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Browsing by Author "Rihab, Guesmi"

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  • Valorisation of Cistus ladanifer L. biomass as a source of compounds for bio-based industries
    Publication . Rihab, Guesmi; Amaral, Joana S.; Barros, Lillian; Heleno, Sandrina A.; Zaghdoudi, Khalil
    Cistus ladanifer L., a perennial shrub from the Cistaceae family that can be found in abundance in the Mediterranean's marginal fields, is known to produce a valuable compound-rich resin called labdanum. C. ladanifer has also been extensively used for different purposes such as cosmetics, traditional medicine, feed, phytoremediation, and biofuel production. The present work aimed at studiyng the chemical composition of different products obtained from the plant, namely the essential oil of and different concretes prepared from the leaves and buds using two different solvents, hexane and ethanol. Three different extraction methods were used for obtaining the concretes, namely soxhlet, microwave assisted extraction and ultrasound assisted extraction. The chemical composition was analysed using gas chromatography coupled to mass spectrometry (GC–MS). Moreover, the obtained ethanol and hexane concretes were assayed for their antioxidant, antimicrobial and antifungal activities. Most of the compounds identified in the essential oils from the buds and leaves belong to different groups of terpene and terpenoid compounds. In the concretes, besides terpene compounds different hydrocarbons were detected in high amounts. Nevertheless, both in the hexane and ethanol concretes the majority of the peaks were not identified. In general, the highest extraction yield was obtained by soxhlet (26.1± 0.8 % and 29±1 % for leaves and buds respectively). However microwave extraction method was privileged for the optimization studies since it requires less time and energy compared to Soxhlet and allowed obtaining extracts with higher content of viridiflorol. The antioxidant potential was determined by applying two different methods namely the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the reduction power assays. The ethanolic concrete obtained from the leaves using microwave gave the best results in DPPH assay (EC50=0.152 ± 0.005 mg/mL) while for reducing power better results were obtained for the ethanolic extract from the buds using ultrasound assisted extraction (EC50=0.15 ± 0.01 mg/mL). All the tested extracts revealed inhibitory activity against the tested Gram-positive and Gram-negative bacteria, with the exception of Pseudomonas aeruginosa.
    2022Master thesis Open access Show more