Crotoscheffleriolides, ent-clerodane diterpenoids from Kenyan Croton scheffleri

Abstract

Kenyan Croton scheffleri has yielded nineteen compounds. The stem bark gave six undescribed ent-clerodane diterpenoids (1–4, 6 and 7), three undescribed sesquiterpene lactones (9, 11 and 12) and four known compounds (5, 8, 10 and 13). From the leaves six known compounds were identified, ayanin (14), pheophytin a (15), ferulic acid (16), 1,3,4-trihydroxybenzene (17), sitosterol (18), and podosterol (19). The structures of the compounds were determined using spectroscopic and spectrometric methods, NMR, IR, UV, polarimetry, ECD, HRESIMS, and GC-MS. The undescribed compounds were assessed against HIV-1 Reverse Transcriptase and both gram-positive bacteria Staphylococcus aureus 29213 and Enterococcus faecalis 29212, as well as gram-negative bacteria Escherichia coli 25922 and Pseudomonas aeruginosa 27853. Compounds 1, 4, 5, 6, 7, 10, 12 and 19 increased the proliferation of serum starved dermal fibroblast cells at a concentration of 100 nM. All compounds inhibited human dermal fibroblast cell proliferation at 100 μM, while compounds 1, 4 and 19 inhibited fibroblast proliferation at 10 μM.