Insecticidal activity of paraherquamides, including paraherquamide H and paraherquamide I, two new alkaloids isolated from Penicillium cluniae.

Paraherquamide H (1) and paraherquamide I (2), two new compounds of the paraherquamide (PHQ)
family, together with the already known paraherquamide A (3), paraherquamide B (4), paraherquamide
E (5), VM55596 (N-oxide paraherquamide) (6), paraherquamide VM55597 (7), and five known
diketopiperazines (8-12) have been isolated from the culture broth of Penicillium cluniae Quintanilla.
The structure of 1 and 2, on the basis of NMR and MS analysis, was established. It is worth noticing
that, in both cases, an unusual oxidative substitution in C-16 was found, which had only previously
been detected in PHQ 7. Isolated compounds were tested for insecticidal activity against the
hemipteran Oncopeltus fasciatus Dallas. Mortality data have allowed preliminary structure activity
relationships to be proposed. The most potent product was 5 with a LD50 of 0.089 íg/nymph