Nowadays, depending on the progress of science and technology, our eating habits have changed. The shape and quality of nutrition is important for human health. Especially, some food components have various effect on central nervous system such as depression, anxiety, sleep, appetite. Food constituents are transported into the central nervous system via the neutral amino acids such as phenylalanine, leucine, isoleucine, tyrosine and valine. Amino acids have an important role in human nutrition. It cannot be synthesized in the body and one of the essential amino acids that must be taken outside, trytophan, is indispensable in human nutrition because of it has the many functions. In recent years, scientific community concentrated on the various functions of L-Trytophan (L-Trp) as pioneer in the secretion of the hormones serotonin and melatoninin in the human body. The hormones serotonin and melatonin is responsible for activities such as psychology, sleep, body temperature, blood pressure balance, antioxidant effect, cancer inhibitor, sexuality, autism and circadian rhythms in human body that they are available in various foods such as milk, kefir, yogurt, orange, strawberry, grape, olive oil, walnut, prune, nut, pomegranate, coffee, kiwi and banana. In this study, L-Trp, serotonin and melatonin biosynthesis and metabolism, food profiles and in terms of their physiological and biological effects on human health has been compiled.

In this context, it is necessary to select and develop salt-tolerant genotypes that can grow in salty soils and have high yields, and formulate strategies which may enhance the plant survival under salinity stress. Melatonin (N-acetyl-5-methoxytryptamine) is an important biological hormone that provides resistance to abiotic stress conditions and can be secreted by plants. Melatonin concentration in plants varies depending on genotype, temperature and growth period. Increase in melatonin concentration is associated with increased SNAT and HIOMAT/ASMT enzyme activity. It plays an important role in gibberellic acid and abscisic acid biosynthesis during the germination and provides plant growth and development. Exogenous application of melatonin significantly alleviates chlorophyll degradation and stomatal closure caused by salt stress, improves photosynthesis and enhances plants' salt tolerance. Besides it significantly reduces the harmful effects of salinity by regulating plant physiology, improving plant morphology, photosynthesis and activities of antioxidant enzymes. The present review discusses the recent studies on the effect of melatonin on plant growth and physiology against salt stress that have important impacts on plant growth and development have been given according to the findings of various researches. It also highlights the mechanim/s of melatonin-induced salinity stress tolerance in plants.

The aim of this study was to investigate the effects of exogenous Melatonin (100, 300 and 500 µM) and L-tryptophan (125, 250, 375 ppm) applications on some growth parameters of lettuce plants grown under salt stress. The study was carried out under semi-controlled greenhouse conditions in spring (March/April) season. The exogenous applications to lettuce plants were carried out two times as foliar spraying. Salt stress was generated by adding NaCl (0 mM, 100 mM, 200 mM) to irrigation water. The complete randomized design was used with three replications in this experiment. At the end of the study, it was found that the highest doses of exogenous applications had the highest effect on the parameters of the number of leaves, salinity necrosis, fresh leaf weight, fresh root weight, and total surface area of lettuce plants under 200 mM salinity condition. When the effects of the subtract on these values were compared, the effect of melatonin was found to be more pronounced. Leaf width, leaf length, and leaf surface temperature values were not affected by the external application. These values only changed depending on salt concentration. As a result of the study, it was concluded that the application of 500 µM melatonin significantly increased salt tolerance in lettuce plants. However, in order to reach a more general conclusion, the dose ranges and genotype/variety numbers should be increased.

Akdeniz diyeti, Akdeniz çevresinde farklı ülkelerde yaşayan insanların yıllar boyu sürdürdüğü benzer yeme alışkanlıklarının bütünü olarak tanımlanmaktadır. Genellikle zengin fitokimyasal içeriği, yüksek miktarda diyet lifi içermesi ve fermente gıdaların ön planda oluşunun sağlık üstünde olumlu etkileri olduğu düşünülmektedir. Akdeniz diyetinde yer alan gıdalar, tüm bu özelliklerinin yanı sıra, melatonin bulundurması ile de öne çıkmaktadır. Melatonin zorunlu bir aminoasit olan triptofandan sentezlenen, bilinen en güçlü antioksidandır. Antioksidan, anti-inflamatuvar, antikanser özellik göstermesinin yanı sıra kardiyovasküler hastalıklar üzerinde iyileştirici etkisi ve vücuttaki sirkadyen ritimden sorumlu olması sağlık üzerinde geniş çapta ve oldukça fazla olumlu etkisi bulunduğunu göstermektedir. Melatonin içeren gıdaların tüketilmesi ile serum melatonin konsantrasyonları artmaktadır. Dolayısıyla, Akdeniz diyetinde bulunan gıdaların tüketimiyle, içeriklerindeki polifenollerin, diğer biyoaktif bileşenlerin melatoninle birlikte sinerjistik etki yaratması ve diyetten sağlanacak yararın maksimum düzeye çıkması beklenmektedir. Bu derlemede Akdeniz diyetinde yer alan gıdalar, bu gıdaların melatonin içerikleri ve tüketimleri sonucu beklenen sağlık faydaları üzerine odaklanılmıştır.