β-Cembrenediol (β-CBT) is a natural product from tobacco plants that is found in cigarette smoke condensate. β-CBT inhibits induction of the early antigen of Epstein-Barr virus (EA-EBV) by 12-O-tetradecanoylphorbol-13-acetate (TPA) in vitro (IC50 = 21.9 μM). It inhibits tumor promoting effects of TPA on 7,12-demethylbenz[a]anthracene-induced papilloma formation in vivo. β-CBT is also released into soil by flue-cured tobacco plants and exerts autotoxicity as well as phytotoxic activity against L. sativa seedlings.
Malformin A is a cyclopentapeptide fungal metabolite that has been found in A. niger and has diverse biological activities. It is a plant growth regulator that induces malformations in plant structure. Malformin A inhibits replication of tobacco mosaic virus (TMV) in local lesion and leaf-disc assays (IC50s = 19.7 and 45.4 μg/ml, respectively). It is cytotoxic to NCI-H460, MIA PaCa-2, MCF-7, SF-268, and WI-38 cancer cells (IC50s = 70, 50, 100, 70, and 100 nM, respectively), inhibits proliferation of PC3 and LNCaP cells (IC50s = 130 and 90 nM, respectively), and induces apoptosis and necrosis in PC3 and LNCaP cells. Malformin A also increases the accumulation of reactive oxygen species, decreases the mitochondrial membrane potential, and induces autophagy in PC3 and LNCaP cells. It is toxic to mice when administered intraperitoneally (LD50 = 3.1 mg/kg) but not orally up to doses of 50 mg/kg.