In vitro investigation of the mutagenic potential of Aloe vera extracts

The absence of genotoxicity of Aloe vera beverages: A review of the literature

Aloe has a long history of topical and systemic use with testimonials of countless health benefits and is one of the most popular botanical medicines in the world for the management of a wide variety both of benign and serious ailments including irritable bowel syndromes, osteoarthritis, Type II diabetes mellitus, and viral respiratory illness. The human consumption of Aloe vera extract in beverage form has substantially grown over the last several decades, in no small part, due to the increased consumer interest in alternative approaches to health benefits. The principal aim of the present paper is to characterize the research to date that has explored the genotoxic potential of Aloe vera inner leaf gel extract and decolorized whole leaf extract used in commercially available food-grade drinkable products which contain no more than 10 ppm aloin. Despite prevailing public health opinion, especially in Europe, the consensus of the reviewed studies retrieved from the peer-reviewed literature together with a mutagenic evaluation of an Aloe vera whole leaf decolorized spray-dried powder is that these products are not genotoxic.

Development of an LC-DAD-MS-Based Method for the Analysis of Hydroxyanthracene Derivatives in Food Supplements and Plant Materials

Products based on plants containing hydroxyanthracene derivatives (HADs)—such as Rheum, Cassia, and Aloe species—are widely used in food supplements or nutraceuticals due to their laxative effects. A more restricted control of HAD contents in food supplements has been implemented by EU Regulation 2021/468, in order to increase the safety of these preparations. Due to their toxicity, aloin A, aloin B, aloe emodin, emodin, and the synthetic derivative danthron have been listed as prohibited substances in food supplements, being tolerated in amounts < 1 mg kg−1 in marketed products. In this work, we report the development of a sensitive and fast LC−DAD−MS-based procedure for the determination of these five compounds in food supplements and plant materials or extracts. The entire procedure includes a simple sample preparation step, where target analytes are concentrated by means of solvent extraction and evaporative concentration (solid samples), or by lyophilisation (liquid samples). The average LOQ of 0.10 mg/L, LOD of 0.03 mg/L, accuracy, and precision with CVs below 12.72 were obtained for the studied analytes. This method is suitable for assessing the compliance of commercial products and raw materials with EU Regulation 2021/468. Furthermore, the proposed method can represent a starting point for the development of a unique and standardised analytical approach for the determination of other HADs under the attention of EU authorities.

The dark side of miracle plant-Aloe vera: a review

BACKGROUND

Aloe vera (Aloe barbadensis Miller), commonly known as Ghritkumari/Gwarpatha, is a member of the Liliaceae family, used in the traditional medicine system for ages. Aloe vera has made its importance as a therapeutic agent, acting as a cure for various diseases such as skin problems, lungs, and heart disorders, diabetes, ulcers, various microbial infections, and asthma. Despite its tremendous health benefits, the dark side of the plant is a reason of concern as there are several active compounds present in the plant, raising questions on its safe oral consumption and application.

METHODS AND RESULTS

The literature review was compiled from information resourced from various national and international journals available at Google Scholar and curated with Mendeley. The data mining was carried out during the period of January to May 2021. This study explored and summarized the dark side of Aloe vera, subjected to various secondary metabolites present in it. Aloin, the most active compound of Aloe vera, is a type of anthraquinone metabolized by human gut microflora, resulting in the formation of aloe-emodin anthraquinone, later being associated with several harmful effects such as carcinogenicity, genotoxicity, nephrotoxicity, and purgative. Besides this, several alkaloids and polysaccharides present in the plant are reported to cause hepatotoxicity and male infertility, respectively.

CONCLUSIONS

The harmful effects of the plants are not adequately discovered yet; hence there is a need to come up with some mechanism to understand and suppress the formation of such toxic compounds completely. This review examined the botany, active compounds, and adverse clinical effects in the range of metabolites associated with this herb - "Aloe vera".

Absence of genotoxicity of purified Aloe vera whole leaf dry juice as assessed by an in vitro mouse lymphoma tk assay and an in vivo comet assay in male F344 rats

Hydroxyanthracene derivatives (HAD) are naturally present in the latex layer of Aloe vera leaf, predominantly as aloins A, B and aloe-emodin. HAD are typically removed from commercial ingestible aloe products through activated charcoal filtration (decolorization). Current research aimed to evaluate genotoxic potential of a purified aloe whole leaf dry juice containing 0.3 ppm of total aloins and non-detectable aloe-emodin (LOD =0.01 ppm) in the L5178Y mouse lymphoma assay (MLA; OECD 490) and in vivo comet assay (OECD 489). No marked increases in mutant frequency at the tk locus were observed in the MLA at concentrations up to 5000 μg/mL for 3 h and 24 h (-S9), and up to a precipitating concentration of 3000 μg/mL for 3 h (+S9) compared to concurrent vehicle control. Relative total growth at the highest analyzable concentrations at 3 h (±S9) and 24 h (-S9) ranged from 64 to 133 %. In the comet assay, no statistically significant increases in DNA strand breaks were detected in the colon or kidney following oral gavage of 500, 1000 or 2000 mg/kg/day in male F344 rats for 2 days compared to concurrent vehicle control. Overall, these findings demonstrated the test article containing minimal HAD is not genotoxic under the described experimental conditions.

Detection of Loss of Heterozygosity in Tk-Deficient Mutants from L5178Y Tk+/--3.7.2C Mouse Lymphoma Cells

The mouse lymphoma assay (MLA), a forward mutation assay using the Tk^+/--3.7.2C clone of the L5178Y mouse lymphoma cell line and the Thymidine kinase (Tk) gene, has been widely used as an in vitro genetic toxicity assay for more than four decades. The MLA can evaluate the ability of mutagens to induce a wide range of genetic events including both gene mutations and chromosomal mutations and has been recommended as one component of several genotoxicity test batteries. Tk-deficient mutants often exhibit chromosomal abnormalities involving the distal end of chromosome 11 where the Tk gene is located, in mice, and the type of chromosome alteration can be analyzed using a loss of heterozygosity (LOH) approach. LOH has been considered an important event in human tumorigenesis and can result from any of the following several mechanisms: large deletions, mitotic recombination, and chromosome loss. In this chapter, the authors describe the procedures for the detection of LOH in the Tk mutants from the MLA, and apply LOH analysis for understanding the types of genetic damage that is induced by individual chemicals.

Aloe veraat the frontier of glycobiology and integrative medicine: Health implications of an ancient plant

Aloe vera plant extracts are ubiquitous in foods, cosmetics, and medicine. Like all plants, these extracts contain an array of potential bioactives or glycans, which may contribute to health when applied or consumed. In the Aloe vera plant, these bioactives are dominated by acemannan, a type of carbohydrate, and related complexes of saccharides, proteins, and lipids. Clinical data suggest aloe extracts may be beneficial in the management of cutaneous and some systemic conditions, such as some forms of immune dysfunction, atherogenesis, malignancy, and numerous cell functions. These extracts also contain an entourage of bioactive substances that may be allergenic and potentially toxic as well as salutary. These substances include aloin and a variety of anthracenes. The concentrations of potential allergens, aloin, and related compounds are markedly reduced through controlled decolorization processes that are utilized by leading Aloe products manufacturers. The entourage effects of contemporary Aloe vera when consumed or applied topically represent opportunities for clinical investigation which may be applied to commercial consumer products and therapeutic indications. Future research should fully explore the range of bioactive glycan components and their respective safety and efficacy. The history and ongoing popularity of Aloe vera products represent a pragmatic mandate for well-designed investigation into the diverse functional roles of glycans.

Safety of hydroxyanthracene derivatives for use in food

The Panel on Food Additives and Nutrient Sources added to Food (ANS) was asked to deliver a scientific opinion on the safety of hydroxyanthracene derivatives and to provide advice on a daily intake that does not give rise to concerns about harmful effects to health. Hydroxyanthracene derivatives are a class of chemical substances naturally occurring in different botanical species and used in food to improve bowel function. The ANS Panel reviewed the available scientific data on a possible relationship between hydroxyanthracene derivatives exposure and genotoxic and carcinogenic effects. On the basis of the data currently available, the Panel noted that emodin, aloe-emodin and the structurally related substance danthron have shown evidence of in vitro genotoxicity. Aloe extracts have also been shown to be genotoxic in vitro possibly due to the presence of hydroxyanthracene derivatives in the extract. Furthermore, aloe-emodin was shown to be genotoxic in vivo and the whole-leaf aloe extract and the structural analogue danthron were shown to be carcinogenic. Epidemiological data suggested an increased risk for colorectal cancer associated with the general use of laxatives, several of which contain hydroxyanthracene derivatives. Considering the possible presence of aloe-emodin and emodin in extracts, the Panel concluded that hydroxyanthracene derivatives should be considered as genotoxic and carcinogenic unless there are specific data to the contrary, such as for rhein, and that there is a safety concern for extracts containing hydroxyanthracene derivatives although uncertainty persists. The Panel was unable to provide advice on a daily intake of hydroxyanthracene derivatives that does not give rise to concerns about harmful effects to health.

Aloe vera: A review of toxicity and adverse clinical effects

The Aloe plant is employed as a dietary supplement in a variety of foods and as an ingredient in cosmetic products. The widespread human exposure and its potential toxic and carcinogenic activities raise safety concerns. Chemical analysis reveals that the Aloe plant contains various polysaccharides and phenolic chemicals, notably anthraquinones. Ingestion of Aloe preparations is associated with diarrhea, hypokalemia, pseudomelanosis coli, kidney failure, as well as phototoxicity and hypersensitive reactions. Recently, Aloe vera whole leaf extract showed clear evidence of carcinogenic activity in rats, and was classified by the International Agency for Research on Cancer as a possible human carcinogen (Group 2B). This review presents updated information on the toxicological effects, including the cytotoxicity, genotoxicity, carcinogenicity, and adverse clinical effects of Aloe vera whole leaf extract, gel, and latex.

Simultaneous encapsulation and stabilization of Aloe vera extract on cotton fabric for wound dressing application

Utilization of some herbal products in wound dressing for rapid healing with no side effects is a highly interesting task.