Recent Patents on Endocrine, Metabolic & Immune Drug Discovery - Volume 5, Issue 2, 2011

Melatonin, first discovered by Aaron B Lerner [1], is synthesized by the pineal gland which is a central structure in the circadian system involved in synchronizing the chronobiology of organisms. The pineal gland consists of two different types of cells: the pinealocytes and interstitial cells. The latter are further classified as the astrocytes and microglia/macrophages [2, 3]. Pinealocytes synthesize the neurohormone melatonin [4], a derivative of the amino acid tryptophan. The secretion of melatonin is regulated by the environmental light/dark cycle via the suprachiasmatic nucleus. Besides the pineal gland, synthesis of melatonin also occurs in other cells and organs such as the bone marrow [5], retina [6, 7], platelets [8], the gastrointestinal tract [9], skin [10, 11] and lymphocytes [12]. However, circulating melatonin in mammals has been reported to be largely derived from the pineal gland. Several experimental and clinical studies have supported antioxidant [13-15], anti-inflammatory [16], neuroprotective [17] and anticonvulsant actions of melatonin [18, 19]. Its oncostatic effects against a variety of tumors such as ovarian, endometrial, prostate, breast, intestinal and lung have also been documented [20-23], and melatonin, either alone or in combination with traditional therapy, has been used in the treatment of human cancers [24]. Beneficial effects of melatonin in treating sleep disorders in children and adults [25-28] as well as alleviating a variety of circadian rhythm-related disorders are well documented [29-31]. It is also known to facilitate the differentiation of neural stem cells into neurons [32]. The production of melatonin is known to decline in old age [33] and in conditions such as Alzheimer's disease [34], dementia [35] and stroke [36]. Melatonin has a remarkable therapeutic potential for treatment of many neurodegenerative disorders due to its antioxidant and immune enhancing properties. It has been shown to improve sleep and has been suggested as a useful add-on drug for treating mild cognitive impairment, epilepsy and cancer. Additionally, melatonin has been shown to be useful in the treatment of hypertension. Experimental data has suggested that melatonin reduces complications of traumatic brain injury. Several patents have been filed for using melatonin, its derivatives and analogues in the treatment or prevention of neurodegenerative diseases, sleep disorders and cancers [37-40]. This thematic issue will present reviews on the use of melatonin in neurodegenerative disorders such as Alzheimer's disease, sleep disorders, peripheral nerve regeneration and in cancer from experts. Although, many clinical trials with melatonin are in progress, future studies to determine the treatment regimens and safety of melatonin in clinical practice are necessary along with further in depth research to understand its role in human health and disease. I am grateful to the authors for their contributions to this volume....

Treatment of circadian rhythm disorders, whether precipitated by intrinsic factors (e.g., sleep disorders, blindness, mental disorders, aging) or by extrinsic factors (e.g., shift work, jet-lag) has led to the development of a new type of agents called “chronobiotics”. The term “chronobiotic” defines a substance displaying the therapeutic activity of shifting the phase or increasing the amplitude of the circadian rhythms. The prototype of this therapeutic group is melatonin, whose administration synchronizes the sleep-wake cycle in blind people and in individuals suffering from circadian rhythm sleep disorders, like delayed sleep phase syndrome, jet lag or shift-work. Daily melatonin production decreases with age, and in several pathologies, attaining its lowest values in Alzheimer's disease (AD) patients. About half of dementia patients have severe disruptions in their sleep-wakefulness cycle. Melatonin replacement is effective to treat sundowning and other sleep wake disorders in fully developed AD, although controversial data on this point exist. Indeed, large interindividual differences between patients suffering from AD exist and can explain these erratic results. Theoretically the effect of melatonin could be more consistent at an earlier stage of the disease, i.e., mild cognitive impairment (MCI), an etiologically heterogeneous syndrome that precedes dementia. PubMed was searched using Entrez for articles including clinical trials. Search terms were “Alzheimer” “mild cognitive impairment” and “melatonin”. Full publications were obtained and references were checked for additional material where appropriate. Only clinical studies with empirical treatment data were reviewed. Five double blind, randomized placebo-controlled trials and 1 open-label retrospective study (N = 651) all agree in indicating that treatment with daily evening melatonin improves sleep quality and cognitive performance in MCI. The analysis of published evidence and patents indicates that melatonin can be a useful ad-on therapeutic tool in the early phases of AD.

Melatonin is an indolamine with a large spectrum of functions that can be divided into chronobiotic and nonchronobiotic. Chronobiotic effects are mediated by the daily rhythm of melatonin in the plasma due to nocturnal pineal synthesis, whereas the melatonin produced by other cells, such as gastrointestinal and immune competent cells, is independent of the light/dark cycle and exert non-chronobiotic effects. The concentrations achieved by the two sources are significantly different, varying in the pM - nM range in the plasma, and may achieve concentrations in the mM range when released locally by activated immune-competent cells. Consequently, the effects of the melatonin produced in these two situations are distinct. Much has been reported about the beneficial response to exogenous melatonin administration in several pathological conditions. However, the relationship between the establishment of a disease and the state of the physiological activity of the pineal gland is still poorly understood. Here, we review the state of art in the modulation of pineal melatonin synthesis, relevant patents, and discuss its relationship with neurodegenerative disorders that involve a central inflammatory response, such as Alzheimer's disease, to suggest the putative relevance of new therapeutic protocols that replace this pineal hormone.

In the available literature, there are thousands of studies on peripheral nerve regeneration using many nerves of several animals at different ages with various types of lesions and different methods of evaluation at certain time of follow-up. Despite many experimental data and clinical observations, there is still no ideal treatment method enhancing peripheral nerve regeneration. In clinical practice, various types of surgical nerve repair techniques do not frequently result in complete recovery due to neuroma formation, lipid peroxidative damage, ischemia and other factors. Recently, a number of neuroscientists demonstrated that pineal neurohormone melatonin (MLT) has an effect on the morphologic features of the nerve tissue, suggesting its neuroprotective, free radical scavenging, antioxidative, and analgesic effects in degenerative diseases of peripheral nerves. At present, it is widely accepted that MLT has a useful effect on axon length and sprouting after traumatic events to peripheral nerves. Our studies using various experimental injury models clearly suggest positive effects of MLT on the number of axons, thickness of myelin sheath by inhibition of collagen accumulation and neuroma formation following traumatic events to peripheral nerves, myelination of developing peripheral nerve after intrauterine ethanol exposure. Nevertheless, further experimental and randomized controlled clinical studies are vital to identify the clinical use of MLT hormone. This is an overview of recent patents and current literature in terms of the effects of MLT on peripheral nerve regeneration based on a critical analysis of electrophysiological, biochemical and light and electron microscopic findings, in addition to functional observations.

Melatonin is a natural substance ubiquitous in distribution and present in almost all species ranging from unicellular organisms to humans. In mammals, melatonin is synthesized not only in the pineal gland but also in many other parts of the body, including the eyes, bone marrow, gastrointestinal tract, skin and lymphocytes. Melatonin influences almost every cell and can be traced in membrane, cytoplasmic, mitochondrial and nuclear compartments of the cell. The decline in the production of melatonin with age has been suggested as one of the major contributors to immunosenescence and development of neoplastic diseases. Melatonin is a natural antioxidant with immunoenhancing properties. T-helper cells play an important role for protection against malignancy and melatonin has been shown to enhance T-helper cell response by releasing interleukin-2, interleukin-10 and interferon-γ. Melatonin is effective in suppressing neoplastic growth in a variety of tumors like melanoma, breast and prostate cancer, and ovarian and colorectal cancer. As an adjuvant therapy, melatonin can be beneficial in treating patients suffering from breast cancer, hepatocellular carcinoma or melanoma. In this paper, a brief review of recent patents on melatonin and cancer has also been presented.

Sixty-six years have elapsed since the discovery of fetuin in 1944, but its importance in mammalian physiology has only recently been appreciated. Fetuin, first isolated from fetal bovine serum and now most commonly known as either fetuin-A, alpha-2-HS-glycoprotein (recommended name by UniprotKB and PIR), or α2-Heremans-Schmid glycoprotein, functions as an important component of diverse normal and pathological processes, including vascular calcification and bone metabolism regulation, insulin resistance, protease activity control, keratinocytes migration, and breast tumor cell proliferative signaling. Fetuin-A has also been identified as a biomarker for neurodegenerative disease. Here, we summarize recent publications focusing on the structural and functional properties of fetuin-A. The emerging importance of fetuin-A for both diagnosis and therapeutics has come to the attention of the pharmaceutical industry. Therefore, we will discuss the status of patents based on fetuin-A.

Skin cancer is the commonest malignant tumour in white skinned individuals in the western world. The incidence of skin cancer is on the rise. Case fatality for melanoma is probably the highest, not only among skin cancers but also among all types of cancers. The notion that cancer stem cells are responsible for disease progress and development has lead researchers towards these initiators of new metastases. Intra- and extracellular path inhibitors are targeted in eliminating crucial functions of tumor cells. Treatments are easily escaped from stem cells with pluripotent functional and proliferative potential. Immunomodulators are a useful treatment adjunct for highly immunogenic cancers such as malignant melanoma. Specific lineages of tumor cells are responsible for this modulation and targeting this cancer function with specific antibodies appears to be a reasonable but also effective treatment option. Chemoprotective agents have been proposed as a mean of reducing dose dependent toxicities and enlarging the therapeutic window of anticancer drugs. Current patent laws skew biomedical research to products that yield high profits rather than to global priority health needs in both developed and developing countries and with melanoma benefiting from this skew many new patents will continue to emerge. Most patents reported in this review follow the cytostatic rather than the cytotoxic paradigm. Based on this trend, one might anticipate that the goal for future advances in the treatment of melanoma patients would be to prolong their lifespan rather than cure them.

The patents annotated in this section have been selected from various patent databases. These recent patents are relevant to the articles published in this journal issue, categorized by therapeutic areas/targets & therapeutic agents related to endocrine, metabolic and immune drug discovery.