Protective effects of ethanolic extract of Delphinium denudatum in a rat model of Parkinson's disease

Neuropharmacological Potential of Diterpenoid Alkaloids

This study provides a narrative review of diterpenoid alkaloids (DAs), a family of extremely important natural products found predominantly in some species of Aconitum and Delphinium (Ranunculaceae). DAs have long been a focus of research attention due to their numerous intricate structures and diverse biological activities, especially in the central nervous system (CNS). These alkaloids originate through the amination reaction of tetra or pentacyclic diterpenoids, which are classified into three categories and 46 types based on the number of carbon atoms in the backbone structure and structural differences. The main chemical characteristics of DAs are their heterocyclic systems containing β-aminoethanol, methylamine, or ethylamine functionality. Although the role of tertiary nitrogen in ring A and the polycyclic complex structure are of great importance in drug-receptor affinity, in silico studies have emphasized the role of certain sidechains in C13, C14, and C8. DAs showed antiepileptic effects in preclinical studies mostly through Na⁺ channels. Aconitine (1) and 3-acetyl aconitine (2) can desensitize Na⁺ channels after persistent activation. Lappaconitine (3), N-deacetyllapaconitine (4), 6-benzoylheteratisine (5), and 1-benzoylnapelline (6) deactivate these channels. Methyllycaconitine (16), mainly found in Delphinium species, possesses an extreme affinity for the binding sites of α7 nicotinic acetylcholine receptors (nAChR) and contributes to a wide range of neurologic functions and the release of neurotransmitters. Several DAs such as bulleyaconitine A (17), (3), and mesaconitine (8) from Aconitum species have a drastic analgesic effect. Among them, compound 17 has been used in China for decades. Their effect is explained by increasing the release of dynorphin A, activating the inhibitory noradrenergic neurons in the β-adrenergic system, and preventing the transmission of pain messages by inactivating the Na⁺ channels that have been stressed. Acetylcholinesterase inhibitory, neuroprotective, antidepressant, and anxiolytic activities are other CNS effects that have been investigated for certain DAs. However, despite various CNS effects, recent advances in developing new drugs from DAs were insignificant due to their neurotoxicity.

Targeting Mitochondrial Dysfunction in Neurodegenerative Diseases: Expanding the Therapeutic Approaches by Plant-Derived Natural Products

Mitochondria are the primary source of energy production in neurons, supporting the high energy consumption of the nervous system. Inefficient and dysfunctional mitochondria in the central nervous system have been implicated in neurodegenerative diseases. Therefore, targeting mitochondria offers a new therapeutic opportunity for neurodegenerative diseases. Many recent studies have proposed that plant-derived natural products, as pleiotropic, safe, and readily obtainable sources of new drugs, potentially treat neurodegenerative diseases by targeting mitochondria. In this review, we summarize recent advances in targeting mitochondria in neurotherapeutics by employing plant-derived natural products. We discuss the mechanism of plant-derived natural products according to their mechanism of action on mitochondria in terms of regulating biogenesis, fusion, fission, bioenergetics, oxidative stress, calcium homeostasis, membrane potential, and mitochondrial DNA stability, as well as repairing damaged mitochondria. In addition, we discuss the potential perspectives and challenges in developing plant-derived natural products to target mitochondria, highlighting the clinical value of phytochemicals as feasible candidates for future neurotherapeutics.

Parkinson's Disease: Is there a Role for Dietary and Herbal Supplements?

Parkinson's Disease (PD) is characterised by degeneration of the neurons of the nigrostriatal dopaminergic pathway of the brain. The pharmacological cornerstone of PD management is mainly the use of dopamine precursors, dopamine receptor agonists, and agents that inhibit the biochemical degradation of dopamine. While these drugs initially provide relief to the symptoms and improve the quality of life of the patients, progression of the underlying pathological processes, such as oxidative stress and neuroinflammation (which have been strongly associated with PD and other neurodegenerative disorders), eventually reduce their benefits, making further benefits achievable, only at high doses due to which the magnitude and frequency of side-effects are amplified. Also, while it is becoming obvious that mainstream pharmacological agents may not always provide the much-needed answer, the question remains what succour can nature provide through dietary supplements, nutraceuticals and herbal remedies? This narrative review examines current literature for evidence of the possible roles (if any) of nutraceuticals, dietary supplements and herbal remedies in the prevention or management of PD by examining how these compounds could modulate key factors and pathways that are crucial to the pathogenesis and/or progression of PD. The likely limitations of this approach and its possible future roles in PD prevention and management are also considered.

Phytotherapy in treatment of Parkinson's disease: a review

Context: Parkinson's disease (PD) is a neurodegenerative disorder due to gradual loss of dopaminergic nerves in the substantia nigra (SN) in the midbrain. PD leads to certain motor disorders including resting tremor, muscle stiffness and slow movement. Medicinal plants have shown positive pharmacological effects in treating different models of PD. Objective: Tendency to use natural products, especially plants, for the treatment of PD has been growing. This article reviews the basic aspects of medicinal plants and their bioactive compounds that could be used to treat PD. Methods: Reliable articles indexed in databases ISI, SID, PubMed, PubMed Central, Scopus and Web of Science were used. A total of 12 plant-derived active ingredients and 18 herbal extracts were included. Different compounds have so far been isolated from plants that affect PD especially by targeting pathways associated with the pathogenesis of the disease. Results: Although some herbal extracts such as Hibiscus asper Hook. f. (Malvaceae), Ginkgo biloba L. (Ginkgoaceae), Carthamus tinctorius L (Asteraceae) and certain active ingredients, such as berberine and curcumin, have shown positive effects in animal models of PD, potential active ingredients and mechanisms of action should be investigated in additional studies. Discussion and conclusions: Despite the wide variety of plants in the world, a limited number of them have been studied for anti-Parkinsonian activity, and therefore, there are numerous perspectives in this field for future studies on plants and their bioactive compounds.

Micro-morphological, environmental and phytochemical investigation of herbal medicines by using LM and SEM: A quality control tool

The use of quality control tool for authentication of Jadwar (Delphinium denudatum Wall. ex Hook.f. & Thomson), a folk herbal drug used for the treatment of different ailments, was studied. People face problems of adulteration for this drug at global, regional, national and local levels. Two different plant species are commercially marketed in the Indo-Pak Subcontinent under the same trade name of Jadwar. One is D. denudatum Wall. ex Hook.f. & Thomson and the other is Aconitum heterophyllum Wall. ex Royle. To focus on this problem, a marketable available drug sample of Jadwar was authenticated by using basic microscopy tools (LM) and advanced chemo-taxonomic markers. Authentication, quality and standardization of this drug was achieved using morphology, organoleptography, UV and IR analyses, scanning electron microscopy of pollen and anatomical investigations. The techniques used for authentication marked the clear difference between the studied plants. Microscopic studies, chemotaxonomic investigation and other techniques used in this project provided the basis for the authentication of this species.

The Role of Reactive Oxygen Species in the Pathogenesis of Alzheimer's Disease, Parkinson's Disease, and Huntington's Disease: A Mini Review

Neurodegenerative diseases affect not only the life quality of aging populations, but also their life spans. All forms of neurodegenerative diseases have a massive impact on the elderly. The major threat of these brain diseases includes progressive loss of memory, Alzheimer's disease (AD), impairments in the movement, Parkinson's disease (PD), and the inability to walk, talk, and think, Huntington's disease (HD). Oxidative stress and mitochondrial dysfunction are highlighted as a central feature of brain degenerative diseases. Oxidative stress, a condition that occurs due to imbalance in oxidant and antioxidant status, has been known to play a vital role in the pathophysiology of neurodegenerative diseases including AD, PD, and HD. A large number of studies have utilized oxidative stress biomarkers to investigate the severity of these neurodegenerative diseases and medications are available, but these only treat the symptoms. In traditional medicine, a large number of medicinal plants have been used to treat the symptoms of these neurodegenerative diseases. Extensive studies scientifically validated the beneficial effect of natural products against neurodegenerative diseases using suitable animal models. This short review focuses the role of oxidative stress in the pathogenesis of AD, PD, and HD and the protective efficacy of natural products against these diseases.

Mining chemodiversity from biodiversity: pharmacophylogeny of medicinal plants of Ranunculaceae

This paper reports a pharmacophylogenetic study of a medicinal plant family, Ranunculaceae, investigating the correlations between their phylogeny, chemical constituents, and pharmaceutical properties. Phytochemical, ethnopharmacological, and pharmacological data were integrated in the context of the systematics and molecular phylogeny of the Ranunculaceae. The chemical components of this family included several representative metabolic groups: benzylisoquinoline alkaloids, ranunculin, triterpenoid saponin, and diterpene alkaloids, among others. Ranunculin and magnoflorine were found to coexist in some genera. The pharmacophylogenetic analysis, integrated with therapeutic information, agreed with the taxonomy proposed previously, in which the family Ranunculaceae was divided into five sub-families: Ranunculoideae, Thalictroideae, Coptidoideae, Hydrastidoideae, and Glaucidioideae. It was plausible to organize the sub-family Ranunculoideae into ten tribes. The chemical constituents and therapeutic efficacy of each taxonomic group were reviewed, revealing the underlying connections between phylogeny, chemical diversity, and clinical use, which should facilitate the conservation and sustainable utilization of the pharmaceutical resources derived from the Ranunculaceae.

Plant-Derived Natural Products for Parkinson's Disease Therapy

Plant-derived natural products have made their own niche in the treatment of neurological diseases since time immemorial. Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, has no cure and the treatment available currently is symptomatic. This chapter thoughtfully and objectively assesses the scientific basis that supports the increasing use of these plant-derived natural products for the treatment of this chronic and progressive disorder. Proper considerations are made on the chemical nature, sources, preclinical tests and their validity, and mechanisms of behavioural or biochemical recovery observed following treatment with various plants derived natural products relevant to PD therapy. The scientific basis underlying the neuroprotective effect of 6 Ayurvedic herbs/formulations, 12 Chinese medicinal herbs/formulations, 33 other plants, and 5 plant-derived molecules have been judiciously examined emphasizing behavioral, cellular, or biochemical aspects of neuroprotection observed in the cellular or animal models of the disease. The molecular mechanisms triggered by these natural products to promote cell survivability and to reduce the risk of cellular degeneration have also been brought to light in this study. The study helped to reveal certain limitations in the scenario: lack of preclinical studies in all cases barring two; heavy dependence on in vitro test systems; singular animal or cellular model to establish any therapeutic potential of drugs. This strongly warrants further studies so as to reproduce and confirm these reported effects. However, the current literature offers scientific credence to traditionally used plant-derived natural products for the treatment of PD.

Recent updates in redox regulation and free radical scavenging effects by herbal products in experimental models of Parkinson's disease

Parkinson’s disease (PD) is a complex multifactorial disease marked by extensive neuropathology in the brain with selective yet prominent and progressive loss of mid-brain dopaminergic neurons. The etiological factors involved in the development of PD are still elusive, but oxidative stress arising when reactive oxygen species (ROS) exceed amounts required for normal redox signaling is considered one of the major factors. ROS cause oxidative damage to proteins, lipids, and DNA and are one of the most prominent factors related to neurodegeneration. Pre-clinical and clinical studies clearly demonstrate the effectiveness of oxidative stress in the pathogenesis of PD. Therefore, regulation of redox signaling and inhibiting excess ROS would contribute greatly not only to extend longevity but also to ameliorate the progression of dopaminergic cell death seen in patients with PD. Several herbal products are beneficial for maintaining nerve cell function and for treating various neurodegenerative disorders by reducing oxidative stress. Here, we summarize the recent knowledge concerning promising herbs that have shown significant beneficial effects based on regulation of redox status and ROS inhibition in toxin-induced PD models.

Neuroprotective effects of curcumin on 6-hydroxydopamine-induced Parkinsonism in rats: behavioral, neurochemical and immunohistochemical studies

Curcumin, the active principle of turmeric used in Indian curry is known for its antitumor, antioxidant, antiarthritic, anti-ischemic and anti-inflammatory properties and might inhibit the accumulation of destructive beta-amyloid in the brains of Alzheimer's disease patients. A Parkinsonian model in rats was developed by giving 6-hydroxydopamine (10 μg/2 μl in 0.1% ascorbic acid-saline) in the right striatum. After 3 weeks of lesioning, the behavior activities (rotarod, narrow beam test, grip test and contra-lateral rotations) were increased in a lesioned group as compared to a sham group and these activities were protected significantly with the pretreatment of curcumin. A significant protection on lipid peroxidation, glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase, tyrosine hydroxylase and D(2) receptor binding was observed in the striatum of lesioned group animals pretreated with 80 mg/kg body weight of curcumin for 21 days as compared to lesion group animals. No significant alterations on behavior and biochemical parameters were observed in sham group animals and the animals of sham group pretreated with curcumin. This study indicates that curcumin, which is an important ingredient of diet in India and also used in various systems of indigenous medicine, is helpful in preventing Parkinsonism and has therapeutic potential in combating this devastating neurologic disorder.

Oral supplementation of Majun Baladar ameliorates antioxidant enzyme activities in cerebral ischaemic damage

Majun Baladar (MB), a traditional herbal formulation of the Unani system of medicine, was studied for its efficacy against cerebral ischaemia-induced oxidative damage in hippocampus and associated neurobehavioural deficits. Adult male Wistar rats were divided into four groups. The first group was sham, the second group was ischaemic (MCAO: middle cerebral artery occluded) and the third group was a MB pre-treated ischaemic group (MCAO + MB). The fourth group was given MB (1.05 g/kg) orally for 15 days as a drug control. The middle cerebral artery was occluded for 2 hr and reperfused for 22 hr in the ischaemic as well as the drug pre-treated group. The activity of the various enzymatic antioxidants like glutathione peroxidase, glutathione reductase, glutathione S-transferase and non-enzymatic antioxidants, glutathione along with levels of lipid peroxidation were evaluated. Cerebral ischaemic rats showed elevated level of lipid peroxidation and decreased levels of various antioxidants significantly over sham values. As a result of MB pre-treatment, the level of lipid peroxidation was found to be significantly depleted as compared to the ischaemic group. Furthermore, depleted levels of glutathione and the activity of glutathione peroxidase, glutathione S-transferase and glutathione reductase were restored significantly in MB treated group. Majun Baladar exhibited a significant improvement in neurobehavioural activities in the drug pre-treated animals as compared to the ischaemic group as evidenced by the grip strength test, Rota-Rod and video path analysis. The results of the present study provide baseline information regarding the neuroprotective efficacy of MB and also open a window for a potent therapeutic use of this traditional herbal Unani medicine.