Armochaetoglobins K–R, Anti‐HIV Pyrrole‐Based Cytochalasans from Chaetomium globosum TW1‐1

Abstract Eight rare pyrrole‐based cytochalasans, termed armochaetoglobins K–R ( 1 – 8 ), along with three known analogues ( 9 – 11 ), were isolated from the solid culture broth of Chaetomium globosum TW1‐1, a symbiotic fungus derived from the medicinal terrestrial arthropod Armadillidium vulgare . Their structures were elucidated using a combination of spectroscopic analysis, a single‐crystal X‐ray diffraction experiment, and an electronic circular dichroism (ECD) calculation. Compounds 4 – 8 represent the first examples of chaetoglobosin‐type cytochalasans with an sp 3 methine carbon at C‐18. All of the isolates were evaluated for their anti‐HIV activities in vitro, and compounds 2 – 4 , 7 , 8 , and 10 showed significant anti‐HIV activities, with EC 50 values ranging from 0.11 to 0.55 μ M , and selectivity index (SI) values ranging from 12.33 to 75.42. A plausible biosynthetic pathway was proposed to explain the origin of the pyrrole ring.