Comparative studies on characterizations and cytotoxicity of oil extracted from Lingzhi (Ganoderma lucidum) G2 spore using Soxhlet extraction and microwave-assisted extraction

This study aimed to compare the characteristics, antioxidant activity, and cytotoxicity of Ganoderma lucidum G2 spore (GLS) oil extracted using two different extraction methods, including Soxhlet extraction (SLE) and microwave-assisted extraction (MAE). The SLE method yielded higher oil content than the MAE method. MAE-extracted oil showed higher lightness (L*) and yellowness (b*) values but lower redness (a*) values. Both methods provided similar fatty acid compositions in GLS oils, including palmitic acid, oleic acid, and linoleic acid as major components. Higher saturated fatty acid content was found in SLE-extracted oil, while MAE-extracted oil had increased levels of mono- and poly-unsaturated fatty acids. The oil obtained from SLE showed slightly higher di- and tri-glycerides than that obtained from MAE (P < 0.05). Furthermore, MAE-extracted oil had high oxidative stability as indicated by lower levels of conjugated diene (CD), peroxide value (PV), thiobarbituric acid-reactive substances (TBARS), and free fatty acids (FFA) as compared to SLE (P < 0.05). MAE-extracted oil had a higher total triterpenoid content than SLE-extracted oil (P < 0.05). Also, MAE-extracted oil showed lower DPPH radical scavenging activity (DPPH-RSA) than SLE-extracted oil (P < 0.05). FTIR spectra of both samples exhibited similar functional groups. Additionally, oils obtained from both processes (at 0.1–10 µg/mL) showed low toxicity on Caco-2 cells (P > 0.05). Therefore, GLS oil with high antioxidant activity and oxidative stability, especially oil extracted by MAE, could be a food supplement for health. Also, the MAE used was a potential implement for extracting oil from GLS.