Joao Batista Calixto

This review critically examines more than four decades of research and innovation conducted by our research group on bioactive constituents and standardized extracts from Brazilian medicinal plants. It integrates phytochemical and preclinical pharmacological evidence, limited clinical studies and translational experiences, highlighting major scientific achievements and the persistent gap between academic research and the development of innovative phytomedicines in Brazil. In parallel, we analyse the evolution of the Brazilian phytomedicine market and regulatory advances aimed at supporting the development of phytotherapeutic agents based on scientific evidence of efficacy and safety. Despite Brazil's exceptional biodiversity and the extensive experimental data generated over several decades on medicinal plants, the translation of scientific knowledge into registered and innovative phytotherapeutic agents remains limited. This review identifies major structural barriers that continue to hinder progress, including the low engagement of the national pharmaceutical industry in innovation‐driven drug development, regulatory and operational challenges related to clinical trials, and the absence of sustained governmental policies to support long‐term basic and translational research. Collectively, these factors restrict Brazil's capacity to develop medicines domestically and to strategically capitalize on its biological resources. By critically reflecting on lessons learned from our long‐term research and innovation efforts, this article underscores the need for integrated strategies aligning scientific excellence, regulatory frameworks, industrial participation and public policies. Strengthening these connections is essential to transform Brazil's medicinal plant biodiversity into clinically validated, safe and accessible therapeutic products that benefit public health and national innovation.

Background and purpose: Chikungunya virus (CHIKV) causes debilitating chronic joint pain. CHIKV‐induced pain mechanisms are not completely understood and models designed to resemble CHIKV chronic pain are critical for the development of novel therapeutic approaches. Experimental approach: Mechanical allodynia was induced by injection of either inactivated CHIKV or its viral RNA into the mouse ipsilateral knee. Both ipsilateral and contralateral joints were collected for histological analysis, collagen Type I content and immunohistochemistry. The effects of paracetamol and sodium diclofenac were assessed and the role of the transient receptor potential ankyrin 1 (TRPA1) was investigated using the antagonist HC‐030031 and TRPA1 knockout (KO) mice. CHIKV‐induced Ca ²⁺ influx was also assessed in mouse dorsal root ganglion (DRG) neurones. Key results: CHIKV or its RNA caused pronounced and time‐dependent bilateral secondary mechanical allodynia. CHIKV caused structural damage in the ipsilateral joint and increased collagen type I content. Higher IL‐10, VEGF and TGF β expressions were observed in the affected joints. Paracetamol or sodium diclofenac reduced allodynia, which was also absent in TRPA1 KO and HC‐030031‐treated mice. TRPA1 expression was up‐regulated in CHIKV‐injected joints whilst CHIKV envelope E2 protein or RNA induced Ca ²⁺ influx in DRG neurones was antagonized by HC‐030031. Conclusion and implications: Insights into CHIKV‐associated pain have been made giving a guide to targeted analgesic strategies. CHIKV or its RNA injection triggers bilateral secondary mechanical allodynia, accompanied by knee joint damage and a TRPA1‐dependent mechanism. Indicating TRPA1 blockers have the potential to be repurposed or further investigated for the clinical management of CHIKV‐associated chronic pain.

Chikungunya virus (CHIKV), the causative agent of the chikungunya fever, is an alphavirus widely transmitted by the bite of the female mosquito of the genus Aedes sp., especially in tropical and subtropical regions. Brazil is the country most affected by the microorganism. CHIKV classically induces articular pain, which can become long lasting for even years in a great number of the infected individuals, reducing their quality of life. The mechanisms of CHIKV-induced pain are poorly understood, but recent evidence indicated a role for the transient receptor potential vanilloid 1 (TRPV1) in this pathology. Herein, we assessed the ability of intra-articularly injected inactivated CHIKV or its RNA to trigger nociception in mice. Both stimuli induced bilateral secondary hyperalgesia to mechanical and heat stimuli. These responses were attenuated by TRPV1 ablation or antagonism. Joint structural alterations and increased cartilage TRPV1 protein expression were detected in the ipsilateral knee joints injected with either CHIKV or viral RNA. However, the lack of this receptor did not influence the histological changes triggered by CHIKV or RNA. The results further support the role of TRPV1 in CHIKV-induced pain and highlight its importance in the chronic phase of the disease.

Background: This study examines the impact of Phα1β, a spider peptide derived from the venom of Phoneutria nigriventer, on the Kv11.1 potassium channel in HEK293 cells transfected with the human ERG potassium channel. Phα1β inhibits high-voltage calcium channels and acts as an antagonist of the TRPA1 receptor, both of which play crucial roles in pain transduction pathways. Over the past 15 years, our research has demonstrated the potential of Phα1β, in both its native and recombinant forms, as a promising analgesic drug through preclinical tests conducted on rodent pain models. Regulatory agencies require the evaluation of new drugs on human ERG channels.

Phα1β a spider peptide, purified from the venom of Phoneutria nigriventer inhibits high voltage calcium channels and is antagonist of TRPA1 receptor two important pain transduction path-ways. In the last 15 years, we have showed, in preclinical tests with Phα1β native and recombi-nant in rodent models of pain the potential of Phα1β to become a new analgesic drug. Evaluation of new drug on human ERG channel is requirement of the regulatory agencies. For the hERG channel inhibition assay it was used the commercial kit FLIPR® Potassium Assay. It was tested the effect of Phα1β and as positive control dofetilide, a well characterized hERG block-er. Phα1β 56, 225, 450 and 900 pMol caused at a higher concentration a very weak inhibition of the hERG channel activity of about 13.47 % with channel inhibition at 50%, IC50 > 900 pMol. Dofetilide (0.0001 - 10 µM), a known hERG inhibitor, caused a well-known, concentra-tion-dependent inhibition of the hERG channel with a mean IC50 of 0.1642 µM (0.1189 – 0.2282 µM. For the cytotoxicity assay, Phα1β concentrations of 56, 225, 450 and 900 pMol incubated for 24 h with HEK293-hERG cells did not alter the viability of the HEK293-hERG cells. It is con-cluded that Phα1β even at high concentrations does not interfere with hERG channels.

Orally available antivirals against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are necessary because of the continuous circulation of new variants that challenge immunized individuals. Because severe COVID-19 is a virus-triggered immune and inflammatory dysfunction, molecules endowed with both antiviral and anti-inflammatory activity are highly desirable. We identified here that kinetin (MB-905) inhibits the in vitro replication of SARS-CoV-2 in human hepatic and pulmonary cell lines. On infected monocytes, MB-905 reduced virus replication, IL-6 and TNFα levels. MB-905 is converted into its triphosphate nucleotide to inhibit viral RNA synthesis and induce error-prone virus replication. Coinhibition of SARS-CoV-2 exonuclease, a proofreading enzyme that corrects erroneously incorporated nucleotides during viral RNA replication, potentiated the inhibitory effect of MB-905. MB-905 shows good oral absorption, its metabolites are stable, achieving long-lasting plasma and lung concentrations, and this drug is not mutagenic nor cardiotoxic in acute and chronic treatments. SARS-CoV-2-infected hACE-mice and hamsters treated with MB-905 show decreased viral replication, lung necrosis, hemorrhage and inflammation. Because kinetin is clinically investigated for a rare genetic disease at regimens beyond the predicted concentrations of antiviral/anti-inflammatory inhibition, our investigation suggests the opportunity for the rapid clinical development of a new antiviral substance for the treatment of COVID-19.