Antioxidant, Hypoglycemic, Antilipidemic, and Protective Effect of Polyherbal Emulsion (F6-SMONSECCE) on Alloxan-Induced Diabetic Rats.

The current study focused on the antioxidant potential, α-amylase inhibitory activity, and hypoglycemic, hypolipidemic, and histoprotective (pancreas and kidney) effects of polyherbal emulsion on the alloxan-induced diabetic rats. Polyherbal formulations were prepared from extracts and oils of Nigella sativa (N. sativa), Citrullus colocynthis (C. colocynthis), and Silybum marianum (S. marianum). Out of nine stable formulations, one formulation named F6-SMONSECCE was found to be the best after its evaluation using antioxidant and in vitro α-amylase inhibition assay. The prepared herbal formulations showed significant (p < 0.05) antioxidant activity in terms of radical scavenging as 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP) assays and also revealed the presence of a significant amount of total phenolic and flavonoid contents. "F6- SMONSECCE" (prepared with composition; Silybum marianum oil (SMO) + Nigella sativa extract (NSE) + Citrullus colocynthis extract CCE) was selected for an in vivo trial to ascertain its antidiabetic potential. The treatment dose was determined by using an acute toxicity trial on rats. Administration of alloxan (150 mg/kg b.w., i.p.) significantly (P < 0.05) augmented the blood glucose levels and lipid contents as total cholesterol (TC), triglycerides (TG), low-density lipoproteins (LDL-c), and very-low-density lipoproteins (VLDL-c). However, the levels of insulin and high-density lipoproteins (HDL-c) were found to be decreased, and the histopathological alterations were also found in the pancreas and kidney. The administration of the polyherbal formulation (F6-SMONSECCE) significantly attenuated the blood glucose levels (22.94%), TC (29.10%), TG (38.15%), LDL-c (27.58%), and VLDL-c (71.52%), whereas on the other side, the insulin (-149.15%) and HDL-c levels (-22.22%) were significantly increased. A significant histopathological normalization was observed in the pancreas and kidney tissues of the F6-SMONSECCE-treated rats. The current findings proposed that the prepared polyherbal formulation "F6-SMONSECCE" exhibited significant antioxidant, antilipidemic, and hypoglycemic potential and hence might be suggested as a remedy against diabetes or as a coadjuvant to synthetic medicines to maintain normal physiology.

Heterologous boost with mRNA vaccines against SARS-CoV-2 Delta/Omicron variants following an inactivated whole-virus vaccine.

The coronavirus SARS-CoV-2 has mutated quickly and caused significant global damage. This study characterizes two mRNA vaccines ZSVG-02 (Delta) and ZSVG-02-O (Omicron BA.1), and associating heterologous prime-boost strategy following the prime of a most widely administrated inactivated whole-virus vaccine (BBIBP-CorV). The ZSVG-02-O induces neutralizing antibodies that effectively cross-react with Omicron subvariants. In naïve animals, ZSVG-02 or ZSVG-02-O induce humoral responses skewed to the vaccine's targeting strains, but cellular immune responses cross-react to all variants of concern (VOCs) tested. Following heterologous prime-boost regimes, animals present comparable neutralizing antibody levels and superior protection against Delta and Omicron BA.1variants. Single-boost only generated ancestral and omicron dual-responsive antibodies, probably by "recall" and "reshape" the prime immunity. New Omicron-specific antibody populations, however, appeared only following the second boost with ZSVG-02-O. Overall, our results support a heterologous boost with ZSVG-02-O, providing the best protection against current VOCs in inactivated virus vaccine-primed populations.

In Vivo and In Silico Assessment of the Cardioprotective Effect of Thymus linearis Extract against Ischemic Myocardial Injury.

Myocardial infarction is irreversible cardiac tissue necrosis due to the blockage of one of the arteries. It leads to an insufficient supply of oxygen and nutrients, creating muscular damage in the affected regions. In the present study, aqueous methanolic extract of Thymus linearis was prepared to evaluate its activity against ischemic stress due to free radical production. GC-MS analysis was performed to evaluate the phytochemicals present in the plant extract. A chemical database of 30 compounds was virtually screened against NF-κB, COX2, and MCL, where γ-cadinene, ß-bisabolene, and ß-caryophyllene were found to be the best interacting ligands. To systematically assess cardioprotective activity against ischemia, isoproterenol and doxorubicin were used to induce cardiotoxicity in rats. The prepared extract of T. linearis (100 mg/kg) was given daily to animals for 21 days before injecting isoproterenol (85 mg/kg of animal weight) subcutaneously in two doses on the 20th and 21st days. In the case of doxorubicin, cardiotoxicity was induced in rats by a single injection (15 mg/kg) on the seventh day, and the extract was given to animals for 10 consecutive days. Animals' blood samples were used to monitor cardiac, liver, and other marker enzymes, including LDH, CPK, and AST. Superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) were also assayed in blood plasma to determine the degree of oxidative stress. H&E staining was performed to evaluate cardioprotection by plant extract, showing significant preventive effects in reducing cardiac injury induced by isoproterenol and doxorubicin.

The Second Class of Tetrahydrofolate (THF-II) Riboswitches Recognizes the Tetrahydrofolic Acid Ligand via Local Conformation Changes.

Riboswitches are regulatory noncoding RNAs found in bacteria, fungi and plants, that modulate gene expressions through structural changes in response to ligand binding. Understanding how ligands interact with riboswitches in solution can shed light on the molecular mechanisms of this ancient regulators. Previous studies showed that riboswitches undergo global conformation changes in response to ligand binding to relay information. Here, we report conformation switching models of the recently discovered tetrahydrofolic acid-responsive second class of tetrahydrofolate (THF-II) riboswitches in response to ligand binding. Using a combination of selective 2'-hydroxyl acylation, analyzed by primer extension (SHAPE) assay, 3D modeling and small-angle X-ray scattering (SAXS), we found that the ligand specifically recognizes and reshapes the THF-II riboswitch loop regions, but does not affect the stability of the P3 helix. Our results show that the THF-II riboswitch undergoes only local conformation changes in response to ligand binding, rearranging the Loop1-P3-Loop2 region and rotating Loop1 from a ~120° angle to a ~75° angle. This distinct conformation changes suggest a unique regulatory mechanism of the THF-II riboswitch, previously unseen in other riboswitches. Our findings may contribute to the fields of RNA sensors and drug design.

Mechanism of phosphate sensing and signaling revealed by rice SPX1-PHR2 complex structure.

Phosphate, a key plant nutrient, is perceived through inositol polyphosphates (InsPs) by SPX domain-containing proteins. SPX1 an inhibit the PHR2 transcription factor to maintain Pi homeostasis. How SPX1 recognizes an InsP molecule and represses transcription activation by PHR2 remains unclear. Here we show that, upon binding InsP6, SPX1 can disrupt PHR2 dimers and form a 1:1 SPX1-PHR2 complex. The complex structure reveals that SPX1 helix α1 can impose a steric hindrance when interacting with the PHR2 dimer. By stabilizing helix α1, InsP6 allosterically decouples the PHR2 dimer and stabilizes the SPX1-PHR2 interaction. In doing so, InsP6 further allows SPX1 to engage with the PHR2 MYB domain and sterically block its interaction with DNA. Taken together, our results suggest that, upon sensing the surrogate signals of phosphate, SPX1 inhibits PHR2 via a dual mechanism that attenuates dimerization and DNA binding activities of PHR2.

Using tRNA Scaffold to Assist RNA Crystallization.

Recent studies have solidified RNA's regulatory and catalytic roles in all life forms. Understanding such functions necessarily requires high-resolution understanding of the molecular structure of RNA. Whereas proteins tend to fold into a globular structure and gain most of the folding energy from tertiary interactions, RNAs behave the opposite. Their tertiary structure tends to be irregular and porous, and they gain the majority of their folding free energy from secondary structure formation. These properties lead to higher conformational dynamics in RNA structure. As a result, structure determination proves more difficult for RNA using X-ray crystallography and other structural biology tools. Despite the painstaking effort to obtain large quantities of chemically pure RNA molecules, many still fail to crystallize due to the presence of conformational impurity. To overcome the challenge, we developed a new method to crystallize the RNA of interest as a tRNA chimera. In most cases, tRNA fusion significantly increased the conformational purity of our RNA target, improved the success rate of obtaining RNA crystals, and made the subsequent structure determination process much easier. Here in this chapter we describe our protocol to design, stabilize, express, and purify an RNA target as a tRNA chimera. While this method continues a series of work utilizing well-behaving macromolecules/motifs as "crystallization tags" (Ke and Wolberger. Protein Sci 12:306-312, 2003; Ferre-D'Amare and Doudna. J Mol Biol 295:541-556, 2000; Koldobskaya et al . Nat Struct Mol Biol 18:100-106, 2011; Ferre-D'Amare et al. J Mol Biol 279:621-631, 1998), it was inspired by the work of Ponchon and Dardel to utilize tRNA scaffold to express, stabilize, and purify RNA of interest in vivo (Ponchon and Dardel. Nat Methods 4:571-576, 2007). The "tRNA scaffold," where the target RNA is inserted into a normal tRNA, replacing the anticodon sequence, can effectively help the RNA fold, express in various sources and even assist crystallization and phase determination. This approach applies to any generic RNA whose 5' and 3' ends join and form a helix.

ATP/ADP modulates gp16-pRNA conformational change in the Phi29 DNA packaging motor.

Packaging of phage phi29 genome requires the ATPase gp16 and prohead RNA (pRNA). The highly conserved pRNA forms the interface between the connector complex and gp16. Understanding how pRNA interacts with gp16 under packaging conditions can shed light on the molecular mechanism of the packaging motor. Here, we present 3D models of the pRNA-gp16 complex and its conformation change in response to ATP or ADP binding. Using a combination of crystallography, small angle X-ray scattering and chemical probing, we find that the pRNA and gp16 forms a 'Z'-shaped complex, with gp16 specifically binds to pRNA domain II. The whole complex closes in the presence of ATP, and pRNA domain II rotates open as ATP hydrolyzes, before resetting after ADP is released. Our results suggest that pRNA domain II actively participates in the packaging process.