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

Abstract

• Lingzhi G2 spore oil was extracted by Soxhlet or microwave-assisted extraction. • Oil obtained from microwave-assisted extraction (MAE) had lowered lipid oxidations. • MAE-extracted oil had higher antioxidant activity than SLE-extracted oil. • The resulting oils had no cytotoxicity on Caco-2 cells at levels of 0.1–10 µg/mL. 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.