Agnuside is an iridoid glycoside originally isolated from V. rotundifolia fruit that has diverse biological activities. It inhibits COX-2 with an IC50 value of 0.026 mg/ml but exhibits less than 10% inhibition of COX-1 at this concentration. It also inhibits 46.3, 66.8, and 82.1% of P-glycoprotein (P-gp) ATPase activity at concentrations of 5, 25, and 100 μM, respectively. Agnuside (0.1-10 μM) induces proliferation of MCF-7 breast cancer cells, an effect that is inhibited by the estrogen receptor antagonist fulvestrant . In vivo, agnuside (50 mg/kg) reduces acetic acid-induced writhing in mice indicating analgesia. It also suppresses production of the pro-inflammatory mediators prostaglandin E2 (PGE2) and leukotriene B4 and the T cell-mediated cytokines IL-2, TNF-α, INF-γ, IL-4, IL-10, and IL-17 in splenocytes and arthritic paw tissue from arthritic adrenalectomized rats.