Edible insects are gaining attention as a source of bioactive compounds of great interest for health. To produce bioactive extracts from insects with a high concentration of bioactive compounds, defatting seems to be relevant for those fat-rich forms of insects as larvae. Supercritical fluid extraction (SFE) might be useful for both the defatting and subsequent extraction of the defatted sample to obtain bioactive extracts from edible insects. Different samples of black soldier fly (Hermetia illucens) larvae were defatted using SFE as an alternative to conventional defatting methods, and the optimal defatted flour was sequentially extracted by SFE employing different levels of ethanol as co-solvent. The resulting extracts were characterised by GC-MS-FID and their bioactivity was then assayed in terms of their antioxidant and pancreatic lipase inhibitory activities. The maximum fat yield by SFE (around 43%) was achieved at 450 bar, 60 °C and 100 g/min of CO2 flow, not being significantly different from conventional defatting with hexane. Extraction yield of SFE extracts increased along with the proportion of co-solvent. The composition of the extracts widely varied depending on the insect sample and the amount of co-solvent used, free amino acids and fatty acids being the two major chemical families among the different extracts. In terms of their bioactivity, a lipase inhibitory activity closer to 50% was exhibited by most extracts, which was favoured by the amount of co-solvent in one of the insect samples. Regardless of the significant differences observed between the insect samples, the exhibited DPPH radical inhibitory activity was weak. It is concluded that SFE is an interesting alternative to the conventional defatting of H. illucens, as well as an integrative and sequential process that allows producing bioactive extracts from this insect, especially towards the inhibition of the pancreatic lipase.

The acid hydrolysis of saponins is commonly performed by conventional heating to produce sapogenin-rich products of bioactive interest, but alternative hydrolysis methods and their impact on bioactivity have been unexplored. We compared the conventional method with microwave-assisted acid hydrolysis (MAAH) of a commercial saponin-rich extract from a typical saponin source, fenugreek, focusing on the study of temperature (100, 120, 130, 140, 150 °C) and time (10, 20, 30, 40 min) of hydrolysis. The impact of these factors was assayed on both the sapogenin yield and the bioactivity of the hydrolyzed products, specifically their antioxidant and lipase inhibitory activities. The highest sapogenin content (34 g/100 g extract) was achieved by MAAH at 140 °C and 30 min, which was higher than conventional hydrolysis at both reference conditions (100 °C, 60 min, 24.6 g/100 g extract) and comparative conditions (140 °C, 30 min, 17 g/100 g extract) (p < 0.001). Typical steroid artifacts from sapogenins were observed in very small amounts, regardless of the method of hydrolysis. Antioxidant activity of MAAH hydrolyzed extracts (around 80% DPPH inhibition) was barely affected by time and temperature, but pancreatic lipase inhibitory activity was higher (>65%) at lower MAAH temperature (<130 °C) and time (<30 min) of hydrolysis. MAAH is shown as a valid alternative to produce selective sapogenin-rich extracts from fenugreek with minor impact on their bioactivities, and whose magnitude can be modulated by the hydrolysis conditions.

The mealworm (Tenebrio molitor Linnaeus 1758) is gaining importance as one of the most popular edible insects. Studies focusing on its bioactivities are increasing, although alternative forms of consumption other than the whole insect or flour, such as bioactive non-protein extracts, remain underexplored. Furthermore, the incidence of metabolic syndrome-related pathologies keeps increasing, hence the importance of seeking novel natural sources for reducing the impact of certain risk factors. The aim was to study the potential of a non-protein mealworm extract on metabolic syndrome-related pathologies, obtained with ethanol:water (1:1, v/v) by ultrasound-assisted extraction. We characterized the extract by gas-chromatography mass-spectrometry and assessed its hypolipidemic potential, its ability to scavenger free radicals, to attenuate the inflammatory response in microglial cells, to affect mitochondrial respiration and to enhance insulin sensitivity in mouse hepatocytes. The extract contained fatty acids, monoglycerides, amino acids, certain acids and sugars. The mealworm extract caused a 30 % pancreatic lipase inhibition, 80 % DPPH· scavenging activity and 55.9 % reduction in the bioaccessibility of cholesterol (p = 0.009). The extract was effective in decreasing iNOS levels, increasing basal, maximal and ATP coupled respiration as well as enhancing insulin-mediated AKT phosphorylation at low insulin concentrations (p < 0.05). The potential of a non-protein bioactive mealworm extract against metabolic syndrome-related pathologies is shown, although further studies are needed to elucidate the mechanisms and relationship with compounds.