Ultrasound-Assisted Extraction of Total Acetogenins from the Soursop Fruit by Response Surface Methodology

Enhanced anti-glioma activity of annonaceous acetogenins based on a novel liposomal co-delivery system with ginsenoside Rh2

Annonaceous acetogenins (ACGs) have potent anti-tumor activity, and the problems of their low solubility, hemolysis, and in vivo delivery have been solved by encapsulation into nanoparticles. However, the high toxicity still limits their application in clinic. In this paper, the co-delivery strategy was tried to enhance the in vivo anti-tumor efficacy and reduce the toxic effects of ACGs. Ginsenoside Rh2, a naturally derived biologically active compound, which was reported to have synergistic effect with paclitaxel, was selected to co-deliver with ACGs. And due to its similarity with cholesterol in chemical structure, the co-loading liposomes, (ACGs + Rh2)-Lipo, were successfully constructed using Rh2 instead of cholesterol as the membrane material. The obtained (ACGs + Rh2)-Lipo and ACGs-Lipo had similar mean particle size (about 80 nm), similar encapsulation efficiency (EE, about 97%) and good stability. The MTS assay indicated that (ACGs + Rh2)-Lipo had stronger toxicity in vitro. In the in vivo study, in contrast to ACGs-Lipo, (ACGs + Rh2)-Lipo demonstrated an improved tumor targetability (3.3-fold in relative tumor targeting index) and significantly enhanced the antitumor efficacy (tumor inhibition rate, 72.9 ± 5.4% vs. 60.5 ± 5.4%, p < .05). The body weight change, liver index, and spleen index of tumor-bearing mice showed that Rh2 can attenuate the side effects of ACGs themselves. In conclusion, (ACGs + Rh2)-Lipo not only alleviated the toxicity of ACGs to the organism, but also enhanced their anti-tumor activity, which is expected to break through their bottleneck.

Design of Experiments for Optimizing Ultrasound-Assisted Extraction of Bioactive Compounds from Plant-Based Sources

Plant-based materials are an important source of bioactive compounds (BC) with interesting industrial applications. Therefore, adequate experimental strategies for maximizing their recovery yield are required. Among all procedures for extracting BC (maceration, Soxhlet, hydro-distillation, pulsed-electric field, enzyme, microwave, high hydrostatic pressure, and supercritical fluids), the ultrasound-assisted extraction (UAE) highlighted as an advanced, cost-efficient, eco-friendly, and sustainable alternative for recovering BC (polyphenols, flavonoids, anthocyanins, and carotenoids) from plant sources with higher yields. However, the UAE efficiency is influenced by several factors, including operational variables and extraction process (frequency, amplitude, ultrasonic power, pulse cycle, type of solvent, extraction time, solvent-to-solid ratio, pH, particle size, and temperature) that exert an impact on the molecular structures of targeted molecules, leading to variations in their biological properties. In this context, a diverse design of experiments (DOEs), including full or fractional factorial, Plackett-Burman, Box-Behnken, Central composite, Taguchi, Mixture, D-optimal, and Doehlert have been investigated alone and in combination to optimize the UAE of BC from plant-based materials, using the response surface methodology and mathematical models in a simple or multi-factorial/multi-response approach. The present review summarizes the advantages and limitations of the most common DOEs investigated to optimize the UAE of bioactive compounds from plant-based materials.

Evaluation of the Biological Properties of an Optimized Extract of Polygonum cuspidatum Using Ultrasonic-Assisted Extraction

Phytochemicals are natural compounds found in plants that have potential health benefits such as antioxidants, anti-inflammatory and anti-cancer properties, and immune reinforcement. Polygonum cuspidatum Sieb. et Zucc. is a source rich in resveratrol, traditionally consumed as an infusion. In this study, P. cuspidatum root extraction conditions were optimized to increase antioxidant capacity (DPPH, ABTS+), extraction yield, resveratrol concentration, and total polyphenolic compounds (TPC) via ultrasonic-assisted extraction using a Box-Behnken design (BBD). The biological activities of the optimized extract and the infusion were compared. The optimized extract was obtained using a solvent/root powder ratio of 4, 60% ethanol concentration, and 60% ultrasonic power. The optimized extract showed higher biological activities than the infusion. The optimized extract contained 16.6 mg mL^-1 resveratrol, high antioxidant activities (135.1 µg TE mL^-1 for DPPH, and 230.4 µg TE mL^-1 for ABTS+), TPC (33.2 mg GAE mL^-1), and extraction yield of 12.4%. The EC₅₀ value (effective concentration 50) of the optimized extract was 0.194 µg mL^-1, which revealed high cytotoxic activity against the Caco-2 cell line. The optimized extract could be used to develop functional beverages with high antioxidant capacity, antioxidants for edible oils, functional foods, and cosmetics.

Extraction of Acetogenins Using Thermosonication-Assisted Extraction from Annona muricata Seeds and Their Antifungal Activity

The objective of this work was to find the optimal conditions by thermosonication-assisted extraction (TSAE) of the total acetogenin content (TAC) and yield from A. muricata seeds, assessing the effect of the temperature (40, 50, and 60 °C), sonication amplitude (80, 90, and 100%), and pulse-cycle (0.5, 0.7, and 1 s). In addition, optimal TSAE conditions of acetogenins (ACGs) were compared with extraction by ultrasound at 25 °C and the soxhlet method measuring TAC and antioxidant capacity. Moreover, solubility and identification of isolated ACGs were performed. Furthermore, the antifungal activity of ACGs crude extract and isolated ACGs was evaluated. Optimal TSAE conditions to extract the highest TAC (35.89 mg/g) and yield (3.6%) were 50 °C, 100% amplitude, and 0.5 s pulse-cycle. TSAE was 2.17-fold and 15.60-fold more effective than ultrasound at 25 °C and the Soxhlet method to extract ACGs with antioxidant capacity. Isolated ACGs were mostly soluble in acetone and methanol. Seven ACGs were identified, and pseudoannonacin was the most abundant. The inhibition of Candida albicans, Candida krusei, and Candida tropicalis was higher from isolated ACGs than crude extract. TSAE was effective to increase the yield in the ACGs extraction from A. muricata seeds and these ACGs have important antifungal activity.

Enhanced Solubility and Antitumor Activity of Annona Squamosa Seed Oil via Nanoparticles Stabilized with TPGS: Preparation and In Vitro and In Vivo Evaluation

Annona squamosa seed oil (ASSO), which is a waste product in the extraction of annonaceous acetogenins (ACGs), displays good antitumor activity against a variety of tumor cells. However, ASSO is insoluble and has low bioavailability. In order to improve the solubility and application value of ASSO, the seed oil nanoparticles (ASSO-NPs) were successfully prepared only using TPGS as a stabilizer. ASSO-NPs obtained were spherical with a uniform size (less than 200 nm). ASSO-NPs showed the good storage stability at 25 ± 2 °C and were suitable for both oral administration and intravenous injection. The antitumor study in vitro and in vivo demonstrated more enhanced antitumor efficacy of ASSO-NPs than free ASSO. The ASSO-NPs group (15 mg/kg) had the highest tumor inhibition rate (TIR) of 69.8%, greater than the ASSO solution (52.7%, 135 mg/kg, p < 0.05) in 4T1 tumor-bearing mice. The in vivo biodistribution data displayed that the fluorescence intensity of ASSO/DiR-NPs in tumor was similar to that in liver in the presence of the reticuloendothelial system. Besides, the relative tumor-targeting index (RTTI) of (ACGs + ASSO)-NPs was 1.47-fold that of ACGs delivered alone, and there is great potential in ASSO-NPs as tumor-targeted delivery vehicles. In this study, ASSO-NPs were firstly prepared by a very simple method with fewer excipients, which improved the solubility and antitumor activity of the ASSO, displaying a good prospect in the in vivo delivery of natural bioactive compounds.

Extraction of Alkaloids Using Ultrasound from Pulp and By-Products of Soursop Fruit (Annona muricata L.)

The main goal of this work was to measure the total alkaloid content (TALC) from pulp, peel, seed, and columella of soursop fruit (Annona muricata L.) by ultrasound-assisted extraction (UAE) and to obtain the best conditions of the UAE with the response surface methodology (RSM). We evaluated the effect of amplitude (40%, 70%, and 100%), time (5, 10, and 15 min) and pulse-cycles (0.4, 0.7, and 1 s) and compared the best UAE conditions of alkaloids with a conventional extraction (maceration). The structural characterization of the raw material with the highest TALC was developed using nuclear magnetic resonance (NMR) techniques [1H, 13C, heteronuclear single quantum correlation (HSQC), heteronuclear multiple bond correlation (HMBC), and homonuclear correlation spectroscopy (COSY)]. According to the RSM, the best conditions in the UAE for extracting alkaloids varied depending on the type of plant tissue. It took 5 min with an amplitude of 70% and pulse-cycles of 1, 0.4, and 1 s, respectively, to extract the highest TALC in peel, seed, and columella while the optimal conditions for extracting the largest amount of alkaloids from the pulp were obtained at 5 min in UAE with pulse-cycles of 0.55 s and 100% amplitude. The TALC was highest in the peel (7.48 mg/g), which was followed by the seed (2.31 mg/g), the pulp (1.20 mg/g), and the columella (0.79 mg/g) and was positively correlated (R2 = 0.98–0.88) with the predicted values. In addition, the extraction alkaloids from the peel, pulp, seed, and columella using the UAE was 56.31, 5.45, 3.06, and 2.96 times higher, respectively, than the extraction by maceration. The alkaloids identified in the peel have not been reported and were nornuciferin, assimilobin, anonaine, and isolaureline. This study showed that the soursop fruit peel can be a source of alkaloids and that UAE has an important potential for extracting these compounds.