Chitosan oligosaccharides affect xanthone and VOC biosynthesis in Hypericum perforatum root cultures and enhance the antifungal activity of root extracts

Abstract

Water-soluble chitosan oligosaccharides (COS) affect xanthone and volatile organic compound content, as well as antifungal activity against human pathogenic fungi of extracts obtained from Hypericum perforatum root cultures. Several studies have demonstrated the elicitor power of chitosan on xanthone biosynthesis in root cultures of H. perforatum. One of the major limitations to the use of chitosan, both for basic and applied research, is the need to use acidified water for solubilization. To overcome this problem, the elicitor effect of water-soluble COS on the biosynthesis of both xanthones and volatile organic compounds (VOCs) was evaluated in the present study. The analysis of xanthones and VOCs was performed by HPLC and GC-MS headspace analysis. The obtained results showed that COS are very effective in enhancing xanthone biosynthesis. With 400 mg L COS, a xanthone content of about 30 mg g DW was obtained. The antifungal activity of extracts obtained with 400 mg L COS was the highest, with MIC of 32 µg mL against Candida albicans and 32-64 µg mL against dermatophytes, depending on the microorganism. Histochemical investigations suggested the accumulation of isoprenoids in the secretory ducts of H. perforatum roots. The presence of monoterpenes and sesquiterpenes was confirmed by the headspace analysis. Other volatile hydrocarbons have been identified. The biosynthesis of most VOCs showed significant changes in response to COS, suggesting their involvement in plant-fungus interactions.

Toward enhanced hyperforin production in St. John's wort root cultures

“…The highest g X was 8.44 for H. tomentosum , transformed with A. rhizogenes A4 . This value is higher than previously reported data for auxin‐induced cultures . Impressively, g X reported in the current study was four to eight times higher than the previously reported values for shake flask cultivations of SJW root cultures (Table ) and the aforementioned hairy root cultures.…”

“…Thus, fixing these two factors might end in reproducible growth factor g X through years. Within the same scenario, comparing the growth factors of root cultures developed at the Italian laboratory (Table ) demonstrated that all cultures possessed similar values even after 8 years of repeated re‐establishment of these cultures, which might be explained by the imitated use of the same source of the explants. Correspondingly, the difference in g X values of the cultures developed in the Korean laboratory was minor when starting with the same inoculum size (Table ).…”

Chitosan Upregulates the Genes of the ROS Pathway and Enhances the Antioxidant Potential of Grape (Vitis vinifera L. ‘Touriga Franca’ and ’Tinto Cão’) Tissues

“…Exogenous chitosan reportedly interacts with chitin synthase, and chitin deacetylase in plants, to produce chitosan oligomers that are responsible for signal perception in cells, leading to the activation of various genes, including genes of the ROS pathway [50,70,71]. Elicitor molecules have been used to stimulate a broad range of responses including defense mechanism [72] in field conditions as well as in vitro cultures for elicitation of secondary metabolites [73,74,75,76]. However, it was reported earlier that acetic acid alone itself may exert some effect [77].…”

Sequential regiospecific gem‐diprenylation of tetrahydroxyxanthone by prenyltransferases from Hypericum sp.

“…The attachment of prenyl moieties increases the lipophilicity of the resulting products, leading to enhanced interaction with biological membranes and hence increased biological activities (Alhassan et al ., ; Chen et al ., ). Prenylated constituents function as chemical defenses against microorganisms (Franklin et al ., ; Tusevski et al ., ; Badiali et al ., ). Xanthones act as both preformed phytoanticipins and induced phytoalexins (Xiao et al ., ; Tocci et al ., ).…”