Dendrite extension by methanol extract of Ashwagandha (roots of Withania somnifera) in SK-N-SH cells

[Overcoming several neurodegenerative diseases by traditional medicines: the development of therapeutic medicines and unraveling pathophysiological mechanisms]

Ashwagandha (root of Withania somnifera) has been used for many purposes, it is mainly considered a tonic in traditional Ayurvedic medicine. This review focuses on the effects of compounds isolated from Ashwagandha on dementia models and on the spinal cord injury model. Our study demonstrated that the active constituents, withanolide A, withanoside IV, and withanoside VI, restored presynapses and postsynapses, in addition to both axons and dendrites in cortical neurons after Abeta(25-35)-induced injury. In vivo, oral withanolide A, withanoside IV, and withanoside VI (10 micromol/kg/day for 12 days) improved Abeta(25-35)-induced memory impairment, neurite atrophy, and synaptic loss in the cerebral cortex and hippocampus in mice. Since spinal cord injury (SCI) is also difficult to treat, and therefore practical and curable strategies for SCI are desired. Oral treatment with withanoside IV improved locomotor functions in mice with SCI. In mice treated with withanoside IV (10 micromol/kg/day for 21 days), the axonal density and peripheral nervous system myelin level increased. The loss of CNS myelin and increase in reactive gliosis were not affected by withanoside IV. Additionally, sominone, an aglycone of withanoside IV, was identified as the main metabolite after oral administration of withanoside IV in mice. Withanolide A, withanoside IV, and withanoside VI are therefore important candidates for the therapeutic treatment of neurodegenerative diseases. In particular, withanoside IV was shown to control neurons as well as glial cells for reconstruction neuronal networks. To clarify key events in overcoming neurodegeneration, we are now studying the molecular targets and signal cascades of sominone.

Withania somnifera: an Indian ginseng

Withania somnifera, popularly known as Ashwagandha is widely considered as the Indian ginseng. In Ayurveda, it is classified as a rasayana (rejuvenation) and expected to promote physical and mental health, rejuvenate the body in debilitated conditions and increase longevity. Having wide range of activity, it is used to treat almost all disorders that affect the human health. The present review discusses the pharmacological basis of the use of W. somnifera in various central nervous system (CNS) disorders, particularly its indication in epilepsy, stress and neurodegenerative diseases such as Parkinson's and Alzheimer's disorders, tardive dyskinesia, cerebral ischemia, and even in the management of drug addiction.

Selective killing of cancer cells by leaf extract of Ashwagandha: identification of a tumor-inhibitory factor and the first molecular insights to its effect

PURPOSE

Ashwagandha is regarded as a wonder shrub of India and is commonly used in Ayurvedic medicine and health tonics that claim its variety of health-promoting effects. Surprisingly, these claims are not well supported by adequate studies, and the molecular mechanisms of its action remain largely unexplored to date. We undertook a study to identify and characterize the antitumor activity of the leaf extract of ashwagandha.

EXPERIMENTAL DESIGN

Selective tumor-inhibitory activity of the leaf extract (i-Extract) was identified by in vivo tumor formation assays in nude mice and by in vitro growth assays of normal and human transformed cells. To investigate the cellular targets of i-Extract, we adopted a gene silencing approach using a selected small hairpin RNA library and found that p53 is required for the killing activity of i-Extract.

RESULTS

By molecular analysis of p53 function in normal and a variety of tumor cells, we found that it is selectively activated in tumor cells, causing either their growth arrest or apoptosis. By fractionation, purification, and structural analysis of the i-Extract constituents, we have identified its p53-activating tumor-inhibiting factor as with a none.

CONCLUSION

We provide the first molecular evidence that the leaf extract of ashwagandha selectively kills tumor cells and, thus, is a natural source for safe anticancer medicine.

Withanoside IV improves hindlimb function by facilitating axonal growth and increase in peripheral nervous system myelin level after spinal cord injury

Although methylprednisolone is the clinically standard medication and almost the only therapy for spinal cord injury (SCI), its effect on functional recovery remains questionable. Transplantation strategies using sources such as neural stem cells and embryonic spinal cord still have some hurdles to overcome before practical applications become available. We therefore aimed to develop a practical medication for SCI. Per oral treatment with withanoside IV, which was previously shown to regenerate neuronal networks in the brain, improved locomotor functions in mice with SCI. In the spinal cord after SCI, axons were crushed in the white matter and gray matter, and central nervous system (CNS) myelin level decreased. In mice treated with withanoside IV (10micromol/kg body weight/day, for 21 days), axonal density and peripheral nervous system (PNS) myelin level increased. The loss of CNS myelin and increase in reactive gliosis were not affected by withanoside IV. These results suggest that oral administration of withanoside IV may ameliorate locomotor functions by facilitating both axonal regrowth and increase in PNS myelin level.

Withania somnifera improves bone calcification in calcium-deficient ovariectomized rats

Osteoporosis, characterized by reduction in bone density, is a significant source of mortality among the elderly, particularly in oestrogen-deficient women. We studied the effect of Withania somnifera (WS) root extract (ethanolic), which contains oestrogen-like withanolides for anti-osteoporotic activity. Female Sprague-Dawley rats were either sham operated (n = 12) or ovariectomized (n = 12) and treated with WS/vehicle (65 mg kg(-1)), orally for 16 weeks (n = 12). All rats were allowed free access to a calcium-deficient diet (0.04% Ca) and distilled water. At termination, urinary excretion of calcium (Ca) and phosphorus (P) and serum levels of Ca, P and alkaline phosphatase (ALP) were measured. Femur and tibia bones were processed for histological (histology), morphological (scanning electron microscopy, SEM), biomechanical strength (impact test) and mineral composition (ash) analysis. Ovariectomized (OVX) rats showed a significant increase in serum ALP levels and urinary Ca and P excretion. Histological findings revealed narrowed, and disappearance of, trabeculae with widened medullary spaces in the OVX group. Ash analysis showed a reduction in ash weight, percent ash, ash Ca, ash P and ash magnesium levels in the OVX group. Further, SEM examination revealed metaphyseal bone loss in femurs and impact test showed a reduction in biomechanical strength of tibias in OVX rats. WS treatment markedly prevented the above changes in OVX rats and thus may be a potential agent in the treatment of osteoporosis.

Withanoside IV and its active metabolite, sominone, attenuate Aβ(25-35)-induced neurodegeneration

At the present, medication of dementia is limited to symptomatic treatments such as the use of cholinesterase inhibitors. To cure dementia completely, that is regaining neuronal function, reconstruction of neuronal networks is necessary. Therefore, we have been exploring antidementia drugs based on reconstructing neuronal networks in the damaged brain and found that withanoside IV (a constituent of Ashwagandha; the root of Withania somnifera) induced neurite outgrowth in cultured rat cortical neurons. Oral administration of withanoside IV (10 micromol/kg/day) significantly improved memory deficits in Abeta(25-35)-injected (25 nmol, i.c.v.) mice and prevented loss of axons, dendrites, and synapses. Sominone, an aglycone of withanoside IV, was identified as the main metabolite after oral administration of withanoside IV. Sominone (1 microM) induced axonal and dendritic regeneration and synaptic reconstruction significantly in cultured rat cortical neurons damaged by 10 microM Abeta(25-35). These data suggest that orally administrated withanoside IV may ameliorate neuronal dysfunction in Alzheimer's disease and that the active principle after metabolism is sominone.

Search for natural products related to regeneration of the neuronal network

The reconstruction of neuronal networks in the damaged brain is necessary for the therapeutic treatment of neurodegenerative diseases. We have screened the neurite outgrowth activity of herbal drugs, and identified several active constituents. In each compound, neurite outgrowth activity was investigated under amyloid-beta-induced neuritic atrophy. Most of the compounds with neurite regenerative activity also demonstrated memory improvement activity in Alzheimer's disease-model mice. Protopanaxadiol-type saponins in Ginseng drugs and their metabolite, M1 (20-O-beta-D-glucopyranosyl-(20S)-protopanaxadiol), showed potent regeneration activity for axons and synapses, and amelioration of memory impairment. Withanolide derivatives (withanolide A, withanoside IV, and withanoside VI) isolated from the Indian herbal drug Ashwagandha, also showed neurite extension in normal and damaged cortical neurons. Trigonelline, a constituent of coffee beans, demonstrated the regeneration of dendrites and axons, in addition to memory improvement.

Neuritic regeneration and synaptic reconstruction induced by withanolide A

We investigated whether withanolide A (WL-A), isolated from the Indian herbal drug Ashwagandha (root of Withania somnifera), could regenerate neurites and reconstruct synapses in severely damaged neurons. We also investigated the effect of WL-A on memory-deficient mice showing neuronal atrophy and synaptic loss in the brain. Axons, dendrites, presynapses, and postsynapses were visualized by immunostaining for phosphorylated neurofilament-H (NF-H), microtubule-associated protein 2 (MAP2), synaptophysin, and postsynaptic density-95 (PSD-95), respectively. Treatment with A beta(25-35) (10 microM) induced axonal and dendritic atrophy, and pre- and postsynaptic loss in cultured rat cortical neurons. Subsequent treatment with WL-A (1 microM) induced significant regeneration of both axons and dendrites, in addition to the reconstruction of pre- and postsynapses in the neurons. WL-A (10 micromol kg(-1) day(-1), for 13 days, p.o.) recovered A beta(25-35)-induced memory deficit in mice. At that time, the decline of axons, dendrites, and synapses in the cerebral cortex and hippocampus was almost recovered. WL-A is therefore an important candidate for the therapeutic treatment of neurodegenerative diseases, as it is able to reconstruct neuronal networks.

Evaluation of the anti-proliferative and anti-oxidative activities of leaf extract from in vivo and in vitro raised Ashwagandha

Withania somnifera (Ashwagandha) is used in Indian traditional medicine, Ayurveda and is believed to have a variety of health promoting effects. Molecular mechanisms and pathways underlying these effects have not been studied. We tried to characterize various activities of leaf extract of Ashwagandha (Lash) raised in the field and in the laboratory. We found that the Lash from field-raised plants has a significant anti-proliferative activity in human tumorigenic cells. However, it did not impart any protection against the oxidative damage caused by high glucose and hydrogen peroxide to human tumor cells suggesting that it can be used as an anti-tumor, but not as an anti-oxidant, substance.

Rasayanas: evidence for the concept of prevention of diseases

Rasayanas are non-toxic Ayurvedic complex herbal preparations or individual herbs used to rejuvenate or attain the complete potential of an individual in order to prevent diseases and degenerative changes that leads to disease. The present paper reviews various activities of rasayanas to support the above concept, its role as a prophylactic medication and significance in the prevention of diseases in both healthy as well as diseased individuals. The emerging data suggest that the possible mechanisms may be by immunostimulation, quenching free radicals, enhancing cellular detoxification mechanisms, repair damaged non-proliferating cells, inducing cell proliferation and self-renewal of damaged proliferating tissues, and replenishing them by eliminating damaged or mutated cells with fresh cells.

Axon- or dendrite-predominant outgrowth induced by constituents from Ashwagandha

We previously reported that the methanol extract of Ashwagandha (roots of Dunal) induced dendrite extension in a human neuroblastoma cell line. In this study, we found that six of the 18 compounds isolated from the methanol extract enhanced neurite outgrowth in human neuroblastoma SH-SY5Y cells. Double immunostaining was performed in rat cortical neurons using antibodies to phosphorylated NF-H as an axonal marker, and to MAP2 as a dendritic marker. In withanolide A-treated cells, the length of NF-H-positive processes was significantly increased compared with vehicle-treated cells, whereas, the length of MAP2-positive processes was increased by withanosides IV and VI. These results suggest that axons are predominantly extended by withanolide A, and dendrites by withanosides IV and VI.

Dammarane-type Saponins from Panax japonicus and their neurite outgrowth activity in SK-N-SH cells

Four new dammarane-type saponins (1-4), named yesanchinosides G-J, together with nine ginsenosides (5-13) were isolated from Ye-Sanchi, the underground part of Panax japonicus collected in the south of Yunnan Province, China. Their structures were elucidated on the basis of spectroscopic and chemical methods. Ginsenosides Rb(1) and Rb(3) and notoginsenosides R(4) (6) and Fa (7) showed significant neurite outgrowth enhancing activities in human neuroblastoma SK-N-SH cells.

Withanolide derivatives from the roots of Withania somnifera and their neurite outgrowth activities

Five new withanolide derivatives (1, 9-12) were isolated from the roots of Withania somnifera together with fourteen known compounds (2-8, 13-19). On the basis of spectroscopic and physiochemical evidence, compounds 1 and 9-12 were determined to be (20S,22R)-3 alpha,6 alpha-epoxy-4 beta,5 beta,27-trihydroxy-1-oxowitha-24-enolide (1), 27-O-beta-D-glucopyranosylpubesenolide 3-O-beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranoside (withanoside VIII, 9), 27-O-beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranosylpubesenolide 3-O-beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranoside (withanoside IX, 10), 27-O-beta-D-glucopyranosylpubesenolide 3-O-beta-D-glucopyranoside (withanoside X, 11), and (20R,22R)-1 alpha,3 beta,20,27-tetrahydroxywitha-5,24-dienolide 3-O-beta-D-glucopyranoside (withanoside XI, 12). Of the isolated compounds, 1, withanolide A (2), (20S,22R)-4 beta,5 beta,6 alpha,27-tetrahydroxy-1-oxowitha-2,24-dienolide (6), withanoside IV (14), withanoside VI (15) and coagulin Q (16) showed significant neurite outgrowth activity at a concentration of 1 microM on a human neuroblastoma SH-SY5Y cell line.