Usuki Toyonobu

ABSTRACT This study examined the synthesis of silver nanoparticles (SNPs) with aqueous extracts of Cyclosorus dentatus and Nephrolepis biserrata fronds and the evaluation of their biological activities. Mixing of AgNO₃ solution and the aqueous extracts resulted in color change, indicating the formation of SNPs. UV‐Vis spectroscopy analysis gave a surface plasmon resonance (SPR) peak at approximately 420 nm, confirming the presence of the synthesized SNPs. Infrared analysis showed C‐O, N‐O, and C‐C vibrations or stretching and aliphatic vibrations of hydrocarbon chains of the synthesized SNPs. x‐Ray diffraction (XRD) analysis indicated the SNPs were face‐centered, cubic, and crystalline in nature, with crystallite sizes. The scanning electron microscopy (SEM) shows the aggregation of the spherical shape nanoparticles. The SNPs significantly reduced phosphomolybdenum and captured H₂O₂ with respective IC₅₀ values of 61.55 and 29.03 µg/mL for C. dentatus SNP (SNP‐Cd), and 92.61 and 9.07 µg/mL for N. biserrata SNP (SNP‐Nb), respectively. In terms of albumin‐denaturing activity, the SNPs gave an IC₅₀ value of 21.20 µg/mL for SNP‐Cd and 7.18 µg/mL for SNP‐Nb. Thus, this work confirmed that SNP‐Cd and SNP‐Nb are potential therapeutic agents for treating oxidative stress, inflammatory problems, and related diseases.

The leaves of Odontonema strictum, a tropical plant used for its antihypertensive properties, are rich in nutrients and biologically active phytochemicals, such as β-sitosterol, stigmasterol, umuravumbolide, deacetylumuravumbolide, dideacetylboronolide, deacetylboronolide, verbascoside, and isoverbascoside. In addition, its roots are rich in β-sitosterol, stigmasterol, and the iridoid glycoside β-O-methyl-unedoside. Ingestion of the roots was reported to have a sedative effect in a dog was previously reported on a dog eating the roots of this plant. In the present study, we report for the first time the cell proliferation- and neurite outgrowth-promoting effects in PC12 neuronal cells of the isolated organic compounds and crude extracts from O. strictum. Pituitary adenylate cyclase-activating peptide (PACAP) and quercetin were used as positive controls. At the concentration of 0.2 μg/mL, β-sitosterol was more potent than quercetin and displayed the same activity (>45 μm/cell) as PACAP (100 nM). At a low concentration (0.04 μg/mL), verbascoside and isoverbascoside showed the strongest neurite outgrowth-promoting effect (neurite length of 30 to 35 μm/cell). Our results indicate that phytomedicines made from O. strictum may be useful in preventing neurodegenerative diseases.

Jamaicamide B was isolated from the cyanobacterium Moorea producens in Jamaica and shows neurotoxicity. Herein we report the first total synthesis and structural confirmation of the marine natural product (9R)-jamaicamide B.

Abstract Umifenovir is a broad‐spectrum antiviral agent used to treat influenza in China and Russia, and it has been studied as an antiviral agent for the treatment of coronavirus disease 2019 (COVID‐19). We have previously reported the synthesis of novel umifenovir analogues and their biological evaluation with a focus on their inhibitory activity against the binding of the spike glycoprotein (S‐protein) of severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) and the angiotensin‐converting enzyme 2 (ACE2) receptor; however, no strong inhibitory activity was observed from these analogues. In the present study, an additional set of umifenovir analogues was synthesized with replacement of the substituents at the 2‐, 3‐, and 4‐positions of the indole, and a cell‐based assay using SARS‐CoV‐2 (B.1.1) was performed to examine the antiviral activity of the analogues. We found that one of the newly synthesized umifenovir analogues exhibited antiviral activity and reduced the viral load to 0.06 % as compared to the control when it was assessed in the presence of nafamostat and marimastat, which inhibit cell‐surface viral entry. In contrast, when this analogue was evaluated without the addition of nafamostat or marimastat, it exhibited less antiviral activity, suggesting that the umifenovir analogue would exert antiviral activity mainly by inhibiting endosome‐mediated viral entry.