The coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged as a pandemic and has inflicted enormous damage on the lives of the people and economy of many countries worldwide. However, therapeutic agents against SARS-CoV-2 remain unclear. SARS-CoV-2 has a spike protein (S protein), and cleavage of the S protein is essential for viral entry. Nattokinase is produced by Bacillus subtilis var. natto and is beneficial to human health. In this study, we examined the effect of nattokinase on the S protein of SARS-CoV-2. When cell lysates transfected with S protein were incubated with nattokinase, the S protein was degraded in a dose- and time-dependent manner. Immunofluorescence analysis showed that S protein on the cell surface was degraded when nattokinase was added to the culture medium. Thus, our findings suggest that nattokinase exhibits potential for the inhibition of SARS-CoV-2 infection via S protein degradation.

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged as a pandemic and has caused damage to the lives of the people and economy of countries. However, the therapeutic reagents against SARS-CoV-2 remain unclear. The spike (S) protein of SARS-CoV-2 contains a cleavage motif at the S1/S2 boundary, known to be cleaved by furin. As cleavage is essential for S protein activation and viral entry, furin was selected as the target compound. In this study, we examined the inhibitory effects of two lignans (honokiol and magnolol) on furin-like enzymatic activity using a fluorogenic substrate with whole-cell lysates. Of two compounds tested, honokiol partially inhibited furin-like enzymatic activity. We further examined the anti-SARS-CoV-2 activity of honokiol using VeroE6 cell line, which is stably expressing a transmembrane protease serine 2 (TMPRSS2). It was shown that honokiol exhibited remarkable inhibition of SARS-CoV-2 infection. Therefore, honokiol and crude drugs which contain honokiol such as Magnolia species have a potential therapeutic reagents for SARS-CoV-2.

Background: Hemp (Cannabis sativa L.) seed contains high contents of various nutrients, including fatty acids and proteins. Cannabidiol (CBD) is a non-psychoactive compound that can be extracted from C. sativa and used for treating epilepsy and pain. Industrial hemp products, including CBD and hemp seed oils, have become increasingly popular. Some products are marketed without a clear distinction between CBD and hemp seed oils. Herein, the CBD content and biological activities of commercial CBD and hemp seed oils were examined. Methods: CBD content was measured by high-performance liquid chromatography. For in vitro antioxidant activity determination, 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radical-scavenging assays were performed. Results: The CBD concentrations in the two CBD oil samples were 18.9 ± 0.5 and 9.2 ± 0.4 mg/mL. Of the seven hemp seed oil samples, six samples contained CBD in concentrations ranging from 2.0 ± 0.1 to 20.5 ± 0.5 µg/mL, but it was not detected in one sample. Antioxidant activity was observed in both CBD oil samples. Conclusions: The results indicate that (1) CBD content varied by hemp seed oil sample and that (2) antioxidant activity could be a useful landmark for discriminating CBD oils from hemp seed oils.

Leaves of Morinda citrifolia (noni) have been used in Polynesian folk medicine for the treatment of pain and inflammation, and their juice is very popular worldwide as a functional food supplement. This study aimed to demonstrate that M. citrifolia seed extract exerts anti-inflammatory effects on RAW264 cells stimulated by lipopolysaccharide. To confirm the inhibitory effect of M. citrifolia seed extract, we assessed the production of nitric oxide (NO) and inflammatory cytokines. The M. citrifolia seed extract showed a significant inhibition of NO production, with no effect on cell viability, and was more active than M. citrifolia seed oil, leaf extract, and fruit extract. The M. citrifolia seed extract was found to reduce the expression of inducible NO synthase and tumor necrosis factor-alpha of pro-inflammatory cytokines. These results suggest that the anti-inflammatory effect of M. citrifolia seed extract is related to a reduction in the expression of inflammatory mediators and support its potential therapeutic use.

Variations in defensive and some other leaf traits were studied in a population of an oak species, Quercus dentata Thunberg, in northern Japan, with reference to attacks by ectophagous herbivores and leafminers. The oak population showed substantial individual variations in concentrations of total phenolics and condensed tannins, nitrogen content, trichome density, leaf area and budburst timing. With the exception of leaf mass per area, which showed a positive relation with leaf toughness and a negative relation with water content, no significant relation was observed between the plant traits studied, suggesting an absence of trade-off or linkage between them. The oaks also showed substantial individual variations in leaf area loss by ectophagous herbivores, densities of major leafminers (Phyllonorycter and Stigmella species) and survival of Phyllonorycter sap-feeding larvae. The density of trichomes showed a significant, negative relation with leaf area loss by ectophagous herbivores, but significant, positive relations with densities of some leafminers. The other leaf traits seldom showed significant relations with herbivore densities or survival. In this oak population, these traits may not have enough variations to be reflected in the abundance and performance of herbivores.