Deep eutectic solvents (DESs) are considered as efficient and green solvents for the extraction of bioactive compounds from medicinal plants. In this work, a novel method of DES-based ultrasound-assisted extraction of bioactive compounds from Baphicacanthus cusia leaves (BCL) was established. Systematic screening and the morphology of the original and treated BCL were observed with scanning electron microscopy to determine the extraction efficiency of different solvents. The extraction conditions were optimized by Box–Behnken design (BBD) tests and the optimal extraction conditions were as follows: lactic acid/L-menthol ratio of 5: 2 (mol/mol), solid–liquid ratio of 80.0 mL/g and temperature of 60.5 °C. The extraction yields of tryptanthrin, indigo and indirubin reached 0.356, 1.744 and 0.562 mg/g, respectively. The results of a 2,2-diphenyl-1-picrylhydrazy (DPPH) radical scavenging activity test indicated the feasibility of DESs in the extraction of bioactive compounds. This study indicated that L-menthol/lactic acid was a green and efficient solvent for the extraction of bioactive compounds from BCL, and DES-based ultrasound-assisted extraction could be used as an effective application strategy for the extraction of bioactive compounds from medicinal plants.

In this study, the hot water extraction process of crude polysaccharides from Morindae officinalis radix (cMORP) was conducted and optimized through a single-factor test and orthogonal experimental design. With the optimal extraction process (extraction temperature of 80 °C, extraction time of 2 h, liquid/solid ratio of 15 mL/g, and number of extraction of 1), the cMORP was obtained by the ethanol precipitation method. The chemical properties and preliminary characterization of the cMORP were analyzed by chemical or instrumental methods. Furthermore, to indicate a preliminary study on safety, a single oral dose of 5000 mg/kg body weight (BW) was administered orally to Kunming (KM) mice for acute toxicity, and the cMORP was administered orally to KM mice once a day at doses of 25, 50, and 100 mg/kg BW for 30 days. General behaviors, body weight variations, histopathology, relative organ weights, and hematological and serum biochemical parameters were observed and recorded. The results suggested there were no toxicologically significant changes. Based on the safety study, cMORP can be initially considered non-toxic with no acute oral toxicity up to 5000 mg/kg BW and safe at up to 100 mg/kg BW in KM mice for 30 days.

A method based on high performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD) was developed for the quantitative analysis of three active compounds and chemical fingerprint analyses of saccharides in Morindae officinalis radix. Ten batches of Morindae officinalis radix were collected from different plantations in the Guangdong region of China and used to establish the fingerprint. The samples were separated with a COSMOIL Sugar-D column (4.6 mm × 250 mm, 5 μm) by using gradient elution with water (A) and acetonitrile (B). In addition, Trapped-Ion-Mobility (tims) Time-Of-Flight (tims TOF) was used to identify saccharides of Morindae officinalis radix. Fingerprint chromatogram presented 26 common characteristic peaks in the roots of Morinda officinalis How, and the similarities were more than 0.926. In quantitative analysis, the three compounds showed good regression (r = 0.9995–0.9998) within the test ranges, and the recoveries of the method were in the range of 96.7–101.7%. The contents of sucrose, kestose and nystose in all samples were determined as 1.21–7.92%, 1.02–3.37%, and 2.38–6.55%, respectively. The developed HPLC fingerprint method is reliable and was validated for the quality control and identification of Morindae officinalis radix and can be successfully used to assess the quality of Morindae officinalis radix.