Hypurpurins A-P, furanolabdane diterpenoids from the aerial parts of Hypoestes purpurea and their bioactivities.

Sixteen previously undescribed furanolabdane diterpenoids, designated hypurpurins A-P (1-16), along with two known analogs, hypopurins B and C (17 and 18), were isolated from the aerial parts of Hypoestes purpurea. The chemical structures of 1-16 were elucidated through comprehensive spectroscopic analyses, including HR-ESI-MS, NMR, UV, and IR spectroscopy. The absolute configurations of these new compounds were further determined by electronic circular dichroism and single-crystal X-ray diffraction analysis. Structurally, compounds 1 and 2 are unprecedented furanolabdane diterpenoids bearing an 8,20:12,20-diepoxy unit; compounds 3 and 4 are unique furanolabdane diterpenoids featuring 12,20-epoxy and 19,20-lactone moieties; compounds 5 and 6 represent the first examples of furanolabdane diterpenoids possessing an 8,12-epoxy and 19,20-lactone ring. All isolated compounds were evaluated for their nitric oxide (NO) inhibitory effects and cytotoxicity against HPAC and ASPC-1 cancer cell lines. Among them, compounds 7 and 17 exhibited moderate inhibitory effects on lipopolysaccharide-induced NO release in RAW 264.7 cells, with IC50 values of 44.14 and 36.48 μM, respectively.