Can the peels of eggplant that is usually thrown away provide the novel treatment for skin and liver cancers?
CHUKWUMA MUANYA (Assistant Editor) writes.
Commonly called eggplant, Jews apple or mad apple, Solanum melongena variety aubergine, is an economic flowering plant belonging to the family Solanaceae. It is related to garden egg (Solanum melongena)
Phytochemical analysis showed they are rich in steroidal glycosides, in the form of glycoalkaloids. These compounds are important both ecologically and commercially. Economically, they are used instead of the steroidal sapogenin diosgenin as a raw material for the industrial production of corticoids.
The fruits of eggplant are well known as a vegetable all over the world. Crude alkaloidal fraction isolated from the leaves of S. melongena exhibited significant analgesic effect and some Central Nervous System (CNS) depressant effect.
Several studies have shown that S. melongena fruits are rich in steroidal alkaloids. The eggplant’s peels were reported to possess antioxidant activity as it contains anthocyanin; delphinidine-3- (p-cumaroylrutinoside)- 5-glucoside (nasunin). The anti carcinogenic effect of steroidal alkaloids isolated from other Solanum species was reported.
A study published in the journal Cancer has demonstrated how the peels of eggplant induce selective killing of skin cancer (melanoma cells).
Also, a novel topical natural treatment has surfaced and it has many advantages over the currently used skin cancer therapies. The treatment is a topical cream that contains an eggplant extract called BEC5.
Another study has shown that the peels of the eggplant are also effective in treating cancer of the liver (hepatocellular carcinoma).
The study published in Journal of Carcinogenesis & Mutagenesis is titled “In Vitro and In Vivo Anticancer Activity of the Fruit Peels of Solanum melongena L. against Hepatocellular Carcinoma.”
The researchers from Cairo University, Cairo, Egypt, concluded: “Our findings supported the reuse of such waste products as a new remedy for treating cancer.”
The first study published in the journal Cancer is titled “Dichloroacetate, 2-Deoxyglucose and a Hydroalcoholic Extract from the Skin of the Fruit of Solanum melogena (Aubergine) Induce Selective Anticancer Activity against Melanoma Cells.”
The Spanish researchers from the Department of Pharmacology, Faculty of Pharmacy, University of Seville, Spain, said their results showed that the glycolysis inhibitors 2-deoxyglucose and dichloroacetate induced a marked selective cytotoxicity towards the cancer cell line, which was statistically significant and higher than that induced by conventional skin cancer drugs- oxaliplatin, 5- fluorouracil and etoposide. “The glycolytic inhibitor 3-bromopyruvate did not induce selective cytotoxicity towards the melanoma cells were slightly more vulnerable than non-malignant cells to the cytotoxicity of this drug,” they noted.
According to the Spanish scientists, numerous reports have shown that the glycolysis inhibitors 2-deoxyglucose, dichloroacetate and 3-bromopyruvate have anticancer potential. In fact, 2-deoxyglucose, and dichloroacetate have already entered clinical trials for the treatment of specific cancers. Results support the possible advancement of these two glycolysis inhibitors into clinical trials for the treatment of patients with metastatic melanomas. “In contrast, our data suggest that 3-bromopyruvate does not have potential for the treatment of this type of cancer.”
They concluded: “Finally, we report that an extract from the skin of the fruit of Solanum melongena (aubergine, eggplant), induce selective killing of melanoma cells. UACC -62 melanoma cells and VH- 10 skin non-malignant cells were exposed for 48 hours to an extract obtained from the aubergine skin, to an extract obtained from the rest of the fruit, and to the anticancer drug hydroxyurea; then, cell viability was estimated with the MTT assay.
“Results show that the extract obtained from the aubergine skin induced a marked selectivity towards cancer cell line, which was statistically significant and higher that that induced by anticancer drugs hydrourea and oxaliplatin, 5-fluorouracil and etoposide. The extract obtained from aubergine without skin showed certain selectivity towards the melanoma cell line; however, this activity was not statistically significant and occurred at higher concentrations. Future studies are warranted to determine which constituent (or constituents) is responsible for the selective anticancer activity of the extract obtained from the aubergine skin. Previous reports suggest that delphinidin, identified in the aubergine skin, may play a role in this activity.”
Meanwhile, the Egyptian researchers noted: “The fruit peels’ of Solanum melongena L. which is a common vegetable in Egypt, were investigated for biologically active metabolites in an approach to find any medicinal benefits from such waste products. Methods: The Methanol Extract of the Peels (MEP) was subjected to fractionation and purification for the isolation of its major constituents.
“Identification of the compounds was carried out on the basis of physico-chemical properties and spectral analysis (1H NMR, 13C NMR, COSY and HMBC). The MEP together with the isolated compounds were tested against five human cancer cell lines representing the most common types of cancer in Egypt: colon cancer cell line (HCT116), larynx cancer cell line (HEP2), breast cancer cell line (MCF7), cervix cancer cell line (HELA) and liver cancer cell line (HEPG2). MEP was tested in vivo against the CCl4- induced hepatocelular carcinoma (HCC) in rats at two dose levels (100 and 200 mg/kg.b.wt).
“Five steroidal compounds; three steroidal alkaloids: solasodine (S1), solamargine (S4) and solasonine (S5) together with two steroidal glycosides: β-sitosterol-3-O- β-D-glucoside (S2) and poriferasterol-3-O- β-D-glucoside (S3) were isolated. The MEP and the five isolated compounds exhibited moderate to potent activities against the tested human cancer cell lines however their pronounced activity was revealed against HEPG2, accordingly, MEP was tested in vivo against the CCl4- induced Hepatocelular Carcinoma (HCC) in rats.
“The MEP showed a dose dependent anticancer activity through stabilization of the hepato-cells revealed by reduction in α-fitorotein (AFP) (which could considered as tumor marker), it also restored the levels of AST, ALT and albumin in a dose dependent manner. Histopathology of liver tissues treated with MEP strongly supported our results.”
Meanwhile, BEC5 consists of the antineoplastic compounds solasodine, rhamnosyl glycosides, solamargine and solasonine, which are derived from the eggplant and are very effective for treating nonmelanoma skin cancers. Advantages of treatment of these lesions with BEC5 compared with well-established surgical interventions and other therapies have been reported in the scientific literature.
The treatment time period with topical BEC5 to completely eliminate skin cancers varies from days to months depending on size and type of the skin tumors. Large nonmelanoma skin cancers can successfully be treated with BEC5 but it may take several months of treatment to eliminate these large tumours.
Unlike established antimitotic drugs, BEC is not antimitotic in its actions. BEC induces apoptosis (planned self-destruction of cells) in cancer cells by up-regulating the expressions of external death receptors. BEC also triggers extrinsic and intrinsic apoptotic pathways in cancer cells.
Solamargine, the main component of BEC, also kills cancer cells by oncosis. After interaction of solamargine with cancer cells, marked changes in cell shape and volume occur. The cells get blebs (bulges or protrusions) on the membrane, the mitochondria swell, the contents of the nuclei clump and the cells die. It has been proposed that apoptosis and oncosis share certain mechanisms and alterations within the cell before they die by bursting. At low concentrations, solamargine kills cancer cells by apoptosis and at higher doses; solamargine kills cancer cells by oncosis. Both types of cell death are induced by intermediate concentrations of solamargine. Thus, the beauty of BEC is that it penetrates and kills cancer cells but does not penetrate normal cells. Normal cells are untouched and unhurt while the cancer cells die.
It has recently been shown that, in addition to causing apoptosis in cancer cells, intralesion administration of BEC also stimulates lasting immunity against cancer.
BEC has also shown in a clinical study done with 78 patients to cure actinic keratosis that can advance to squamous cell carcinoma, which in turn is associated with a risk of metastasis. In this study, 92 per cent of the patients had complete clearance after treatment and had 82 per cent clearance after one year.
In conclusion, for individuals with skin cancer, BEC could be a very viable alternative to current cancer treatments, especially considering its safety and efficacy.
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