Outbreaks of coronaviruses (CoVs), especially severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), have posed serious threats to humans and animals, which urgently calls for effective broad‐spectrum antivirals. RNA‐dependent RNA polymerase (RdRp) plays an essential role in viral RNA synthesis and is an ideal pan‐coronaviral therapeutic target. Herein, based on cryo‐electron microscopy and biochemical approaches, gossypol (GOS) is identified from 881 natural products to directly block SARS‐CoV‐2 RdRp, thus inhibiting SARS‐CoV‐2 replication in both cellular and mouse infection models. GOS also acts as a potent inhibitor against the SARS‐CoV‐2 variant of concern (VOC) and exerts same inhibitory effects toward mutated RdRps of VOCs as the RdRp of the original SARS‐CoV‐2. Moreover, that the RdRp inhibitor GOS has broad‐spectrum anti‐coronavirus activity against alphacoronaviruses (porcine epidemic diarrhea virus and swine acute diarrhea syndrome coronavirus), betacoronaviruses (SARS‐CoV‐2), gammacoronaviruses (avian infectious bronchitis virus), and deltacoronaviruses (porcine deltacoronavirus) is showed. The findings demonstrate that GOS may serve as a promising lead compound for combating the ongoing COVID‐19 pandemic and other coronavirus outbreaks.

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has been spreading globally for over 2 years, causing serious contagious disease and incalculable damage. The introduction of vaccines has slowed the spread of SARS‐CoV‐2 to some extent, but there remains a need for specific and effective treatment. The high chemical diversity and safety profiles of natural products make them a potential source of effective anti‐SARS‐CoV‐2 drugs. Cotton plant is one of the most important economic and medical crops and is the source of a large number of antiviral phytochemicals. In this work, we used SARS‐CoV‐2 main protein (M pro ) as the target to identify potential anti‐SARS‐CoV‐2 natural products in cotton. An in vitro assay showed that of all cotton tissues examined, cotton flower extracts (CFs) exhibited optimal inhibitory effects against M pro . We proceeded to use the CF metabolite database to screen natural M pro inhibitors by combining virtual screening and biochemical assays. We identified that several CF natural products, including astragalin, myricitrin, and astilbin, significantly inhibited M pro with half‐maximal inhibitory concentrations (IC50s) of 0.13, 10.73, and 7.92 μ m , respectively. These findings may serve as a basis for further studies into the suitability of cotton as a source of potential therapeutics for SARS‐CoV‐2.