A new griseofulvin derivative, 4'-demethoxy-4'-N-isopentylisogriseofulvin (1), three new indole alkaloids, 2-demethylcyclopiamide E (2), 2-demethylsperadine F (3), and clopiamine C (4), and five known metabolites (5-9) were isolated from Penicillium griseofulvum CPCC 400528. Compound 1 is the first reported griseofulvin analogue with an N-isopentane group and the first example of a naturally occurring N-containing griseofulvin analogue. Their structures and absolute configurations were elucidated through extensive spectroscopic analyses, calculated ECD, and single-crystal X-ray diffraction (Cu Kα). The possible biogenetic pathway of 1-3 was proposed. Compounds 1, 2, and 5 exhibited anti-HIV activities with IC50 values of 33.2, 20.5, and 12.6 μM, respectively.