Bioactive β-indoloquinazoline Alkaloids from Oricia renieri.

Three new β-indoloquinazoline alkaloids, orirenierine A (1), B (2) and C (4), together with eleven known compounds were isolated from the methanol extract of the stems of Oricia renieri. The structures of all compounds were determined by comprehensive analyses of their spectroscopic data and comparison with literature information. The alkaloids 9-11 were isolated for the first time from this genus. All compounds were tested for their activity against bacteria, fungi, and plant pathogen oomycetes using the paper disk agar diffusion assay. The agar diffusion test gave only low antimicrobial activities, corresponding to MICs > 1 mg/mL. However, compounds 1-4 and 11 exhibited a strong suppressive effect on phagocytosis response upon activation with serum opsonized zymosan in the range of IC₅₀ = 2.6- 6.5 μM, while low cytotoxic activity against the human Caucasian prostate adenocarcinoma cell line PC-3 was observed with IC₅₀ values ranging from 22.9 to 39.4 μM. [ABSTRACT FROM AUTHOR]