Extraction and quantification of toxins from Karwinskia humboldtiana (tullidora)

Histopathological, ultrastructural, and biochemical traits of apoptosis induced by peroxisomicine A1 (toxin T-514) from Karwinskia parvifolia in kidney and lung

Peroxisomicine A1 (PA1) is a toxin isolated from the Karwinskia genus plants whose target organs are the liver, kidney, and lung. In vitro studies demonstrated the induction of apoptosis by PA1 in cancer cell lines, and in vivo in the liver. Apoptosis has a wide range of morphological features such as cell shrinkage, plasma membrane blistering, loss of microvilli, cytoplasm, and chromatin condensation, internucleosomal DNA fragmentation, and formation of apoptotic bodies that are phagocytized by resident macrophages or nearby cells. Early stages of apoptosis can be detected by mitochondrial alterations. We investigated the presence of apoptosis in vivo at the morphological, ultrastructural, and biochemical levels in two target organs of PA1: kidney and lung. Sixty CD-1 mice were divided into three groups (n = 20): untreated control (ST), vehicle control (VH), and PA1 intoxicated group (2LD50). Five animals of each group were sacrificed at 4, 8, 12, and 24 h post-intoxication. Kidney and lung were examined by morphometry, histopathology, ultrastructural, and DNA fragmentation analysis. Pre-apoptotic mitochondrial alterations were present at 4 h. Apoptotic bodies were observed at 8 h and increased over time. TUNEL positive cells were detected as early as 4 h, and the DNA ladder pattern was observed at 12 h and 24 h. The liver showed the highest value of fragmented DNA, followed by the kidney and the lung. We demonstrated the induction of apoptosis by a toxic dose of PA1 in the kidney and lung in vivo. These results could be useful in understanding the mechanism of action of this compound at toxic doses in vivo.

Myopia

Myopia, also known as short-sightedness or near-sightedness, is a very common condition that typically starts in childhood. Severe forms of myopia (pathologic myopia) are associated with a risk of other associated ophthalmic problems. This disorder affects all populations and is reaching epidemic proportions in East Asia, although there are differences in prevalence between countries. Myopia is caused by both environmental and genetic risk factors. A range of myopia management and control strategies are available that can treat this condition, but it is clear that understanding the factors involved in delaying myopia onset and slowing its progression will be key to reducing the rapid rise in its global prevalence. To achieve this goal, improved data collection using wearable technology, in combination with collection and assessment of data on demographic, genetic and environmental risk factors and with artificial intelligence are needed. Improved public health strategies focusing on early detection or prevention combined with additional effective therapeutic interventions to limit myopia progression are also needed.

Toxicity and Anticancer Potential of Karwinskia: A Review

Karwinskia genus consists of shrubs and small trees. Four toxic compounds have been isolated from Karwinskia plants, which were typified as dimeric anthracenones and named T496, T514, T516, and T544. Moreover, several related compounds have been isolated and characterized. Here we review the toxicity of the fruit of Karwinskia plants when ingested (accidentally or experimentally), as well as the toxicity of its isolated compounds. Additionally, we analyze the probable antineoplastic effect of T514. Toxins cause damage mainly to nervous system, liver, lung, and kidney. The pathophysiological mechanism has not been fully understood but includes metabolic and structural alterations that can lead cells to apoptosis or necrosis. T514 has shown selective toxicity in vitro against human cancer cells. T514 causes selective and irreversible damage to peroxisomes; for this reason, it was renamed peroxisomicine A1 (PA1). Since a significant number of malignant cell types contain fewer peroxisomes than normal cells, tumor cells would be more easily destroyed by PA1 than healthy cells. Inhibition of topoisomerase II has also been suggested to play a role in the effect of PA1 on malignant cells. More research is needed, but the evidence obtained so far indicates that PA1 could be an effective anticancer agent.

Peroxisomicine A1, a potential antineoplastic agent, causes micropexophagy in addition to macropexophagy

Peroxisomicine A1 (PA1) is a potential antineoplastic agent with high and selective toxicity toward peroxisomes of tumor cells. Pexophagy is a selective autophagy process that degrades damaged peroxisomes; this process has been studied mainly in methylotrophic yeasts. There are two main modes of pexophagy in yeast: macropexophagy and micropexophagy. Previous studies showed that peroxisomes damaged by a prolonged exposition to PA1 are eliminated by macropexophagy. In this work, Candida boidinii was grown in methanol-containing media, and PA1 was added to the cultures at 2 µg/mL after they reached the mid-exponential growth phase. Samples were taken at 5, 10, 15, 20, and 25 min after the addition of PA1 and processed for ultrastructural analysis. Typical morphological characteristics of micropexophagy were observed: the direct engulfment of peroxisomes by the vacuolar membrane and the presence of the micropexophagic membrane apparatus (MIPA), which mediates the fusion between the opposing tips of the vacuole to complete sequestration of peroxisomes from the cytosol. In conclusion, here we report that, in addition to macropexophagy, peroxisomes damaged by PA1 can be eliminated by micropexophagy. This information is useful to deepen the knowledge of the mechanism of action of PA1 and of that of pexophagy per se.

Peroxisomicine A1 (toxin T-514) induces cell death of hepatocytes in vivo by triggering the intrinsic apoptotic pathway

Karwinskia parvifolia possesses the highest concentration levels of the anthracenone T-514 (PA1). Studies have demonstrated the induction of apoptosis by PA1 in cancer cell lines. The aim was to investigate the effects of PA1 on the apoptosis of the mouse liver in vivo and its underlying pathway. Sixty CD-1 mice were divided into three groups: untreated, vehicle, and treated with PA1. The animals were euthanized at 4, 8, 12, and 24 h post-treatment. To confirm the toxic effect of PA1 we determined the activity of catalase. Liver sections were prepared for morphological examination and for immunohistochemical evaluation of anti and pro-apoptotic markers. DNA fragmentation was detected by TUNEL assay and electrophoresis. Pre-apoptotic mitochondrial alterations and cytochrome c oxidase activity were analyzed by transmission electron microscopy. PA1 induced pre-apoptotic mitochondrial alterations, a high activity of the cytochrome oxidase, and apoptosis in hepatocytes. PA1 caused p53 over-expression and down regulation of PCNA. PA1 also increased the expression levels of the pro-apoptotic markers Bax and Bak, whereas the anti-apoptotic molecule Bcl-2 was decreased. PA1 induces apoptosis by activating the intrinsic mitochondrial apoptotic pathway. These results will be useful for studies regarding the use of PA1 as an antineoplastic agent.

Medicinal Plants from North and Central America and the Caribbean Considered Toxic for Humans: The Other Side of the Coin

The consumption of medicinal plants has notably increased over the past two decades. People consider herbal products as safe because of their natural origin, without taking into consideration whether these plants contain a toxic principle. This represents a serious health problem. A bibliographic search was carried out using published scientific material on native plants from Mexico, Central America, and the Caribbean, which describe the ethnobotanical and toxicological information of medicinal plants empirically considered to be toxic. A total of 216 medicinal plants belonging to 77 families have been reported as toxic. Of these plants, 76 had been studied, and 140 plants lacked studies regarding their toxicological effects. The toxicity of 16 plants species has been reported in clinical cases, particularly in children. From these plants, deaths have been reported with the consumption of Chenopodium ambrosioides, Argemone mexicana, and Thevetia peruviana. In most of the cases, the principle of the plant responsible for the toxicity is unknown. There is limited information about the toxicity of medicinal plants used in Mexico, Central America, and the Caribbean. More toxicological studies are necessary to contribute information about the safe use of the medicinal plants cited in this review.

In vitro metabolism and toxicity assessment of toxin T-514 (Peroxisomicine A1) of Karwinskia humboldtiana in microsomes and primary cultured hepatocytes

T-514 (Peroxisomicine A(1)) from Karwinskia humboldtiana is a dimeric hydroxyanthracenone with a highly selective cytotoxic effect on tumor cells. We evaluated the metabolism of this compound in two in vitro systems (liver microsomes and hepatocytes) and assessed the cytotoxicity of its metabolites on normal and tumor cells. Microsomes (12.5, 125 and 250 microg of protein/ml) and hepatocytes (1 x 10(6) cells/ml) were incubated with the toxin (25 microM) for 0.5, 1, 3, 6, 9, 12 and 24 h and the samples were examined using chromatographic analysis and UV spectra. Two metabolites (M1 and M2) were detected in the rat microsomes and one (M1) in the monkey microsomes. The retention times and UV spectra of the peaks were very similar to those of the toxin T-514. M1 was isolated and identified as a mixture of two isomers. The cytotoxicity of the metabolites was evaluated in Chang liver and Hep G2 cells but they did not show the selective cytotoxic effect on tumor cells seen in the original compound.

Production of reactive oxygen species by toxin T-514 of genus Karwinskia in vitro

In the present study we have analyzed the production of reactive oxygen species by toxin T-514 of the genus Karwinskia in vitro (primary liver cell cultures and microsomes), as well as their possible role in its cytotoxicity. The role of catalase and superoxide dismutase (SOD) as defense mechanisms against oxidative stress was also studied. Freshly isolated hepatocytes or microsomes were exposed to T-514 in the presence or absence of catalase and SOD. Cytotoxicity was determined by methylthiazoltetrazolium (MTT) reduction. Oxidative stress was evaluated by the dichlorofluorescein diacetate (DCFDA) fluorescent probe and the reduction of ferricytochrome c. Exposure of hepatocytes to toxin T-514 for 2-, 4-, 6- and 24-h periods resulted in a time- and concentration-dependent increase in the suppression of mitochondrial metabolic activity. T-514 induced the production of reactive oxygen species in both hepatocytes and microsomes. Catalase and superoxide dismutase had a protective effect against the cytotoxicity of T-514 in hepatocytes and also inhibited the production of oxygen reactive species in microsomes. The results indicate that oxidative stress mediated by reactive intermediates may be a mechanism by which T-514 induces its cytotoxic effect.

Optimization and validation of an analytical procedure by high-performance liquid chromatography for the quantification of peroxisomicines and isoperoxisomicines

Peroxisomicine A1 is a potential antineoplastic substance extracted from plants of the genus Karwinskia. An RP-HPLC-DAD method was developed and validated for the separation and quantification of four isomers of this compound. These isomers coelute in the preparative procedure and are present at a proportion ranging between 3 and 5% in the peroxisomicine A1 purified in the laboratory. The desirability coefficient of the method described here was enhanced 140% with respect to the previously reported method.

Apoptosis induction and cell cycle perturbation in established cell lines by peroxysomicine A1 (T-514)

Peroxysomicine A1, a novel potential anticancer compound induced cell death in established cell lines and in a primary culture of rat neonatal cardiomyocytes. Non-transformed cells are less sensitive to the compound than transformed cell lines. Fluorescent microscopy of dying cells stained with DNA-specific dyes revealed chromatin condensation and nuclear fragmentation as well as membrane blebbing characteristic of apoptosis. Flow cytometry of cells treated with peroxysomicine A1, demonstrated appearance of cells containing less than 2C DNA, that indicated degradation of nuclear DNA, another hallmark of apoptotic cell death. Z-VAD, a nonspecific caspase inhibitor, prevented DNA fragmentation but not cell death registered by permeabilization of cell outer membrane. Peroxysomicine A1 also inhibited proliferation of various cell lines. Flow cytometry analysis showed significant accumulation of dividing cells in G2/M phases of cell cycle indicating, most likely delay in G2. These results provide initial insight into the mechanisms of action of peroxysomicine A1 and suggest that peroxysomicine A1 is a potent inhibitor of cell proliferation and inducer of apoptosis and may be a useful antineoplastic chemotherapeutic agent.

High-performance liquid chromatographic determination of peroxisomicine A1 (T-514) in genus Karwinskia

A chromatographic method was developed for the T-514 determination in Karwinskia leaves, stems and roots. A C18 analytical column and a mobile phase consisting of methanol and McIlvaine buffer (pH 3) were used. T-514 was detected using a diode array detector and the chromatograms were recorded at 269 and 410 nm. A linear dependence of a peak area on the T-514 concentration (r=0.9991) was obtained in the range of 0.126-12.6 microg/ml. Limits of T-514 quantification (signal-to-noise ratio 10) in plant samples were 126 ng/ml at 410 nm and 28 ng/ml at 269 nm. T-514 was extracted from the plant material with ethyl acetate. Optimal extraction conditions were studied: number of extraction steps, volume of extracting agent and extraction time. The extracts were cleaned up using solid-phase extraction (SPE). SPE recoveries of 99.9% and 98.4% were achieved for the T-514 concentrations of 1.4 microg/ml and 0.26 microg/ml, respectively.

Clinical diagnosis in Karwinskia humboldtiana polyneuropathy

Intoxication by Karwinskia humboldtiana presents a neurological picture similar to that for Guillain-Barré syndrome or other polyradiculoneuropathies. Clinical diagnosis in poisoned humans may be difficult if no evidence of previous fruit ingestion is available. We present our experience in the clinical diagnosis of Karwinskia humboldtiana polyneuropathy, as confirmed by toxin detection in blood. We designed an open trial at the Pediatric Neurology service and included all cases with acute ascending paralysis that were admitted to our hospital in the last two years. In all cases, we performed hematological, immunological and biochemical profiles, CSF analysis including immunological studies, oligoclonal bands and myelin basic protein determinations. Electrodiagnostic studies were performed, including motor conduction velocities, distal latencies, F-wave latency and compound muscle action potential (CAMP) amplitude. The presence of Karwinskia humboldtiana toxins in blood were determined by thin layer chromatography. In six cases, T-514 Karwinskia humboldtiana toxin was detected. These cases had a symmetric motor polyneuropathy with the absence of tendon reflexes and no sensory signs or cranial nerve involvement. Only one patient required assisted ventilation due to bulbar paralysis. In two of these cases, a sural nerve biopsy revealed a segmental demyelination with swelling and phagocytic chambers in Schwann cells and without lymphocytic infiltration. All six cases survived, with complete recovery in five. We conclude that this intoxication is common in Mexico. The availability of toxin detection in blood samples allows the clinician to establish an accurate diagnosis and should be included in the study of children with polyradiculoneuropathy, especially in countries where this poisonous plant grows.

Effect of peroxisomicine A2 and T 544 of the genus Karwinskia on peroxisomes of Candida boidinii

Dimeric anthracenones have been isolated from toxic plants of the genus Karwinskia (Rhamnaceae). T 514 or peroxisomicine A1 is one of the anthracenonic compounds which produce irreversible and selective damage on the peroxisomes of yeast cells in vivo. In this paper we describe the effect of two structurally related anthracenones on cell viability and on the peroxisomes of the methylotrophic yeast Candida boidinii. As has been described for peroxisomicine A1, peroxisomicine A2 and T 544 caused a decrease in the viability of C. boidinii at all concentrations tested, and disruption of the peroxisomal membrane, T 544 showing the strongest effect. In C. boidinii cell death and peroxisomal damage seem to be independent events.

Experimental evidence for toxic damage induced by a dimeric anthracenone: diast T-514 (peroxisomicine A2)

Dimeric anthracenones obtained from the genus Karwinskia (Rhamnaceae) are characteristic compounds isolated from the plants of this species. Previous toxicity studies demonstrated Diast T-514 to be toxic to animals in experimental settings. Diast T-514 extracted and characterized from Karwinskia parvifolia, was studied in CD1 mice. The LD50 for this compound was determined. Animals were tested with Diast T-514 following enteral and parenteral administration. An LD50 dose by both oral and intraperitoneal administration showed selective damage to target organs.

Natural anthracenone subcellular distribution and effects on NADPH-cytochrome P450 reductase microsomal activity

Natural anthracenone subcellular distribution and effects on NADPH-cytochrome P450 reductase microsomal activity. Subcellular distribution study of a natural anthracenone (T-514) isolated from Karwinskia humboldtiana showed to be homogeneous on subcellular (nuclear, mitochondrial, peroxisomal and microsomal) fractions prepared from rat liver treated with an acute dose of T-514. These results indicate that T-514 can pass easily through subcellular compartment membranes and an absence of selectivity for some subcellular organelles. A significant increase of protein on liver homogenates and NADPH-cytochrome P450 reductase microsomal activity indicates that T-514 may act as a microsomal enzymatic inducer. In addition, this enzymatic specific activity increment could be due to the interaction of T-514 with the microsomal redox cycling.

Effect of toxins 544 and 514 from Karwinskia humboldtiana (buckthorn) plant upon fetal development of the mouse

The teratogenic effect of toxins 544 and 514 from K. humboldtiana upon the mouse embryo was evaluated. One half of the LD50 dose for the mouse was administered at day 8 of gestation. At the end of pregnancy, reproduction and fetal data were recorded. Dams treated with toxin 544, but not with toxin 514, showed a higher incidence of reabsorptions, malformations, as well as lower fetal length compared to the control group.

Experimental acute intoxication with ripe fruit of Karwinskia humboldtiana (Tullidora) in rat, guinea-pig, hamster and dog

Previous acute toxicity studies with 'Tullidora' in mice showed mainly hepatic and pulmonary complications. We tested samples in rat, guinea-pig, hamster and dog, searching for the mechanism of death. A single oral preparation of ripe fruit of Karwinskia humboldtiana was given to all animals. Clinical signs and histopathology were reproduced in all species except dogs. We propose a selective toxicity of the toxins of this fruit to the lungs and liver.

Toxicity assessment of toxins T-514 and T-544 of buckthorn (Karwinskia humboldtiana) in primary skin and liver cell cultures

The present study was undertaken to assess and compare the in vitro cytotoxicity of toxins T-514 and T-544 of Buckthorn (Karvinskia humboldtiana) using primary cultures of rat hepatocytes and keratinocytes. Cell cultures were exposed to 6, 12, 25 and 50 microM concentrations of the toxins for 2, 4, 6 and 24-h periods. Cytotoxicity was determined by release of the cytoplasmic enzyme, lactate dehydrogenase (LDH), in culture media, methylthiazoltetrazolium (MTT) reduction and neutral red (NR) uptake. An increase in LDH leakage was observed in liver cell cultures as early as 2 h with 50 microM T-544 and with 6 microM T-514 and T-544 at 6 h and 24 h, respectively. In the NR assay the toxicity was evident at 2 h with 12 microM T-514 and T-544 and with 6 microM concentrations of both toxins at 6 h. On the other hand, a decrease in MTT reduction was detected at 4 h with 50 microM concentrations of both toxins and with 25 microM T-544 and 12 microM T-514 at 6 h and 6 microM T-514 and T-544 at 24 h. Both toxins were shown to be highly hepatotoxic; T-514 was more toxic than T-544. In the skin cell cultures, the toxicity of the toxins was not as severe and was not expressed until 12 h of exposure.

Toxicity assessment of toxins T-514 and T-544 of buckthorn (Karwinskia humboldtiana) in primary skin and liver cell cultures

The present study was undertaken to assess and compare the in vitro cytotoxicity of toxins T-514 and T-544 of buckthorn (Karwinskia humboldtiana) using primary cultures of rat hepatocytes and keratinocytes. Cell cultures were exposed to 6, 12, 25 and 50 microM toxins for 2-, 4-, 6- and 24-h periods. Cytotoxicity was determined by release of the cytoplasmic enzyme, lactate dehydrogenase (LDH), in culture media, methylthiazoltetrazolium (MTT) reduction and neutral red (NR) uptake. An increase in LDH leakage was observed in liver cell cultures as early as 2 h with 50 microM T-544 and with 6 microM T-514 and T-544 at 6 h and 24 h, respectively. In the NR assay the toxicity was evident at 2 h with 12 microM T-514 and T-544 and with 6 microM concentrations of both toxins at 6 h. On the other hand, a decrease in MTT reduction was detected at 4 h with 50 microM concentrations of both toxins and with 25 microM T-544 and 12 microM T-514 at 6 h and 6 microM T-514 and T-544 at 24 h. Both toxins were shown to be highly hepatotoxic; T-514 was more toxic than T-544. In the skin cell cultures, the toxicity of the toxins was not as severe and was not expressed until 12 h of exposure.

Effects of toxin T-544 from the Karwinskia humboldtiana (buckthorn) plant upon mouse embryos explanted at 11 days

Eleven-day mouse embryos were exposed to the K. humboldtiana toxin T-544 for 24 hr. At the end of the culture period, embryos were examined grossly for malformations and biochemically for altered protein levels. There was a significant difference in malformations in those embryos exposed to 0.05 and 0.2 microgram/ml of toxin compared with controls. Embryo protein content was significantly lower in those embryos exposed to 0.1 microgram/ml of T-544 compared with control group.