Melatonin contents in mulberry (Morus spp.) leaves: Effects of sample preparation, cultivar, leaf age and tea processing

► Significant amount of melatonin was identified in mulberry leaves. ► Suitable sample preparation was important factor for accuracy of melatonin analysis. ► Melatonin contents in mulberry leaves depend on cultivar and leaf age. ► Tea processing could decrease melatonin content in mulberry leaves.