Chemopreventive potential of Aloe vera against 7,12-dimethylbenz(a)anthracene induced skin papillomagenesis in mice

Traditionally Used Natural Products in Preventing Ionizing Radiation-Induced Dermatitis: First Review on the Clinical Studies

In the treatment of cancer, the use of ionizing radiation is an important modality. However, on the downside, radiation, when used for curative purposes, causes acute dermatitis or radiodermatitis at the site of radiation in most individuals. From a clinical viewpoint, severe dermatitis causes a burning and itching sensation is very painful, and severely affects the quality of life of the individual undergoing treatment. In worse situations, acute radiation dermatitis can cause gaps or breaks in the planned treatment and this can adversely affect the treatment objective and outcome.

BACKGROUND

In various traditional and folk systems of medicine, plants and plant products have been used since time immemorial for treating various skin ailments. Further, many cosmeceutical creams formulated based on knowledge from ethnomedicinal use are marketed and used to treat various ailments. In the current review, an attempt is made at summarizing the beneficial effects of some plants and plant products in mitigating acute radiation dermatitis in humans undergoing curative radiotherapy. Additionally, the emphasis is also placed on the mechanism/s responsible for the beneficial effects.

OBJECTIVE

The objective of this review is to summarize the clinical observations on the prevention of radiodermatitis by plant products. In this review, the protective effects of Adlay (Coix lachryma-jobi L.) bran extract, Aloe vera, Calendula officinalis, Cucumis sativus, green tea constituent the epigallocatechin-3-gallate, honey, Achillea millefolium, Matricaria chamomilla, olive oil and some polyherbal creams are addressed by also addressing on the mechanism of action for the beneficial effects.

METHODS

Two authors' data mined for information in Google Scholar, PubMed, Embase and the Cochrane Library for publications in the field from 1901 up to July 2020. The focus was on acute radiation dermatitis, ionizing radiation, curative radiotherapy, human cancer. The articles were collected and analyzed.

RESULTS

For the first time, this review addresses the usefulness of natural products like adlay bran, Aloe vera, Calendula officinalis, Cucumis sativus, green tea constituent the epigallocatechin-3-gallate, honey, Achillea millefolium, Matricaria chamomilla, olive oil and some experimentally constituted and commercially available polyherbal creams as skincare agents against the deleterious effects of ionizing radiation on the skin. The protective effects are possibly due to the free radical scavenging, antioxidant, anti-inflammatory, wound healing and skin protective effects.

CONCLUSION

The authors suggest that these plants have been used since antiquity as medicinal agents and require in-depth investigation with both clinical and preclinical validated models of study. The results of these studies will be extremely useful to cancer patients requiring curative radiotherapy, the dermatology fraternity, agro-based and pharmaceutical sectors at large.

Treatment of Skin Disorders with Aloe Materials

The skin is the largest organ and functions as a barrier to protect the underlying tissues against the elements and pathogens, while also fulfilling many physiological roles and biochemical functions such as preventing excessive water loss. Skin disorders vary greatly in terms of origin, severity, symptoms and affect persons of all ages. Many plants have been used for medicinal purposes since ancient times including the treatment of skin disorders and diseases. Aloe represents one of the earliest medicinal plant species mentioned in antique scriptures and even in rock art dating back thousands of years. Different Aloe species and materials have been used in the prevention and treatment of skin related disorders. Aloe vera is the most commonly used Aloe species for medicinal purposes. Some of the most prominent skin related applications and disorders that Aloe materials have been investigated for are discussed in this paper, which include cosmetic, radiation, cancer, wound and antimicrobial applications. Both in vitro and in vivo studies are included in the discussions of this paper and comprehensive summaries of all these studies are given in tables in each section. Although some contradictory results were obtained among studies, certain Aloe materials have shown excellent efficacy and exhibited potential for the treatment of skin related disorders and cosmetic applications.

Pre-Exposure to Chronic Unpredictable Stress Suppresses the Chemopreventive Potential of Aloe Vera (Av) Leaf Gel Against 7,12-Dimethylbenz(a)anthracene (DMBA) Induced Carcinogenesis

The present study evaluates the topical application of aloe vera (Av) leaf gel as a protective natural product against 7,12-dimethylbenz(a)anthracene (DMBA)-induced skin lesions in Swiss albino mice and as an antioxidant for the systemic toxicity of DMBA in the presence and absence of chronic unpredictable stress (CUS). Animals were randomized into seven groups and sacrificed after 16 weeks of treatment. Av gel application along with DMBA + 12-O-tetradecanoylphorbol-13-acetate (TPA) was found to be effective in reducing tumor incidence, cumulative number of papillomas, tumor burden and tumor yield when compared to untreated groups. Furthermore, topical treatment with Av gel significantly increased the overall in vivo antioxidant status of mice. Conversely, lipid peroxidation levels were significantly decreased in skin and circulation. However, pre-exposure to CUS followed by DMBA + TPA + Av gel application reduced the chemopreventive efficacy of Av gel as evidenced by increased tumor incidence, tumor burden, tumor yield and MDA levels accompanied by decrease in the enzymatic and nonenzymatic antioxidants. These observations were further supported by the results of fluorescent studies and comet assay. The study demonstrates a reduction in the antioxidant and antitumor potential of Av gel in presence of CUS thereby, signifying the need of stress reduction during cancer chemopreventive trials.

An Aloe Vera-Based Cosmeceutical Cream Delays and Mitigates Ionizing Radiation-Induced Dermatitis in Head and Neck Cancer Patients Undergoing Curative Radiotherapy: A Clinical Study

Background: This study was planned to evaluate the efficacy of topical application of an Aloe vera-based cream (AVC) for the prevention of ionizing radiation (X ray)-induced dermatitis in head and neck cancer patients requiring therapeutic radiation treatment (>62 Gy). Methods: From July 2012 to December 2012, a total of 60 head and neck cancer patients requiring curative radiotherapy (RT) of more than 66 Gy were prospectively enrolled and treated with AVC or a comparator Johnson’s Baby Oil (JBO). Acute skin reaction was monitored and classified according to the Radiation Therapy Oncology Group (RTOG) four-point rating scale on a weekly basis. Results: The results indicate that there was a statistically significant delay in the incidence (p = 0.04) of dermatitis at week three in the AVC application group. Application of AVC reduced the incidence of Grade 1, 2, and 3 dermatitis at subsequent time points, while Grade 4 dermatitis was not seen in either cohort. The other most important observation was that the continued application of AVC two weeks after the completion of RT was effective in reducing the average grade of dermatitis and was statistically significant (p < 0.02). Conclusions: Prophylactic use of an AVC-based cream is thus effective in delaying radiation dermatitis in head and neck cancer.

Ethnobotanical survey of usage of fresh medicinal plants in Singapore

ETHNOPHARMACOLOGICAL RELEVANCE

The use of medicinal plants in human health has been documented since ancient times and they provide a useful source of new therapeutics. In Singapore, despite the accessibility to modern healthcare, there still exist pockets of the population who choose to use locally grown fresh medicinal plants for health promotion and even therapeutic purposes. However to date, there is no published report of first-hand account of their usage in Singapore. As land is scarce and rapidly used for re-development, such important knowledge may be lost if not properly documented in time. This work safeguards the local folk knowledge, and provides information on common and scarcely reported fresh medicinal plants. The objective of this study is to gather information regarding the usage of fresh medicinal plants in Singapore through face-to-face interviews.

MATERIALS AND METHODS

Information on demographic data and plant-use methods were collated via face-to-face interviews of 200 fresh medicinal plant users who have used fresh medicinal plants in the last five years. The survey protocol was approved by the National University of Singapore Institutional Review Board and informed consent was obtained from every participant.

RESULTS

A total of 414 plants represented by 104 plant species from 44 families were reportedly used by the 200 participants. The five most commonly used plants were Clinacanthus nutans (34 users), Strobilanthes crispus (31 users), Pereskia bleo (25 users), Aloe vera (18 users) and Zingiber officinale (16 users). Leaves were the most commonly used plant part while preparing a decoction was the most common method of preparation. The majority of interviewees used plants for general health purposes and to treat diseases related to the respiratory system and cancer.

CONCLUSIONS

Our survey has successfully documented the rich wealth of traditional usage and knowledge on 414 fresh medicinal plants grown in Singapore through face-to-face interviews with 200 users. This study will serve as a useful resource for identifying promising plants for future drug discovery efforts. Scientific evaluations of these medicinal plants are warranted and should be carried out.

Chemopreventive effects of aloin against 1,2-dimethylhydrazine-induced preneoplastic lesions in the colon of Wistar rats

Chemoprevention opens new window in the prevention of all types of cancers including colon cancer. Aloin, an anthracycline in plant pigment, can be utilized as a protective agent in cancer induction. In the present study, we have evaluated the chemopreventive efficacy of aloin against 1,2-dimethylhydrazine (DMH)-induced preneoplastic lesions in the colon of Wistar rats. DMH-induced aberrant crypt foci (ACF) and mucin-depleted foci (MDF) have been used as biomarkers of colon cancer. Efficacy of aloin against the colon toxicity was evaluated in terms of biochemical estimation of antioxidant enzyme activities, lipid peroxidation, ACF, MDF, histopathological changes, and expression levels of molecular markers of inflammation and tumor promotion. Aloin pretreatment ameliorates the damaging effects induced by DMH through a protective mechanism that involved reduction in increased oxidative stress enzymes (p < 0.001), ACF, MDF, cyclooxygenase-2, inducible nitric oxide synthase, interleukin-6, proliferating cell nuclear antigen protein expression, and tumor necrosis factor-α (p < 0.001) release. From the results, it could be concluded that aloin clearly protects against chemically induced colon toxicity and acts reasonably by inducing antioxidant level, anti-inflammatory and antiproliferative markers.

Implications for degenerative disorders: antioxidative activity, total phenols, flavonoids, ascorbic acid, beta-carotene and beta-tocopherol in Aloe vera

In order to demonstrate whether the known biological effects of Aloe vera (L.) Burm. fil. could correlate with the antioxidant activity of the plant, the antioxidant activity of the aqueous leaf extract was investigated. The present study demonstrated that the aqueous extract from A. vera leaves contained naturally occuring antioxidant components, including total phenols, flavonoids, ascorbic acid, beta-carotene and alpha-tocopherol. The extract exhibited inhibitory capacity against Fe(3+)/ascorbic acid induced phosphatidylcholine liposome oxidation, scavenged stable DPPH(*), ABTS(*+) and superoxide anion radicals, and acted as reductant. In contrast, the leaf inner gel did not show any antioxidant activity. It was concluded that the known beneficial effects of Aloe vera could be attributed to its antioxidant activity and could be related to the presence of phenolic compounds and antioxidant vitamins.