An update review of emerging small-molecule therapeutic options for COVID-19.

The SARS-CoV-2 outbreak and pandemic that began near the end of 2019 has posed a challenge to global health. At present, many candidate small-molecule therapeutics have been developed that can inhibit both the infection and replication of SARS-CoV-2 and even potentially relieve cytokine storms and other related complications. Meanwhile, host-targeted drugs that inhibit cellular transmembrane serine protease (TMPRSS2) can prevent SARS-CoV-2 from entering cells, and its combination with chloroquine and dihydroorotate dehydrogenase (DHODH) inhibitors can limit the spread of SARS-CoV-2 and reduce the morbidity and mortality of patients with COVID-19. The present article provides an overview of these small-molecule therapeutics based on insights from medicinal chemistry research and focuses on RNA-dependent RNA polymerase (RdRp) inhibitors, such as the nucleoside analogues remdesivir, favipiravir and ribavirin. This review also covers inhibitors of 3C-like protease (3CLpro), papain-like protease (PLpro) and other potentially innovative active ingredient molecules, describing their potential targets, activities, clinical status and side effects.

Crystal structure of gluconate 5-dehydrogenase from Lentibacter algarum.

Gluconate 5-dehydrogenase (Ga5DH; EC 1.1.1.69) from Lentibacter algarum (LaGa5DH) was recombinantly expressed in Escherichia coli and purified to homogeneity. The protein was crystallized and the crystal structure was solved at 2.1 Šresolution. The crystal belonged to the monoclinic system, with space group P1 and unit-cell parameters a = 55.42, b = 55.48, c = 79.16 Å, α = 100.51, ß = 105.66, γ = 97.99°. The structure revealed LaGaDH to be a tetramer, with each subunit consisting of six α-helices and three antiparallel ß-hairpins. LaGa5DH has high structural similarity to other Ga5DH proteins, demonstrating that this enzyme is highly conserved.

Hypertensive nephropathy treatment by heart-protecting musk pill: a study of anti-inflammatory therapy for target organ damage of hypertension.

This study was designed to investigate the protective effect of the heart-protecting musk pill (HMP) on inflammatory injury of kidney from spontaneously hypertensive rat (SHR). Male SHRs aged 4 weeks were divided into SHR model group, HMP low-dosage group (13.5 mg/kg), and HMP high-dosage group (40 mg/kg). Age-matched Wistar-Kyoto rats were used as normal control. All rats were killed at 12 weeks of age. Tail-cuff method and enzyme-linked immunosorbent assay were used to determine rat systolic blood pressure and angiotensin II (Ang II) contents, respectively. Renal inflammatory damage was evaluated by the following parameters: protein expressions of inflammatory cytokines, carbonyl protein contents, nitrite concentration, infiltration of monocytes/macrophages in interstitium and glomeruli, kidney pathological changes, and excretion rate of urinary protein. HMP did not prevent the development of hypertension in SHR. However, this Chinese medicinal compound decreased renal Ang II content. Consistent with the change of renal Ang II, all the parameters of renal inflammatory injury were significantly decreased by HMP. This study indicates that HMP is a potent suppressor of renal inflammatory damage in SHR, which may serve as a basis for the advanced preventive and therapeutic investigation of HMP in hypertensive nephropathy.

Inflammatory reaction versus endogenous peroxisome proliferator-activated receptors expression, re-exploring secondary organ complications of spontaneously hypertensive rats.

BACKGROUND: The chronic pathological changes in vascular walls of hypertension may exert destructive effects on multiple organ systems. Accumulating evidence indicates that inflammatory reactions are involved in the pathological changes of hypertension. Three peroxisome proliferator-activated receptors (PPARs) have been identified: PPARalpha, PPARbeta/delta, and PPARgamma, all of which have multiple biological effects, especially the inhibition of inflammation. The aim of this study was to evaluate PPAR isoforms expression profile in important organs of spontaneously hypertensive rats (SHR) and to understand the modulation of endogenous PPAR isoforms under inflammatory condition. METHODS: Tissues (kidney, liver, heart, and brain) were dissected from SHR and age-matched control Wistar-Kyoto rats (WKY) to investigate the abundance of PPAR isoforms and PPAR-responsive genes (acyl-CoA oxidase and CD36). The expression of CCAAT/enhancer-binding protein delta (C/EBPdelta), which can trans-activate PPARgamma expression, was also observed. The inflammatory response was analyzed by the expression of inflammatory mediators inducible nitric oxide synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, interleukin-1 beta (IL-1beta), and tumor necrosis factor alpha (TNFalpha), and formation of carbonyl and nitrated proteins. RESULTS: The expressions of 3 PPAR isoforms and PPAR-responsive genes were markedly upregulated in SHR compared with those of WKY. Specifically, the expression of PPARalpha protein in the kidney, liver, heart and brain increased by 130.76%, 91.48%, 306.24%, and 90.70%; PPARbeta/delta upregulated by 109.34%, 161.98%, 137.04%, and 131.66%; PPARgamma increased by 393.76%, 193.17%, 559.29%, and 591.18%. In consistent with the changes in PPARgamma, the expression of C/EBPdelta was also dramatically elevated in SHR. Inflammatory mediators expressions were significantly increased in the most organs of SHR than WKY. As a consequence, increased formation of carbonyl and nitrated proteins were also observed in the most organs of SHR. CONCLUSIONS: These findings suggest an enhanced inflammatory response in the organs of SHR, which might play a key role in pathogenesis of hypertension and secondary organ complications. Changes (increases) in PPARs expression may reflect a compensatory mechanism to the inflammatory status of hypertensive rats.

Inflammation of different tissues in spontaneously hypertensive rats.

The hypertension is one of chronic vascular diseases, which often implicates multiple tissues causing stroke, cardiac hypertrophy, and renal failure. A growing body of evidence suggests that inflammatory mechanisms are important participants in the pathophysiology of hypertension. In this study, the inflammatory status of these tissues (kidney, liver, heart, and brain) in spontaneously hypertensive rats (SHR) was analyzed and its molecular mechanism was explored. The tissues were dissected from SHR and age-matched control Wistar-Kyoto (WKY) rats to investigate the abundance of inflammation-related mediators (IL-1beta, TNFalpha, ICAM-1, iNOS, C/EBPdelta and PPARgamma). mRNA levels were determined by reverse transcription-polymerase chain reaction and protein expression was evaluated by Western blot. To evaluate the oxidative stress of tissues, carbonyl protein content and total antioxidant capacity of tissues were detected by spectrophotometry and ferric reduction ability power (FRAP) method. The results suggest that: (1) Expressions of inflammation-related mediators (IL-1beta, TNFalpha, ICAM-1, iNOS, C/EBPdelta and PPARgamma) in SHR were higher compared with those in WKY rats except no evident increase of IL-1beta mRNA in liver and brain in SHR. (2) Tissues in SHR contained obviously increased carbonyl protein (nmol/mg protein) compared to that in WKY rats (8.93+/-1.08 vs 2.27+/-0.43 for kidney, 2.23+/-0.23 vs 0.17+/-0.02 for heart, 13.42+/-1.10 vs 5.72+/-1.01 for brain, respectively, P<0.05). However, no evident difference in the amount of carbonyl protein in liver was detected between SHR and WKY rats. (3) Total antioxidant capacities of kidney, liver, heart and brain were markedly lower in SHR than that in WKY rats (P<0.05). Thus, the present data reveal a higher inflammatory status in the important tissues in SHR and indicate that inflammation might play a potential role in pathogenesis of hypertension and secondary organ complications.