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Naphthoquinones have been studied extensively due to their activity as topoisomerase inhibitors. These enzymes are critical to DNA replication in cells. beta-Lapachone (beta-lap) is an o-naphthoquinone chemically obtained from lapachol. This work results in a toxicological evaluation of beta-lap in Wistar rats observing the following parameters: teratology, histology, hematology and serum biochemistry. The data demonstrate teratogenic action at the doses used, as well as hematological alterations in the total leukocytes, monocytes and segmented. The biochemical data demonstrated an increase in gamma glutamyl transferase, alkaline phosphatase and glutamate pyruvate transaminase levels. Histological study showed significant alterations in the spleen, however, the liver and kidney did not present significant alterations.

1,8-Cineole (cineole), a terpenoid oxide present in many plant essential oils displays an inhibitory effect on some types of experimental inflammation in rats, i.e. paw oedema induced by carrageenan and cotton pellet-induced granuloma. Cineole also inhibits in mice, the acetic acid-induced increase in peritoneal capillary permeability and the chemical nociception induced by intraplantar formalin and intraperitoneal acetic acid. Activity was present in these tests, at an oral dose range of 100-400 mg/kg. In the formalin test, the antinociceptive effect of cineole was not reversed by pretreatment of mice with naloxone (1 mg/kg, s.c.), a mu-opioid receptor antagonist, suggesting the involvement of a non-opioid mechanism. Cineole demonstrated a significant inhibitory effect on locomotion and also potentiated the pentobarbital sleeping time in mice, indicating a plausible depressant effect on the central nervous system. The present results, when taken together with the recent reports that describe the inhibitory effects of cineole on the formation of prostaglandins and cytokines by stimulated monocytes in vitro, may provide additional evidence for its potential beneficial use in therapy as an antiinflammatory and analgesic agent.

The bark of M. urundeuva (Anacardiaceae) used in popular medicine as an antidiarrhoeal agent has been investigated for its effects on castor oil-induced diarrhoea and on intestinal motility. In rats, the ethanol extract of stem bark significantly inhibited the castor oil-induced diarrhoea, small intestinal transit and accumulation of fluid volume at an oral dose of 400mg/kg. Furthermore, the plant extract caused marked inhibition of the contractile responses evoked by acetylcholine and histamine on guinea-pig ileum in vitro. These results point to a possible antidiarrhoeic effect of M. urundeuva bark extract since inhibition of intestinal motility and secretion can greatly control clinical diarrhoea.

The essential oil from flower heads of Egletes viscosaL. was investigated for possible antinociceptive, anticonvulsant effects in mice and for antibacterial efficacy against resistant Staphylococcus aureus in vitro. It was found to possess a significant dose-dependent analgesic activity as assessed by acetic acid writhing and formalin tests and also an anticonvulsant activity against convulsions induced by pentylenetetrazol in mice. The plant oil displayed good antibacterial activity against resistant strains of S. aureus with the minimal inhibitory concentrations (MIC) ranging from 0.625 to 2.5 μL/mL. © 1998 John Wiley & Sons, Ltd.

The antinociceptive effect of leaf essential oil from Psidium guajava and its major constituents, b-caryophyllene and a-pinene was assessed using chemical (formalin and acetic acid) and thermal (hot-plate) nociceptive tests in adult male albino mice. Oral administration of 100, 200 and 400 mg/kg of essential oil produced a significant antinociceptive effect in the formalin test and at 200 and 400 mg/kg in the acetic acid- induced writhing test. Of the major components only a-pinene, but not the b-caryophyllene, demonstrated significant antinociception in the formalin test. Neither the essential oil nor the major components could exert any significant effect in the hotplate test. Pretreatment of mice with caffeine (20 mg/kg, i.p.), significantly inhibited the antinociceptive effect of essential oil in the formalin test. Naloxone (1 mg/kg, s.c.), the opioid antagonist, however, failed to antagonize it. These results suggest that the antinociceptive effect of P. guajava essential oil is probably mediated by endogenously released adenosine. © 1997 John Wiley & Sons, Ltd. Phytother. Res. 12, 24‐27 (1998)

The essential oils extracted from the leaves of Psidium guyanensis Pers. and Psidium pohlianum Berg, were evaluated for their neuropharmacological effects. Both the oils (400 mg/kg, p.o.) in mice displayed potentiation of pentobarbital sleeping time and an increase of immobility time in the behavioural forced swimming test. Also at a similar dose, they reduced the mortality associated with amphetamine toxicity and pentylenetetrazol-induced convulsions. The Psidium essential oils demonstrated no influence on small intestinal secretion but caused significant inhibition of intestinal transit. No overt toxicity was observed in mice that received essential oils orally up to 4 g/kg. The results suggest a probable depressant action of the essential oils of Psidium on central and peripheral nervous systems.

The wound healing activity of oleo-resin from Copaifera langsdorffii Desf. (Leguminaceae) bark was evaluated in rats on experimental wounds. The oleo-resin was tested by monitoring wound contraction in excised wounds and by measuring tensile strength in healing incision wounds. The topical application of oleo-resin at a concentration of 4% accelerated wound contraction in open wounds. The mean values of wound contraction in oleo-resin treated rats on day 9 was 84.05% +/- 2.37% as against 51.29% +/- 9.54% seen in controls and the difference was statistically significant (p < 0.05). No significant differences in the rates of wound contraction were observed on days 12, 15, 18 and 21. Also, the tensile strength in healing incised wounds was found to be significantly higher in the group of animals treated with 4% oleo-resin on day 5 but not on days 7 and 12 (controls: 35.95 +/- 7.44 g/cm; oleo-resin: 71.48 +/- 5.77 g/cm; p < 0.05). These results indicate the beneficial effect of C. langsdorffii oleo-resin on wound healing and justify its traditional use for the treatment of wounds.

The antibacterial activity of six essential oils obtained from the leaves of Pilocarpus and Psidium species of plants have been studied. The leaf oils of Psidium guyanensis, Psidium pohlianum and Pilocarpus spicatus showed the most potent antibacterial activity (MIC 52.5–75.0 μg/mL) against Gram-negative Pseudomonas aeruginosa. Against Gram-positive Staphylococcus aereus, P. guyanensis demonstrated marked activity (MIC 75.0±15.0 μg/mL) followed by P. spicatus and Pilocarpus pauciflorus (MIC 100.0±28.9 μg/mL). The efficacy of some tested oils against P. aeruginosa, the most resistant organism may have significant clinical implication. © 1997 John Wiley & Sons, Ltd.