Withanolide D, carrying the baton of Indian rasayana herb as a lead candidate of antileukemic agent in modern medicine

Natural withanolides, an update

Covering: March 2010 to December 2020. Previous review: Nat. Prod. Rep., 2011, 28, 705This review summarizes the latest progress and perspectives on the structural classification, biological activities and mechanisms, metabolism and pharmacokinetic investigations, biosynthesis, chemical synthesis and structural modifications, as well as future research directions of the promising natural withanolides. The literature from March 2010 to December 2020 is reviewed, and 287 references are cited.

Improving the inhibition of β-amyloid aggregation by withanolide and withanoside derivatives

Here, we have studied the ameliorative effects of Withania somnifera derivatives (Withanolide A, Withanolide B, Withanoside IV, and Withanoside V) on the fibril formation of amyloid-β ₄₂ for Alzheimer's disease. We analyzed reduction in the aggregation of β amyloid protein with these Ashwagandha derivatives by Thioflavin T assay in the oligomeric and fibrillar state. We have tested the cytotoxic activity of these compounds against human SK-N-SH cell line for 48 h, and the IC ₅₀ value found to be 28.61 ± 2.91, 14.84 ± 1.45, 18.76 ± 0.76 and 30.14 ± 2.59 μM, respectively. After the treatment of the cells with half the concentration of IC ₅₀ value, there was a remarkable decrease in the number of apoptotic cells stained by TUNEL assay indicating the DNA damage and also observed significant decrease of reactive oxygen species. Also, the binding and molecular stability of these derivatives with amyloid β was also studied using bioinformatics tools where these molecules were interacted at LVFFA region which is inhibition site of amyloid-β1 ₄₂. These studies revealed that the Withanolides and Withanosides interact with the hydrophobic core of amyloid-β _1-42 in the oligomeric stage, preventing further interaction with the monomers and diminishing aggregation.

Withania somnifera L.: Insights into the phytochemical profile, therapeutic potential, clinical trials, and future prospective

Withania somnifera L. is a multipurpose medicinal plant of family Solanaceae occurring abundantly in sub-tropical regions of the world. The folk healers used the plant to treat several diseases such as fever, cancer, asthma, diabetes, ulcer, hepatitis, eyesores, arthritis, heart problems, and hemorrhoids. The plant is famous for the anti-cancerous activity, low back pain treatment, and muscle strengthening, which may be attributed to the withanolide alkaloids. W. somnifera is also rich in numerous valued secondary metabolites such as steroids, alkaloids, flavonoids, phenolics, saponins, and glycosides. A wide range of preclinical trials such as cardioprotective, anticancer, antioxidant, antibacterial, antifungal, anti-inflammatory, hepatoprotective, anti-depressant, and hypoglycemic have been attributed to various parts of the plant. Different parts of the plant have also been evaluated for the clinical trials such as male infertility, obsessive-compulsive disorder, antianxiety, bone and muscle strengthening potential, hypolipidemic, and antidiabetic. This review focuses on folk medicinal uses, phytochemistry, pharmacological, and nutrapharmaceutical potential of the versatile plant.

Studies on Ashwagandha Ghrita with reference to murcchana process and storage conditions

Background

Withania somnifera (L.) (family-Solanaceae), known as ‘Indian ginseng’ or ‘Ashwagandha’ is acclaimed as an effective adaptogen, immunomodulator, aphrodisiac and sedative. Ashwagandhaghrita is a recognized ghee based Ayurvedic formulation. Few ancient texts suggest murcchana process for preparation of Ashwagandha ghrita.

Objective

The study was undertaken to evaluate probable effects of murcchana process on ghrita preparation with reference to time and storage conditions.

Materials and Methods

Ashwagandha ghrita samples were prepared separately using plain ghee (Indian cow's ghee) and murcchana ghee. These formulations were stored separately in different glass bottles at room temperature and 400C/75%RH. Organoleptic characters (colour, odour, taste, texture and touch) and physicochemical parameters (acid value, peroxide value, iodine value, saponification value, unsaponifiable matter, refractive index and specific gravity) were determined after 3, 6, 9 and 12 months. Plain ghee and prepared ghrita were subjected for antioxidant evaluation by various in vitro methods.

Results

Changes were observed in organoleptic characters and physicochemical parameters of plain ghee and Ashwagandha ghrita formulations. Alterations in these parameters were more pronounced at high temperature and on long storage. Ashwagandha ghrita prepared with murcchana process exhibited better antioxidant potential in all in vitro methods.

Conclusion

The murcchana process was found to be beneficial towards quality of ghrita. Hence, Ashwagandha ghrita may be prepared along with murcchana herbs and stored in a good quality glass bottle to ensure improved shelf life of ghrita.

Three new C23 steroids from the leaves and stems of Nicandra physaloides

Nicandra physaloides is a medicinal and edible plant and has been used as traditionally herbal medicine to treat various diseases in folk. Its characteristic withanolides, a kind of ergostane-type steroids, are reported to display plentiful biological activities that many explain the effect of N. physaloides to some extent. Thus, to further find bioactive steroids, the stems and leaves of N. physaloides were investigated and three new C23 steroids, nic-physatones I-J (1-2), and nic-physatone S (3), together with a known C25 steroid, nic 17 (4), were isolated. Their structures were elucidated by extensive 1D NMR and 2D NMR (HSQC, HMBC, ¹H-¹H COSY, and ROESY), UV and MS analyses. Compounds 1-3 possess a rare C23 steroid skeleton. Among them, compound 3 represented the first example of a C23 steroid featuring a benzene ring (D ring). The isolated compounds showed no cytotoxic activity.

Eburneolins A and B, new withanolide glucosides from Tricholepis eburnea

Eburneolins A (1) and B (2), new withanolide glucosides, have been isolated from the n-butanolic fraction of the 75% methanolic extract of aerial parts of Tricholepis eburnea. Their structures were elucidated through spectroscopic analysis including ESI-MS, 2D NMR and acid hydrolysis.

Biochemical and biophysical methodologies open the road for effective schistosomiasis therapy and vaccination

BACKGROUND

Schistosomiasis caused by blood-dwelling flukes, namely Schistosoma mansoni and Schistosoma haematobium is a severe debilitating disease, widespread in sub-Saharan Africa, the Middle East, and South America. Developing and adult worms are unscathed by the surrounding immune effectors and antibodies because the parasite is protected by a double lipid bilayer armor which allows access of nutrients, while binding of specific antibodies is denied.

SCOPE OF REVIEW

Fluorescence recovery after bleaching, extraction of surface membrane cholesterol by methyl-β-cyclodextrin, inhibition and activation of sphingomyelin biosynthesis and hydrolysis, and elastic incoherent and quasi-elastic neutron scattering approaches have helped to clarify the basic mechanism of this immune evasion, and showed that sphingomyelin (SM) molecules in the worm apical lipid bilayer form with surrounding water molecules a tight hydrogen bond barrier. Viability of the parasite and permeability of the outer shield are controlled by equilibrium between SM biosynthesis and activity of a tegument-associated neutral sphingomyelinase (nSMase).

MAJOR CONCLUSIONS

Excessive nSMase activation by polyunsaturated fatty acids (PUFA), such as arachidonic acid (ARA) leads to disruption of the SM molecules and associated hydrogen bond network, with subsequent access of host antibodies and immune effectors to the outer membrane and eventual parasite death.

GENERAL SIGNIFICANCE

ARA was predicted and shown to be a potent schistosomicide in vitro and in vivo in experimental animals and in children. Additionally, it was advocated that schistosomiasis vaccine candidates should be selected uniquely among excretory-secretory products of developing worms, as contrary to cytosolic and surface membrane antigens, they are able to activate the effector functions of the host antibodies and toxic molecules. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo".

Tropine forming tropinone reductase gene from Withania somnifera (Ashwagandha): biochemical characteristics of the recombinant enzyme and novel physiological overtones of tissue-wide gene expression patterns

Withania somnifera is one of the most reputed medicinal plants of Indian systems of medicine synthesizing diverse types of secondary metabolites such as withanolides, alkaloids, withanamides etc. Present study comprises cloning and E. coli over-expression of a tropinone reductase gene (WsTR-I) from W. somnifera, and elucidation of biochemical characteristics and physiological role of tropinone reductase enzyme in tropane alkaloid biosynthesis in aerial tissues of the plant. The recombinant enzyme was demonstrated to catalyze NADPH-dependent tropinone to tropine conversion step in tropane metabolism, through TLC, GC and GC-MS-MS analyses of the reaction product. The functionally active homodimeric ∼60 kDa enzyme catalyzed the reaction in reversible manner at optimum pH 6.7. Catalytic kinetics of the enzyme favoured its forward reaction (tropine formation). Comparative 3-D models of landscape of the enzyme active site contours and tropinone binding site were also developed. Tissue-wide and ontogenic stage-wise assessment of WsTR-I transcript levels revealed constitutive expression of the gene with relatively lower abundance in berries and young leaves. The tissue profiles of WsTR-I expression matched those of tropine levels. The data suggest that, in W. somnifera, aerial tissues as well possess tropane alkaloid biosynthetic competence. In vivo feeding of U-[¹⁴C]-sucrose to orphan shoot (twigs) and [¹⁴C]-chasing revealed substantial radiolabel incorporation in tropinone and tropine, confirming the de novo synthesizing ability of the aerial tissues. This inherent independent ability heralds a conceptual novelty in the backdrop of classical view that these tissues acquire the alkaloids through transportation from roots rather than synthesis. The TR-I gene expression was found to be up-regulated on exposure to signal molecules (methyl jasmonate and salicylic acid) and on mechanical injury. The enzyme's catalytic and structural properties as well as gene expression profiles are discussed with respect to their physiological overtones.

Molecular characterization and promoter analysis of squalene epoxidase gene from Withania somnifera (L.) Dunal

Withania somnifera is a rich reservoir of pharmaceutically active steroidal lactones known as withanolides. The plant is well characterized in terms of its chemistry and pharmacology, but very little is known about the pathway involved in the biosynthesis of withanolides. The present investigation describes the cloning, characterization and expression of squalene epoxidase (SE) gene from W. somnifera. SE (SQE; EC. 1.14.99.7) is one of the rate limiting enzymes in the biosynthesis of triterpenoids, catalyzing the stereospecific epoxidation of squalene to 2,3-oxidosqualene. A full length SE gene (WsSQE) of 1,956 bp was cloned which contained an open reading frame of 1,596 bp, encoding a protein of 531 amino acids with a predicted molecular mass of 57.67 kDa and theoretical PI of 8.48. Full length WsSQE was cloned into pGEX4T-2 vector and expressed in E.coli. Phylogenetic analysis indicated a significant evolutionary relatedness of WsSQE with squalene epoxidases of other plant species and the degree of relatedness with deduced amino acid sequences showed a significant correlation with different plant species. Using genome walking approach, a promoter sequence of 513 bp of WsSQE was isolated which revealed several key cis-regulatory elements known to be involved in various biotic and abiotic plant stresses. Comparative expression analysis of tissue specific WsSQE done by quantitative-PCR demonstrated the highest transcript levels in leaves, as compared to stalk and root tissues. This is the first report of cloning and bacterial expression of SE from W. somnifera and may be of significant interest to understand the regulatory role of SE in the biosynthesis of withanolides.