Efeito atenuante do análogo sintético N-metil do alcaloide caulerpina no processo inflamatório em modelos murinos de inflamação

Abstract

Inflammation is a response of the body to different types of injuries, aiming to repair damaged tissues and eliminate dead cells Caulerpine is an alkaloid extracted from the marine algae Caulerpa racemosa with anti-inflammatory properties. Through structural modifications in the indole core and the ester group of classic caulerpine (CLPc), the N-methyl analog (CLPNmt) was generated, improving its solubility and lipophilicity. Thus, the present study aimed to evaluate the anti-inflammatory action of the CLPNmt analog in different murine models of acute inflammation, comparing it with CLPc and dexamethasone. Initially, a peritonitis model was conducted, where male Swiss mice were treated orally with CLPc (2 mg/kg), CLPNmt (4, 2, and 1 mg/kg), and intraperitoneally with dexamethasone (1 mg/kg). One hour later, they received zymosan (40 mg/kg) intraperitoneally. After 24 hours, the mice were euthanized, the peritoneal lavage was collected and centrifuged, and the total and differential leukocyte counts were determined. The supernatant was used for the quantification of IL-1β, IL-6, and TNF-α by ELISA. For the ear edema model, Swiss mice were treated with CLPNmt (2 mg/kg) and the other previously mentioned treatments, followed by the topical application of xylene (40 μL) on the right ears. One hour after treatment, the left and right ears were removed and weighed on a precision balance to determine the percentage of edema inhibition. The ears were then preserved in PBS/10% formalin for histological analysis. In the acute lung injury (ALI) model, the animals were treated orally with CLPc or CLPNmt (2 mg/kg) or intraperitoneally with dexamethasone (1 mg/kg). One hour later, the animals received 50 μL of LPS (100 μg/kg) intranasally. After 24 hours, the mice were euthanized, and the bronchoalveolar lavage (BAL) was collected and centrifuged. The cell pellet was used for total and differential leukocyte counts, while the supernatant was used for the quantification of inflammatory cytokines by ELISA and nitrite measurement using the Griess reaction. Lung samples were processed for histological analysis and RNA extraction to evaluate the quantitative expression of TNF-α by real-time polymerase chain reaction (qPCR). The results showed that CLPNmt treatment effectively reduced cell migration and IL-6 secretion in the peritoneal cavity, with the 2 mg/kg dose being the most efficient, which was then used as the standard dose in subsequent experiments. Moreover, CLPNmt significantly inhibited edema formation in the xyleneinduced model, similar to CLPc and dexamethasone. It also inhibited leukocyte recruitment to the pulmonary cavity, reduced IL-1β, IL-6, TNF-α, IFN-γ, and nitrite levels in BAL, and decreased lung damage in the ALI model. Therefore, the methylation of CLP maintained its anti-inflammatory potential, similar to what was observed for CLPc and compared to dexamethasone, making this analog a potential pharmacological target.