Two novel pyrroloquinoline alkaloids, martinelline (1) and martinellic acid (2), were isolated from an organic extract of Martinella iquitosensis roots. The ethnobotanical use of the two Martinella species as an eye medication in South America may be explained in part by the presence of 1 and to a lesser extent 2; this study relates the bradykinin (BK) B-1 and B-2 receptor antagonist activity of 1 and 2 as well as the affinity of 1 for histaminergic, alpha(1)-adrenergic, and muscarinic receptors. 1 and 2 represent the only naturally occurring nonpeptide BK antagonists reported to date. The antibiotic potential, cytotoxicity, and lytic activity were also evaluated for these compounds.