Intramolecular Interactions Enhance the Potency of Gallinamide A Analogues against Trypanosoma cruzi.

Gallinamide A, a metabolite of the marine cyanobacterium Schizothrix sp., selectively inhibits cathepsin L-like cysteine proteases. We evaluated the potency of gallinamide A and 23 synthetic analogues against intracellular Trypanosoma cruzi amastigotes and the cysteine protease, cruzain. We determined the co-crystal structures of cruzain with gallinamide A and two synthetic analogues at ∼2 Å. SAR data revealed that the N-terminal end of gallinamide A is loosely bound and weakly contributes in drug-target interactions. At the C-terminus, the intramolecular π-π stacking interactions between the aromatic substituents at P1' and P1 restrict the bioactive conformation of the inhibitors, thus minimizing the entropic loss associated with target binding. Molecular dynamics simulations showed that in the absence of an aromatic group at P1, the substituent at P1' interacts with tryptophan-184. The P1-P1' interactions had no effect on anti-cruzain activity, whereas anti-T. cruzi potency increased by ∼fivefold, likely due to an increase in solubility/permeability of the analogues.

Potent Anti-SARS-CoV-2 Activity by the Natural Product Gallinamide A and Analogues via Inhibition of Cathepsin L.

Cathepsin L is a key host cysteine protease utilized by coronaviruses for cell entry and is a promising drug target for novel antivirals against SARS-CoV-2. The marine natural product gallinamide A and several synthetic analogues were identified as potent inhibitors of cathepsin L with IC50 values in the picomolar range. Lead molecules possessed selectivity over other cathepsins and alternative host proteases involved in viral entry. Gallinamide A directly interacted with cathepsin L in cells and, together with two lead analogues, potently inhibited SARS-CoV-2 infection in vitro, with EC50 values in the nanomolar range. Reduced antiviral activity was observed in cells overexpressing transmembrane protease, serine 2 (TMPRSS2); however, a synergistic improvement in antiviral activity was achieved when combined with a TMPRSS2 inhibitor. These data highlight the potential of cathepsin L as a COVID-19 drug target as well as the likely need to inhibit multiple routes of viral entry to achieve efficacy.

Brimonidine Eye Drops Causing Encephalopathy in a Patient With Advanced Chronic Kidney Disease.

Brimonidine eye drops are frequently prescribed for the treatment of glaucoma and ocular hypertension in adults. Systemic toxicities including neurological side effects have been reported with its use, especially in the paediatric population. In this report, we present a case of encephalopathy secondary to the use of brimonidine eye drops in a patient with underlying advanced chronic kidney disease, who recovered promptly after drug cessation. Herein, we also review the pharmacokinetics of eye drops leading to their systemic side effects, especially in the context of renal impairment. We also explore the possibility of extracorporeal treatment, such as by haemodialysis, for the treatment of these manifestations. This case demonstrates the need to clarify a patient's drug history and stop offending medications early on in a patient with delirium, while treatments such as antidotes or extracorporeal treatment are being considered.

Clinicopathological features of Chinese patients with B-cell lymphoproliferative disorders and kidney infiltration.

AIM: Direct kidney involvement in B-cell lymphoproliferative disease is a rare disorder with only a few studies reported in Caucasian patients. The clinicopathological characteristics and outcome of this entity remain poorly described. METHODS: We retrospectively studied all adult Chinese patients who had histology-proven renal parenchymal infiltration by malignant B-cells between 1 January 2000 and 31 December 2018 at two tertiary hospitals in Hong Kong. Clinical, pathological and radiological data were collected from 20 patients. Follow-up data were analysed until 31 December 2019. RESULTS: Median follow-up duration was 22 (1-171) months. Only seven patients (35%) had established diagnosis of haematological cancer before kidney biopsy. Diffuse large B-cell lymphoma (DLBCL) was the most common subtype in our cohort (n = 5, 25%). Others included low-grade B-cell lymphoma (n = 11), intravascular large B-cell lymphoma (n = 1), mantle cell lymphoma (n = 1) and multiple myeloma (n = 2). Fourteen patients (70%) presented with AKI while 12 patients (60%) had proteinuria. Seven patients (35%) had unilateral renal mass, one had bilateral renal masses and one had bilateral diffuse nephromegaly in computed tomography. Lymphomatous tubulointerstitial infiltration was the prevalent histological finding. Nine patients (45%) had coexisting renal lesions other than direct tumour infiltration. All but one patient received chemotherapy. Ten patients died and renal responders had a significantly better survival than non-renal responders (p = .03). CONCLUSION: Direct tumour infiltration can occur in a wide variety of B-cell lymphoproliferative disorders. Coexisting immunoglobulin-related nephropathy is frequently found. Renal biopsy is required for early diagnosis which allows timely and appropriate treatment.

Total Synthesis and Antitrypanosomal Activity of Janadolide and Simplified Analogues.

Janadolide is a cyclic depsipeptide natural product isolated from the marine cyanobacterium Okeania sp. Herein, we describe the total synthesis of janadolide, along with eight simplified analogues, via an efficient solid-phase strategy. Crucial to the synthesis of the natural product was the construction of a key polyketide fragment via an enantioselective (-)-B-chlorodiisopinocampheylborane-mediated reduction and a B-alkyl Suzuki reaction. Janadolide and the simplified analogues exhibited antitrypanosomal activity against pathogenic Trypanosoma brucei rhodesiense and Trypanosoma cruzi parasites.

Potent in vitro anti-SARS-CoV-2 activity by gallinamide A and analogues via inhibition of cathepsin L.

The emergence of SARS-CoV-2 in late 2019, and the subsequent COVID-19 pandemic, has led to substantial mortality, together with mass global disruption. There is an urgent need for novel antiviral drugs for therapeutic or prophylactic application. Cathepsin L is a key host cysteine protease utilized by coronaviruses for cell entry and is recognized as a promising drug target. The marine natural product, gallinamide A and several synthetic analogues, were identified as potent inhibitors of cathepsin L activity with IC 50 values in the picomolar range. Lead molecules possessed selectivity over cathepsin B and other related human cathepsin proteases and did not exhibit inhibitory activity against viral proteases Mpro and PLpro. We demonstrate that gallinamide A and two lead analogues potently inhibit SARS-CoV-2 infection in vitro , with EC 50 values in the nanomolar range, thus further highlighting the potential of cathepsin L as a COVID-19 antiviral drug target.

A Solution to Chemical Pseudaminylation via a Bimodal Glycosyl Donor for Highly Stereocontrolled α- and ß-Glycosylation.

A robust methodology for the stereocontrolled chemical glycosylation of pseudaminic acid has been developed to afford both α- (axial) and ß- (equatorial) glycosides reliably with complete stereoselectivity, using a common glycosyl donor (7 N-Cbz/5 N-azido Pse thioglycoside) simply by changing the reaction conditions. In the CH2Cl2/MeCN cosolvent, highly ß-selective pseudaminylation was observed, while addition of 5.0 equiv DMF in CH2Cl2 gave the α-pseudaminosides.

Falcipain Inhibitors Based on the Natural Product Gallinamide A Are Potent in Vitro and in Vivo Antimalarials.

A library of analogues of the cyanobacterium-derived depsipeptide natural product gallinamide A were designed and prepared using a highly efficient and convergent synthetic route. Analogues were shown to exhibit potent inhibitory activity against the Plasmodium falciparum cysteine proteases falcipain 2 and falcipain 3 and against cultured chloroquine-sensitive (3D7) and chloroquine-resistant (W2) strains of P. falciparum. Three lead compounds were selected for evaluation of in vivo efficacy against Plasmodium berghei infection in mice on the basis of their improved blood, plasma, and microsomal stability profiles compared with the parent natural product. One of the lead analogues cured P. berghei-infected mice in the Peters 4 day-suppressive test when administered 25 mg kg-1 intraperitoneally daily for 4 days. The compound was also capable of clearing parasites in established infections at 50 mg kg-1 intraperitoneally daily for 4 days and exhibited moderate activity when administered as four oral doses of 100 mg kg-1.