Chemical investigation of the 80% $Me_2CO$ extract from the seeds of Prunus tomentosa led to the isolation and identification of six flavonoids: kaempferol (1), kaempferol $3-O-{alpha}-L-rhamnopy-ranoside$ (2; afzelin), kaempferol $3-O-{eta}-D-(6-acetyl)-glucopyranosyl(1{ ightarrow}4)-{alpha}-L-rhamnopyrano-side$ (3; multiflorin A), kaempferol $3-O-{eta}-D-glucopyranosyl(1{ ightarrow}4)-{alpha}-L-rhamnopyranoside$ (4; multiflorin B), quercetin $3-O-{alpha}-L-rhamnopyranoside$ (5; quercitrin), and quercetin $3-O-{eta}-D-glucopyranosyl$ $(1{ ightarrow}4)-{alpha}-L-rhamnopyranoside$ (6; multinoside A). Anti-oxidative and inhibitory activities on nitric oxide (NO) and prostaglandin $E_2$ production in $interferon-{gamma}$ $(INF-{gamma})$ and lipopolysaccharide (LPS)-activated RAW 264.7 cells in vitro (COX-2) of the isolated compounds were evaluated. Compounds 1, 5, and 6 exhibited potent anti-oxidative activity in the DPPH radical scavenging assay with $IC_{50}$ values of 57.2, 59.4, and 54.3 ${mu}g/mL$ respectively. The positive control, ascorbic acid, had an $IC_{50}$ of 55.5 ${mu}g/mL$. Compounds 1, 5, and 6 also reduced COX-2 levels in a dose dependent manner with $IC_{50}$ values of 10.2, 8.7, and 9.6 ${mu}g/mL$ respectively, with the positive control, indomethacin, having an $IC_{50}$ of 5.1 ${mu}g/mL$. All six compounds inhibited NO production in a dose dependent manner with $IC_{50}$ values of 35.1, 42.8, 40.0, 44.8, 43.7, and 43.9 ${mu}g/mL$ respectively, while the positive control, L-NMMA, had an $IC_{50}$ of 42.1 ${mu}g/mL$.