Current Medicinal Chemistry - Volume 27, Issue 26, 2020

Essential oils constituents are a diverse family of low molecular weight organic compounds with comprehensive biological activity. According to their chemical structure, these active compounds can be divided into four major groups: terpenes, terpenoids, phenylpropenes, and "others". In addition, they may contain diverse functional groups according to which they can be classified as hydrocarbons (monoterpenes, sesquiterpenes, and aliphatic hydrocarbons); oxygenated compounds (monoterpene and sesquiterpene alcohols, aldehydes, ketones, esters, and other oxygenated compounds); and sulfur and/or nitrogen containing compounds (thioesters, sulfides, isothiocyanates, nitriles, and others). Compounds that act as cholinesterase inhibitors still represent the only pharmacological treatment of Alzheimer´s disease. Numerous in vitro studies showed that some compounds, found in essential oils, have a promising cholinesterase inhibitory activity, such as α-pinene, δ-3-carene, 1,8-cineole, carvacrol, thymohydroquinone, α- and β-asarone, anethole, etc. This review summarizes the most relevant research published to date on essential oil constituents and their acetylcholinesterase/butyrylcholinesterase inhibitory potential as well as their structure related activity, synergistic and antagonistic effects.

Background: Neurodegenerative disorders have achieved epidemic levels in the last decades; not only the elderly but also adult individuals have been increasingly affected. Among them, Alzheimer’s disease is one of the most prevalent and crippling diseases, associated with high rates of multi-morbidities and dependency. Despite the existence of a wide variety of drugs used as the symptomatic treatment, they have some side effects and toxicity, apart from their limited effectiveness. Botanical preparations have a secular use, being widely recommended for a multitude of purposes, such as for the improvement of brain health. Objective: The aim of the present report is to systematize the knowledge on plant-food derived bioactive molecules with promising in vitro enzymatic inhibitory activities. Results: Alkaloids, phenolic compounds and terpenes are the most studied phytochemicals, both derived from natural and commercial sources. In spite of their efficient activity as enzymatic inhibitors, the number of in vivo studies and even clinical trials have confirmed that their real bioactive potential remains scarce. Conclusion: Thus, it is of the utmost importance to deepen knowledge in this area, once those relevant and informative tools can significantly contribute to the promising advances in the field of Alzheimer’s disease treatment.

The following review is oriented towards microbes linked to Alzheimer’s disease (AD) and antimicrobial effect of compounds and extracts derived from aquatic organisms against specific bacteria, fungi and viruses which were found previously in patients suffering from AD. Major group of microbes linked to AD include bacteria: Chlamydia pneumoniae, Helicobacter pylori, Porphyromonas gingivalis, Fusobacterium nucleatum, Prevotella intermedia, Actinomyces naeslundii, spirochete group; fungi: Candida sp., Cryptococcus sp., Saccharomyces sp., Malassezia sp., Botrytis sp., and viruses: herpes simplex virus type 1 (HSV-1), Human cytomegalovirus (CMV), hepatitis C virus (HCV). In the light of that fact, this review is the first to link antimicrobial potential of aquatic organisms against these sorts of microbes. This literature review might serve as a starting platform to develop novel supportive therapy for patients suffering from AD and to possibly prevent escalation of the disease in patients already having high-risk factors for AD occurrence.

Alzheimer’s disease (AD) is a complex, neurodegenerative pathology showing, among others, high cholinergic and neurotransmitter deficits, oxidative stress, inflammation, Aβ-aggregation resulting in senile plaques formation, and hyperphosphorylation of tau-protein leading to neurofibrillary tangles. Due to its multifactorial and complex nature, multitarget directed small-molecules able to simultaneously inhibit or bind diverse biological targets involved in the progress and development of AD are considered now the best therapeutic strategy to design new compounds for AD therapy. Among them, tacrine is a very well known standard-gold ligand, and natural products have been a traditional source of new agents for diverse therapeutic treatments. In this review, we will update recent developments of multitarget tacrinenatural products hybrids for AD therapy.

Spices are not only just herbs used in culinary for improving the taste of dishes, they are also sources of a numerous bioactive compounds significantly beneficial for health. They have been used since ancient times because of their antimicrobial, anti-inflammatory and carminative properties. Several scientific studies have suggested their protective role against chronic diseases. In fact, their active compounds may help in arthritis, neurodegenerative disorders (Alzheimer’s, Parkinson, Huntington’s disease, amyotrophic lateral sclerosis, etc.), diabetes, sore muscles, gastrointestinal problems and many more. In the present study, possible roles of spices and their active components, in chronic diseases (cancer, arthritis, cardiovascular diseases, etc.) along with their mechanism of action have been reviewed.

Sulfur-containing secondary metabolites are a relatively small group of substances of plant origin. The present review is focused on their neuroprotective properties. The results obtained in a series of in vitro and in vivo studies are reported. Among glucosinolates, the wide class of compounds in the sulfur-containing metabolites, glucoraphanin, sulforaphane and isothiocyanates proved to be the more studied in this context and showed interesting properties as modulators of several systems involved in the pathogenesis of neurologic diseases such as oxidative stress, inflammation and apoptosis. Allium sativum L. (garlic) is widely known for its sulfur-containing components endowed with health-promoting activities and its medicinal properties are known from ancient times. In recent studies, garlic components proved active in neuroprotection due to the direct and indirect antioxidant properties, modulation of apoptosis mediators and inhibiting the formation of amyloid protein. Dihydroasparagusic acid, the first dimercaptanic compound isolated from a natural source, effectively inhibited inflammatory and oxidative processes that are important factors for the etiopathogenesis of neurodegenerative diseases, not only for its antioxidant and radical scavenging properties but also because it may down-regulate the expression of several microglial-derived inflammatory mediators. Serofendic acid represents a rare case of sulfur-containing animal-derived secondary metabolite isolated from fetal calf serum extract. It proved effective in the suppression of ROS generation and in the expression of several inflammatory and apoptosis mediators and showed a cytotrophic property in astrocytes, promoting the stellation process. Lastly, the properties of hydrogen sulfide were also reported since in recent times it has been recognized as a signaling molecule and as a mediator in regulating neuron death or survival. It may be produced endogenously from cysteine but may also be released by sulfur-containing secondary metabolites, mainly from those present in garlic.