Standardized Extract of Asparagus officinalis Stem Attenuates SARS-CoV-2 Spike Protein-Induced IL-6 and IL-1β Production by Suppressing p44/42 MAPK and Akt Phosphorylation in Murine Primary Macrophages

Excessive host inflammation following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with severity and mortality in coronavirus disease 2019 (COVID-19). We recently reported that the SARS-CoV-2 spike protein S1 subunit (S1) induces pro-inflammatory responses by activating toll-like receptor 4 (TLR4) signaling in macrophages. A standardized extract of Asparagus officinalis stem (EAS) is a unique functional food that elicits anti-photoaging effects by suppressing pro-inflammatory signaling in hydrogen peroxide and ultraviolet B-exposed skin fibroblasts. To elucidate its potential in preventing excessive inflammation in COVID-19, we examined the effects of EAS on pro-inflammatory responses in S1-stimulated macrophages. Murine peritoneal exudate macrophages were co-treated with EAS and S1. Concentrations and mRNA levels of pro-inflammatory cytokines were assessed using enzyme-linked immunosorbent assay and reverse transcription and real-time polymerase chain reaction, respectively. Expression and phosphorylation levels of signaling proteins were analyzed using western blotting and fluorescence immunomicroscopy. EAS significantly attenuated S1-induced secretion of interleukin (IL)-6 in a concentration-dependent manner without reducing cell viability. EAS also markedly suppressed the S1-induced transcription of IL-6 and IL-1β. However, among the TLR4 signaling proteins, EAS did not affect the degradation of inhibitor κBα, nuclear translocation of nuclear factor-κB p65 subunit, and phosphorylation of c-Jun N-terminal kinase p54 subunit after S1 exposure. In contrast, EAS significantly suppressed S1-induced phosphorylation of p44/42 mitogen-activated protein kinase (MAPK) and Akt. Attenuation of S1-induced transcription of IL-6 and IL-1β by the MAPK kinase inhibitor U0126 was greater than that by the Akt inhibitor perifosine, and the effects were potentiated by simultaneous treatment with both inhibitors. These results suggest that EAS attenuates S1-induced IL-6 and IL-1β production by suppressing p44/42 MAPK and Akt signaling in macrophages. Therefore, EAS may be beneficial in regulating excessive inflammation in patients with COVID-19.

A Standardized Extract of Asparagus officinalis Stem (ETAS®) Ameliorates Cognitive Impairment, Inhibits Amyloid β Deposition via BACE-1 and Normalizes Circadian Rhythm Signaling via MT1 and MT2

The prevalence of cognitive impairments and circadian disturbances increases in the elderly and Alzheimer’s disease (AD) patients. This study investigated the effects of a standardized extract of Asparagus officinalis stem, ETAS^® on cognitive impairments and circadian rhythm status in senescence-accelerated mice prone 8 (SAMP8). ETAS^® consists of two major bioactive constituents: 5-hydroxymethyl-2-furfural (HMF), an abundant constituent, and (S)-asfural, a novel constituent, which is a derivative of HMF. Three-month-old SAMP8 male mice were divided into a control, 200 and 1000 mg/kg BW ETAS^® groups, while senescence-accelerated resistant mice (SAMR1) were used as the normal control. After 12-week feeding, ETAS^® significantly enhanced cognitive performance by an active avoidance test, inhibited the expressions of amyloid-beta precursor protein (APP) and BACE-1 and lowered the accumulation of amyloid β (Aβ) in the brain. ETAS^® also significantly increased neuron number in the suprachiasmatic nucleus (SCN) and normalized the expressions of the melatonin receptor 1 (MT1) and melatonin receptor 2 (MT2). In conclusion, ETAS^® enhances the cognitive ability, inhibits Aβ deposition and normalizes circadian rhythm signaling, suggesting it is beneficial for preventing cognitive impairments and circadian rhythm disturbances in aging.