Gastroprotective effects and antimicrobial activity of Lithraea molleoides and isolated compounds against Helicobacter pylori.

ETHNOPHARMACOLOGICAL RELEVANCE: Lithraea molleoides (Vell.) Engl. (Anacardiaceae) is a medicinal plant traditionally used in South America to treat various ailments, including diseases of the digestive system. AIM OF THE STUDY: To evaluate the in vivo antiulcer and antimicrobial activities against Helicobacter pylori of L. molleoides and its isolated compounds. MATERIALS AND METHODS: Methanolic extract 250 and 500 mg/kg, (LmE 250 and LmE 500, respectively) and infusions, 10 g and 20 g en 100mL (LmI 10 and LmI 20, respectively) of L. molleoides was evaluated for antiulcer activity against 0.6N HCl, 0.2N NaOH, 200mg/kg acetilsalicilic acid and absolute ethanol-induced gastric ulcers in rats. The degree of erosion in the glandular part of the stomach was assessed from a scoring system. Acute toxicity in mice was also evaluated. The antiulcer effect of the isolated compounds (catechol, mannitol, rutin, gallic acid, ferulic acid and caffeic acid, 100mg/kg) was evaluated against absolute ethanol-induced gastric ulcers in rats. The anti-Helicobacter pylori activity of L. molleoides and isolated compounds was performed using broth dilution methods. RESULTS: The LmE 250, LmE 500, LmI 10 and LmI 20 produced significant inhibition on the ulcer index in 0.6N HCl, 0.2N NaOH, 200mg/kg acetilsalicilic acid and absolute ethanol- induced gastric ulcers in rats. The isolated compounds, catechol, mannitol, rutin, ferulic acid and caffeic acid were active in absolute ethanol- induced gastric ulcers in rats. L. molleoides and different compounds showed antimicrobial activity in all strains tested. The lowest MIC value (0. 5 µg/mL) was obtained with catechol in six of eleven strains assayed. No signs of toxicity were observed with doses up to 2g/kg in an acute toxicity assay. CONCLUSION: These findings indicate that L. molleoides displays potential antiulcerogenic and antimicrobial activities and the identification of active principles could support the use of this plant for the treatment of digestive affections.

Jodina rhombifolia leaves lyophilized aqueous extract decreases ethanol intake and preference in adolescent male Wistar rats.

The leaves of Jodina rhombifolia (Hook. & Arn.) Reissek (Santalaceae) are utilized as anti-alcoholic in Argentine folk medicine. This study was designed to investigate the anti-alcohol properties in adolescent male Wistar rats (postnatal day 29; 83-105 g of weight). We utilized the "self-administration model", which ethanol was offered in the standard home-cage through two-bottle free-choice regimen between an ethanolic solution (20% in tap water, v/v) and tap water with unlimited access for 24h per day for 10 consecutive days. The results obtained show that repeated administration of J. rhombifolia lyophilized extract, markedly reduced ethanol voluntary intake on dose dependent bases. The magnitude in reduction of daily ethanol intake was approximately 29%, 44% and 68%, for the rat groups treated with 62.5, 125 and 250 mg/kg of extract, respectively. Ethanol preference (proportion of ethanol intake versus total fluid intake) was significantly reduced: 21.37% ± 0.79 (0 mg/kg); 15.83% ± 0.93 (62.5 mg/kg); 15.22% ± 1.30 (125 mg/kg) and 9.38% ± 0.57 (250 mg/kg). Daily food intake was significantly higher (p<0.05) in the group treated with 250 mg/kg of JRLE in comparison with vehicle-dose group; the reduction in ethanol intake was associated with a compensatory increase in food intake, probably because in the control group animals a part of the total caloric intake was supplied by ethanol. Treatment was very well tolerated by all animals and without apparent side-effects. These results contribute to the scientific validation of the antialcoholic indication of this botanic species in Argentine folk medicine.

Reduction in voluntary ethanol intake following repeated oral administration of Jodina rhombifolia lyophilized aqueous extract in male Wistar rats.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves of Jodina rhombifolia (Hook. & Arn.) Reissek (SANTALACEAE) is utilized in Argentine folk medicine for the treatment of alcoholism. AIM OF THE STUDY: To evaluate the antialcoholic activity of Jodina rhombifolia lyophilized aqueous extract (JRLE) in male Wistar rats. MATERIALS AND METHODS: Rats were housed individually in standard plastic cages with wood chip bedding. Throughout the duration of experiment, ethanol was offered in the standard home-cage; two-bottle free-choice regimen between an ethanolic solution (20% in tap water, v/v) and tap water with unlimited access for 24h per day for 10 consecutive days. Rats were administrated intragastrically twice daily (1 ml/200 g) for 10 consecutive days, with the control vehicle (distilled water) or one of the doses of JRLE (125, 250 and 500 mg/Kg weight). Body weight, ethanol, water and food intake were measured every day at the same hour during the 10 days of experimentation. RESULTS: The reducing effect of JRLE on daily ethanol intake was evidenced from the first day of treatment and persisted throughout the entire treatment period. The treatment did not significantly affect daily water intake neither the body weight gain. Daily food intake was higher in rat groups treated with JRLE. CONCLUSION: The results obtained in the present preliminary study show that repeated administration of JRLE, markedly reduces ethanol voluntary intake in male Wistar rats. The reduction of consumption was of remarkable magnitude and stable during the treatment 10-days.

Histological changes in the retina provoked by lithium treatment in a nocturnal rodent (Lagostomus maximus maximus).

Daily morphological variations have been previously described in the viscacha (Lagostomus maximus maximus) retina. The aim of this work was to determine the effects of lithium administration on the histology of retinas from this nocturnal rodent since lithium is a drug that has been shown to affect different parameters of circadian rhythms. Adult male viscachas were divided into 2 groups, injected daily with lithium chloride or vehicle for 35 days, and sacrificed at 08:00, 16:00, and 24:00 h for light and electron microscopy studies. The following morphometric parameters were analyzed: the thickness of the photoreceptor layer, the rod outer and inner segments, and the outer nuclear layer. The control group displayed a true daily cycle of photoreceptor renewal similar to that previously reported by us for (untreated) viscachas in their normal habitat. In all lithium-treated groups, we did not observe histological changes in the thickness measurement of the retinal layers. In these groups, the retinas presented ultrastructural characteristics similar to those observed in control animals sacrificed at 24:00 h. In conclusion, chronic lithium administration abolished the daily histological rhythm in the viscacha retina, probably via inhibition of the phagocytosis process in pigment epithelial cells.

Anti-inflammatory activity of Bromelia hieronymi: comparison with bromelain.

Some plant proteases (e. g., papain, bromelain, ficin) have been used as anti-inflammatory agents for some years, and especially bromelain is still being used as alternative and/or complementary therapy to glucocorticoids, nonsteroidal antirheumatics, and immunomodulators. Bromelain is an extract rich in cysteine endopeptidases obtained from Ananas comosus. In this study the anti-inflammatory action of a partially purified extract of Bromelia hieronymi fruits, whose main components are cysteine endopeptidases, is presented. Different doses of a partially purified extract of B. hieronymi were assayed on carrageenan-induced and serotonine-induced rat paw edema, as well as in cotton pellet granuloma model. Doses with equal proteolytic activity of the partially purified extract and bromelain showed significantly similar anti-inflammatory responses. Treatment of the partially purified extract and bromelain with E-64 provoked loss of anti-inflammatory activity on carrageenan-induced paw edema, a fact which is consistent with the hypothesis that the proteolytic activity would be responsible for the anti-inflammatory action.

Evaluation of anti-inflammatory activity of Pseudananas macrodontes (Morr.) Harms (Bromeliaceae) fruit extract in rats.

Several species of the family Bromeliaceae are characterized by the production of proteases in unusual amounts, especially in fruits. Bromelain, an extract rich in cysteine endopeptidases obtained from Ananas comosus L., and a few other proteases have been used as anti-inflammatory agents for some years, but bromelain is still mainly being used as alternative and/or complementary therapy to the treatment with glucocorticoids, nonsteroidal antirheumatics, and immunomodulators. In this study, the anti-inflammatory action of a partially purified extract from Pseudananas macrodontes (Morr.) Harms fruits (PPE(Pm)) is presented, whose main components are cysteine endopeptidases. The effect of PPE(Pm) was assessed in carrageenan-induced and serotonin-induced rat paw edema, as well as in the cotton pellet granuloma model. Doses with equal proteolytic activity of PPE(Pm) and bromelain produced significantly similar anti-inflammatory responses in the acute inflammatory models assayed, supporting the hypothesis that proteolytic activity could be responsible for the anti-inflammatory action. On the contrary, comparable anti-inflammatory effects of PPE(Pm) and bromelain in the chronic inflammatory assay required a much lower proteolytic activity content of PPE(Pm), which could be due to a differential affinity for the protein target involved in this process.

Lethal effect of dehydroleucodine (DhL) on amphibian Bufo arenarum embryos.

The dehydroleucodine is a sesquiterpene lactone isolated from Artemisia douglasiana Besser which is used in popular medicine. Toxicity tests using embryos of amphibian have been widely used in order to predict toxic effects of different compounds. However, to our knowledge, there are not studies focussed on the toxic effects of dehydroleucodine on Bufo arenarum, which is an anuran widely distributed in South America. The effect of dehydroleucodine on the survival of embryos was evaluated in an acute test during the early life stage of B. arenarum embryos. Lethality and the degree of adverse effects were dehydroleucodine dose-dependent. Overall, amphibian early life stages appeared to be more susceptible to the embryotoxicity associated with exposure to dehydroleucodine, especially at concentration greater that 3mM. This increased susceptibility may result from the relatively high rate of cellular differentiation and morphogenesis that occurs at this early stage of development.

Effect of dehydroleucodine on intestinal transit: structural basis of the interaction with the α(2)-adrenergic receptor.

The activity of dehydroleucodine, a sesquiterpene lactone obtained from Artemisia douglasiana, was studied in mice small intestinal transit. Its mechanism was evaluated in the presence of several adrenergic and cholinergic antagonist drugs and one opioid antagonist. Docking of dehydroleucodine into the homology model of the α2-adrenergic receptor allowed us to analyze the structural basis of their interactions. The experiments showed that dehydroleucodine delayed intestinal transit. The docking of dehydroleucodine showed a unique binding site, equivalent to the binding site of carozolol in the ß-adrenergic receptor. The results suggested that dehydroleucodine produced an inhibitory effect on intestinal transit. Its action could be mediated, at least in part, through the α2-adrenergic receptor.

Anti-inflammatory properties from isolated compounds of Cyclolepis genistoides.

CONTEXT: Cyclolepis genistoides D. Don (Asteraceae) is an Argentinean endemic shrub, known by the vernacular name "palo azul" or "matorro negro". It is widely used in folk medicine as a diuretic, an antirheumatic, and an antispasmodic agent. OBJECTIVE: The aim of this work was to describe the activity of two isolated compounds of C. genistoides, oleanolic acid (1) and deacylcynaropicrin (2), using the carrageenan-induced paw edema method in mice. MATERIALS AND METHODS: Aerial parts of C. genistoides were dried, powdered, and extracted with petroleum ether, ethyl acetate, dichloromethane, and methanol for 48 h. The fractions obtained from the ethyl acetate extract yielded oleanolic acid, while deacylcynaropicrin was obtained according to Abdei-Mogib et al. Structures were elucidated by ¹H-NMR and ¹³C-NMR. The products were administered intraperitoneally at doses of 40, 75, and 100 mg/kg. RESULTS AND DISCUSSION: Compound 1 exhibited significant activity during the first 7 h of the inflammatory phase (at 1, 3, 5, and 7 h), exercising its inhibitory action on inflammation mediated by histamine, prostaglandins, serotonin, and kinins, while compound 2 showed a significant inhibition at 3 and 5 h contributing to this effect, acting in the intermediate phase. CONCLUSIONS: According to the results of this work, the intraperitoneal administration of oleanolic acid and deacylcynaropicrin isolated from the aerial parts of C. genistoides produced a significant inhibition of carrageenan-induced inflammation at doses of 75 and 100 mg/kg. These results give support to the use of this plant as an anti-inflammatory in traditional medicine.

Anti-inflammatory effect of Acacia visco extracts in animal models.

The aqueous and organic extracts of Acacia visco Lor. Ap Griseb (Fabaceae) were tested for anti-inflammatory activity in experimental models in rat. Besides, the free-radical scavenging capacity of extracts from A. visco was determined. The extracts revealed anti-inflammatory effect against carrageenan-induced oedema, phospholipase A(2)-induced oedema, cotton pellet-induced granuloma and they did not show acute toxic effect. Among the class of compounds characterized from A. visco leaves, the triterpenoid 20(29)-lupen-3ß-ol (lupeol), 12-ursen-3ß-ol (α-amyrin) and 12-oleanen-3ß-ol (ß-amyrin) may be mainly responsible for the pharmacological activities.

Structural basis of the anti-inflammatory activity of quercetin: inhibition of the 5-hydroxytryptamine type 2 receptor.

The anti-inflammatory activity of quercetin was evaluated through serotonin-induced rat-paw edema. The experiments showed that quercetin had an important effect on acute inflammatory processes. Docking of serotonin and quercetin into the homology model of the 5-Hydroxytryptamine Type 2 Receptor allowed to analyze the structural basis of the anti-inflammatory activity. Results showed that serotonin and quercetin bind in the same region of the active site with a similar binding energy but quercetin has a much bigger inhibition constant. Therefore, it seems possible that quercetin may act as a natural inhibitor of the receptor blocking the acute inflammation generated by serotonin.

Structural basis of the anti-inflammatory activity of melatonin.

The anti-inflammatory activity of melatonin (CAS 73-31-4) was examined, using the rat paw edema model, and compared with the non-steroidal anti-inflammatory drug (NSAID) indometacin (CAS 53-86-1) which exerts its effects by inhibition of prostaglandin production on acute inflammation. The experiments showed that melatonin has an important effect on acute inflammatory processes acting as an inhibitor in a similar manner to indometacin. The structural interactions of melatonin with cyclooxygenase (COX), the pharmacological target of NSAIDs, were investigated using computer graphics applications. The results indicated that melatonin has an excellent steric and electronic complementarity with COX. It was found, similarly to previously studied crystal structures of protein-inhibitor complexes, that almost all interactions were of the hydrophobic type but for the typical carboxylate or electronegative group interaction, at the mouth of the active site channel, with Arg 120 and Tyr 355. Therefore, it seems possible that melatonin might bind to the active site of COX-1 and COX-2 suggesting that it may act as a natural inhibitor of the functions of cyclooxygenase modulating in a natural manner the activity of this enzyme.

Anti-ulcerogenic and anti-inflammatory activity of the methanolic extract of Larrea divaricata Cav. in rat.

Larrea divaricata Cav. (Zygophyllaceae) is used in popular medicine as anti-inflammatory and anti-rheumatic drug, containing higher amounts of nordihydroguaiaretic acid, a well-known free radical scavenger. Here we describe the gastric anti-ulcerogenic effect of the methanolic extract of Larrea divaricata (LdME) leaves in rat, using absolute ethanol and HCl 0.6N as necrotizing agents, and the effect of blocking endogenous sulfhydryl (SH) groups with N-ethylmaleimide (NEM). We also studied the anti-inflammatory activity of LdME in two rat experimental models: cotton pellet induced granuloma and arthritis induced by adjuvant-carrageenan. Influence of treatment in body weight and some lymphoid organs was evaluated. Finally, the free radical scavenging capacity of LdME was determined by the method of 1,1-diphenyl-2-picrylhydrazyl (DPPH) inhibition. LdME demonstrated anti-ulcerogenic effect in rats, and it was shown that the endogenous SH compounds were not involved in the mechanism of action. LdME also showed inhibitory activity in the applied models of inflammation, being more effective in the acute phase. No effect was observed concerning the weight of spleen, thymus and body. The extract proved to possess elevated free radical scavenging capacity which may contribute to the observed gastric anti-ulcerogenic and anti-inflammatory activity.

Morphological and biochemical study of the pineal gland of pregnant and non-pregnant female vizcachas (Lagostomus maximus maximus).

OBJECTIVES: The morphological and biochemical aspects of the pineal gland of pregnant and non-pregnant female vizcachas were investigated to examine whether there is a relationship between the pregnancy and this gland. METHODS: Pregnant and non-pregnant adult female vizcachas were used. The ultrastructure of type I cell (dark and light pinealocytes) was studied. Pineal and serum melatonin were investigated by radioimmunoassay. Radiometric methods were applied to investigate the arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT) activities. RESULTS: The morphological study showed the existence of dark and light pinealocytes. The differences between both cells are slight. However, the appearance of dark pinealocytes suggests that they have a high activity. These cells were more abundant in the pineal gland of pregnant females. The pineal melatonin levels and the AA-NAT activity were higher in the pregnant females. Serum melatonin and HIOMT activity did not show significant differences. CONCLUSION: Our results suggest that the morphological and biochemical changes in the pineal gland of pregnant vizcachas are associated with the gestation. However, the relation between the pineal gland and the pregnancy is complex and further studies are necessaries to clearly establish it.

Anti-ulcerogenic activity of xanthanolide sesquiterpenes from Xanthium cavanillesii in rats.

The preventive effect of natural xanthanolides as well as a series of synthetic derivatives on ulcer formation induced by absolute ethanol in rats was examined. Among the compounds tested, xanthatin gave the strongest protective activity. The inhibitory action exerted by this molecule on the lesions induced by 0.6N HCl and 0.2N NaOH was highly significant, reducing ulceration in the range of 58-96% at a dose from 12.5 to 100mg/kg. These results appear to confirm that the presence of a non-hindered alpha,beta-unsaturated carbonyl group seems to be an essential structural requirement for the gastric cytoprotective activity of these compounds. In order to explore this possibility, a theoretical conformational analysis was performed. We suggest that the mechanism of protection would involve, at least in part, a nucleophylic attack of the sulfhydryl group from the biological molecules present in the gastric mucosa to electrophylic carbons accessible in suitable Michael acceptors.

Different effects of melatonin on experimental granulomatous inflammation.

Several experiments have detected that melatonin exerts a marked influence on the inflammatory process. In the present study we evaluated the effect of exogenous melatonin on the experimental granulomatous tissues in rat. Our data show that subcutaneous administration of different doses of melatonin given daily during 6 days at 9:00 h do not have significant action on the granuloma weight. On the other hand melatonin (4 mg/kg) administered at 17:00 h showed a remarkable action pro-inflammatory. However, this effect was abolished when the animals received previously higher doses of melatonin (40 mg/kg) at 9:00 h.

Comparative study of flavonoids in experimental models of inflammation.

The anti-inflammatory activities of flavonols (quercetin, rutin and morin) and flavanones (hesperetin and hesperidin) were investigated in animal models of acute and chronic inflammation. Rutin was only effective in the chronic process, principally in adjuvant arthritis. On neurogenic inflammation induced by xylene, only the flavanones were effective; besides, these compounds were the most effective on subchronic process. The most important compound in reducing paw oedema induced by carrageenan was quercetin.

Daily morphological variations in the viscacha (Lagostomus maximus maximus) retina. Probable local modulatory action of melatonin.

Given that the local melatonin levels exhibit rhythmic daily changes in the retina of the viscacha, we considered it important to study the likely daily variations in morphology and specific 2-[(125)I]-iodomelatonin binding in retinas from this rodent and to correlate these putative changes with local indole levels. Adult animals of both sexes were captured in their habitat and were kept under a natural photoperiod. For light and electron microscopic studies the viscachas were sacrificed by decapitation at 08:00, 16:00, and 24:00 hr. A computer-assisted image analysis system was used to measure the thickness of the complete retina, the photoreceptor layer, the rod outer and inner segments, and the outer nuclear layer. The daily variation in 2-[(125)I]-iodomelatonin binding sites was followed during a 24-hr light-dark cycle, the animals being sacrificed at six time points. The parameters studied showed significant variations throughout the 24-hr period. Maximal specific binding, lysosomal content in the pigment epithelium, and photoreceptor layer outer segment thicknesses were observed at 24:00 hr. Close contact between photoreceptor membranes and microvilli of the pigment epithelium was observed at 08:00 and 16:00 hr. Moreover, the minimal outer segment thickness at 16:00 hr was accompanied by a scarcity of dense bodies, such as lysosomes, a maximum dispersion of melanin pigment granules, and a minimum density of radioligand binding sites. Therefore, in the retina of the viscacha, we suggest that the interaction between melatonin and specific sites could be one of the factors or causes that participate in the regulation of the daily morphological changes observed in viscacha.

Pineal serotonin N - acetyltransferase and hydroxyindole - 0 - methyltransferase activities in vizcacha (Lagostomus maximus maximus) maintained under various photoperiods

Este trabajo tiene como propósito estudiar las actividades de las enzimas NAT y HIOMT en glándula pineal de vizcacha, bajo distintos regímenes de iluminación. La actividad de NAT presentó marcada variación diaria en los animales mantenidos en condiciones de LD 12:12, permaneciendo descendida durante las horas de iluminación y siendo máxima en oscuridad. En oscuridad permanente aumenta significativamente y se anulan las variaciones diarias de NAT. La actividad de HIOMT en pineal de vizcachas mantenidas en LD 12:12 no presentó ritmos diarios; en iluminación la actividad desciende, no recuperándose en la etapa de oscuridad. En el lote de oscuridad permanente se observó un marcado aumento, mientras que en iluminación permanente descendió a 1/7 de los valores encontrados en oscuridad. En iluminación natural día-noche la HIOMT recuperó su actividad en las horas de oscuridad. Concluimos que en este roedor la actividad de las enzimas estudiadas es afectada por la luz, siendo la HIOMT la más sensible

Pineal serotonin N - acetyltransferase and hydroxyindole - 0 - methyltransferase activities in vizcacha (Lagostomus maximus maximus) maintained under various photoperiods

Este trabajo tiene como propósito estudiar las actividades de las enzimas NAT y HIOMT en glándula pineal de vizcacha, bajo distintos regímenes de iluminación. La actividad de NAT presentó marcada variación diaria en los animales mantenidos en condiciones de LD 12:12, permaneciendo descendida durante las horas de iluminación y siendo máxima en oscuridad. En oscuridad permanente aumenta significativamente y se anulan las variaciones diarias de NAT. La actividad de HIOMT en pineal de vizcachas mantenidas en LD 12:12 no presentó ritmos diarios; en iluminación la actividad desciende, no recuperándose en la etapa de oscuridad. En el lote de oscuridad permanente se observó un marcado aumento, mientras que en iluminación permanente descendió a 1/7 de los valores encontrados en oscuridad. En iluminación natural día-noche la HIOMT recuperó su actividad en las horas de oscuridad. Concluimos que en este roedor la actividad de las enzimas estudiadas es afectada por la luz, siendo la HIOMT la más sensible (AU)