Evaluation of Aloin and Aloe-Emodin as Anti-Inflammatory Agents in Aloe by Using Murine Macrophages

TLDR

The specific aloe constituents and their effective concentrations for physiological effects remain unclear. The study compares the anti‑inflammatory effects of aloin and aloe‑emodin to other polyphenols. Aloe‑emodin dose‑dependently inhibited iNOS mRNA and NO production and, at 40 μM, suppressed COX‑2 mRNA and PGE₂, while aloin reduced NO but not PGE₂; both compounds likely suppress inflammation by blocking iNOS and COX‑2 expression, with aloe‑emodin’s effect comparable to kaempferol and quercetin.

Abstract

The aloe ingredients responsible for physiological effects and the concentrations required to exert their biological activities are not fully understood. This study compares the anti-inflammatory effects of aloin and aloe-emodin with other polyphenols. Our results demonstrated that aloe-emodin dose-dependently inhibited inducible nitric oxide synthase (iNOS) mRNA expression and nitric oxide (NO) production at 5–40 μm. In addition, the levels of cyclooxygenase-2 (COX-2) mRNA and prostaglandin E2 (PGE2) production were suppressed by 40 μm aloe-emodin. Aloin also suppressed the production of NO at 5–40 μm, although it did not suppress PGE2 production. The present results indicate that aloin and aloe-emodin possibly suppress the inflammatory responses by blocking iNOS and COX-2 mRNA expression. The anti-inflammatory effect of aloe-emodin was comparable to that of kaempferol and quercetin, indicating aloe-emodin as a possible key constituent responsible for the anti-inflammatory activity of aloe.