Antiulcerogenic activity of trans-dehydrocrotonin from Croton cajucara

Antiulcerogenic effect of a hydroalcoholic extract and its organic fractions of Neurolaena lobata (L.) R.BR

Neurolaena lobata is a species used widely in Caribbean folk medicine to treat gastric pain and ulcers. The hexane (HxF), chloroform (ClF) and aqueous (H2OF) fractions of a hydroalcoholic extract (HE) of N. lobata aerial parts were investigated for their ability to prevent ulceration of the gastric mucosa. In the stress-induced gastric model the HE, HxF and ClF fractions produced a significant reduction of gastric lesion formation by 48, 70 and 52%, respectively. HE, HxF and ClF fractions (41, 57 and 51%, respectively) also reduced significantly the gastric lesions induced by the combination of indomethacin and bethanechol, and the ulcers induced by HCl/ethanol solution by 77, 86 and 83%, respectively (P < 0.05). The pylorus-ligature experiment demonstrated that the HE, HxF and ClF fractions changed significantly the gastric juice parameters, such as pH values (increases to 5.4, 4.9 and 4.8, respectively) and acid output (decreased by 4.6, 5.8 and 6.2 mEq mL(-1) 4h respectively) and gastric content (increased by 400, 410 and 390 mg, respectively) in animals. In the animals pre-treated orally with the HxF fraction, prostaglandin synthesis was increased significantly, by 104%, and free mucus production was increased by 54 % in the gastric mucosa (P < 0.001). The H2OF did not exhibit activity in any of the experimental models assayed. The data suggest that the HE and mainly the HxF of fractions from N. lobata present a significant anti-ulcer effect when assessed in these ulcer-induced models. Although the mechanism underlying this antiulcerogenic effect remains unknown, it seems to be related to an increased activity of the defensive mechanisms of the stomach, such as prostaglandin synthesis and mucus production.

Ethnopharmacology, phytochemistry and pharmacology: a successful combination in the study of Croton cajucara

Phytochemical and pharmacological studies of Croton cajucara were oriented by traditional medicine. The stem bark of the mature plant is a rich source of clerodane-type diterpenes: trans-dehydrocrotonin (DCTN), trans-crotonin (CTN), cis-cajucarin B, cajucarin A, cajucarinolide and two novel clerodanes, trans-cajucarin B and sacacarin. In young (18-month-old) plants, the triterpene acetyl aleuritolic acid (AAA) was the major stem bark component and in these the diterpene DCTN was not present. The highest concentration of DCTN (1.4% of dry bark) was detected in 4-6 year-old plants, while 3-year-old plants contained only 0.26% of this diterpene. Three steroids (beta-sitosterol, stigmasterol and sitosterol-3-O-beta-glucoside), two flavonoids (kaempferol 3,4', 7-trimethyl ether and 3,7-dimethyl ether) and one diterpene (cajucarinolide) were isolated from the leaves of this Croton. The main pharmacological activity was correlated with DCTN. This clerodane produced anti-inflammatory and antinociceptive effects and a significant hypoglycemia in alloxan-induced diabetic rats. The compound also reduced the index of gastric lesions induced by restraint-in-cold. Dose-related DCTN and CTN inhibited in vivo the basal acid secretion in pylorus-ligature rats and oxyntic glands isolated from rabbit gastric mucosa, DCTN, CTN or AAA decreased in vitro uptake basal acid secretion induced by histamine and measured with the 14C-aminopyrine uptake method. Uniquely DCTN inhibited 14C-AP uptake induced by bethanechol. The terpenoids, DCTN and AAA, and the chloroform extract of 6-month-old plants reduced gastrointestinal transit in mice. The effects of DCTN and CTN on the survival of mice bearing Sarcoma 180 and Ehrlich carcinoma ascitic tumors, on the proliferation of cultured cells and TNFalpha were determined. DCTN was also evaluated for a possible antioestrogenic activity using the immature rat as a model system for bioassay of oestrogen and for an anti-implantation effect in regularly cycling rats. The biological experiments, using the plant extracts and the terpenoids DCTN, CTN and AAA, are herein discussed.

Gastroprotective effect of essential oil from Croton cajucara Benth. (Euphorbiaceae)

The gastroprotective activity of the essential oil from the bark of Croton cajucara Benth (Euphorbiaceae) was assessed in three different models of experimentally induced gastric ulcer in mice. At oral dose of 100 mg/kg the essential oil reduced gastric lesions induced by hypothermic restraint stress and HCl/ethanol significantly. In the HCl/ethanol model a dose-dependent gastroprotective effect was found. Moreover, significant changes in gastric parameters such as pH, secretion rate and total gastric acid were found after intraduodenal administration of essential oil under ligated pylorus (Shay) conditions. The acute toxicity of essential oil was assessed in mice. The LD50 values were 9.3 and 680 mg/kg for oral and intraperitoneal administrations, respectively. The cytotoxicity of essential oil was studied also. A dose-dependent cell viability inhibition was found in V79 fibroblast cell cultures with an IC50 of 22.9 microg/ml. Our results support the pharmacological study of this essential oil.

Investigation of genotoxic activity of trans-dehydrocrotonin, a clerodane diterpene from Croton cajucara

The genotoxic action of three doses of trans-dehydrocrotonin (t-DCTN), an active ingredient obtained from the bark extracts of an Amazon native plant, Croton cajucara, were examined in Swiss mouse bone marrow cells in vivo, submitted to acute intraperitoneal treatment, by micronucleus (MN) and chromosomal aberration (CA) tests. The statistical tests (Anova and Tukey) made to compare the results obtained in each of the three doses of t-DCTN with the negative-control group showed that the frequencies of MN and mitotic index were equal to the negative-control and that the frequencies of CA were lower than that observed in the negative-control. Therefore, based on our results it can be said that t-DCTN is not genotoxic nor cytotoxic to mouse bone marrow cells, submitted to acute intraperitoneal treatment in vivo. Teratogenesis Carcinog. Mutagen. 19:377-384, 1999.

Anti-inflammatory and antinociceptive effects in rodents of the essential oil of Croton cajucara Benth

The plant Croton cajucara Benth. (Euphorbiaceae) is widely used in Amazonian folk medicine for the treatment of a wide range of illnesses. In this investigation the analgesic and anti-inflammatory properties of the essential oil from the bark of C. cajucara Benth., administered orally, were determined in several standard rodent models of pain and inflammation. We observed that pretreatment with essential oil significantly reduced the latency of sleeping time evoked by pentobarbital compared with the control group (P < 0.001). Doses of 100 or 1000 mg kg(-1) also increased the sleeping time induced by pentobarbital (30.9 +/- 3.91 and 52.1 +/- 15.6 min, respectively) compared with the negative control (12.4 +/- 4.27 min). We investigated the antinociceptive effect of the essential oil in chemical (acetic acid) and thermal (hot-plate) models of nociception in mice. Dipyrone (200 mg kg(-1)) and the highest doses of the essential oil (1000 mg kg(-1)) significantly inhibited acetic acid-induced abdominal constriction in mice (5.00 +/- 1.38 and 6.8 +/- 2.1 constrictions, respectively) compared with the negative control (33.1 +/- 2). The same dose of essential oil also raised the pain thresholds of mice in the hot-plate test and significantly (P < 0.05) increased the latency at all observation times. In acetic acid-induced abdominal constriction in mice pretreatment of the animals with naloxone (5 mg kg(-1)) significantly reversed the analgesic effect of morphine and of the essential oil at the highest dose (1000 mg kg(-1)). The essential oil of C. cajucara was also investigated for its anti-inflammatory properties. At the lowest dose (100 mg kg(-1)) the essential oil had anti-inflammatory effects in animal models of acute (carrageenin-induced paw oedema in mice) and chronic (cotton pellet granuloma) inflammation. The essential oil at doses of 50, 100 and 200 mg kg(-1) significantly and dose-dependently inhibited carrageenan-induced oedema (49 +/- 5; 37 +/- 5; 34 +/- 8 mg, respectively) compared with the negative control (74 +/- 8 mg). The essential oil (100 mg kg(-1)) also inhibited chronic inflammation by 38% whereas diclofenac inhibited it by 36%. However, the essential oil did not inhibit the migration of neutrophils into the peritoneal cavity. These data show that the essential oil from C. cajucara contains compounds that had a significant antinociceptive effect when the oil was administered at the highest dose. This effect seems to be related to interaction with the opioid system. The essential oil also had a significant anti-inflammatory effect in acute and chronic inflammation models when administered at lower doses. This effect seems to be related to cyclooxygenase inhibition.

Effects of an essential oil from the bark of Croton cajucara Benth. on experimental gastric ulcer models in rats and mice

Croton cajucara Benth. (Euphorbiaceae) is widely used in Amazonian folk medicine for the treatment of a wide range of gastrointestinal symptoms. The essential oil from its bark was investigated for acute toxicity in mice and for its ability to prevent the formation of ulceration of the gastric mucosa in different models of experimentally induced gastric ulcer in mice and rats. When previously administered orally at a dose of 100 mg kg(-1), the essential oil significantly reduced (P < 0.01) the gastric injury induced by hypothermic restraint stress (48%), indomethacin (47%), ethanol (86%) and pylorus ligature models (87%) in rats. In the HCl/ethanol-induced gastric ulcer model in mice, at oral doses of 100 and 200 mg kg(-1), the essential oil from C. cajucara significantly reduced (P < 0.01) the formation of gastric lesions by 52% and 67%, respectively, when compared with the control group. In rats submitted to pylorus ligature, the essential oil given orally increased the volume of gastric juice when compared with the control group (P < 0.01). When the essential oil (100 mg kg(-1)) was administered intraduodenally to mice, significant modifications were found in gastric parameters such as pH and total acid content after oil treatment. We observed significant changes (P < 0.01) in gastric juice parameters such as an increase in volume and a decrease in gastric acidity (pH and total acid content). The acute toxicologic effects of the essential oil from C. cajucara were assessed in mice. The LD50 values were 9.3 g kg(-1) by the oral route and 680 mg kg(-1) by the intraperitoneal route. The good yield of essential oil obtained from dried C. cajucara bark (1%) as well as its anti-ulcerogenic activity and low toxicity suggest that pharmacological studies of this substance as a potential new anti-ulcerogenic drug are warranted.