Microglial activation drives neuroinflammation, a key factor in many neurological diseases. The purinergic system is a major regulator of inflammatory responses and represents a promising target for controlling neuroinflammation. Capsaicin, a bioactive compound found in chili peppers, exhibits significant anti-inflammatory and antioxidant properties. This study aimed to investigate the modulatory effects of capsaicin on microglial activation and purinergic system regulation. For this, BV-2 microglial cells were exposed to lipopolysaccharide (1 μg/mL) and treated with capsaicin (25 and 50 μM) for 24 hours. Cell viability was assessed by MTT and trypan blue assays. Cell cycle and apoptosis were evaluated by flow cytometry. Nitric oxide, reactive species and malondialdehyde levels were evaluated as markers of oxidative stress. Activities of NTPDase, 5'-nucleotidase (5’-NT), and adenosine deaminase (ADA) were evaluated. Gene expression of inflammatory mediators and purinergic receptors were analyzed by qRT-PCR, and molecular docking analyses were performed. As a result, capsaicin decreased the expression of pro-inflammatory mediators (NLRP3, CASP-1, IL-1β, IL-6, and TNF-α), increased IL-10 expression, and attenuated oxidative stress. It reduced NTPDase, 5'-NT, and ADA activities, downregulated P2X7 and A2A receptor expression, and upregulated A1 receptor expression. Molecular docking revealed that capsaicin has a high affinity for the A1 and A2A receptors, as well as for ADA. Collectively, these findings suggest that capsaicin exerts neuroprotective effect by suppressing pro-inflammatory signaling, enhancing anti-inflammatory responses, reducing oxidative stress, and modulating key components of the purinergic system, including ectoenzyme activities and P2X7, A1, and A2A receptor expression. Graphical Abstract Lipopolysaccharide (LPS) activates microglia via the NLRP3 pathway, increasing pro-inflammatory cytokines, purinergic receptors expression (P2X7 and A2A), and the activity of CD39, CD73, and ADA. Capsaicin mitigates this inflammatory profile by inhibiting NLRP3 signaling, reducing pro-inflammatory cytokine expression and modulating purinergic signaling toward an anti-inflammatory profile. Illustrations were obtained from Servier Medical Art ( https://smart.servier.com/ ), licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).

Cutaneous melanoma (CM) is an aggressive and metastatic tumor, resulting in high mortality rates. Despite significant advances in therapeutics, the available treatments still require improvements. Thus, purinergic signaling emerged as a potential pathway to cancer therapy due to its involvement in cell communication, proliferation, differentiation, and apoptosis. In addition, due to safety and acceptable clinical tolerability, carotenoids from microalgae have been investigated as adjuvants in anti-melanoma therapy. Then, this work aimed to investigate the in vitro anti-melanogenic effect of carotenoid extract (CA) and total biomass (BM) of the Scenedesmus obliquus microalgae on two cutaneous melanoma cell lines (A375 and B16F10). Cells were cultivated under ideal conditions and treated with 10, 25, 50, and 100 μM of CA or BM for 24 h. The effects of the compounds on viability, oxidant status, and purinergic signaling were verified. The IC50 cell viability results showed that CA and BM decreased B16F10 viability at 24.29 μM and 74.85 μM, respectively and decreased A375 viability at 73.93 μM and 127.80 μM, respectively. Carotenoid treatment for 24 h in B16F10 and A375 cells increased the release of reactive oxygen species compared to the control. In addition, CA and BM isolated or combined with cisplatin chemotherapy (CIS) modulated the purinergic system in B16F10 and A375 cell lines through P2X7, A2AR, CD39, and 5′-nucleotidase. They led to cell apoptosis and immunoregulation by activating A2A receptors and CD73 inhibition. The results disclose that CA and BM from Scenedesmus obliquus exhibit an anti-melanogenic effect, inhibiting melanoma cell growth.