Melatonin (N-acetyl-5-methoxytryptamine) is a naturally synthesized hormone secreted from the pineal gland in a variety of animals and is primarily involved in the regulation of the circadian rhythm, which is the natural cycle controlling sleep in organisms. Melatonin acts on specific receptors and has an important role in overall energy metabolism. This review encompasses several aspects of melatonin activity, such as synthesis, source, structure, distribution, function, signaling and its role in normal physiology. The review highlights the cellular signaling and messenger systems involved in melatonin’s action on the body and their wider implications, the distribution and diverse action of different melatonin receptors in specific areas of the brain, and the pharmacological agonists and antagonists that have specific action on these melatonin receptors. This review also incorporates the antitumor effects of melatonin in considerable detail, emphasizing on melatonin’s role as an adjuvant therapeutic agent in glioma treatment. We conclude that the diminishing levels of melatonin have significant debilitating effects on normal physiology and can also be associated with malignant conditions such as glioma. Based on the review of the available evidence, our study provides a broad platform for a better understanding of the specific roles of melatonin and serves as a starting point for further investigation into the therapeutic effect of melatonin in glioma as an adjuvant therapeutic agent.
Methanolic extract of tea leaves (Camellia sinensis Linn.) of autumn and rain collections (SA and SR respectively) were investigated for in vitro antioxidants, antibacterial and wound healing activities to correlate with the impact of seasonal variation on phytoconstitutional content and commercial disparity. Both the extracts were subjected for quantitative and qualitative analysis and different concentrations (SA100, SA200, SR100 and SR200) were investigated for in vitro antioxidant activity performing DPPH, super oxide anion, hydrogen peroxide, hydroxyl radical scavenging assay and measurement of reductive ability. The antibacterial activity of SA and SR was evaluated against eight human pathogens (two Gram positive and six Gram negative) using disc diffusion method and minimum inhibitory concentration of each was determined. The influence of SA and SR in 250 and 500 mg/Kg body wt. on rate of wound closure were investigated using the excision wound model on female wister rats (Sprague Dawley) and histological investigations of treated and untreated wound tissues were performed to observe epithelialisation, fibroblast proliferation, neovascularisation, neutrophil infiltration, and collagen deposition. The SR extract showed higher antioxidant activities compared to SA. Both the extracts showed significant antibacterial activities. The topical administration of SR500 caused significantly faster healing (99.05%), more epithelialisation, less neutrophils infiltration, higher deposition of collagen and better angiogenesis in wound area as compared to the SA500 and standard. These results limpidly showed that the SR extract possess superior wound healing properties due to its higher anti oxidant and better microbial spectrum coverage probably by containing sesquiterpene derivative and higher flavonoid analogues.
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