Differentiation, Quantification and Identification of Abrin and Abrus precatorius Agglutinin.

Abrin, the toxic lectin from the rosary pea plant Abrus precatorius, has gained considerable interest in the recent past due to its potential malevolent use. However, reliable and easy-to-use assays for the detection and discrimination of abrin from related plant proteins such as Abrus precatorius agglutinin or the homologous toxin ricin from Ricinus communis are sparse. To address this gap, a panel of highly specific monoclonal antibodies was generated against abrin and the related Abrus precatorius agglutinin. These antibodies were used to establish two sandwich ELISAs to preferentially detect abrin or A. precatorius agglutinin (limit of detection 22 pg/mL for abrin; 35 pg/mL for A. precatorius agglutinin). Furthermore, an abrin-specific lateral flow assay was developed for rapid on-site detection (limit of detection ~1 ng/mL abrin). Assays were validated for complex food, environmental and clinical matrices illustrating broad applicability in different threat scenarios. Additionally, the antibodies turned out to be suitable for immuno-enrichment strategies in combination with mass spectrometry-based approaches for unambiguous identification. Finally, we were able to demonstrate for the first time how the developed assays can be applied to detect, identify and quantify abrin from a clinical sample derived from an attempted suicide case involving A. precatorius.

4-Methoxylonchocarpin attenuates inflammation by inhibiting lipopolysaccharide binding to Toll-like receptor of macrophages and M1 macrophage polarization.

The roots of Abrus precatorius (AP, Fabaceae) have traditionally been used in Vietnam and China for the treatment of inflammatory diseases such as stomatitis, asthma, bronchitis, and hepatitis. Therefore, in this study, we isolated 4-methoxylonchocarpin (ML), an anti-inflammatory compound present in AP, and studied its anti-inflammatory effects in mice with 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis. In lipopolysaccharide (LPS)-stimulated macrophages, ML was found to inhibit nuclear factor (NF)-κB activation and tumor necrosis factor (TNF) and interleukin (IL)-6 expression by inhibiting LPS binding to Toll-like receptor 4 (TLR4) in vitro. Oral administration of ML in mice with TNBS-induced colitis suppressed colon shortening and colonic myeloperoxidase activity. ML treatment significantly inhibited the activation of nuclear factor (NF)-κB and phosphorylation of transforming growth factor ß-activated kinase 1 in the colon. Treatment with ML also inhibited TNBS-induced expression of IL-1ß, IL-17A, and TNF. While ML reduced the TNBS-induced expression of M1 macrophage markers such as arginase-2 and TNF, it was found to increase the expression of M2 macrophage markers such as arginase-1 and IL-10. In conclusion, oral administration of ML attenuated colitis in mice by inhibiting the binding of LPS to TLR4 on immune cells and increasing the polarization of M1 macrophages to M2 macrophages.

A chimeric protein of abrin and Abrus precatorius agglutinin that neutralizes abrin mediated lethality in mice.

Abrin, a type II ribosome inactivating protein from the Abrus precatorius plant, is extremely toxic. It has been shown to be 75 times more potent than its infamous sister toxin, ricin and their potential use in bio-warfare is a cause of major concern. Although several vaccine candidates are under clinical trials for ricin, none are available against abrin. The present study proposes a chimeric protein, comprising of 1-123 amino acids taken from the A chain of abrin and 124-175 amino acids from Abrus precatorius agglutinin A chain, as a vaccine candidate against abrin intoxication. The design was based on the inclusion of the immunogenic region of the full length protein and the minimal essential folding domains required for inducing neutralizing antibody response. The chimera also contains the epitope for the only two neutralizing antibodies; D6F10 and A7C4, reported against abrin till now. Active immunization with the chimera protected all the mice challenged with 45 X LD50 of abrin. Also, passive transfer of antibodies raised against the chimera rescued all mice challenged with 50 X LD50 of toxin. Hence the chimeric protein appears to be a promising vaccine candidate against abrin induced lethality.

Immunomodulatory activity of the aqueous extract of seeds of Abrus precatorius Linn (Jequirity) in mice.

BACKGROUND: Various compounds of plant origin have been widely investigated since ancient times for their possible immunomodulatory properties as well as for the treatment of a wide range of diseases. OBJECTIVE: To study the immunomodulatory functions of the aqueous extract of the seeds of Abrus precatorius commonly known as Indian liquorice (Fabaceae), a medicinal plant native to central India. METHODS: Swiss albino mice were intraperitoneally treated with three doses (0.75, 1.25 and 2.5 µg/kg b.w.) of extract for 7 days. Relative organ weight, delayed type hypersensitivity (DTH) response, haemagglutination titre (HT) and Phagocytic index (PI) were studied in various groups of animals. RESULTS: The results showed no significant difference in relative organ weight of spleen, liver, thymus and kidney in various groups of animals. Treatment of rats with increasing concentrations of the extract decreased the footpad thickness indicating a dose related inhibitory effect of the extract on delayed type hypersensitivity. In the HT test, the plant extract showed a suppressive effect at all doses, and these changes were significant as the dose increased. Phagocytic index was also increased in a dose dependent manner. CONCLUSION: The reduction of antibody titre, delayed type hypersensitivity response and the increase in phagocytic index indicates that Abrus precatorius has an inhibitory effect on the immune functions in mice.

Stimulation of murine B and T lymphocytes by native and heat-denatured Abrus agglutinin.

In our previous studies, Abrus agglutinin showed non-specific immunostimulatory activity both native (NA) and heat-denatured (HDA) condition in mouse model. The present study was investigated to decipher the specific immune response towards B and T cell by NA and HDA. It was observed that the proliferation index for NA and HDA of stimulated B cells are 1.35 and 1.41 respectively and on the other hand, T cell proliferation index for NA and HDA are 1.67 and 1.54 respectively. At the same time, expression of surface and activation marker for B and T cells was significantly different compared to control as quantified by flow cytometry. But the expression of co-stimulatory markers (CD 80 and CD 86) was not significantly different and NA and HDA in immunized splenocytes with Dalton's lymphoma antigen induced antibodies titer 4.37 and 4.2 times more than control. This study indicates Abrus agglutinin (NA and HDA) acts as a B cell and T cell stimulator.