Spike-Dependent Opsonization Indicates Both Dose-Dependent Inhibition of Phagocytosis and That Non-Neutralizing Antibodies Can Confer Protection to SARS-CoV-2

Spike-specific antibodies are central to effective COVID19 immunity. Research efforts have focused on antibodies that neutralize the ACE2-Spike interaction but not on non-neutralizing antibodies. Antibody-dependent phagocytosis is an immune mechanism enhanced by opsonization, where typically, more bound antibodies trigger a stronger phagocyte response. Here, we show that Spike-specific antibodies, dependent on concentration, can either enhance or reduce Spike-bead phagocytosis by monocytes independently of the antibody neutralization potential. Surprisingly, we find that both convalescent patient plasma and patient-derived monoclonal antibodies lead to maximum opsonization already at low levels of bound antibodies and is reduced as antibody binding to Spike protein increases. Moreover, we show that this Spike-dependent modulation of opsonization correlate with the outcome in an experimental SARS-CoV-2 infection model. These results suggest that the levels of anti-Spike antibodies could influence monocyte-mediated immune functions and propose that non-neutralizing antibodies could confer protection to SARS-CoV-2 infection by mediating phagocytosis.

Inhibition of LPMOs by Fermented Persimmon Juice

Fermented persimmon juice, Kakishibu, has traditionally been used for wood and paper protection. This protective effect stems at least partially from inhibition of microbial cellulose degrading enzymes. The inhibitory effect of Kakishibu on lytic polysaccharide monooxygenases (LPMOs) and on a cocktail of cellulose hydrolases was studied, using three different cellulosic substrates. Dose dependent inhibition of LPMO activity by a commercial Kakishibu product was assessed for the well-characterized LPMO from Thermoascus aurantiacus TaAA9A, and the inhibitory effect was confirmed on five additional microbial LPMOs. The model tannin compound, tannic acid exhibited a similar inhibitory effect on TaAA9A as Kakishibu. It was further shown that both polyethylene glycol and tannase can alleviate the inhibitory effect of Kakishibu and tannic acid, indicating a likely mechanism of inhibition caused by unspecific tannin–protein interactions.

Potential Antidiabetic Effects of Extracts from Four Medicinal Plants Used in Burkina Faso by Inhibition of Alpha-Amylase

Background: The purpose of this study was to evaluate α-amylase inhibitory effects of hydroethanolic extracts of bark from Daniella oliveri, Sclerocarya birrea, Maranthes polyandra, and Pteleopsis suberosa to fight type-II diabetes. Methods: Compound extractions were performed by hydroethanol maceration followed by liquid-liquid fractionation with solvents. TLC profiling was carried out with different fractions. The inhibitory effects of plant extracts on α-amylase activity were determined using rice starch as a substrate. Results: TLC profiling of different fractions showed different phytochemical compounds. The hydroethanolic plant extracts exhibited dose-dependent inhibition of α-amylase. D. oliveri displayed competitive inhibition, M. polyandra and S. birrea showed uncompetitive inhibition and Pteleopsis suberosa exerted mixed-inhibition. M. polyandra extract exerted the highest inhibitory effect (IC50 = 0.5 mg/mL). Conclusions: The barks of M. polyandra exhibit a remarkable α-amylase inhibitory effect which can be a novel source of antidiabetic molecules.

Discovery of New Chemical Tools against Leishmania amazonensis via the MMV Pathogen Box

The protozoan parasite Leishmania causes a spectrum of diseases and there are over 1 million infections each year. Current treatments are toxic, expensive, and difficult to administer, and resistance to them is emerging. In this study, we screened the antileishmanial activity of the Pathogen Box compounds from the Medicine for Malaria Venture against Leishmania amazonensis, and compared their structures and cytotoxicity. The compounds MMV676388 (3), MMV690103 (5), MMV022029 (7), MMV022478 (9) and MMV021013 (10) exerted a significant dose-dependent inhibition effect on the proliferation of L. amazonensis promastigotes and intracellular amastigotes. Moreover, studies on the mechanism of cell death showed that compounds 3 and 5 induced an apoptotic process while the compounds 7, 9 and 10 seem to induce an autophagic mechanism. The present findings underline the potential of these five molecules as novel therapeutic leishmanicidal agents.

Pharmacological Potential of Anti-Inflammatory and Anti Nociceptive Activity of Bioactive Fractions from Leaves of Maytenus emarginata

The antinociceptive & anti-inflammatory activities of extract were compared to dose of Phenylbutazone. The phytochemical secondary metabolites tested for include alkaloids, cardiac glycosides, flavonoids, phenols, saponins, steroids and terpenoids. Maytenus emarginata leaves extract demonstrated significant antinociceptive and anti- inflammatory effects in a dose-dependent manner. The extract dose at 200mg/kg bw exhibited the highest antinociceptive and anti-inflammatory activities & its activities were comparable to those of the respective reference drugs. BFLME (suspended in 1% carboxy methyl cellulose) in doses of 50, 100 and 200 mg/kg caused a dose-dependent inhibition of swelling caused by carrageenin equivalent to 30.2–63.2% protection (P<0.05– P<0.001) and in cotton pellet granuloma, 47.2–45.4% protection (P<0.01-P<0.001) was observed from inflammation. There was a significant increase in analgesiometer force induced pain in rat equivalent to 98.1–146.5% protection (P<0.01-P<0.001) and 7.19–37.8 % (P<0.05–P<0.001) protection against Acetic acid induced writhing. Phytochemical screening of the extract indicated the presence of alkaloids, cardiac glycosides, flavonoids, phenols, saponins, steroids and terpenoids. The present study therefore demonstrated the antinociceptive and anti-inflammatory properties of bioactive fraction of ethyl acetate extract from leaves of M. emarginata (BFLME), hence providing a basis for further research that may result in pure compounds that can be advanced into drug discovery.

Analgesic and Anti-Inflammatory Activities of Sophocarpine from Sophora viciifolia Hance

Sophora viciifolia Hance is an edible plant used in traditional Chinese medicine. Sophocarpine, a tetracyclic quinolizidine alkaloid, is one of the most abundant active ingredients in Sophora viciifolia Hance. Here, we study the analgesic and anti-inflammatory effects, as well as the acute toxicity of sophocarpine from Sophora viciifolia Hance in mice. Sophocarpine (20, 40, and 80 mg/kgbw) significantly prolonged the delay period before a hot plate reaction occurred (all P < 0.05 ), and the delay before a tail-flick response was induced by a warm bath ( P < 0.05 ; P < 0.01 ). Sophocarpine (40, 80 mg/kg) resulted in dose-dependent inhibition of the writhing reaction induced by acetic acid in mice ( P < 0.05 ; P < 0.001 , respectively). Sophocarpine (80 mg/kg) reduced the total duration of a formalin-induced pain response ( P < 0.05 ). Sophocarpine prolonged the foot-licking latency of mice after the hot plate reaction, and this effect was antagonized by calcium chloride and enhanced by verapamil. Sophocarpine (20, 40, and 80 mg/kg) significantly inhibited xylene-induced ear edema ( P < 0.01 ; P < 0.001 ; P < 0.001 , respectively) and the penetration of acetic acid-induced dye into the peritoneal cavity ( P < 0.01 ; P < 0.01 ; P < 0.001 , respectively). It also reduced the levels of proinflammatory cytokine interleukin (IL)-1β, IL-6, and prostaglandin E2 ( P < 0.05 , P < 0.01 , P < 0.001 ) and those of serum nitric oxide ( P < 0.05 ). The results of this study suggest that sophocarpine possesses certain analgesic and anti-inflammatory activities, which may be related to calcium and inhibition of the secretion of inflammatory factors.

Flavonoid Library Screening Reveals Kaempferol as a Potential Antiviral Agent Against African Swine Fever Virus

Naturally occurring plant flavonoids are a promising class of antiviral agents to inhibit African swine fever virus (ASFV), which causes highly fatal disease in pigs and is a major threat to the swine industry. Currently known flavonoids with anti-ASFV activity demonstrate a wide range of antiviral mechanisms, which motivates exploration of new antiviral candidates within this class. The objective of this study was to determine whether other flavonoids may significantly inhibit ASFV infection in vitro. We performed a cell-based library screen of 90 flavonoids. Our screening method allowed us to track the development of virus-induced cytopathic effect by MTT in the presence of tested flavonoids. This screening method was shown to be robust for hit identification, with an average Z-factor of 0.683. We identified nine compounds that inhibit ASFV Ba71V strain in Vero cells. Among them, kaempferol was the most potent and exhibited dose-dependent inhibition, which occurred through a virostatic effect. Time-of-addition studies revealed that kaempferol acts on the entry and post-entry stages of the ASFV replication cycle and impairs viral protein and DNA synthesis. It was further identified that kaempferol induces autophagy in ASFV-infected Vero cells, which is related to its antiviral activity and could be partially abrogated by the addition of an autophagy inhibitor. Kaempferol also exhibited dose-dependent inhibition of a highly virulent ASFV Arm/07 isolate in porcine macrophages. Together, these findings support that kaempferol is a promising anti-ASFV agent and has a distinct antiviral mechanism compared to other anti-ASFV flavonoids.

Systemic and intrathecal baclofen produce bladder antinociception in rats

Background Baclofen, a clinically available GABAB receptor agonist, produces non-opioid analgesia in multiple models of pain but has not been tested for effects on bladder nociception. Methods A series of experiments examined the effects of systemic and spinally administered baclofen on bladder nociception in female anesthetized rats. Models of bladder nociception included those which employed neonatal and adult bladder inflammation to produce bladder hypersensitivity. Results Cumulative intraperitoneal dosing (1–8 mg/kg IP) and cumulative intrathecal dosing (10–160 ng IT) of baclofen led to dose-dependent inhibition of visceromotor responses (VMRs) to urinary bladder distension (UBD) in all tested models. There were no differences in the magnitude of the analgesic effects of baclofen as a function of inflammation versus no inflammation treatments. Hemodynamic (pressor) responses to UBD were similarly inhibited by IT baclofen as well as UBD-evoked excitatory responses of spinal dorsal horn neurons. The GABAB receptor antagonist, CGP 35,348, antagonized the antinociceptive effects of IT baclofen on VMRs in all tested models but did not affect the magnitude of the VMRs by itself suggesting no tonic GABAB activity was present in this preparation. Tolerance to a seven day continuous IT infusion of baclofen was not observed. Conclusions These data provide support for a clinical trial of baclofen as a non-opioid treatment of human bladder pain.

Pterostilbene Inhibits the Melanogenesis Activity in UVB-Irradiated B164A5 Cells

Pterostilbene is a potent antioxidant and anti-inflammatory agent. However, its chemopreventive effects via anti-tyrosinase activity and inhibitory effects on melanin content have not been reported previously. Hence, this study aimed to investigate the anti-melanogenic activity of pterostilbene on UVB-irradiated B164A5 mouse melanoma cells. The effects of pterostilbene and resveratrol on cell viability were determined by MTT assay, whereas melanin content and tyrosinase assay were employed to assess melanogenesis activity. Western blot analysis was performed to determine the tyrosinase expression. Based on the MTT assay, the IC50 value of pterostilbene on UVB-irradiated B164A5 cells was 34.0 ± 3.43 μM, in comparison to resveratrol (>100 μM). Next, 5 and 10 μM pterostilbene showed a significant dose-dependent inhibition ( P < .01) of tyrosinase activity in UVB-irradiated B164A5 cells at 37.14 ± 2.71% and 58.36 ± 6.8%, respectively. The findings from the tyrosinase assay also confirmed the downregulation of tyrosinase expression in UVB-irradiated B164A5 cells as measured by Western blot analysis. Finally, 10 μM pterostilbene showed a significantly decreased melanin content ( P < .01) in UVB-irradiated B164A5 cells, at 27.34 ± .98 μg/mL. In conclusion, pterostilbene showed anti-melanogenic activity that was 10 times more potent than resveratrol in the UVB-irradiated B164A5 cell.

Discovery of a Non-Nucleoside SETD2 Methyltransferase Inhibitor against Acute Myeloid Leukemia

Histone methyltransferases (HMTs) have attracted considerable attention as potential targets for pharmaceutical intervention in various malignant diseases. These enzymes are known for introducing methyl marks at specific locations of histone proteins, creating a complex system that regulates epigenetic control of gene expression and cell differentiation. Here, we describe the identification of first-generation cell-permeable non-nucleoside type inhibitors of SETD2, the only mammalian HMT that is able to tri-methylate the K36 residue of histone H3. By generating the epigenetic mark H3K36me3, SETD2 is involved in the progression of acute myeloid leukemia. We developed a structure-based virtual screening protocol that was first validated in retrospective studies. Next, prospective screening was performed on a large library of commercially available compounds. Experimental validation of 22 virtual hits led to the discovery of three compounds that showed dose-dependent inhibition of the enzymatic activity of SETD2. Compound C13 effectively blocked the proliferation of two acute myeloid leukemia (AML) cell lines with MLL rearrangements and led to decreased H3K36me3 levels, prioritizing this chemotype as a viable chemical starting point for drug discovery projects.