Harrisonia perforata for COVID-19

Since the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its resultant pneumonia in December 2019, the cumulative number of infected people worldwide has exceeded 670 million, with over 6.8 million deaths. Despite the marketing of multiple series of vaccines and the implementation of strict prevention and control measures in many countries, the spread and prevalence of SARS-CoV-2 have not been completely and effectively controlled. The latest research shows that in addition to angiotensin converting enzyme II (ACE2), dozens of protein molecules, including AXL, can act as host receptors for SARS-CoV-2 infecting human cells, and virus mutation and immune evasion never seem to stop. To sum up, this review summarizes and organizes the latest relevant literature, comprehensively reviews the genome characteristics of SARS-CoV-2 as well as receptor-based pathogenesis (including ACE2 and other new receptors), mutation and immune evasion, vaccine development and other aspects, and proposes a series of prevention and treatment opinions. It is expected to provide a theoretical basis for an in-depth understanding of the pathogenic mechanism of SARS-CoV-2 along with a research basis and new ideas for the diagnosis and classification, of COVID-19-related disease and for drug and vaccine research and development.

The COVID-19-related long-standing effect or Post-Acute Sequelae of COVID-19 (PASC) is often associated with NLRP3 inflammasome activation in pulmonary inflammation elicited by SARS-CoV-2 spike proteins. Spike proteins engage toll-like receptors (TLRs) in respiratory epithelial cells, leading to excessive cytokine production. Given the need for effective therapeutic strategies to mitigate spike protein-stimulated lung inflammation, we examined the anti-inflammatory properties of luteolin and ethanolic extract from Harrisonia perforata (Blanco) Merr. root. The ethanolic extract of H. perforata root (HPEE) contained a high concentration of luteolin flavonoid (143.53 ± 1.58 mg/g extract). Both HPEE (25–100 μg/mL) and luteolin (4.5–36 μM) significantly inhibited inflammation stimulated by the Wuhan (W) and Omicron (O) spike protein S1, as evidenced by a dose-dependent significant decrease in IL-6, IL-1β, and IL-18 secretion in A549 lung epithelial cells (p < 0.05). Furthermore, pretreatment with HPEE or luteolin prior to spike protein exposure (100 ng/mL) significantly, in a dose-dependent manner, repressed the inflammatory mRNA expression (p < 0.05). Mechanistic study revealed that HPEE and luteolin suppressed NLRP3 inflammasome signaling activation by reducing their machinery protein expressions. Additionally, they inhibited the ERK/JNK/p38 MAPK signaling activation, resulting in decreased inflammatory mRNA expression and cytokine release. These findings suggest that H. perforata root extract and its major flavonoid luteolin exert potent anti-inflammatory effects and may offer therapeutic potential against spike protein-induced lung inflammation.