Two new withanolides from the halophyte Datura stramonium L

Cytotoxic withanolides from the leaves of Datura stramonium L

Six novel withanolides, along with nine known related compounds were isolated from the leaves of Datura stramonium L. The structures and absolute configurations of the new withanolides were elucidated by employing various spectral techniques and comparing them with those previously reported in the literature. In addition, four withanlides demonstrated interesting cytotoxic activity on LN229 cells with IC50 <20 μM.

Identification of P450 Candidates Associated with the Biosynthesis of Physalin-Class Compounds in Physalis angulata

The Physalis genus has long been used as traditional medicine in the treatment of various diseases. Physalins, the characteristic class of compounds in this genus, are major bioactive constituents. To date, the biogenesis of physalins remains largely unknown, except for the recently established knowledge that 24-methyldesmosterol is a precursor of physalin. To identify the genes encoding P450s that are putatively involved in converting 24-methyldesmosterol to physalins, a total of 306 P450-encoding unigenes were retrieved from our recently constructed P. angulata transcriptome. Extensive phylogenetic analysis proposed 21 P450s that might participate in physalin biosynthesis. To validate the candidates, we developed a virus-induced gene silencing (VIGS) system for P. angulata, and four P450 candidates were selected for the VIGS experiments. The reduction in the transcripts of the four P450 candidates by VIGS all led to decreased levels of physalin-class compounds in the P. angulata leaves. Thus, this study provides a number of P450 candidates that are likely associated with the biosynthesis of physalin-class compounds, forming a strong basis to reveal the unknown physalin biosynthetic pathway in the future.

Datura stramonium Flowers as a Potential Natural Resource of Bioactive Molecules: Identification of Anti-Inflammatory Agents and Molecular Docking Analysis

The present study investigated the antioxidant, antibacterial, antiviral and anti-inflammatory activities of different aerial parts (flowers, leaves and seeds) of Datura stramonium. The plant material was extracted with 80% methanol for about 24 h. The sensitivity to microorganisms analysis was performed by the microdilution technique. Antioxidant tests were performed by scavenging the DPPH and ABTS radicals, and by FRAP assay. Anti-inflammatory activity was evaluated through the inhibition of nitric oxide production in activated macrophage RAW 264.7 cells. Cell viability was assessed with an MTT assay. Results show that the flower extract revealed a powerful antimicrobial capacity against Gram-positive bacteria and strong antioxidant and anti-inflammatory activities. No significant cytotoxicity to activated macrophages was recorded. High resolution electrospray ionization mass spectrometry and nuclear magnetic resonance analysis identified two molecules with important anti-inflammatory effects: 12α-hydroxydaturametelin B and daturametelin B. Molecular docking analysis with both pro-inflammatory agents tumor necrosis factor alpha and interleukin-6 revealed that both compounds showed good binding features with the selected target proteins. Our results suggest that D. stramonium flower is a promising source of compounds with potential antioxidant, antibacterial, and anti-inflammatory activities. Isolated withanolide steroidal lactones from D. stramonium flower extract with promising anti-inflammatory activity have therapeutic potential against inflammatory disorders.

Three new α-glucosidase inhibitor benzo-isochromenes from Datura stramonium

Three new α-glucosidase inhibitory benzo-isochromenes were isolated from the chloroform fraction of Datura stramonium. Their structures were established with the help of modern spectroscopic techniques and were assigned the names as 1,6,8-triimethoxy-2-methyl-3,4-dihydrobenzoisochromene-5,10-diol, 3,6-dimethoxy-5-hydroxy-4-methylbenzoisochromene-9,11-dione and demethylflavasperon for compounds 1-3 respectively. The α-glucosidase inhibiting activity of compound 2 showed strong inhibition with an IC₅₀ value of 27.5 µM, while compound 1 exhibited moderate activity with IC₅₀ value of 60.2 µM compared to positive control (acarbose).

Magnesium and Zinc Oxide Nanoparticles from Datura alba Improve Cognitive Impairment and Blood Brain Barrier Leakage

Epilepsy is a neurological disorder involving persistent spontaneous seizures and uncontrolled neuronal excitability that leads to cognitive impairments and blood–brain barrier (BBB) disruption. Currently available antiepileptic drugs present side effects and researchers are trying to discover new agents with properties to overcome these drawbacks. The aim was to synthesize magnesium oxide (MgO) and zinc oxide (ZnO) nanoparticles from Datura alba fresh leaf extracts and evaluate their anti-epileptic potential in mice kindling or a repetitive seizures model. The phytoassisted synthesized nanoparticles were characterized using spectroscopy; FT-IR, XRD, SEM, and EDX. Analysis of the NPs confirmed the crystalline pleomorphic shape using the salts of both zinc and magnesium possibly stabilized, functionalized and reduced by bioactive molecules present in plant extract. By using several characterization techniques, NPs were confirmed. UV-Vis spectroscopy of biologically produced ZnO and MgO revealed distinctive peaks at 380 nm and 242 nm, respectively. Our findings categorically demonstrated the reductive role of biomolecules in the formation of ZnO and MgO NPs. The mice kindling model was induced using seven injections of Pentylenetetrazole (PTZ, 40 mg/kg, i.p) for 15 days alternatively. The results showed that mice post-treated with either ZnO or MgO nanoparticles (10 mg/kg, i.p) significantly improved in respect of behavior and memory as confirmed in the Morris water maze (MWM), open field (OF), novel object recognition (NOR) test compared with PTZ treated mice. Furthermore, the ZnO and MgO nanoparticle treatment also maintained the integrity of the BBB, reducing the leakage, as confirmed by Evans blue dye (EBD) compared with PTZ treated mice only. In summary, the current finding demonstrates that green synthesized ZnO and MgO nanoparticles have neuroprotective, ant-epileptic potential, molecular mechanisms, and clinical implications need to be further explored.

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.

Preclinical anticancer studies on the ethyl acetate leaf extracts of Datura stramonium and Datura inoxia

Background

Cancer is a horrific disease relentlessly affecting human population round the globe. Genus Datura encompasses numerous species with reported medicinal uses. However, its potential as a source of natural anticancer agents is yet to be determined. Datura stramonium (DS) and Datura inoxia (DI) are the two species chosen for this study.

Methods

Total phenolic and flavonoid content (TPC and TFC) as well as antioxidant activity were assessed through colorimetric method. Polyphenolic quantification was done by RP-HPLC. Following extract standardization ethyl acetate leaf extracts of both species (DSL-EA and DIL-EA) were chosen for anticancer studies. In vitro cytotoxicity using various models including cancer cell lines was monitored. Following toxicity studies, benzene (0.2 ml) was used to induce leukemia in Sprague-Dawley rats. Extracts were orally administered to preventive (100 and 200 mg/kg) and treatment (200 mg/kg only) groups. The antileukemic potential of extracts was assessed through haematological, biochemical, endogenous antioxidants and histological parameters.

Results

Significant TPC and TFC were estimated in DSL-EA and DIL-EA. RP-HPLC quantified (μg/mg extract) rutin (0.89 ± 0.03), gallic acid (0.35 ± 0.07), catechin (0.24 ± 0.02) and apigenin (0.29 ± 0.09) in DSL-EA while rutin (0.036 ± 0.004) and caffeic acid (0.27 ± 0.03) in DIL-EA. Both extracts exhibited significant brine shrimp cytotoxicity (LC₅₀ < 12.5 μg/ml). DIL-EA exhibited greater cytotoxicity against PC-3, MDA-MB 231 and MCF-7 cell lines (IC₅₀ < 3 μg/ml in each case) as well as higher protein kinase inhibitory action (MIC: 25 μg/disc) compared to DSL-EA. Leukemia induced in rats was affirmed by elevated serum levels of WBCs (7.78 ± 0.012 (× 10³) /μl), bilirubin (7.56 ± 0.97 mg/dl), Thiobarbituric acid reactive substances (TBARs) (133.75 ± 2.61 nM/min/mg protein), decreased RBCs (4.33 ± 0.065 (× 10⁶)/μl), platelets (344 ± 3.19 (× 10³)/μl), total proteins (2.14 ± 0.11 g/dl), Glutathione S-transferases (GST) (81.01 ± 0.44 nM/min/ml), endogenous antioxidant enzymes levels and abnormal liver and kidney functionality in disease control rats. Both species revealed almost identical and significant (p < 0.05) alleviative effects in benzene induced leukemia.

Conclusion

Comprehensive screening divulged the tremendous potential of selected species as potent source of natural anticancer agents in a variety of cancers particularly leukemia. Present study might provide useful finger prints in cancer research and mechanistic studies are prerequisite in logical hunt of this goal.

Synthesis of Ergosterol Peroxide Conjugates as Mitochondria Targeting Probes for Enhanced Anticancer Activity

Inspired by the significant bioactivity of ergosterol peroxide, we designed and synthesized four fluorescent coumarin and ergosterol peroxide conjugates 8a–d through the combination of ergosterol peroxide with 7-N,N-diethylamino coumarins fluorophore. The cytotoxicity of synthesized conjugates against three human cancer cells (HepG2, SK-Hep1, and MCF-7) was evaluated. The results of fluorescent imaging showed that the synthesized conjugates 8a–d localized and enriched mainly in mitochondria, leading to significantly enhanced cytotoxicity over ergosterol peroxide. Furthermore, the results of biological functions of 8d showed that it could suppress cell colony formation, invasion, and migration; induce G2/M phase arrest of HepG2 cells, and increase the intracellular ROS level.

Antioxidant Potential, Phytochemicals Composition, and Metal Contents of Datura alba

This study investigated the phytochemical characteristics and antioxidant activity in leaves, roots, stem, flower, and seed parts of Datura alba (D. alba). The study also assessed the heavy metal (Cr, Mn, Zn, and Cu) accumulation in each part of the plant. Among the phytochemicals, alkaloids were found only in leaves while tannins, flavonoids, and phenols were present in all parts of the plant. For antioxidant activity, free radical scavenging assay for 2,2-diphenyl-1-picrylhydrazyl (DPPH) was performed using ascorbic acid as the standard. Higher activity was shown by stem extract in methanol and leaf extract in n-hexane, ethyl acetate, and chloroform. Furthermore, all the target heavy metals were detected in all plant sections with the highest concentration of Zn in leaves and Cu in stem, root, flower, and seed. Due to stronger antioxidant potential and phytochemical composition, D. alba could prove as valuable prospect in pharmaceutical formulations by taking part in the antioxidant defense system against generation of free radicals.

Synthesis of 5α,8α-Ergosterol Peroxide 3-Carbamate Derivatives and a Fluorescent Mitochondria-Targeting Conjugate for Enhanced Anticancer Activities

Inspired by the significant anticancer activity of our previously screened natural ergosterol peroxide (1), we synthesized and characterized a series of novel ergosterol peroxide 3-carbamate derivatives. The antiproliferative activities of the synthesized compounds against human hepatocellular carcinoma cells (HepG2, SK-Hep1) and human breast cancer cells (MCF-7, MDA-MB231) were investigated. 5α,8α-Epidioxyergosta-3-yl-(piperazine-1)carbamate (3 d) and 5α,8α-epidioxyergosta-3-yl-(piperidin-4-methylamine)carbamate (3 f) and their hydrochloride salts exhibited significant in vitro antiproliferative activities against the tested tumor cell lines, with IC₅₀ values ranging from 0.85 to 4.62 μm. Furthermore, fluorescent imaging showed that the designed coumarin-3 d conjugate (5) localized mainly in mitochondria, leading to enhanced anticancer activities over the parent structure 1. As a whole, it appeared that substituent changes at the C3 position could serve as a promising launch point for further design of this type of steroidal anticancer agent.

Crude extract and solvent fractions of Calystegia soldanella induce G1 and S phase arrest of the cell cycle in HepG2 cells

The representative halophyte Calystegia soldanella (L) Roem. et Schult is a perennial vine herb that grows in coastal dunes throughout South Korea as well as in other regions around the world. This plant has long been used as an edible and medicinal herb to cure rheumatic arthritis, sore throat, dropsy, and scurvy. Some studies have also shown that this plant species exhibits various biological activities. However, there are few studies on cytotoxicity induced by C. soldanella treatment in HepG2 human hepatocellular carcinoma cells. In this study, we investigated the viability of HepG2 cells following treatment with crude extracts and four solvent-partitioned fractions of C. soldanella. Of the crude extract and four solvent fractions tested, treatment with the 85% aqueous methanol (aq. MeOH) fraction resulted in the greatest inhibition of HepG2 cell proliferation. Flow cytometry showed that the 85% aq. MeOH fraction induced a G0/G1 and S phase arrest of the cell cycle progression. The 85% aq. MeOH fraction arrested HepG2 cells at the G0/G1 phase in a concentration-dependent manner, and resulted in decreased expression of cyclin D1, cyclin E, cyclin-dependent kinase (CDK)2, CDK4, CDK6, p21, and p27. Additionally, the 85% aq. MeOH fraction treatment also arrested HepG2 cells in the S phase, with decreased expression of cyclin A, CDK2, and CDC25A. Also, treatment with this fraction reduced the expression of retinoblastoma (RB) protein and the transcription factor E2F. These results suggest that the 85% aq. MeOH fraction exhibits potential anticancer activity in HepG2 cells by inducing G0/G1 and S phase arrest of the cell cycle.

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.

Withanolide Structural Revisions by (13)C NMR Spectroscopic Analysis Inclusive of the γ-Gauche Effect

A classic withanolide is defined as a highly oxygenated C28 ergostane-type steroid that is characterized by a C22-hydroxy-C26-oic acid δ-lactone in the nine-carbon side chain. Analysis of the reported (13)C NMR data of classic withanolides with hydroxy groups (C-14, C-17, and C-20) revealed that (1) a hydroxy (C-14 or C-17) substituent significantly alters the chemical shifts (C-7, C-9, C-12, and C-21) via the γ-gauche effect; (2) the chemical shift values (C-9, C-12, and C-21) reflect the orientation (α or β) of the hydroxy moiety (C-14 or C-17); (3) a double-bond positional change in ring A (Δ(2) to Δ(3)), or hydroxylation (C-27), results in a minuscule effect on the chemical shifts of carbons in rings C and D (from C-12 to C-18); and (4) the (13)C NMR γ-gauche effect method is more convenient and reliable than the traditional approach ((1)H NMR shift comparisons in C5D5N versus CDCl3) to probe the orientation of the hydroxy substituent (C-14 and C-17). Utilization of these rules demonstrated that the reported (13)C NMR data of withanolides 1a-29a were inconsistent with their published structures, which were subsequently revised as 1-16 and 12 and 18-29, respectively. When combined, this strongly supports the application of these methods to determine the relative configuration of steroidal substituents.

Chemical composition and cytotoxicity of the essential oil from different parts of Datura metel L

The essential oil from different parts of Datura metel L. were extracted using hydrodistillation and GC-MS was used to analyse the essential oil. The main components of flowers were ketone (23.61%) and ethyl palmitate (15.84%). The main components of leaves were ketone (18.84%) and phytol (18.71%). Ketone (39.45%) and phytol (31.32%) were the major components of petioles. Palmitic acid (30.60%) and ethyl linoleate (21.56%) were the major components of seeds. The major ingredient of roots was palmitic acid (52.61%). The main ingredients of the stems were palmitic acid (38.38%) and ethyl linoleate (17.38%). All the different parts of essential oil were screened for cytotoxicity. The roots and stems showed the inhibitory effects against HepG-2 with IC50 levels of 613.88 and 341.12 mg/L. The leaves and roots showed the inhibitory effects against HeLa with IC50 levels of 267.76 and 348.35 mg/L. All the six parts have inhibitory effects against SGC-7901 cell lines.

A new minor diketopiperazine from the sponge-derived fungus Simplicillium sp. YZ-11

Chemical investigation of the cultures of a sponge-derived fungus Simplicillium sp. YZ-11 led to the isolation of a new minor diketopiperazine alkaloid cyclo-(2-hydroxy-Pro-Gly) (1) and a natural lactone (S)-dihydro-5-[(S)- hydroxyphenylmethyl]-2(3H)-furanone (2), together with five known ergostane-type sterols (3-7). Their structures were established based on extensive spectroscopic methods ((1)H and (13)C NMR, (1)H-(1)H COSY, HSQC and HMBC) and optical rotation analysis.

New anti-inflammatory withanolides from the leaves of Datura metel L

Nine new withanolides, named daturafolisides A-I (1-9), along with six known compounds (22R)-27-hydroxy-7α-methoxy-1-oxowitha-3,5,24-trienolide-27-O-β-d-glucopyranoside, daturataturin A, daturametelin J, daturataurin B, baimantuoluoside B, 12-deoxywithastramonolide (10-15), were isolated from the leaves of Datura metel L. The structures and absolute stereochemistry of these compounds were elucidated by means of spectroscopic methods including 1D and 2D NMR techniques, mass spectrometry and circular dichroism (CD) analyses. All isolates were evaluated for in vitro anti-inflammatory potential using LPS-stimulated RAW 264.7 murine macrophages. Among them, compounds 1, 2, 14, and 15 exhibited significant inhibition of nitrite production with values of IC50 at 20.9, 17.7, 17.8, and 18.4μM. Compounds 3, 4, 6, and 13 presented moderate inhibitory activities with values of IC50 at 59.0, 52.8, 71.2, and 53.1μM, while the rest compounds displayed weak suppressive effect.

Withanolides from Physalis hispida

Nine new withanolides (1-9), withahisolides A-I, were isolated along with nine known compounds (10-18) from the aerial parts of Physalis hispida. The structures of 1-9 were elucidated through a variety of spectroscopic techniques, while the structures of 1 and 2 were confirmed by X-ray crystallographic analysis. Compounds 1-3 are the first withanolides with nonaromatic six-membered ring D moieties. In addition, withanolide 8 represents a novel withanolide skeleton due to the absence of a C-13-C-17 bond within the steroidal nucleus.