Transbilayer lipid interactions mediate nanoclustering of lipid-anchored proteins.

Understanding how functional lipid domains in live cell membranes are generated has posed a challenge. Here, we show that transbilayer interactions are necessary for the generation of cholesterol-dependent nanoclusters of GPI-anchored proteins mediated by membrane-adjacent dynamic actin filaments. We find that long saturated acyl-chains are required for forming GPI-anchor nanoclusters. Simultaneously, at the inner leaflet, long acyl-chain-containing phosphatidylserine (PS) is necessary for transbilayer coupling. All-atom molecular dynamics simulations of asymmetric multicomponent-membrane bilayers in a mixed phase provide evidence that immobilization of long saturated acyl-chain lipids at either leaflet stabilizes cholesterol-dependent transbilayer interactions forming local domains with characteristics similar to a liquid-ordered (lo) phase. This is verified by experiments wherein immobilization of long acyl-chain lipids at one leaflet effects transbilayer interactions of corresponding lipids at the opposite leaflet. This suggests a general mechanism for the generation and stabilization of nanoscale cholesterol-dependent and actin-mediated lipid clusters in live cell membranes.

Scoparone chemical modification into semi-synthetic analogues featuring 3-substitution for their anti-inflammatory activity.

Natural products (NPs) continue to serve as a structural model for the development of new bioactive molecules and improve the process of identifying novel medicines. The biological effects of coumarins, one of the most researched compounds among NPs, are currently being thoroughly investigated. In the present investigation, we reported the synthesis of nineteen semi-synthetic 3-substituted scoparone analogues, followed by their characterization using analytical methods such as NMR, HPLC, and HRMS. All compounds screened for in vitro and in vivo study for their ability to reduce inflammation. The SAR study worked effectively for this particular scoparone 3-substitution, as compounds 3, 4, 9, 16, 18, and 20 displayed improved in vitro results for TNF-α than the parent molecule. Similarly, compounds 3, and 17 showed a higher percentage of IL-6 inhibition. Compounds 3, 4, and 12 have also been identified by in vivo studies as promising candidates with higher percent inhibition than the parent scoparone molecule. As evident from all in vitro and in vivo studies, compound 3 showed the most potent anti-inflammatory activity among all.

Stereoselective Synthesis of Nonpsychotic Natural Cannabidiol and Its Unnatural/Terpenyl/Tail-Modified Analogues.

Here, we report a three-step concise and stereoselective synthesis route to one of the most important phytocannabinoids, namely, (-)-cannabidiol (-CBD), from inexpensive and readily available starting material R-(+)-limonene. The synthesis involved the diastereoselective bifunctionalization of limonene, followed by effective elimination leading to the generation of key chiral p-mentha-2,8-dien-1-ol. The chiral p-mentha-2,8-dien-1-ol on coupling with olivetol under silver catalysis provided regiospecific (-)-CBD, contrary to reported ones which gave a mixture. The newly developed approach was further extended to its structural analogues cannabidiorcin and other tail/terpenyl-modified analogues. Moreover, its opposite isomer (+)-cannabidiol was also successfully synthesized from S-(-)-limonene.

Safranal inhibits NLRP3 inflammasome activation by preventing ASC oligomerization.

NLRP3 inflammasome is involved in several chronic inflammatory diseases. The inflammatory effect of the NLRP3 inflammasome is executed through IL-1ß and IL-18. Therefore, IL-1ß is one of the primary targets in chronic inflammatory conditions. However, current treatment regimens are dependent on anti- IL-1ß biologicals. The therapies targeting IL-1ß through inhibition of NLRP3 inflammasome are thus being actively explored. We identified safranal, a small molecule responsible for the essence of saffron as a potential inhibitor of the NLRP3 inflammasome. Safranal significantly suppressed the release of IL-1ß from ATP stimulated J774A.1 and bone marrow-derived macrophages (BMDMs) by regulating CASP1 and CASP8 dependent cleavage of pro-IL-1ß. Safranal markedly suppressed the expression of NLRP3 and its ATPase activity. Safranal treatment enhanced the expression of NRF2, whereas, si-RNA mediated silencing of Nrf2 abrogated the anti-NLRP3 effect of safranal. Furthermore, safranal inhibited ASC oligomerization and formation of ASC specks. Safranal also displayed anti-NLRP3 activity in multiple mice models. Treatment of animals with safranal reduced the production of IL-1ß in ATP elicited peritoneal inflammation, MSU induced air pouch inflammation, and MSU injected foot paw edema in mice. Thus, our data projects safranal as a potential preclinical drug candidate against NLRP3 inflammasome triggered chronic inflammation.

Optimization and validation of RT-LAMP assay for diagnosis of SARS-CoV2 including the globally dominant Delta variant.

BACKGROUND: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19 pandemic, has infected more than 179 million people worldwide. Testing of infected individuals is crucial for identification and isolation, thereby preventing further spread of the disease. Presently, Taqman™ Reverse Transcription Real Time PCR is considered gold standard, and is the most common technique used for molecular testing of COVID-19, though it requires sophisticated equipments, expertise and is also relatively expensive. OBJECTIVE: Development and optimization of an alternate molecular testing method for the diagnosis of COVID-19, through a two step Reverse Transcription Loop-mediated isothermal AMPlification (RT-LAMP). RESULTS: Primers for LAMP were carefully designed for discrimination from other closely related human pathogenic coronaviruses. Care was also taken that primer binding sites are present in conserved regions of SARS-CoV2. Our analysis shows that the primer binding sites are well conserved in all the variants of concern (VOC) and variants of interest (VOI), notified by World Health Organization (WHO). These lineages include B.1.1.7, B.1.351, P.1, B.1.617.2, B.1.427/B.1.429, P.2, B.1.525, P.3, B.1.526 and B.1.617.1. Various DNA polymerases with strand displacement activity were evaluated and conditions were optimized for LAMP amplification and visualization. Different LAMP primer sets were also evaluated using synthetic templates as well as patient samples. CONCLUSION: In a double blind study, the RT-LAMP assay was validated on more than 150 patient samples at two different sites. The RT-LAMP assay appeared to be 89.2% accurate when compared to the Taqman™ rt-RT-PCR assay.

Screening of compound library identifies novel inhibitors against the MurA enzyme of Escherichia coli.

Bacterial cell has always been an attractive target for anti-infective drug discovery. MurA (UDP-N-acetylglucosamine enolpyruvyl transferase) enzyme of Escherichia coli (E.coli) is crucial for peptidoglycan biosynthetic pathway, as it is involved in the early stages of bacterial cell wall biosynthesis. In the present study we aim to identify novel chemical structures targeting the MurA enzyme. For screening purpose, we used in silico approach (pharmacophore based strategy) for 52,026 library compounds (Chembridge, Chemdiv and in house synthetics) which resulted in identification of 50 compounds. These compounds were screened in vitro against MurA enzyme and release of inorganic phosphate (Pi) was estimated. Two compounds (IN00152 and IN00156) were found to inhibit MurA enzyme > 70% in primary screening and IC50 of 14.03 to 32.30 µM respectively. These two hits were further evaluated for their mode of inhibition studies and whole-cell activity where we observed 2-4 folds increase in activity in presence of Permeabilizer EDTA (Ethylenediaminetetraacetic acid). Combination studies were also performed with known antibiotics in presence of EDTA. Hits are reported for the first time against this target and our report also support the use of OM permeabilizer in combination with antibacterial compounds to address the permeability and efficacy issue. These lead hits can be further optimized for drug discovery. KEY POINTS: • Emerging Gram negative resistant strains is a matter of concern. • Need for new screening strategies to cope with drying up antibiotics pipeline. • Outer membrane permeabilizers could be useful to improve potency of molecules to reach its target.

Membrane transporters: the key drivers of transport of secondary metabolites in plants.

KEY MESSAGE: This review summarizes the recent updates in the area of transporters of plant secondary metabolites, including their applied aspects in metabolic engineering of economically important secondary metabolites. Plants have evolved biosynthetic pathways to produce structurally diverse secondary metabolites, which serve distinct functions, including defense against pathogens and herbivory, thereby playing a pivotal role in plant ecological interactions. These compounds often display interesting bioactivities and, therefore, have been used as repositories of natural drugs and phytoceuticals for humans. At an elevated level, plant secondary metabolites could be cytotoxic to the plant cell itself; therefore, plants have developed sophisticated mechanisms to sequester these compounds to prevent cytotoxicity. Many of these valuable natural compounds and their precursors are biosynthesized and accumulated at diverse subcellular locations, and few are even transported to sink organs via long-distance transport, implying the involvement of compartmentalization via intra- and intercellular transport mechanisms. The transporter proteins belonging to different families of transporters, especially ATP binding cassette (ABC) and multidrug and toxic compound extrusion (MATE) have been implicated in membrane-mediated transport of certain plant secondary metabolites. Despite increasing reports on the characterization of transporter proteins and their genes, our knowledge about the transporters of several medicinally and economically important plant secondary metabolites is still enigmatic. A comprehensive understanding of the molecular mechanisms underlying the whole route of secondary metabolite transportome, in addition to the biosynthetic pathways, will aid in systematic and targeted metabolic engineering of high-value secondary metabolites. The present review embodies a comprehensive update on the progress made in the elucidation of transporters of secondary metabolites in view of basic and applied aspects of their transport mechanism.

Total Synthesis of Phospholipomannan of Candida albicans.

First, total synthesis of the cell surface phospholipomannan anchor [ß-Manp-(1 → 2)-ß-Manp]n-(1 → 2)-ß-Manp-(1 → 2)-α-Manp-1 → P-(O → 6)-α-Manp-(1 → 2)-Inositol-1-P-(O → 1)-phytoceramide of Candida albicans is reported. The target phospholipomannan (PLM) anchor poses synthetic challenges such as the unusual kinetically controlled (1 → 2)-ß-oligomannan domain, anomeric phosphodiester, and unique phytoceramide lipid tail linked to the glycan through a phosphate group. The synthesis of PLM anchor was accomplished using a convergent block synthetic approach using three main appropriately protected building blocks: (1 → 2)-ß-tetramannan repeats, pseudodisaccharide, and phytoceramide-1-H-phosphonate. The most challenging (1 → 2)-ß-tetramannan domain was synthesized in one pot using the preactivation method. The phytoceramide-1-H-phosphonate was synthesized through an enantioselective A3 three-component coupling reaction. Finally, the phytoceramide-1-H-phosphonate moiety was coupled with pseudodisaccharide followed by deacetylation to produce the acceptor, which on subsequent coupling with tetramannosyl-H-phosphonate provided the fully protected PLM anchor. Final deprotection was successfully achieved by Pearlman's hydrogenation.

Glycyrrhizic Acid Prevents Oxidative Stress Mediated DNA Damage Response through Modulation of Autophagy in Ultraviolet-B-Irradiated Human Primary Dermal Fibroblasts.

BACKGROUND/AIMS: Excessive exposure to UV radiation negatively affects the human skin, characterized by photo-damage (premature aging & carcinogenesis). UV-B radiation causes about 90% of non-melanoma skin cancers by damaging de-oxy ribonucleic acids (DNA). We have previously reported that UV-B radiation induces skin photodamage through oxidative & Endoplasmic Reticulum (ER) stresses and Glycyrrhizic acid (GA), a natural triterpene, protects skin cells against such stresses. UV-B radiation elicits signalling cascade by activation of proteins involved in sensing, signalling, and repair process of DNA damage. In this study, we explored the effects & mechanisms of Glycyrrhizic acid (GA) against UV-B -induced photodamage using a well established cellular model. METHODS: We used primary human dermal fibroblasts as a cellular model. The cells were cultured in the presence or absence of GA for 3,6, & 24 h. Effect of UV-B was assessed by examining cell viability, cell morphology, oxidative stress, ER stress, DNA damage & cellular autophagy levels through biochemical assays, microscopy & protein expression studies. RESULTS: In this study, we have determined the effect of GA on autophagy mediated DNA damage response system as the main mechanism in preventing photodamage due to UV-B -irradiation to primary human dermal fibroblasts (HDFs). GA treatment to UV-B exposed HDFs, significantly inhibited cell death, oxidative & ER stress responses, prevented Cyclobutane Pyrimidine dimer (CPD) DNA adduct formation, and DNA fragmentation via modulation of UV-B induced autophagic flux. Present results showed that GA treatment quenched reactive oxygen species (ROS), relieved ER stress response, improved autophagy (6 hr's post-UV-B -irradiation) and prevented UV-B induced DNA damage. CONCLUSION: The present study links autophagy induction by GA as the main mechanism in the prevention of DNA damage and provides a mechanistic basis for the photoprotective effect of GA and suggests that GA can be potentially developed as a promising agent against UV-B induced skin photo-damage.

Discovery of Quinazolin-4(3 H)-ones as NLRP3 Inflammasome Inhibitors: Computational Design, Metal-Free Synthesis, and in Vitro Biological Evaluation.

NLRP3 inflammasome is an important therapeutic target for a number of human diseases. Herein, computationally designed series of quinazolin-4(3 H)-ones were synthesized using iodine-catalyzed coupling of arylalkynes (or styrenes) with O-aminobenzamides. The key event in this transformation involves the oxidative cleavage of the C-C triple/double bond and the release of formaldehyde. The reaction relies on the C-N bond formation along with the C-C bond cleavage under metal-free conditions. The nitro-substituted quinazolin-4(3 H)-one 2k inhibited NLRP3 inflammasome (IC50 5 µM) via the suppression of IL-1ß release from ATP-stimulated J774A.1 cells.

Introducing Oxo-Phenylacetyl (OPAc) as a Protecting Group for Carbohydrates.

A series of oxo-phenylacetyl (OPAc)-protected saccharides, with divergent base sensitivity profiles against benzoyl (Bz) and acetyl (Ac) were synthesized, and KHSO5/AcCl in methanol was identified as an easy, mild, selective, and efficient deprotecting reagent for their removal in the perspective of carbohydrate synthesis. Timely monitoring of AcCl reagent was supportive in both sequential and simultaneous deprotecting of OPAc, Bz, and Ac. The salient feature of our method is the orthogonal stability against different groups, its ease to generate different valuable acceptors using designed monosaccharides, and use of OPAc as a glycosyl donar.

Analyzing the role of cannabinoids as modulators of Wnt/ß-catenin signaling pathway for their use in the management of neuropathic pain.

Neuropathic pain is a debilitating form of treatment-resistant chronic pain caused by damage to the nervous system. Cannabinoids have been known for suppressing neuropathic pain by modulating the endo cannabinoid system. Since the canonical Wnt/ß-catenin signaling has recently been implicated in pain sensation, we investigated the impact of major cannabinoids (1-6) from the leaves of Cannabis sativa and an epoxy derivative of compound 2, here upon referred to as 2a, on modulating Wnt/ß-catenin signaling pathway. The results presented in this study show that compound 1, 2 and 2a exhibited potent inhibitory activity against Wnt/ß-catenin pathway in a dose-dependent manner. Compound 2a was seen to inhibit this pathway at slightly lower concentrations than its parent molecule 2, under similar conditions. Taken together, compound 1, 2 and 2a, by virtue of their inhibition of Wnt/ß-catenin signaling pathway, could be developed as effective neuroprotective agents for the management of neuropathic pain.

Transformation of Santonin to a Naproxen Analogue with Anti-Inflammatory Activity.

Santonin, a natural product, was aromatized with molecular iodine as the catalyst. The new compound was characterized as ( S)-methyl-2-(7-hydroxy-5,8-dimethylnaphthalen-2-yl) propanoate (2) based on 2D NMR spectroscopic data. Structurally, compound 2 was highly similar to the anti-inflammatory drug naproxen. The new naproxen analogue had significant potency against cyclooxygenase 1 and 2 (IC50 = 31.0 and 66.1 µM, respectively).

Design, synthesis and biological evaluation of pyrazolopyrimidinone based potent and selective PDE5 inhibitors for treatment of erectile dysfunction.

Our previous discovery of series of pyrazolopyrimidinone based PDE5 inhibitors led to find potent leads but with low aqueous solubility and poor bioavailability, and low selectivity. Now, a new series of same pyrazolopyrimidinone scaffold is designed, synthesized and evaluated for its PDE5 inhibitory potential. In this study, some of the molecules are found more potent and selective PDE5 inhibitors in vitro than sildenafil. The studies revealed that compound 5 is 20 fold selective to PDE5 against PDE6. As PDE6 enzyme is involved in the phototransduction pathway in the retina and creates distortion problem, the selectivity for PDE5 specifically against PDE6 enzyme is preferred for any development candidate and in present study, compound 5 has been found to be devoid of this liability of selectivity issue. Moreover, compound 5 has shown excellent in vivo efficacy in conscious rabbit model, it's almost comparable to sildenafil. The preclinical pharmacology including pharmacokinetic and physicochemical parameter studies were also performed for compound 5, it was found to have good PK properties and other physicochemical parameters. The development of these selective PDE5 inhibitors can further lead to draw strategies for the novel preclinical and/or clinical candidates based on pyrazolopyrimidinone scaffold.

Functional Characterization of CsBGlu12, a ß-Glucosidase from Crocus sativus, Provides Insights into Its Role in Abiotic Stress through Accumulation of Antioxidant Flavonols.

Glycosylation and deglycosylation are impressive mechanisms that allow plants to regulate the biological activity of an array of secondary metabolites. Although glycosylation improves solubility and renders the metabolites suitable for transport and sequestration, deglycosylation activates them to carry out biological functions. Herein, we report the functional characterization of CsBGlu12, a ß-glucosidase from Crocus sativus. CsBGlu12 has a characteristic glucoside hydrolase 1 family (α/ß)8 triose-phosphate isomerase (TIM) barrel structure with a highly conserved active site. In vitro enzyme activity revealed that CsBGlu12 catalyzes the hydrolysis of flavonol ß-glucosides and cello-oligosaccharides. Site-directed mutagenesis of any of the two conserved catalytic glutamic acid residues (Glu200 and Glu414) of the active site completely abolishes the ß-glucosidase activity. Transcript analysis revealed that Csbglu12 is highly induced in response to UV-B, dehydration, NaCl, methyl jasmonate, and abscisic acid treatments indicating its possible role in plant stress response. Transient overexpression of CsBGlu12 leads to the accumulation of antioxidant flavonols in Nicotiana benthamiana and confers tolerance to abiotic stresses. Antioxidant assays indicated that accumulation of flavonols alleviated the accretion of reactive oxygen species during abiotic stress conditions. ß-Glucosidases are known to play a role in abiotic stresses, particularly dehydration through abscisic acid; however, their role through accumulation of reactive oxygen species (ROS) scavenging flavonols has not been established. Furthermore, only one ß-glucosidase 12 homolog has been characterized so far. Therefore, this work presents an important report on characterization of CsBGlu12 and its role in abiotic stress through ROS scavenging.

Soluble Aß1-42 suppresses TNF-α and activates NLRP3 inflammasome in THP-1 macrophages.

Deposition of amyloid-ß in Alzheimer's disease is accompanied by chronic inflammation, which involves raised levels of pro-inflammatory cytokines TNF-α, IL-6 and IL-1ß. However, the role of Aß1-42 in the inflammatory process, before it gets deposited into aggregates has not been investigated thoroughly. Through this study, we are illustrating the dual role of soluble Aß1-42 (sAß1-42) in activating the NLRP3 inflammasome and simultaneously inhibiting TNF-α secretion. Our data suggested that the treatment of chronically induced THP-1 macrophages and N9 microglial cells with sAß1-42 can suppress the major inflammatory cytokine TNF-α without affecting the level of IL-6. However, the activation of NLRP3 inflammasome was well evidenced by secretion of IL-1ß, increased expression of NLRP3 and caspase-1, implicating sAß1-42 in enhancing and suppressing one or other type of inflammation. Further investigation revealed that sAß1-42 was able to severely abrogate the expression of NF-κB, p50 and restricting the translocation of NF-κB, p65 to nucleus by inhibiting phosphorylation of IκB-α in THP-1 macrophages. These data indicate that the sAß1-42 may play a dual role during inflammatory process, wherein, it may be involved in protecting the cells from inflammatory damage due to TNF-α. This ability of sAß1-42 might be playing some role in protecting the brain cells during the process of aging and Alzheimer's disease, where, chronic inflammatory environment plays a vital role.

Physicochemical, pharmacokinetic, efficacy and toxicity profiling of a potential nitrofuranyl methyl piperazine derivative IIIM-MCD-211 for oral tuberculosis therapy via in-silico-in-vitro-in-vivo approach.

Recent tuberculosis (TB) drug discovery programme involve continuous pursuit for new chemical entity (NCE) which can be not only effective against both susceptible and resistant strains of Mycobacterium tuberculosis (Mtb) but also safe and faster acting with the target, thereby shortening the prolonged TB treatments. We have identified a potential nitrofuranyl methyl piperazine derivative, IIIM-MCD-211 as new antitubercular agent with minimum inhibitory concentration (MIC) value of 0.0072 µM against H37Rv strain. Objective of the present study is to investigate physicochemical, pharmacokinetic, efficacy and toxicity profile using in-silico, in-vitro and in-vivo model in comprehensive manner to assess the likelihood of developing IIIM-MCD-211 as a clinical candidate. Results of computational prediction reveal that compound does not violate Lipinski's, Veber's and Jorgensen's rule linked with drug like properties and oral bioavailability. Experimentally, IIIM-MCD-211 exhibits excellent lipophilicity that is optimal for oral administration. IIIM-MCD-211 displays evidence of P-glycoprotein (P-gp) induction but no inhibition ability in rhodamine cell exclusion assay. IIIM-MCD-211 shows high permeability and plasma protein binding based on parallel artificial membrane permeability assay (PAMPA) and rapid equilibrium dialysis (RED) assay model, respectively. IIIM-MCD-211 has adequate metabolic stability in rat liver microsomes (RLM) and favourable pharmacokinetics with admirable correlation during dose escalation study in Swiss mice. IIIM-MCD-211 has capability to appear into highly perfusable tissues. IIIM-MCD-211 is able to actively prevent progression of TB infection in chronic infection mice model. IIIM-MCD-211 shows no substantial cytotoxicity in HepG2 cell line. In acute toxicity study, significant increase of total white blood cell (WBC) count in treatment group as compared to control group is observed. Overall, amenable preclinical data make IIIM-MCD-211 ideal candidate for further development of oral anti-TB agent.

Room Temperature Metal-Catalyzed Oxidative Acylation of Electron-Deficient Heteroarenes with Alkynes, Its Mechanism, and Application Studies.

Herein, we report an original one-step, simple, room-temperature, regioselective Minisci reaction for the acylation of electron-deficient heteroarenes with alkynes. The method has broad functional group compatibility and gives exclusively monoacylated products in good to excellent yields. The mechanistic pathway was analyzed based on a series of experiments confirming the involvement of a radical pathway. The 18O-labeling experiment suggested that water is a source of oxygen in the acylated product, and head space GC-MS experiment shows the C-C cleavage occurs via release as CO2.

Design and synthesis of 1,4-substituted 1H-1,2,3-triazolo-quinazolin-4(3H)-ones by Huisgen 1,3-dipolar cycloaddition with PI3Kγ isoform selective activity.

A strategy for construction of medicinally important 1,4-substituted 1H-1,2,3-triazolo-quinazolin-4(3H)-ones has been devised and presented here. The compounds have been synthesized using one-pot multicomponent strategy under microwave assisted conditions. Triazolyl-quinazolinone based D-ring modified analogs are designed based on IC87114 scaffold, which is first known isoform selective inhibitor of PI3Kδ. Herein, we identified two triazolyl-quinazolinone compounds (5a and 5l) based on same scaffold with PI3Kγ specific inhibitory potential, the selectivity towards this isoform is well supported by in silico results, wherein, these compounds show better interaction and affinity and inhibitory activity for PI3Kγ rather than PI3Kδ. This repositioning of scaffold from PI3Kδ to PI3Kγ isoform can be very useful from medicinal chemistry and drug discovery perspective to unravel molecular interactions of this new scaffold in different cellular pathways.

Lipovelutibols A-D: Cytotoxic Lipopeptaibols from the Himalayan Cold Habitat Fungus Trichoderma velutinum.

Four novel lipovelutibols A (1), B (2), C (3), and D (4) containing six amino acid residues with leucinol at the C-terminus and a fatty acyl moiety (n-octanoyl) at its N-terminus were isolated from the psychrotrophic fungus Trichoderma velutinum collected from the Himalayan cold habitat. The structures (1-4) were determined by NMR and MS/MS, and the stereochemistry of amino acids by Marfey's method. Lipopeptaibols 2 and 4 were found to contain d-isovaline, a nonproteinogenic amino acid, but lacked α-aminoisobutyric acid, characteristic of peptaibols. Cytotoxic activity of 2 and 4 was observed against HL-60, LS180, MDA-MB-231, and A549 cancer cell lines.