Immunological evaluation of SW–HSA conjugate on goats

Raising antibodies against epoxyscillirosidine, the toxic principle contained in Moraea pallida Bak. (Iridaceae), in rabbits

Moraea pallida Bak. (yellow tulp) poisoning is the most important plant cardiac glycoside toxicosis in South Africa. The toxic principle, a bufadienolide, is 1α, 2α-epoxyscillirosidine. The aim was to investigate the potential to develop a vaccine against epoxyscillirosidine. Epoxyscillirosidine, proscillaridin and bufalin, were successfully conjugated to hen ovalbumin (OVA), bovine serum albumin (BSA) and keyhole limpet haemocyanin (KLH). There was a low immune response following vaccination of adult male New Zealand White rabbits with epoxyscillirosidine-OVA (n = 3) and OVA (n = 3) using Freund's adjuvant in Trial (T) 1. The immune response improved significantly in T2 following doubling of the dose to 0.8 mg/rabbit and changing the adjuvant to Montanide. In T3, the rabbits (n = 15), allocated into 5 equal groups, vaccinated with proscillaridin-BSA, bufalin-BSA, epoxyscillirosidine-KLH, epoxyscillirosidine-BSA and BSA respectively, using Montanide adjuvant, developed antibodies against the administered immunogens, with epoxyscillirosidine-KLH inducing the highest immune response. Proscillaridin and bufalin antibodies cross-reacted with epoxyscillirosidine in an enzyme linked immunosorbent assay. The conjugation methodology will be adjusted in the future to target optimal conjugation efficiency. Additional vaccination will be conducted in search of neutralizing antibodies against the yellow tulp toxin. The cross-reactivity of proscillaridin and bufalin antibodies with epoxyscillirosidine could be studied in future to explore the potential to prevent yellow tulp poisoning.

Evaluation of in vitro neutralization of epoxyscillirosidine by antibodies raised in sheep

Intoxication by Moraea pallida Bak. (yellow tulp) in livestock is of great importance in South Africa, ranking top among all plant-induced cardiac glycoside toxicosis. The toxic principle, a bufadienolide, is 1α, 2α-epoxyscillirosidine. Treatment of poisoning is challenging and affected livestock often succumbs due to the stress of handling. Manipulating animals to resist poisoning is a potential management strategy. The goal of this study was to explore the potential to develop a vaccine against epoxyscillirosidine by raising antibodies against epoxyscillirosidine in sheep and to assess the neutralization ability of the antibodies in vitro. Epoxyscillirosidine was successfully conjugated to keyhole limpet haemocyanin (KLH) and bovine serum albumin (BSA) rendering them immunogenic. The sheep, vaccinated with epoxyscillirosidine-KLH conjugate (n = 4) and KLH (n = 2) with Montanide, developed antibodies as determined with an indirect enzyme linked immunosorbent assay (ELISA). Total immunoglobulins from sera of vaccinated and control sheep that were purified and concentrated using ammonium sulphate precipitation were 11,940 and 7850 μg, respectively. The in vitro neutralization assay using the methyl blue tetrazolium bromide (MTT) cell viability assay indicated no significant difference (p > 0.05) between anti-epoxyscillirosidine-KLH and KLH antibodies. Rather, the antibodies seemed to enhance the cytotoxicity of epoxyscillirosidine in H9c2 cells. Thus, it is necessary to develop improved vaccination methods to generate antibodies capable of neutralizing the functional group responsible for epoxyscillirosidine toxicity.

Reproductive Toxicities Caused by Swainsonine from Locoweed in Mice

Swainsonine is the primary toxin in locoweeds. It causes intention tremors, reproductive dysfunction, emaciation, and death. The objective of the present study was to evaluate the potential reproductive and developmental toxicities caused by swainsonine in mice. The treatment groups consisting of three generations of mice were given a range of concentrations of swainsonine by intraperitoneal injection (2.50 mg/kg body weight (BW), 1.20 mg/kg BW, 0.60 mg/kg BW, and 0 mg/kg BW). The 0 mg/kg BW group exhibited significantly fewer estrous cycles and an increased number of estrous ones compared to the 2.50 mg/kg BW, 1.20 mg/kg BW, and 0.60 mg/kg BW groups (P < 0.05). All three generations of mice treated with swainsonine had significantly higher spleen, liver, and kidney indices and significantly lower body weights compared to the 0 mg/kg BW group (P < 0.05). For the first and second generations of treatment group, the copulation indices and the numbers of live pups on postnatal days (PND) 0, 4, and 15 were significantly decreased compared to those of the 0 mg/kg BW group (P < 0.05). The fertility and gestation indices of the treatment group of the first generation were significantly increased compared to the 2.50 mg/kg BW, 1.20 mg/kg BW, and 0.60 mg/kg BW groups of the second generation (P < 0.05). Cumulatively, these results indicate that swainsonine may cause reproductive and developmental toxicities in mice in both parents and offspring.

Degradation of Swainsonine by the NADP-Dependent Alcohol Dehydrogenase A1R6C3 in Arthrobacter sp. HW08

Swainsonine is an indolizidine alkaloid that has been found in locoweeds and some fungi. Our previous study demonstrated that Arthrobacter sp. HW08 or its crude enzyme extract could degrade swainsonie efficiently. However, the mechanism of swainsonine degradation in bacteria remains unclear. In this study, we used label-free quantitative proteomics method based on liquid chromatography-electrospray ionization-tandem mass spectrometry to dissect the mechanism of swainsonine biodegradation by Arthrobacter sp. HW08. The results showed that 129 differentially expressed proteins were relevant to swainsonine degradation. These differentially expressed proteins were mostly related to the biological process of metabolism and the molecular function of catalytic activity. Among the 129 differentially expressed proteins, putative sugar phosphate isomerase/epimerase A1R5X7, Acetyl-CoA acetyltransferase A0JZ95, and nicotinamide adenine dinucleotide phosphate (NADP)-dependent alcohol dehydrogenase A1R6C3 were found to contribute to the swainsonine degradation. Notably, NADP-dependent alcohol dehyrodgenase A1R6C3 appeared to play a major role in degrading swainsonine, but not as much as Arthrobacter sp. HW08 did. Collectively, our findings here provide insights to understand the mechanism of swainsonine degradation in bacteria.

Simple Indolizidine and Quinolizidine Alkaloids

This review of simple indolizidine and quinolizidine alkaloids (i.e., those in which the parent bicyclic systems are in general not embedded in polycyclic arrays) is an update of the previous coverage in Volume 55 of this series (2001). The present survey covers the literature from mid-1999 to the end of 2013; and in addition to aspects of the isolation, characterization, and biological activity of the alkaloids, much emphasis is placed on their total synthesis. A brief introduction to the topic is followed by an overview of relevant alkaloids from fungal and microbial sources, among them slaframine, cyclizidine, Steptomyces metabolites, and the pantocins. The important iminosugar alkaloids lentiginosine, steviamine, swainsonine, castanospermine, and related hydroxyindolizidines are dealt with in the subsequent section. The fourth and fifth sections cover metabolites from terrestrial plants. Pertinent plant alkaloids bearing alkyl, functionalized alkyl or alkenyl substituents include dendroprimine, anibamine, simple alkaloids belonging to the genera Prosopis, Elaeocarpus, Lycopodium, and Poranthera, and bicyclic alkaloids of the lupin family. Plant alkaloids bearing aryl or heteroaryl substituents include ipalbidine and analogs, secophenanthroindolizidine and secophenanthroquinolizidine alkaloids (among them septicine, julandine, and analogs), ficuseptine, lasubines, and other simple quinolizidines of the Lythraceae, the simple furyl-substituted Nuphar alkaloids, and a mixed quinolizidine-quinazoline alkaloid. The penultimate section of the review deals with the sizable group of simple indolizidine and quinolizidine alkaloids isolated from, or detected in, ants, mites, and terrestrial amphibians, and includes an overview of the "dietary hypothesis" for the origin of the amphibian metabolites. The final section surveys relevant alkaloids from marine sources, and includes clathryimines and analogs, stellettamides, the clavepictines and pictamine, and bis(quinolizidine) alkaloids.

Hematological and histopathological effects of swainsonine in mouse

BACKGROUND

Livestock that consume locoweed exhibit multiple neurological symptoms, including dispirited behavior, staggered gait, trembling, ataxia, impaired reproductive function and cellular vacuolar degeneration of multiple tissues due to toxicity from plant-derived alkaloids such as swainsonine.

RESULTS

Swainsonine was administered to F(0) and F(1) mice by intraperitoneal injection before, during and after pregnancy at the following doses: 0.525 mg/kg BW(I), 0.2625 mg/kg BW(II), 0.175 mg/kg BW(III) and 0 mg/kg BW(IV). Hemosiderin deposits were observed the lamina propria of endometrium in uterus and the red pulp of spleen. Ovary corpus lutea counts in F(0) mice were higher in swainsonine-treated mice compared to control mice. Indirect bilirubin content and reticulocyte numbers were increased in swainsonine-treated F(0) and F(1) generation mice compared to control group (P < 0.05). Lactate dehydrogenase, alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase content in F(0)-I and F(0)-II mice were significantly increased compared with F(0)-IV group mice (P < 0.05). Red blood cells, hemoglobin and mean corpuscular hemoglobin levels were significantly decreased in F(0) and F(1) mice compared with the control group (P < 0.05).

CONCLUSIONS

Swainsonine exerts effects on estrus period and reproductive ability, and offspring of dams dosed with swainsonine were affected in-utero or from nursing. Damage to liver, uterus and spleen, as well as hematological changes, are observable before neurological symptoms present.

Swainsonine differentially affects steroidogenesis and viability in caprine luteal cells in vitro

Plants containing swainsonine (SW) have been reported to impair reproductive function and fertility after long-term ingestion by livestock. However, direct effects of SW on luteal cell steroidogenesis remain unclear. In this study, primary and transfected luteal cells were used to investigate the effects of SW on progesterone secretion and cell viability and the mechanisms involved in these processes. After treatment with various concentrations of SW for 24 or 48 hours, progesterone production and the number of living cells were assessed using radioimmunoassay and trypan blue dye exclusion assay, respectively. Lower concentrations of SW enhanced basal, 22R-hydroxycholesterol- or pregnenolone-stimulated progesterone secretion (P < 0.05), whereas higher concentrations of SW inhibited progesterone secretion (P < 0.05). Lower concentrations of SW promoted expression of P450 side-chain cleavage enzyme and 3β-hydroxysteroid dehydrogenase, two key enzymes involved in luteal cell steroidogenesis, at mRNA and protein levels (P < 0.05), but did not affect expression of steroidogenic acute regulatory protein and cell proliferation. In contrast, higher concentrations of SW inhibited luteal cell proliferation by inducing growth phase 1/quiescent state cell cycle arrest and apoptosis (P < 0.05). Taken together, these results demonstrated that lower concentrations of SW induced progesterone production through upregulation of P450 side-chain cleavage enzyme and 3β-hydroxysteroid dehydrogenase without affecting cell viability, whereas higher concentrations of SW induced cell cycle arrest and apoptosis and impaired steroidogenesis. These findings provided new insights into understanding the effect of SW on luteal cell steroidogenesis.

Swainsonine activates mitochondria-mediated apoptotic pathway in human lung cancer A549 cells and retards the growth of lung cancer xenografts

Swainsonine (1, 2, 8-trihyroxyindolizidine, SW), a natural alkaloid, has been reported to exhibit anti-cancer activity on several mouse models of human cancer and human cancers in vivo. However, the mechanisms of SW-mediated tumor regression are not clear. In this study, we investigated the effects of SW on several human lung cancer cell lines in vitro. The results showed that SW significantly inhibited these cells growth through induction of apoptosis in different extent in vitro. Further studies showed that SW treatment up-regulated Bax, down-regulated Bcl-2 expression, promoted Bax translocation to mitochondria, activated mitochondria-mediated apoptotic pathway, which in turn caused the release of cytochrome c, the activation of caspase-9 and caspase-3, and the cleavage of poly (ADP-ribose) polymerase (PARP), resulting in A549 cell apoptosis. However, the expression of Fas, Fas ligand (FasL) or caspase-8 activity did not appear significant changes in the process of SW-induced apoptosis. Moreover, SW treatment inhibited Bcl-2 expression, promoted Bax translocation, cytochrome c release and caspase-3 activity in xenograft tumor cells, resulting in a significant decrease of tumor volume and tumor weight in the SW-treated xenograft mice groups in comparison to the control group. Taken together, this study demonstrated for the first time that SW inhibited A549 cancer cells growth through a mitochondria-mediated, caspase-dependent apoptotic pathway in vitro and in vivo.