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Abrus mollis is commonly used as a traditional Chinese medicine for the treatment of liver diseases due to its hepatoprotection and anti-inflammation, but the absorption properties of its main bioactive ingredients remain unclear. Our previous studies verified that the flavonoid C-glycosides, including vicenin-2 (1), isoschaftoside (2), and schaftoside (3), were the major active components in A. mollis for hepatic protection against nonalcoholic fatty liver disease, hepatitis, and hepatic fibrosis. This study investigated the bioaccessibility and transport mechanisms of total flavonoid C-glycoside, as well as vicenin-2 (1), isoschaftoside (2), and schaftoside (3), in A. mollis by simulated digestion and use of the Caco-2 cell model. Moreover, this study attempted to verify their absorption properties by in situ gastrointestinal perfusion in rats. Total flavonoid C-glycoside and 1, 2, and 3 exhibited similar bioaccessibility of 84.58%, 85.13%, 83.05%, and 81.65% respectively after simulated digestion. The transport of total flavonoid C-glycoside in the Caco-2 cell model increased with the concentration, and the transport showed saturation characteristics with the time and concentration of total flavonoid C-glycoside to a certain degree. The Papp values of total flavonoid C-glycoside and the 3 flavonoid C-glycosides were significantly improved by verapamil, probenecid, and EDTA-Na2. Their absorption properties in the gastrointestinal tract were consistent with that found in Caco-2 cells, and superior absorption rates were observed in the duodenum and jejunum. The absorption pattern of total flavonoid C-glycoside may involve multiple transport pathways, including active transport, passive diffusion, and the paracellular pathway. TFC was actively pumped out by P-glycoprotein and multidrug resistance-associated protein. These results revealed that the bioaccessibility and intestinal absorption characteristic of total flavonoid C-glycoside were consistent with the 3 major flavonoids.

Abrus pulchellus subsp. mollis (Hance) Verdc. (Leguminosae) is a well-known edible plant usually added to soups and beverages. In this study, vicenin-2 (1), isoschaftoside (2), schaftoside (3), and their enrichment fraction, total flavonoid C-glycosides, derived from the extracts of A. mollis, were firstly found to prevent nonalcoholic fatty liver disease both in vitro and in vivo. In the in vitro study, total flavonoid C-glycosides decreased the lipid accumulation in oleic acid-treated HepG2 cells. The mechanisms of total flavonoid C-glycosides are involved in the regulation of peroxisome proliferator-activated receptor α and its downstream, and the reduction of proinflammatory cytokines. In high-fat diet-induced fatty liver rats, total flavonoid C-glycosides decreased the levels of glutamic-oxalacetic transaminease and glutamic-pyruvic transaminase, and decreased the lipid accumulation both in the liver and blood without affecting food intake. In addition, total flavonoid C-glycosides also increased the activities of the antioxidant enzyme system in vivo. In conclusion, total flavonoid C-glycosides are active components of A. mollis on nonalcoholic fatty liver disease, and can be used in functional food and supplements for nonalcoholic fatty liver disease prevention and treatment.

A library of 206 extracts from selected South African plants was screened in vitro against a panel of protozoan parasites, Plasmodium falciparum, Trypanosoma brucei rhodesiense, and Leishmania donovani. A CH2Cl2/MeOH (1 : 1) extract of Abrus precatorius L. ssp. africanus strongly inhibited P. falciparum (98 %), T. b. rhodesiense (100 %), and L. donovani (76 %) when tested at a concentration of 10.0 µg/mL. The active constituents were tracked by HPLC-based activity profiling and isolated by preparative and semipreparative RP-HPLC chromatography. Structures were established by HR-ESIMS, and 1D and 2D NMR (1H, 13C, COSY, HMBC, HSQC, and NOE difference spectroscopy). Five compounds were obtained and identified as two isoflavan hydroquinones, abruquinone H (1) and abruquinone G (2), and three isoflavan quinones, abruquinone I (3), abruquinone B (4), and 7,8,3′‚5′-tetramethoxyisoflavan-1′,4′-quinone (5). Compounds 1 and 3 were new natural products. The absolute configuration of compounds was determined by comparison of electronic circular dichroism spectra with calculated ECD data. Compounds 3 and 4 showed strong activity against T. b. rhodesiense (IC50 values of 0.30 and 0.16 µM, respectively) and good selectivity (selectivity indices of 73.7 and 50.5, respectively).

The present study investigated the flavonoids from Abrus cantoniensis against ethanol-induced gastric ulcers in mice. The flavonoids from A. cantoniensis were extracted with ethanol and purified by macroporous resin and polyamide. The 2,2-diphenyl-1-picrylhydrazyl assay was used to measure the antioxidative activities in vitro. The ethanol-induced ulcer mouse model was used to evaluate the gastroprotective activities of the flavonoids from A. cantoniensis. In addition, a method was established to ensure accuracy for animal ulcer evaluation. The flavonoids from A. cantoniensis showed a strong free radical scavenging capacity with an IC50 of 43.83 µg/mL in the 2,2-diphenyl-1-picrylhydrazyl assay. At doses between 28.16-112.67 mg/kg, the flavonoids conspicuously reduced the ulcer index in ethanol-induced mice (p0.001). Significant differences were found in the levels of superoxide dismutase, catalase, glutathione, and myeloperoxidase in the stomach tissues between the flavonoids from the A. cantoniensis groups and the ethanol control group. The gastroprotective effect of the flavonoids from A. cantoniensis could be due to its antioxidative activity of the defensive mechanism. The data revealed that the flavonoids from A. cantoniensis could be a potential therapeutic agent for gastric ulcer prevention and treatment.

The antihepatotoxic activities of soyasaponin I and kaikasaponin III, triterpenoidal saponins isolated from Abri Herba, the whole plant of Abrus cantoniensis, were studied on liver injury induced by CCl4 in primary cultured rat hepatocytes. The antihepatotoxic activities of these saponins and glycyrrhizin (positive control) were demonstrated by measuring the levels of glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT). Soyasaponin I inhibited the elevation of GOT and GPT activities. The activities were comparable to those of glycyrrhizin. On the other hand, kaikasaponin III was more effective than soyasaponin I and glycyrrhizin. Kaikasaponin III showed the antihepatotoxic activity at less than 100 micrograms/ml. Furthermore, the highest activity was observed even in the lower doses (50, 100 micrograms/ml). However, soyasaponin I and kaikasaponin III showed some toxicity at the highest dose (500 micrograms/ml), though glycyrrhizin did not show toxicity at any dose.

A known isoflavanquinone, abruquinone B ( 1), and a new derivative, abruquinone G ( 2), were isolated from the aerial parts of Abrus precatorius. Chemical structures of these compounds were elucidated by spectral analyses. While 1 exhibited antitubercular, antiplasmodial and cytotoxic activities, compound 2 showed mild antiviral and cytotoxic activities.

After hydrolysis of the saponin fraction of the roots of Abrus cantoniensis, a new triterpenoid sapogenol, cantoniensistriol, was isolated together with sophoradiol, soyasapogenol B and soyasapogenol A. The structures of cantoniensistriol and sophoradiol were elucidated by spectroscopic methods. On the basis of the relation between cantoniensistriol and soyasapogenol A, the steric assignment of the C-21 and C-22 hydroxyl groups of the latter was discussed.