L-theanine is an amino acid occurring in green tea. A population study recommends that green tea consumption may aid reduce stroke risk, but it is a little vague whether L-theanine contributes to this gain. L-theanine may help promote sleep and reduce stress, but more extensive, well-designed trials are demanded to confirm this effect.
L-theanine may improve sleep quality, but more extensive studies are needed to confirm protection and effectiveness in patients with several conditions.
Theanine, a practical component of green tea (Camellia sinensis), is estimated as a modulator of chemotherapy.
Laboratory experiments that suggest L-theanine may boost the performance of chemotherapy drugs or reduce side results have yet not been established in humans. Patients undergoing chemotherapy should consider using L-theanine with their physicians because safety data in cancer patients are insufficient. Another ingredient found in green tea called epigallocatechin-3-gallate (EGCG) reduces the action of the chemotherapy drug bortezomib.
SUMMARY
L-theanine is a water-soluble amino acid obtained in green tea and mushrooms. Purified L-theanine is an oral dietary supplement used for its distinguished antioxidant and relaxant outcomes. Numerous in vitro and animal studies propose lipid-lowering effects, neuroprotective effects, antiobesity effects, and also antitumor qualities.
Preclinical studies propose that L-theanine improves chemotherapeutic effects of doxorubicin and idarubicin and mitigates adverse effects from the use of these agents. However, patients undergoing chemotherapy should review the use of L-theanine with their practitioners because these conclusions do not rely on clinical trials. Also, epigallocatechin-3-gallate (EGCG) in green tea is known to decreases the activity of the chemotherapeutic drug bortezomib.
MECHANISM OF ACTION
Being a non-protein amino acid, L-theanine crisscrosses the blood-brain obstacle, exerting different neurophysiological and pharmacological outcomes including anxiolytic and calming effects because of inhibitory neurotransmitters and particular serotonin and dopamine modulation; cognitive developments perhaps through reduced NMDA-dependent CA1 long-term potentiation (LTP) and raised NMDA-independent CA1-LTP and advanced selective attention when mental tasks are likely to change in alpha brain wave activity. Neuroprotective effects are also deemed to be due to its selective merging to glutamate receptors.
L-theanine was conferred to increase the antitumor action of chemotherapeutic drugs like doxorubicin and idarubicin. These agents typically bind the glutamate receptor, and the group is transported beyond the cell resulting in diminished concentrations, hence attenuating the effects of these drugs. Resulting mechanistic studies exposed that L-theanine, a glutamate analog, competes with glutamate to bind the glutamate receptor, resulting in chemotherapy efflux (extracellular transport), increasing their concentration.
Surprisingly, L-theanine also depreciates the conflicting effects of doxorubicin. The suggested mechanism is based on the variety of glutamate receptors displayed in healthy and tumor cells. Theanine binds the glutamate receptor in tumor cells while it is metabolized to glutamate in healthy cells. This rise in glutamate likely results in the extended efflux of doxorubicin from the cells, thereby reducing toxicity.
Researchers found some novel theanine derivatives to inhibit lung tumor growth by aiming for EGFR/VEGFR-Akt/NF-kappaB pathways.
L-THEANINE AND LIVER CANCER
Liver cancer has historically been viewed as a therapeutic challenge due to its cytotoxic drug-resistant characteristic and related liver function disorder, which decreases some conventional chemotherapeutic agents. In addition to cytotoxic drugs, certain chemicals from traditional Chinese medicine or dietary foods target apoptosis and are investigated for cancer treatment. A recent study demonstrated that theanine, a free amino acid from green tea, caused human hepatocellular carcinoma HepG2 cell death, which was considerably enhanced by acute glutamine restriction or loss. It was finally found that theanine induced HepG2 cell destruction through apoptosis.
L-THEANINE AND PROSTATE CANCER
A prevalent male-specific malignancy is seen in prostate cancer (PCa); most PCa patients eventually encounter death due to metastasis. L-theanine (C7H14N2O3) is a non-protein amino acid derivative from green tea leaves, which has been proved to work as an anticarcinogen via pro-apoptotic and anti-proliferative outcomes. But, the antimetastatic effect of L-theanine in tumor cells and its underlying mechanism are still to be studied.
A study revealed that L-theanine could overcome invasion, migration and strengthen cell-cell adhesion of prostate cancer cells in vitro and in vivo. Along with it, there was a confirmation that L-theanine could restrain the epithelial-mesenchymal transition procedure in PCa. the investigation showed that L-theanine could downregulate MMP9, N-cadherin, Vimentin, Snail, and upregulate E-cadherin. Moreover, L-theanine crushed the transcription of MMP9 and Snail by significantly repressing the ERK/NF-κB signaling pathway and the confining activity of p65 to the promoter sections of MMP9 and Snail. All of these conclusions suggest that L-theanine has remedial potential for metastatic PCa and may be counted as a promising competitor for antimetastatic remedies of prostate cancer.
L-THEANINE AND LUNG CANCER AND LEUKAEMIA CELLS
A study demonstrated that theanine overcame the in vitro and ex vivo maturation of human non-small cell lung cancer A549 and leukemia K562 cell lines in a dose- and time-dependent manner. Additionally, theanine displayed an inhibitory effect on the movement of A549 cells. More importantly, theanine intensified the anticancer activity of anticancer agents such as trichostatin A, a histone deacetylase inhibitor, berbamine, and norcantharidin, (anticancer drugs used in China) by steadily reducing the viability and migration rate in A549 cells. Plus, theanine significantly overpowered A549 cell invasion.
HERB AND DRUG INTERACTIONS
- Midazolam: In animal illustrations, L-theanine had synergistic or additive results. Clinical importance has yet to be ascertained.
CONCLUSION
The role of L-Theanine in cancer prevention and treatment is of great importance. Asians have a feebler rate of cardiovascular disease and cancer, notwithstanding high rates of cigarette smoking. The logic for this protection may be an extraordinary consumption of tea, mainly green tea. Approximately 1.2 liters of green tea is consumed daily by many people in Asia, contributing to the antioxidant protection from the polyphenolic aggregates in green tea. Consequently, the modulating influence of theanine on the effectiveness of antitumor agents is assumed to be applicable in clinical cancer chemo. L-theanine may be used as an efficient chemopreventive agent for cancer.
A study proposed that a concentration >300 µg/ml of theanine was needed for producing significant cell apoptosis when the cells were cultured in DMEM supplemented with 4 mM glutamine. It is sensible to suggest that glutamine antagonized the apoptotic impact of theanine due to their comparable structures.
Appropriate exogenous glutamine amount is considered to participate beneficially to deteriorate risks of high-dose chemotherapy. Likewise, theanine has been attested to protect healthy cells from destruction by chemotherapeutic drugs.
