(24e) Sub- and Supercritical Fluid Extraction of Bioactive Compounds from Ganoderma Lucidum

Ganoderma lucidum, a polypore group fungus, provides bioactive copounds in which several triterpenoids and polysaccharides are core structures that claim to posses cancerous and immunomodulatory properties. These substances may be useful as starting materials for the development of chemical therapeutic agents in cancer treatment and for other ailments. Up to now, numerous methods of extraction have been developed to obtain extracts with higher yields and lower costs. Such is the case of extraction with organic solvents, such as methanol, ethanol, and acetone. Recently, supercritical CO₂ (SCCO₂) and pressurized hot water or sub-critical water has become of great interest as an alternative solvent for extraction of natural active compounds. The objective of this work has been to establish a method of extraction from grinded form of Ganoderma lucidum with water in sub-critical conditions and with SCCO₂ at distinct temperatures to obtain extracts rich in water soluble organic compounds (WSOC), including mostly beta glucans and triterpenoids including ganoderic acids and alcohols respectively. SCCO₂ experiments were carried out at pressures of 10, 20 and 30 Mpa and temperatures ranging from 313 to 333 K with and without modifier. Ethanol was used as modifier at flow rates of 0.1, 0.2 and 0.4 mL/min. The CO₂ flow rate was maintained at 4 mL/min for 2 hours extraction time. The extracts were analyzed by HPLC. The temperatures for experiments that were carried out by batch-scale sub-critical water extraction kept constant at different time intervals starting from 373 up to 573 K. For semi-continuous scale experiments, samples were extracted once with water at 373, 423, 448 and 473 K, respectively, working at pressure around 10 Mpa to keep the water in the liquid state. The flow rate used was 1 mL/min. The extracts were analysed by TOC for water soluble organic compound recovery. The highest yield obtained at 473 K as 78.1 % and as 57.4 % for batch- and semi continuous scale experiments respectively. It was demonstrated that the modified SCCO₂ extraction is suitable for the extraction of Ganoderma lucidum. The advantage of modified supercritical extraction over non-modified supercritical extraction was in the polarity component extraction and enhancement of the fluidity of extracts. It was also seen that molecular weights of extracts became smaller for high temperatures having increasing values for SCCO₂ extraction in comparison to hydrothermal treatment.