Garlic: There’s more to this regularly used kitchen condiment than meets the eye, and we are not just talking about its pungent spicy flavor that is adored in cuisine. Aside from keeping evil spirits at bay, or so the myth says, the garlic brags thousands of years of traditional medicinal use – dating back to the Sumerians who employed its healing qualities, ancient China (since 2700 BC) where it was regarded as a heating and stimulating agent, and ancient India as a tonic that can remedy conditions such as lack of appetite, weakness, cough, skin disease, and rheumatism. Garlic has even been found in Egyptian pyramids and ancient Greek temples, with notable references to it in the Bible.
The Medicinal Wonders of Garlic
A bulb of garlic, as validated by several research studies, embodies a “pharmacy” in itself due to the numerous health-promoting effects it confers and a wide range of applications. For instance, garlic has been reported to reduce the risk for cardiovascular diseases, with important effects such as reduction of blood pressure, prevention of atherosclerosis, decrease in serum cholesterol and triglyceride, and inhibition of platelet aggregation, among others. Several studies had also claimed garlic’s efficacy in lowering blood glucose levels in diabetic animals and protecting liver cells against some drug toxicities, particularly those of acetaminophen and gentamycin. According to in vitro studies, garlic has also antibiotic, antibacterial, and antifungal properties.
Garlic and Cancer
There’s a reason why garlic has remained for centuries as an important plant in medicine: a wide variety of biologically active chemical compounds have been isolated and identified in this seasoning, and almost all of them have been proven by research to help prevent and/or treat a number diseases, including different types of human cancers . Epidemiological observations and laboratory studies using cell culture and animal models have pointed out the potential of garlic and its constituents to hinder tumor growth and development.
Garlic predominantly owes its medicinal properties from the organosulfur compounds it contains, largely allyl derivatives. These compounds have been demonstrated in studies to prevent the process of tumor development in the stomach, esophagus, colon, mammary glands, and lungs of experimental animals . Garlic contains three vital sulfur compounds, namely, allicin, ajoene (4, 5, 9-trithiadodeca-1, 6, 11-triene-9-oxide), and alliin, as well as other compounds such as α-phellandrene, β-phellandrene, citral, linalool, and geraniol . Upon tissue damage in garlic, allicin is produced from alliin (S-allylcysteine sulfoxide) through a catalysis reaction that involves the enzyme alliinase. In mammals, and hence humans, allicin has been shown to trigger death of cancer cells and to inhibit their proliferation and lowers cholesterol and blood pressure levels.
The cancer-preventive power of garlic has also been credited to its ability to regulate metabolizing enzymes that either activate or detoxify carcinogens through cytochrome P450s or glutathione S-transferases, respectively, and to exert antioxidative and free radical scavenging properties . Other mechanisms that have been purported to elucidate the cancer-preventive activities of garlic-derived products take account of the inhibition of the formation of the DNA adduct (or the DNA segment bound to a cancer-causing chemical) and the modulation of cancer cell proliferation, apoptosis, and immune responses.
Garlic and Brain Cancer
When brain tumors occur, malignant cancer cells start to grow and spread in the tissues of the brain, affecting the brain’s functions such as memory, learning, and senses. Tumors located in the central nervous system are notorious for being a difficult-to-treat cause of mental impairment or death at several occasions .
Glucocorticoids are among the frequently used treatment that serves to beneficially reduce the edema and swelling associated with brain cancer in patients. They have been demonstrated as well to diminish tumor-related pain, control nausea and vomiting, and enhance appetite in brain cancer patients. However, as powerful as they are, these drugs’ efficacy is also coupled with adverse effects. Common neurological complications of corticosteroid use include myopathy, visual blurring, tremor, insomnia, and cerebral atrophy, but other rare cases of psychosis, hallucinations, dementia, and seizures have been documented .
Glioblastoma is a type of brain tumor that resists insistent chemotherapy and surgical efforts, making it one of the most deadly and incurable brain cancers with poor prognosis . A 2007 study published in the journal Cancer had concluded that organosulfur compounds in garlic stimulate the apoptosis, or programmed cell death, of glioblastoma cells and hence grant noteworthy protection against brain cancers. These compounds include diallyl sulfide, diallyl disulfide, and diallyl trisulfide. Based on the results of the study, treating glioblastoma cells with these garlic compounds leads to the production of reactive oxygen species, which in turn promotes apoptosis of human glioblastoma cells by activating stress kinases and cysteine proteases . In a more recent study by Wallace IV et al. (2013), diallyl trisulfide intraperitoneally injected to mice at a dose of 10 μg/kg–10 mg/kg had been shown to dose-dependently decrease the tumor mass and number of mitotic cells within brain tumors. Additionally, data from histological and biochemical assays of this study expressed that diallyl trisulfide prevents the progression of tumor development. This inhibition is evinced by the reduced mitosis or cell division in the tumors and the decreased activity of histone deacetylase, an enzyme that regulates the activities and expression of several proteins that play a role in both cancer initiation and cancer progression. Also, protumor markers such as survivin, Bcl-2, c-Myc, mTOR, and EGFR VEGF had been observed to have decreased, whereas factors that induce apoptosis in human glioblastoma in vivo, including bax, mcalpian, and active caspase-3, were promoted without impairing hepatic function.
A 2014 study from the journal Molecules and Cells had demonstrated the antiproliferative activity of Z-ajoene, another garlic-derived compound and an antioxidant itself, and its ability to specifically suppress the growth and sphere-forming process of cancer stem cells in glioblastoma multiforme. Such inhibition occurred at a concentration that did not produce cytotoxicity or harm against normal cell cultures. The findings from this study put forward garlic’s Z-ajoene as a selective anticancer agent that can particularly target the activities of cancer stem cells in glioblastoma but not cause injury or damage to normal healthy cells.
Source : www.herbsandhealth.net