharides, which makes up the majority of the mucilaginous Aloe vera gel (t’Hart et al., 1989). Furthermore, the refined polysaccharide has been shown to act as an immunostimulant, displaying adjuvant activity on specific antibody production (t’Hart et al., 1989) and enhancing the release of interleukin-1, interleukin-6, tumor necrosis factor-a and interferon-c (Peng et al., 1991). Release of these cytokines stimulates an increase in the replication of fibroblasts in tissue culture and proliferation of fibroblasts is known to be responsible for healing burns, ulcers and other wounds of the skin and gastrointestinal lining (Kahlon et al., 1991, Yates et al., 1992).

People use the Aloe vera orally or topically and the latter is believed to promote cellular regeneration (Yagi et al., 2002), healing of burns (Somboonwong et al., 2000), act in dermatitis, skin irritation after shaving and after exposure to the sun, flabbiness, scalp irritations, fungi infections and hair loss (Choi et al., 2001). By acting in this way, it is frequently added to soap, toilet paper, shampoo, conditioning and moisturizing creams (Reynolds and Dweck, 1999). Besides, the aloe extract is indicated for patients submitted to radiotherapy treatment to minimize the burn and skin lesions induced by this kind of procedure (Olsen et al., 2001). In spite of its wide pharmaceutical use, there are few data on aloe toxicity.

Sunlight has many components, including the near ultraviolet (near-UV) light, which is in the range between 290 and 400 nm, reaching the earth's surface. This radiation can be divided in UVA (320–400 nm) and UVB (290–320 nm). In this study, UVA (365 nm) was used, as the most abundant solar UV component that reaches the surface of our planet (Kuluncsics et al., 1999). Near-UV can produce lesions in different cell structures, for instance, enzymes, DNA and cellular membranes, with the participation of endogen sensibilizators (Peak, 1970). In Escherichia coli, the generation of this kind of damage only occurs in aerobic conditions, contributing to the induction of SOS response (Favre et al., 1986), conferring to it a mutagenic potentiality (Caldeira-de-Araújo and Favre, 1986). In sub-letal doses, below 200 kJ/m2, the UVA is capable to induce, in Escherichia coli, a temporary blockage in growth and cellular division (Favre et al., 1985).

Since Aloe vera is a tropical plant, it receives much UVA radiation from sunlight. Also, its extract has a wide spread topical use, leading people to expose themselves to sunlight, with residual extract on the body.

Thus, the aim of this work was to evaluate the toxicity of Aloe vera extract, either alone or associated with UVA radiation.

Section snippets

Preparation of Aloe vera extract

Aloe vera (babosa) leaves were collected and processed from a single garden plant, to obtain a fresh extract for each experiment during this work. The extract was prepared by using 3 g from the vegetable leaf pulp, mixing it with 5 mL of 0.9% NaCl solution in order to carry out the bacterial inactivation assays or solved in the same volume of Milli-Q water (Millipore Corp., Bedford, MA, USA), to proceed to DNA electrophoresis and bacterial transformation experiments. The solution was then

Results and discussion

The ability of Aloe vera to decrease Escherichia coli survival was first evaluated and, as it can be seen in Fig. 1, panels A–D, the Aloe vera extract was not capable of inducing Escherichia coli inactivation, in a significant way, in all strains tested, neither alone nor associated with a sub-lethal dose of UVA. These results pointed either to a Aloe vera absence of cytotoxic activity or to a lack of its entry into the cells.

In order to better understand this point, transformation efficiency

Conclusion

From the experiments, we can conclude that Aloe vera has no cytotoxicity, whether associated or not with UVA, in the conditions tested, because the values encountered in all the mutants were similar and near the control level. However, it has a genotoxic action, mainly at high concentrations, as shown in the results of transformation and electrophoresis. The transformation assays also shows that the cellular mechanisms most effective against lesions induced by Aloe vera seem to be base excision

Acknowledgements

This work was supported by CNPq, FAPERJ and UERJ

References (28)

  • K.M. Yates et al.

    Pilot study of the effect of acemannan in cats infected with feline immunodeficiency virus

    Veterinary Immunology and Immunopathology

    (1992)
  • M.K. Ang-Lee et al.

    Herbal medicines and perioperative care

    The Journal of the American Medical Association

    (2001)
  • D.P. Briskin

    Medicinal plants and phytomedicines

    Plant Physiology

    (2000)
  • A. Caldeira-de-Araújo et al.

    Near ultraviolet DNA damage induces the SOS response in E. coli

    The EMBO Journal

    (1986)
  • Cited by (34)

    • Herbal Remedies

      2023, Haschek and Rousseaux's Handbook of Toxicologic Pathology, Volume 3: Environmental Toxicologic Pathology and Major Toxicant Classes
    • The chemical composition of different leaf extracts of Lantana fucata Lindl. influences its cytotoxic potential: A study using the Allium cepa model

      2022, Journal of Ethnopharmacology
      Citation Excerpt :

      Undeniably, medicinal plants and herbal medicines play an important role in therapy: about 25% of the drugs prescribed worldwide are of vegetable origin (Ghislane and Aziz, 2016). Despite being a rich source of useful chemical compounds with different pharmacological benefits on biological systems (Butler, 2004; Khumalo et al., 2022; Moshi et al., 2009) some plants have been shown to be potentially toxic (Akinboro and Bakare, 2007; Effraim et al., 2001; Gadano et al., 2002, 2006; Moody et al., 1999; Paes-Leme et al., 2005; Teixeira et al., 2003). In addition, there are some toxicity problems associated to medicinal plants, such as allergic reactions, gastrointestinal irritation, haemolysis, organ damage and carcinogenicity have been reported. (

    • Pretreatment of red palm oil extracted from palm fruit (Elaeis guineensis) attenuates carbon tetrachloride induced toxicity in Wistar rats

      2021, Phytomedicine Plus
      Citation Excerpt :

      In addition, hepatorenal systems are the key targets for toxicants since they are actively involved in biotransformation, excretion and metabolism of xenobiotics. Today, hepatic and renal disruptions have been linked to medicinal plants used in the treatment of multifactorial diseases (Paes-Leme et al., 2005; Mapanga and Musabayane, 2010). In traditional medicine practices, red palm oil can be given to an individual who is suspected to have ingested poison (Owoyele and Owolabi, 2014).

    • Genotoxicity evaluation of nutraceuticals

      2021, Nutraceuticals: Efficacy, Safety and Toxicity
    • Assessment of Genotoxic Effects of Selected Herbal Dietary Supplements

      2016, Nutraceuticals: Efficacy, Safety and Toxicity
    View all citing articles on Scopus
    View full text