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Fractionation of geopropolis from Melipona scutellaris, guided by antiproliferative activity against two colon cancer cell lines (COLO205 and KM12), led to the isolation of two new cinnamic acid esters, mammea-type coumarins 5,7-dihydroxy-6-(3-methyl-2-butenyl)-8-(4-cinnamoyl-3-methyl-1-oxobutyl)-4-propyl-coumarin (1) and 5,7-dihydroxy-6-(4-cinnamoyl-3-methyl-1-oxobutyl)-4-phenylcoumarin (2), along with five known coumarins, mammeigin (3), hydroxymammeigin (4), mammeisin (5), cinnamoyloxy-mammeisin (6), and mammein (7), and the prenylated benzophenone ent-nemorosone (8). Among the isolated compounds, 5 and 7 showed the highest cell growth inhibition against COLO205 (GI50 9.7 and 10.7 µM, respectively) and KM12 (GI50 12.0 and 10.9 µM, respectively). The presence of these compounds suggests that plants of Clusiaceae family, especially the genera Kielmeyera and Clusia, are likely to be major sources of geopropolis produced by M. scutellaris., (Georg Thieme Verlag KG Stuttgart · New York.)

In a search for natural product inhibitors of hypoxia inducible factor-1 (HIF-1) function, crinamine (1), a crinane type alkaloid, showed potent dose dependent inhibition (IC50 = 2.7 microM) of HIF-1alpha in a cell-based reporter gene assay. Crinamine (1) was isolated from the aerial parts of Crinum asiaticum var. japonicum together with lycorine (2), norgalanthamine (3) and epinorgalanthamine (4). The other components (2-4) showed no significant inhibition of HIF-1alpha induced transcriptional activity.