Phytotherapeutic alternatives for neurodegenerative dementias: Scientific review, discussion and therapeutic proposal.

The incidence and prevalence of age-related neurodegenerative dementias have been increasing. There is no curative therapy and conventional drug treatment can cause problems for patients. Medicinal plants traditionally used for problems associated with ageing are emerging as a therapeutic resource. The main aim is to give a proposal for use and future research based on scientific knowledge and tradition. A literature search was conducted in several searchable databases. The keywords used were related to neurodegenerative dementias, ageing and medicinal plants. Boolean operators and filters were used to focus the search. As a result, there is current clinical and preclinical scientific information on 49 species used in traditional medicine for ageing-related problems, including neurodegenerative dementias. There are preclinical and clinical scientific evidences on their properties against protein aggregates in the central nervous system and their effects on neuroinflammation, apoptosis dysregulation, mitochondrial dysfunction, gabaergic, glutamatergic and dopaminergic systems alterations, monoamine oxidase alterations, serotonin depletion and oestrogenic protection. In conclusion, the potential therapeutic effect of the different medicinal plants depends on the type of neurodegenerative dementia and its stage of development, but more clinical and preclinical research is needed to find better, safer and more effective treatments.

The Use of Herbal Medicine in the Treatment of Vitiligo: An Updated Review.

Vitiligo is a chronic disease of unknown etiology that causes progressive cutaneous depigmentation. Current pharmacological treatments have limited success and present significant risks. Many efforts have been made in recent years to explore new anti-vitiligo therapeutic strategies, including herbal-based therapies. The objective of the present review is to provide an updated overview on the most frequently used medicinal plants in the treatment of vitiligo. A bibliographical search was carried out in scientific databases Pubmed, Scifinder, Scopus, Google Scholar, and Medline up to October 2021 using the descriptors vitiligo, herbal, medicinal plants, and alternative therapies. In our search, the highest number of published studies comprise plants commonly used in traditional herbal medicine, highlighting the usefulness of ethnopharmacology in the discovery of new therapeutic agents. The review outlines current understanding and provides an insight into the role of psoralens and khellin (photosensitizing agents obtained from plants such as Cullen corylifolium or Ammi visnaga). The paper also describes other traditional herbs such as Ginkgo biloba, Phlebodium aureum, Piper nigrum, Picrorhiza kurroa, and Baccharoides anthelmintica that can likewise act as potential therapeutical agents. Based on our findings, photosensitizing agents in combination with phototherapy, the association of oral Phebodium aureum with phototherapies as well as oral G. biloba in monotherapy showed greater scientific evidence as therapeutic options. The research results emphasize that further investigation in this area is merited. More long-term follow up clinical trials and higher quality randomized trials are needed.

Medicinal plants and natural products as neuroprotective agents in age-related macular degeneration.

The retina may suffer neurodegenerative damages, as other tissues of the central nervous system do, and serious eye diseases may develop. One of them is age-related macular degeneration, which causes progressive loss of vision due to retina degeneration. Treatment of age-related macular degeneration focuses on antioxidant agents and anti-vascular endothelial growth factor compounds, among others, that prevent/diminish oxidative stress and reduce neovascularisation respectively. The phytochemicals, medicinal plants and/or plant-diet supplements might be a useful adjunct in prevention or treatment of age-related macular degeneration owing to their antioxidant and anti-vascular endothelial growth factor properties. This review article presents the most investigated plants and natural products in relation to age-related macular degeneration, such as saffron, ginkgo, bilberry and blueberry, curcuma or turmeric, carotenoids, polyphenols, and vitamins C and E. This study provides up-to-date information on the effects, treatments, safety and efficiency of these phytotherapy products.

Neuroprotective Potential of Ginkgo biloba in Retinal Diseases.

Like other tissues of the central nervous system, the retina is susceptible to damage by oxidative processes that result in several neurodegenerative disease such as age-related macular degeneration, diabetic retinopathy, glaucoma, ischaemic retinal disease, retinal disease produced by light oxidation, and detached retina, among other diseases. The use of antioxidant substances is a solution to some health problems caused by oxidative stress, because they regulate redox homeostasis and reduce oxidative stress. This is important for neurodegeneration linked to oxidation processes. In line with this, Ginkgo biloba is a medicinal plant with excellent antioxidant properties whose effects have been demonstrated in several degenerative processes, including retinal diseases associated with neurodegeneration. This review describes the current literature on the role of ginkgo in retinal diseases associated with neurodegeneration. The information leads to the conclusion that G. biloba extracts might be a good option to improve certain neurodegenerative retinal diseases, but more research is needed to determine the safety and efficacy of G. biloba in these retinal degenerative processes.

Stereodynamics and edge-to-face CH-π aromatic interactions in imino compounds containing heterocyclic rings.

By comparison with close contact interactions between benzene rings there is a paucity of experimental data available for attractive interactions involving aromatic heterocyclic rings, especially for small molecules in solution. Herein we describe aromatic heterocyclic and carbocyclic edge-to face interactions and conformational stereodynamics of N-1,2-diphenylethyl imines bearing a phenyl group and either a 2-pyridyl, 3-pyridyl, 2-thiophene or 2-furanyl moiety on the imino carbon. X-ray crystal structures have been determined for two compounds. Slow rotation about the phenyl-imino bond in the E-isomers and around the heterocycle-imino bond in the Z-isomers of the pyridyl compounds was observed at low temperatures by NMR. Abnormally large shielding of one ortho hydrogen indicates that both the imino phenyl and heterocycle rings can engage in an edge-to-face interaction with the N-terminal phenyl moiety in the appropriate isomer. Some rotational barriers around the phenyl-imino and heterocycle-imino bonds were measured.

In vivo and in vitro anti-leishmanial activities of 4-nitro-N-pyrimidin- and N-pyrazin-2-ylbenzenesulfonamides, and N2-(4-nitrophenyl)-N1-propylglycinamide.

A series of compounds containing the nitrobenzene and sulfonamido moieties were synthesized and their leishmanicidal effect was assessed in vitro against Leishmaniainfantum promastigotes. Among the compounds evaluated, the p-nitrobenzenesulfonamides 4Aa and 4Ba, and the p-nitroaniline 5 showed significant activity with a good selectivity index. In a Balb/c mice model of L. Infantum, administration of compounds 4Aa, 4Ba or 5 (5mg/kg/day for 10 days, injected ip route) led to a clear-cut parasite burden reduction (ca. 99%). In an attempt to elucidate their mechanism of action, the DNA interaction of 4Aa and 5 was investigated by means of viscosity studies, thermal denaturation and nuclease activity assay. Both compounds showed nuclease activity in the presence of copper salt. The results suggest that compounds 4Aa, 4Ba and 5 represent possible candidates for drug development in the therapeutic control of leishmaniasis.

2-sulfonyliminodihydropyrimidines: a novel class of analgesic compounds.

A series of 2-sulfonyliminodihydropyrimidine derivatives have been synthesized and evaluated in vivo for their antinociceptive and anti-inflammatory activities. The results were compared with that of acetyl salicylic acid. Compounds 6Ab-d and 6Be displayed an interesting analgesic profile in the acetic acid-induced abdominal contractions test. Based on the results of the carrageenan-hind paw edema test, compound 6Af showed potential anti-inflammatory activity.

Diastereoselectivity in Organometallic Additions to the Carbonyl Group of Protected Erythrulose Derivatives.

We have investigated a number of nucleophillic additions to L-erythrulose derivatives (4-12) bearing protective O-silyl, O-benzyl, and O-trityl groups in various relative positions. The results are discussed in the frame of chelated vs nonchelated transition states with additional support of previously published theoretical calculations. Sound evidence appears to exist for the formation of alpha-chelates as the key intermediates in nucleophillic additions to these alpha,beta-dioxygenated ketones. Since such evidence is still lacking in the case of beta-chelates, proposals of their intermediacy have been relegated in favor of the more solid Felkin-Anh model, which predicts the same stereochemical result. The behavior of these highly functionalized ketones does not always match that of structurally similar aldehydes.