Wood species resistant to biodegradation by fungi contain phenolic compounds with proven fungicidal activity. Saprophytic fungi are able to colonize wood and later begin to break down its polymeric components through metal-dependent reactions. These generate free radicals at the onset of the degradation process. Later on, extracellular enzymes are active that use metallic cofactors. Five lignans were isolated from the methanolic extracts of the Chilean heartwoods (Austrocedrus chilensis, Fitzroya cupressoides, and Pilgerodendron uviferum) belonging to the Cupressaceae: isotaxiresinol, secoisolariciresinol, isolariciresinol, didemethylmatairesinol, and matairesinol. Their structures were determined spectroscopically. The antioxidant activity of the methanolic extracts and the isolated compounds was determined in vitro against the radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and their iron-chelating capacity was evaluated by the Chrome Azurol S assay. All isolated methanolic extracts and lignans exhibited antioxidant activity against DPPH and Fe-chelating capacity with values greater than 87%. This may be interpreted that the antioxidant properties and metal-chelating capacity of these compounds have a protective effect on the wood of these species when exposed to attacks by saprophytic fungi.

Materials and methods:The antiproliferative activity of yatein, isotaxiresinol, ferruginol, and isorhamnetin was evaluated in vitro using the MTT assay. The effect of yatein at the cellular level, due to its high antiproliferative activity was evaluated. P3X cells treated for 24 h with 12.5 and 25 mg/mL of yatein were also examined at the cytological level using immunofluorescence and scanning and transmission electron microscopy.Results: Yatein, a lignan isolated from A. chilensis, potentially inhibited P3X murine myeloma cell proliferation, resulting in approximately 75% cell death in response to a 25 mg/mL treatment with the lignan. P3X cells lost membrane integrity at the nuclear and cytoplasmic levels, including organelles, in response to yatein treatment (12.5 mg/mL), and we observed changes in the cytoplasmic organization and distribution of microtubules. The other compounds tested had low activity. Discussion and conclusions: Yatein is a lignan precursor of podophyllotoxin, a key agent in anticancer drugs. Due to its structural similarities to podophyllotoxin, yatein could have similar cytoplasmic target(s), such as the microtubular apparatus. These findings suggest that yatein may be of potential pharmacological interest and warrants further investigation in human cell lines.

The genus Heliotropium is formed of herbaceous plants belonging to the family Boraginaceae. In Chile and around the world, many Heliotropium species are commonly used in traditional and complementary medicine to treat various diseases. Members of this genus are also recognized for unique biosynthesized phytochemicals, mainly terpenoids, phenolics and alkaloids. Due to important phyto-constituents, as well as their therapeutic potential, many Heliotropium species have been subjected to chemical, biological and pharmacological investigations. This review details the many ethnomedicinal uses for Heliotropium, with an emphasis on Chilean species, and analyzes their scientific validation based on the chemical constituents and pharmacological properties of Heliotropium reported in academic publications. In addition, we discuss the critical conclusions, as well as some suggestions for future phytochemical and biological studies with Heliotropium species.