Fractionation of a MeOH/CH2Cl2 (1/1) extract of the aerial parts of Senecio erechtitoides led to the isolation of six compounds including the hitherto unknown N-phenethylamide derivative named N-(phydroxyphenethyl)pentacosanamide (1), and a kauranoid derivative named derivative named ent-7 oxo-16a,17-dihydroxykauran-19-oic acid (2), as well as four known compounds, ent-Kaur-16-en-19-oic acid (3), ent-7b-hydroxykaur-16-en-19-oic acid (4), ent-7-oxokaur-16-en-19-oic acid (5), steppogenin 40 -O-b-D-glucoside (6). Their structures and relative configurations were elucidated on the basis of spectroscopic methods, chemical reactions, and comparison with previously known analogs. All isolates were evaluated for their antimicrobial activity and only diterpenoids were found to possess a potent inhibitor effect against the range of microorganism.