Antimicrobial compounds as side products from the agricultural processing industry

Antimicrobial compounds have many applications, in medicines, food, agriculture, livestock, textiles, paints, and wood protectants. Microorganisms resistant to most antibiotics are rapidly spreading. Consequently there is an urgent and continuous need for novel antimicrobial compounds. Most antibiotics have been developed from microorganisms. Plants also represent an important source for finding novel antimicrobial compounds, as plants in their permanent fight with microorganisms in their environment produce a wide spectrum of compounds with antimicrobial activity. This thesis focuses specifically on abundantly available plant sources, with the idea that plants already processed in the agricultural industry might be the source of antimicrobial compounds which could add extra value to these crops. It was shown in this project that Cannabis sativa (Cannabis), Humulus lupulus (Hop) and Tectona grandis (Teak) extracts display antimicrobial activities in general screening methods. Teak sawdust extract also showed antifungal activities against Aspergillus niger and four strains of wood rot fungi. Several active compounds were isolated. Deoxylapachol, for example isolated from teak sawdust extract, inhibits wood rot fungi by induction of fungal cell wall stress and inhibition of cellulase activity. This project shows __the proof of concept__ for the hypothesis that raw and waste materials from common agri/horticultural industry processes can serve as sources for new biologically active compounds