The Structures of Pulvomycins A-B

Abstract

Pulvomycin was isolated and identified about 30 years ago. However, fewer efforts were made to determine the full absolute configurations of pulvomycin. Hence, we decided to determine the absolute configuration of pulvomycin. Pulvomycins were isolated from the culture of Streptomyces sp. derived from a sediment sample. After about 8 days of culturing, pulvomycin and its derivatives were extracted from the bacterial culture and purified using HPLC (High Performance Liquid Chromatography). Planar structure of pulvomycin was confirmed by a combination of 1D and 2D NMR experiments, mass, IR and UV spectroscopy. In addition, we isolated one more derivative of pulvomycin called pulvomycin B. By interpreting the coupling constants from 1H NMR data, HETLOC NMR data and ROESY experiments and by using J-based relative configuration analysis, we were able to determine the relative configurations of pulvomycin. Absolute configurations of 4 chiral centers in pulvomycin were determined using the modified Moshers method. Pulvomycin B showed significant cytotoxic activity against SNU638 cell, a gastric carcinoma cell line and it also displayed moderate antibacterial activity.