Anhydroparthenin as a dual-target inhibitor against Sterol C-24 methyltransferase and Sterol 14-α demethylase of Leishmania donovani: A comprehensive in vitro and in silico study

Parthenium hysterophorus plant has a diverse chemical profile and immense bioactive potential. It exhibits excellent pharmacological properties such as anti-cancer, anti-inflammatory, anti-malarial, microbicidal, and anti-trypanosomal. The present study aims to evaluate the anti-leishmanial potential and toxicological safety of anhydroparthenin isolated from P. hysterophorus. Anydroparthenin was extracted from the leaves of P. hysterophorus and characterized through detailed analysis of 1H, 13C NMR, and HRMS. Dye-based in vitro and ex vivo assays confirmed that anhydroparthenin significantly inhibited both promastigote and amastigote forms of the Leishmania donovani parasites. Both the cytotoxicity experiment and hemolytic assay revealed its non-toxic nature and safety index in the range of 10 to 15. Further, various mechanistic assays suggested that anhydroparthenin led to the generation of oxidative stress, intracellular ATP depletion, alterations in morphology and mitochondrial membrane potential, formation of intracellular lipid bodies, and acidic vesicles, ultimately leading to parasite death. As a dual targeting approach, computational studies and sterol quantification assays confirmed that anhydroparthenin inhibits the Sterol C-24 methyl transferase and Sterol 14-α demethylase proteins involved in the ergosterol biosynthesis in Leishmania parasites. These results suggest that anhydroparthenin could be a promising anti-leishmanial molecule and can be developed as a novel therapeutic stratagem against leishmaniasis.

Semisynthesis of Novel Dispiro-pyrrolizidino/thiopyrrolizidino-oxindolo/indanedione Natural Product Hybrids of Parthenin Followed by Their Cytotoxicity Evaluation

Natural products possess unique and broader intricacies in the chemical space and have been essential for drug discovery. The crucial factor for drug discovery success is not the size of the library but rather its structural diversity. Although reports on the number of new structurally diverse natural products (NPs) have declined recently, researchers follow the next logical step: synthesizing natural product hybrids and their analogues using the most potent tool, diversity-oriented synthesis (DOS). Here, we use weed Parthenium hysterophorus as a source of parthenin for synthesis of novel dispiro-pyrrolizidino/thiopyrrolizidino-oxindolo/indanedione natural product hybrids of parthenin via chemo-, regio-, and stereoselective azomethine ylide cycloaddition. All synthesized compounds were characterized through a detailed analysis of one-dimensional (1D) and two-dimensional (2D) NMR and HRMS data, and the stereochemistries of the compounds were confirmed by X-ray diffraction analysis. All compounds were evaluated for their cytotoxicity against four cell lines (HCT-116, A549, Mia-Paca-2, and MCF-7), and compound 6 inhibited the HCT-116 cells with an IC50 of 5.0 ± 0.08 μM.

TFA-mediated stereoselective aza-Michael addition for the synthesis of 3β-arylamine derivatives of withaferin A and evaluation of their anticancer potential

A simple and efficient protocol for the aza-Michael addition of various aromatic anilines to ring A of withaferin A has been developed. Stereoselectivity, functional group tolerance, broad substrate scope, short reaction time and moderate to high yield are the merits of the protocol. One of the synthesized compounds 11 shows an IC 50 value of 3.8 μM against aggressive, highly metastatic triple-negative breast cancer cell line MDA-MB-231.

Two new cycloartane type triterpenes from Dysoxyllum binectariferum

Dysoxyllum binectariferum is an important medicinal plant known for various biological activities like anti-inflammatory, CNS depressants, contraceptive, analgesic, immunomodulatory, antimalarial, antifeedant, leishmanicidal and antiviral. It is a rich source of rohitukine, a basic skeleton of flavopiridol. Phytochemical investigation of chloroform extracts of Dysoxyllum binectariferum leaves, lead to the isolation of beddomeilactone (1) and two new cycloartane type triterpenoids beddomeilactol (2) and binectarilactone-A (3) with modified A ring. Compounds were assessed for their in-vitro α-glucosidase inhibitory activity. Compound 1 was found to be most potent, showing IC50 of 17.99 ± 0.26 µg/ml which is comparable to the positive control acarbose.

Natural Products Containing Olefinic Bond: Important Substrates for Semi-synthetic Modification Towards Value Addition

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Semi-synthesis, the way of preparing novel bioactive molecules via modification of compounds isolated from natural sources is very much useful nowadays in the drug discovery process. The modification is based on the reaction of functional group(s) present in a natural compound. Among the examples of functional group transformation, double bond modification is also common in the literature. Several reactions like hydrogenation, cyclopropanation, epoxidation, addition reaction (halogenations, hydroxylation), Michael addition, Heck reaction, cycloaddition, dipolar cycloaddition, etc. are employed for this purpose. In this review, we have tried to gather the reactions performed with several double bond containing classes of natural products like diterpenes, xanthones, sesquiterpene exomethylene lactones, diaryl heptanoids, steroidal lactones, triterpenoids, limonoids, and alkamides. Where available, the effects of transformations on the biological activities of the molecules are also mentioned.

Azomethine ylide cycloaddition: a versatile tool for preparing novel pyrrolizidino-spiro-oxindolo hybrids of the doubly conjugated alkamide piperine

A facile, multicomponent (MCR) atom-economic synthesis of novel spiro-oxindolo pyrrolizidine adducts of piperine has been achieved via an intermolecular 1,3-dipolar azomethine ylide cycloaddition reaction. Either of the two conjugated double bonds in piperine takes part in the reaction to produce two regioisomeric adducts in racemic form. Acenaphthoquinone, ninhydrin and different isatin derivatives were reacted with proline and piperine to afford a never before reported library of 22 compounds. The structures of the products were determined by 1D/2D NMR, mass spectral analysis and confirmed by X-ray crystallography of selected products. Chiral HPLC separation was performed to measure the specific rotation and CD spectra of the enantiomers for two racemic compounds.

Semi-synthesis of a novel hybrid isoxazolidino withaferin via chemoselective and diastereoselective 1,3-dipolar nitrone cycloaddition reaction

A facile, atom-economic synthesis of isoxazilidino withaferin, a novel hybrid of withaferin A, has been accomplished via two-step reaction of nitrone synthesis followed by nitrone 1,3-dipolar cycloaddition. The reaction is highly chemoselective (preferential reaction only on one of the two double bonds present on withaferin A) and diastereoselective affording exclusively the cis-fused products. The structure was determined by detailed analysis of 1D, 2D NMR and mass spectral data.

Synthesis of diversely substituted bis-pyrrolizidino/ thiopyrrolizidino oxindolo/acenaphthyleno curcuminoids via sequential azomethine ylide cycloaddition

Curcumin has been transformed to several diversely substituted bis-pyrrolizidino/thiopyrrolizidino oxindolo/acenaphthyleno curcuminoids via a sequential azomethine ylide cycloaddition reaction using isatins/acenaphthoquinone and proline/thioproline as the reagents. The products were separated via extensive chromatography and characterized by 1D/2D NMR and HRMS analysis.

Curcumin has been transformed to several diversely substituted bis-pyrrolizidino/thiopyrrolizidino oxindolo/acenaphthyleno curcuminoids via a sequential azomethine ylide cycloaddition reaction.

Tamarixetin 3-O-β-d-Glucopyranoside from Azadirachta indica Leaves: Gastroprotective Role through Inhibition of Matrix Metalloproteinase-9 Activity in Mice

Neem (Azadirachta indica) is a well-known medicinal and insecticidal plant. Although previous studies have reported the antiulcer activity of neem leaf extract, the lead compound is still unidentified. The present study reports tamarixetin 3-O-β-d-glucopyranoside (1) from a methanol extract of neem leaves and its gastroprotective activity in an animal model. Compound 1 showed significant protection against indomethacin-induced gastric ulceration in mice in a dose-dependent manner. Moreover, ex vivo and circular dichroism studies confirmed that 1 inhibited the enzyme matrix metalloproteinase-9 (MMP-9) activity with an IC₅₀ value of ca. 50 μM. Molecular docking and dynamics showed the binding of 1 into the pocket of the active site of MMP-9, forming a coordination complex with the catalytic zinc, thus leading to inhibition of MMP-9 activity.

Ultrastructural changes in Raillietina (Platyhelminthes: cestoda), exposed to sulfonoquinovosyldiacylglyceride (SQDG), isolated from Neem (Azadirachta indica)

Neem (Azadirachta indica), has been known to be a curative for various ailments and diseases in the traditional Indian medicinal system from times immemorial. A glycolipid sulfonoquinovosyldiacylglyceride (SQDG) isolated from the leaves of neem has been found to be a proactive antibacterial and antiviral agent in previous studies. The current communication pertains to the anthelmintic activity of SQDG in vitro against a model cestode Raillietina spp. The results of efficacy tests showed a paralysis time of 1.0 ± 0.1 and 0.7 ± 0.01 h, whereas death time of 1.6 ± 0.3 and 0.9 ± 0.02 h, following treatments with dosages of 0.5 and 1.0 mg/mL, respectively. The scanning electron microscopic studies showed significant and unique changes in the ultrastructure of the worms with prominent breakages and furrows on the surface.

Importance of Neem Leaf: An insight into its role in combating diseases

The neem (Azadirachta indica A. Juss) is a tropical evergreen tree (Fam. Meliacae; Subfam. Melioideae) traditionally well known for its medicinal value. Beneficialt effects of different parts of neem are attributed to its biologically active principle ‘Azadirachtin’. Apart from Indian subcontinent, neem is widely used in African countries as therapeutics, preservatives and insecticides. Neem leaves, natural source of flavonoids, polyphenols, isoprenoids, sulphurous and polysaccharides, play important role in scavenging the free radical and subsequently arresting disease pathogenesis. Considerable research has gone into neem for developing cost effective and non-toxic products. The present review has compiled different phytochemicals isolated from neem leaves, methods of extraction and their therapeutic use in preventing several diseases. Here, we highlighted the mechanism of anti-inflammatory and antioxidant activity of neem leaf that underscores the disease through regulation of physiological responses. Also, multiple roles of neem leaf and commercial use of neem formulation as an alternative in paving a frontier in the field of drug discovery are discussed.

Synthesis of Bis-pyrrolizidine-Fused Dispiro-oxindole Analogues of Curcumin via One-Pot Azomethine Ylide Cycloaddition: Experimental and Computational Approach toward Regio- and Diastereoselection

Curcumin has been transformed to racemic curcuminoids via an azomethine ylide cycloaddition reaction using isatin/acenaphthoquinone and proline as the reagents. The products were characterized by extensive 1D/2D NMR analysis and single-crystal X-ray crystallographic studies. The enantiomers of one racemic product were separated by HPLC on a Chiralcel OD-H column and were indeed confirmed by the CD spectra of the separated enantiomers.

Cytotoxic potential of dispirooxindolo/acenaphthoquino andrographolide derivatives against MCF-7 cell line

Dispiro andrographolides induce a caspase-dependent apoptotic cell death pathway in breast cancer (MCF-7) cells.

Copper-phenanthroline catalysts for regioselective synthesis of pyrrolo[3',4':3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines and of pyrrolo[1,2-a]phenanthrolines under mild conditions

A new series of pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines and pyrrolo[1,2-a]phenanthrolines were efficiently built up from an 8-hydroxyquinoline derivative or phenanthroline via 1,3-dipolar cycloaddition reaction involving non-stabilized azomethine ylides, generated in situ from the parent furo[3,2-h]quinoliniums/phenanthroliums, in presence of a copper(II) chloride–phenanthroline catalytic system. The methodology combines general applicability with high yields.

Antibacterial and antiviral evaluation of sulfonoquinovosyldiacylglyceride: a glycolipid isolated from Azadirachta indica leaves

Assessment of antibacterial as well as antiherpes virus activity of sulfonoquinovosyldiacylglyceride (SQDG), a glycolipid, isolated from the leaves of Azadirachta indica has been described. Antimicrobial activity was evaluated against Gram-positive, Gram-negative bacteria and herpes simplex virus. SQDG showed significant inhibitory activity against Salmonella typhi and two isolates of Shigella dysenteriae with MIC values 32 μg ml(-1) , while three isolates of Salm. typhi, Escherichia coli and Vibrio cholerae were inhibited at 64 μg ml(-1) and have shown zone diameter ranging from 6.2 to 12.3 mm. The growth kinetics study of SQDG on Salm. typhi and Sh. dysenteriae revealed that the growths were completely inhibited at their MIC values within 24 h of exposure. Interestingly, SQDG inhibits herpes simplex virus (HSV) type 1 and 2 with the EC50 of 9.1 and 8.5 μg ml(-1) , compared with acyclovir (2.2 and 2.8 μg ml(-1) against HSV-1 and HSV-2). The selectivity index (SI) was found to be 12.4 against HSV-1 and 13.41 with HSV-2. Furthermore, the expression of proinflammatory cytokines of HSV-infected and SQDG-treated macrophages using ELISA kit revealed that SQDG significantly downregulated the production of TNF-α, IL-1β, IL-12 and IL-6.

SIGNIFICANCE AND IMPACT OF THE STUDY

The water-soluble metabolite sulfonoquinovosyldiacylglyceride (SQDG) isolated from Azadirachta indica (Neem) possess significant antibacterial as well as anti-HSV activity. The efficacies as well as the solubility factor of SQDG substantiate a greater attention for its use as phytotherapeutic drug for controlling microbial infections as most consumers have better acceptance of phytomedicines than synthetic drugs.

Evaluation of the wound healing activity of Shorea robusta, an Indian ethnomedicine, and its isolated constituent(s) in topical formulation

ETHNOPHARMACOLOGICAL RELEVANCE

Different parts of Indian ethnomedicinal plant Shorea robusta is traditionally used for several ailments including wounds and burn by different tribal groups, since ages. Here we have validated, for the first time, the effectiveness and the possible mechanism of action of young leaf extracts of Shorea robusta, used by two distinct tribes of India, and its isolated compounds as a topical formulation in three wound models in rats.

MATERIALS AND METHODS

Bioactivity-guided study of the active extract resulted in the isolation of two known compounds. The prepared ointment containing extracts (2.5 and 5%, w/w), fractions (5% w/w) and isolated compounds (0.25% w/w) were evaluated on excision, incision and dead space wound models in rats by the rate of wound closure, period of epithelialisation, tensile strength, granulation tissue weight, hydroxyproline content and histopathology.

RESULTS

The animals treated with the extracts and fractions (5%) showed significant reduction in wound area 96.55 and 96.41% with faster epithelialisation (17.50 and 17.86), while the isolated compounds bergenin and ursolic acid heal the wound faster, but complete epithelialisation with 100% wound contraction was evident with 5% povidone-iodine group on 18th post-wounding day. Moreover, the tensile strength of incision wound, granuloma tissue weight, and hydroxyproline content was significantly increased in both the extract and compound(s) treated animals. Furthermore, the tissue histology of animals treated with the isolated compound(s) showed complete epithelialisation with increased collagenation, similar to povidone-iodine group.

CONCLUSION

Thus, our results validated the traditional use of Shorea robusta young leaves in wound management.

Regio- and stereoselective synthesis of a library of bioactive dispiro-oxindolo/acenaphthoquino andrographolides via 1,3-dipolar cycloaddition reaction under microwave irradiation

Dispiro-pyrrolidino/pyrrolizidino fused oxindoles/acenaphthoquinones have been derived from andrographolide via azomethine ylide cycloaddition to the conjugated double-bond under microwave (MW) irradiation. The reactions are chemo-, stereo-, and regioselective in nature. Change in amino acid from sarcosine/N-benzyl glycine to l-proline changes the regiochemistry. A representative library of 40 compounds along with in vitro anticancer evaluation is reported.