Subdural B cell lymphoma. Imaging features, histopathology. Literature review.

Dural-based B cell lymphomas are rare and have a female preponderance. A 60-year-old Asian man with a history of trivial trauma presented with generalised tonic clonic seizures and headache. Imaging and clinical work-up was done. A temporoparietal subdural lesion with no evidence of systemic lymphoma was detected. Intraoperatively, a dural-based mass lesion was seen with thickened dura and biopsy-proven B cell lymphoma, and the patient was then kept on chemotherapy. A suspicion of this rare entity should be considered in imaging of dural-based lesions.

Structure-mutagenicity relationship of kaurenoic acid from Xylopia sericeae (Annonaceae).

Kaurane diterpenes are considered important compounds in the development of new highly effective anticancer chemotherapeutic agents. Genotoxic effects of anticancer drugs in non-tumour cells are of special significance due to the possibility that they induce secondary tumours in cancer patients. In this context, we evaluated the genotoxic and mutagenic potential of the natural diterpenoid kaurenoic acid (KA), i.e. (-)-kaur-16-en-19-oic acid, isolated from Xylopia sericeae St. Hill, using several standard in vitro and in vivo protocols (comet, chromosomal aberration, micronucleus and Saccharomyces cerevisiae assays). Also, an analysis of structure-activity relationships was performed with two natural diterpenoid compounds, 14-hydroxy-kaurane (1) and xylopic acid (2), isolated from X. sericeae, and three semi-synthetic derivatives of KA (3-5). In addition, considering the importance of the exocyclic double bond (C16) moiety as an active pharmacophore of KA cytotoxicity, we also evaluated the hydrogenated derivative of KA, (-)-kauran-19-oic acid (KAH), to determine the role of the exocyclic bond (C16) in the genotoxic activity of KA. In summary, the present study shows that KA is genotoxic and mutagenic in human peripheral blood leukocytes (PBLs), yeast (S. cerevisiae) and mice (bone marrow, liver and kidney) probably due to the generation of DNA double-strand breaks (DSB) and/or inhibition of topoisomerase I. Unlike KA, compounds 1-5 and KAH are completely devoid of genotoxic and mutagenic effects under the experimental conditions used in this study, suggesting that the exocyclic double bond (C16) moiety may be the active pharmacophore of the genetic toxicity of KA.

Relaxant effects of an alkaloid-rich fraction from Aspidosperma ulei root bark on isolated rabbit corpus cavernosum.

We described earlier that an alkaloid-rich fraction (F(3-5)) from Aspidosperma ulei (Markgr) induces penile erection-like behavioral responses in mice. This study verified a possible relaxant effect of this fraction on isolated rabbit corpus cavernosum (RbCC) strips precontracted by phenylephrine (1 microM) or K+ 60 mM. F(3-5) (1-300 microg ml(-1)) relaxed the RbCC strips in a concentration-dependent and reversible manner. The relaxant effect of F(3-5) (100 microg ml(-1)) on phenylephrine contraction was unaffected in the presence of atropine, N-omega-nitro-L-arginine methyl ester or 1H-[1,2,4]oxadiazole[4,3-a] quinoxalin-1-one and by preincubation with tetrodotoxin, glibenclamide, apamine and charybdotoxin suggesting that mechanisms other than cholinergic, nitrergic, sGC activation or potassium channel opening are probably involved. However, the phasic component of the contraction induced by K+ 60 mM as well as the maximal contraction elicited by increasing external Ca2+ concentrations in depolarized corpora cavernosa was inhibited by F(3-5). We conclude that F(3-5) relaxes the RbCC smooth muscle, at least in part, through a blockade of calcium influx or its function.

The role of high-resolution imaging in the evaluation of nanosystems for bioactive encapsulation and targeted nanotherapy.

Nanotechnology has already started to significantly impact many industries and scientific fields including biotechnology, pharmaceutics, food technology and semiconductors. Nanotechnology-based tools and devices, including high-resolution imaging techniques, enable characterization and manipulation of materials at the nanolevel and further elucidate nanoscale phenomena and equip us with the ability to fabricate novel materials and structures. One of the most promising impacts of nanotechnology is in the area of nanotherapy. Employing nanosystems such as dendrimers, nanoliposomes, niosomes, nanotubes, emulsions and quantum dots, nanotherapy leads toward the concept of personalized medicine and the potential for early diagnoses coupled with efficient targeted therapy. The development of smart targeted nanocarriers that can deliver bioactives at a controlled rate directly to the designated cells and tissues will provide better efficacy and reduced side effects. Nanocarriers improve the solubility of bioactives and allow for the delivery of not only small-molecule drugs but also the delivery of nucleic acids and proteins. This review will focus on nanoscale bioactive delivery and targeting mechanisms and the role of high-resolution imaging techniques in the evaluation and development of nanocarriers.

Microscopical investigations of nisin-loaded nanoliposomes prepared by Mozafari method and their bacterial targeting.

Nanoencapsulation may improve activity of protein or polypeptide antimicrobials against a variety of microorganisms. In this study, nanoliposomes prepared from different lipids (Phospholipon 90H, Phospholipon 100H, dipalmitoylphosphatidylcholine (DPPC), stearylamine (SA), dicetyl phosphate (DCP) and cholesterol) by a new, non-toxic and scalable method, were tested for their capacity to encapsulate nisin Z and target bacteria (Bacillus subtilis and Pseudomonasaeruginosa). Factors affecting the entrapment efficiency (charge and cholesterol concentration in the vesicles) and stability of nanoliposomes were assessed. The nanoliposomes and their bacterial targeting were visualised, using different microscopes under air and liquid environments. Nisin was entrapped in different nanoliposomes with encapsulation efficiencies (EE) ranging from 12% to 54%. Anionic vesicles possessed the highest EE for nisin while increase in cholesterol content in lipid membranes up to 20% molar ratio resulted in a reduction in EE. Stability of nanoliposome-encapsulated nisin was demonstrated for at least 14 months at 4 degrees C (DPPC:DCP:CHOL vesicles) and for 12 months at 25 degrees C (DPPC:SA:CHOL vesicles).

Modulation of acute visceral nociception and bladder inflammation by plant triterpene, alpha, beta-amyrin in a mouse model of cystitis: role of tachykinin NK(1)-receptors, and K(+)(ATP) channels.

OBJECTIVE AND DESIGN: We previously described the visceral antinociceptive property of alpha, beta-amyrin in a mouse model of cystitis induced by cyclophosphamide (CPM). This study examined the contribution of vanilloid-1 (TRPV1), peripheral NK1 receptors to CPM-evoked nociceptive behaviors and bladder edema, and its possible modulation by alpha, beta-amyrin. METHODS: The effect of alpha, beta-amyrin (10, 30, and 100 mg/kg, p. o.) and N-acetylcysteine (NAC) on CPM (400 mg/kg, i. p.)-induced cystitis was studied in mice. Sensory deafferentation was done by a high dose capsaicin. The parameters analysed were: CPM-evoked noxious behaviors, bladder edema, vascular permeability, and NK(1) immunoreactivity. To assess the role of K(+) (ATP) channels in alpha, beta-amyrin effect, animals were pretreated with glibenclamide. RESULTS: alpha, beta-amyrin (30 and 100 mg/kg) and NAC significantly (p < 0.01) suppressed the visceral pain-related behaviors and NK(1) immunoreactivity, but bladder edema was reduced weakly. Glibenclamide reversed the effects of alpha, beta-amyrin. Sensory deafferentation by capsaicin significantly reduced the nociceptive responses and the NK(1) immunoreactivity to noxious stimulation by CPM. CONCLUSIONS: alpha, beta-amyrin attenuates CPM-induced visceral pain and bladder edema by mechanisms that involve, at least in part, a block either of Substance P release or its receptor function, and partly by opening K(+) (ATP) channels.

Genotoxicity evaluation of kaurenoic acid, a bioactive diterpenoid present in Copaiba oil.

Copaiba oil extracted from the Amazon traditional medicinal plant Copaifera langsdorffii is rich in kaurenoic acid (ent-kaur-16-en-19-oic acid), a diterpene that has been shown to exert anti-inflammatory, hypotensive, and diuretic effects in vivo and antimicrobial, smooth muscle relaxant and cytotoxic actions in vitro. This study evaluated its potential genotoxicity against Chinese hamster lung fibroblast (V79) cells in vitro, using the Comet and the micronucleus assays. Kaurenoic acid was tested at concentrations of 2.5, 5,10, 30 and 60 microg/mL. The positive control was the methylmethanesulfonate (MMS). The duration of the treatment of V79 cells with these agents was 3h. The results showed that unlike MMS, kaurenoic acid (2.5, 5, and 10 microg/mL) failed to induce significantly elevated cell DNA damage or the micronucleus frequencies in the studied tests. However, exposure of V79 cells to higher concentrations of kaurenoic acid (30 and 60 microg/mL) caused significant increases in cell damage index and frequency. The data obtained provide support to the view that the diterpene kaurenoic acid induces genotoxicity.

Acute effects of guarana (Paullinia cupana Mart.) on mouse behaviour in forced swimming and open field tests.

Guarana, a herbal extract from the seeds of Paullinia cupana Mart. has been evaluated in comparison with caffeine on mouse behaviour in forced swimming and open field tests. Guarana (25 and 50 mg/kg, p.o.) and caffeine (10 and 20 mg/kg, p.o.) each significantly reduced the duration of immobility in the forced swimming test suggesting an antidepressant-like effect in mice. At these doses, neither substance affected ambulation in the open field test. However, a high dose of guarana (100 mg/kg) and caffeine (30 mg/kg) significantly enhanced the locomotor activity in the open field test. Caffeine, but not guarana, could effectively block an adenosine agonist, cyclopentyl adenosine (CPA)-induced increase in swimming immobility suggesting that mechanism(s) other than the adenosinergic mechanism are involved in the antidepressant-like activity of guarana.

Antinociceptive effect of leaf essential oil from Croton sonderianus in mice.

The leaf essential oil from Croton sonderianus (EOCS) was evaluated for antinociceptive activity in mice using chemical and thermal models of nociception. Given orally, the essential oil at doses of 50, 100 and 200 mg/kg produced significant inhibitions on chemical nociception induced by intraperitoneal acetic acid and subplantar formalin or capsaicin injections. However, it evidenced no efficacy against thermal nociception in hot-plate test. More prominent inhibition of acetic acid-induced writhing and capsaicin-induced hind-paw licking responses was observed at 100 and 200 mg/kg of EOCS. At similar doses, the paw licking behavior in formalin test was more potently suppressed during the late phase (20-25 min, inflammatory) than in early phase (0-5 min, neurogenic). The EOCS-induced antinociception in both capsaicin and formalin tests was insensitive to naloxone (1 mg/kg, s.c.), but was significantly antagonized by glibenclamide (2 mg/kg, i.p.). In mice, the essential oil (100 and 200 mg/kg) neither significantly enhanced the pentobarbital-sleeping time nor impaired the motor performance in rota-rod test, indicating that the observed antinociception is unlikely due to sedation or motor abnormality. These results suggest that EOCS produces antinociception possibly involving glibenclamide-sensitive KATP+ channels, which merit further studies on its efficacy in more specific models of hyperalgesia and neuropathic pain.

Attenuation of ischemia/reperfusion-induced intestinal injury by oleo-resin from Copaifera langsdorffii in rats.

Copaifera langsdorffii oleo-resin (CLOR) is a reputed herbal medicine used to combat gastrointestinal functional disorders. Our previous studies show that CLOR prevents gastric ulceration and promotes wound healing. This study examined the effects of CLOR on intestinal damage associated with mesenteric ischemia/reperfusion in rat. Wistar albino rats were divided into four groups of six in each. Group 1: Sham operated, Group 2: Vehicle + 45 min of ischemia followed by 60 min reperfusion (I/R), Groups 3 and 4: I/R + CLOR (200 and 400 mg /kg, p.o., respectively). All treatments were given 24 h, 12 h and 2 h before I/R. Animals were sacrificed at the end of reperfusion period and ileal tissue samples were obtained for biochemical analysis. Myeloperoxidase (MPO), an index of polymorphonuclear leukocytes; malondialdehyde (MDA), an end product of lipoperoxidation; catalase (CAT), an antioxidant enzyme; reduced glutathione (GSH), a key antioxidant; and nitrite, a marker of nitric oxide (NO) production were determined in ileum homogenates. The results show that I/R produces a significant increase in MDA content, MPO, and CAT activities with a significant decrease in GSH and an elevation in nitrite production, as compared to sham control. CLOR treatment caused significant attenuations in I/R-associated increases of MPO, MDA and CAT activities and on nitrite level. Besides, CLOR could effectively prevent the I/R-associated depletion of GSH. The data indicate that the oleo-resin has a protective action against I/R-induced intestinal tissue damage, which appeared to be, at least in part, due to an antioxidant and anti-lipid peroxidation mechanism.

Protective effect of Copaifera langsdorffii oleo-resin against acetic acid-induced colitis in rats.

The oleo-resin from Copaifera langsdorffii (Leguminosae) was evaluated in rats on acetic acid-induced colitis. Rats were pretreated orally (15 and 2 h) or rectally (2 h) before the induction of colitis with copaiba oleo-resin (200 and 400 mg/kg) or vehicle (1 ml, 2% Tween 80). Colitis was induced by intracolonic instillation of a 2 ml of 4% (v/v) acetic acid solution and 24 h later, the colonic mucosal damage was analyzed for the severity of macroscopic colonic damage, myeloperoxidase (MPO) activity, and malondialdehyde levels. A significant reduction in gross damage score and in wet weight/length ratio of colonic tissue were evident in test substance-pretreated animals as compared to vehicle or oleo-resin alone-treated controls. This effect was confirmed biochemically by a reduction in colonic myeloperoxidase activity, the marker of neutrophilic infiltration, and by a marked decrease in malondialdehyde level, an indicator of lipoperoxidation. Furthermore, microscopical examination revealed the diminution of inflammatory cell infiltration, and submucosal edema in the colon segments of rats treated with copaiba oleo-resin. The data indicate the protective effect of copaiba oleo-resin in the animal model of acute colitis possibly through an antioxidant and or anti-lipoperoxidative mechanism.

1,8-cineole (eucalyptol), a monoterpene oxide attenuates the colonic damage in rats on acute TNBS-colitis.

The monoterpene oxide, 1,8-cineole (cineole, eucalyptol) was examined for its possible influence on the acute phase of trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. The test compound, 1,8-cineole (200 and 400 mg/kg) or vehicle (1 ml, 2% Tween 80) was instilled rectally, 24, and 2 h before (pre-treatment) or 2 and 24 h after (post-treatment) the induction of colitis by intracolonic administration of TNBS (0.25 ml of 25 mg of TNBS in 50% ethanol). Rats were killed 48 h after colitis induction and colonic segments were analysed for gross damage scores, changes in wet weights, myeloperoxidase activity, an indicator of neutrophilic infiltration and glutathione level, a major cellular antioxidant. TNBS induced an extensive inflammation and ulceration in the colon. Colonic damage was associated with an increase in myeloperoxidase activity and by a decrease in glutathione. When compared to vehicle-treated TNBS controls, a marked reduction in gross damage scores and wet weights (mg/cm) of colonic segments were evident in animals pre-treated but not post-treated with 1,8-cineole. Cineole also significantly reduced the myeloperoxidase activity, and caused repletion of glutathione. These results confirm the anti-inflammatory action of 1,8-cineole and suggest its potential value as a dietary flavoring agent in the prevention of gastrointestinal inflammation and ulceration.

Guarana (Paullinia cupana Mart.) offers protection against gastric lesions induced by ethanol and indomethacin in rats.

The effects of guarana (Paullinia cupana) extract were analyzed in rats on acute gastric lesions induced by ethanol and indomethacin and were compared to those produced by caffeine, a methylxanthine. Guarana (50 and 100 mg/kg p.o.) pretreated animals showed a significant reduction in the severity of gastric lesions induced by absolute ethanol in a manner similar to caffeine (20 and 30 mg/kg p.o.). Against indomethacin-induced gastric ulceration, guarana at a higher dose offered significant protection but caffeine was ineffective at the doses tested. In 4 h pylorus-ligated rats, both guarana and caffeine caused significant diminution in the gastric secretory volume as well as the total acidity. Gastrointestinal transit in mice was not significantly affected by either of these agents. These findings indicate that guarana has a gastroprotective property that needs further elucidation as regards to its mechanism.

Ternatin, an anti-inflammatory flavonoid, inhibits thioglycolate-elicited rat peritoneal neutrophil accumulation and LPS-activated nitric oxide production in murine macrophages.

Ternatin, an anti-inflammatory flavonoid from Egletes viscosa Less., was examined for its possible influence on thioglycolate-elicited neutrophil influx into the rat peritoneal cavity in vivo and nitric oxide production in lipopolysaccharide (LPS)-activated mouse peritoneal macrophages ex vivo. The neutrophil influx induced by thioglycolate was found to be significantly lower in ternatin (25 and 50 mg/kg, s. c.) pre-treated rats with a similar magnitude of inhibition produced by dexamethasone (1 mg/kg, s. c.), a known anti-inflammatory agent. Also, peritoneal macrophages from ternatin (25 mg/kg)-treated mice that were exposed to LPS demonstrated significantly less production of nitric oxide (NO). These results suggest that ternatin exerts its anti-inflammatory action, at least in part, through inhibition of neutrophil migration and modulation of macrophage function.

Catechin attenuates 6-hydroxydopamine (6-OHDA)-induced cell death in primary cultures of mesencephalic cells.

Past studies have shown the protective effects of tea catechins on oxidative cell damage induced by 6-OHDA in PC12 cells. In this study we verified whether or not catechin prevents 6-OHDA-induced oxidative cell damage in primary cultures of rat mesencephalic cells. On exposure to 6-OHDA (200 microM), the cultures showed a marked decrease in cell viability, disturbances in lipid peroxidation, and an increased generation of NO, as assayed by MTT, TBARS and nitrite assays, respectively. Introduction of catechin significantly attenuated the cell death caused by 6-OHDA at concentrations of 3.4, 34 and 340 microM in a dose-related manner. Catechin produced no marked changes on 6-OHDA-induced increases in NO, but caused a significant inhibition of lipid peroxidation. These results suggest that catechins offer similar cytoprotection against 6-OHDA-induced oxidative cell damage in mesencephalic cell cultures, as previously described in PC12 cells. The cytoprotective function of catechin results from its antioxidant property and is not due to the inhibition of nitric oxide synthase. These findings further support and substantiate traditional consumption of catechin rich green/black tea as protection against neurodegenerative diseases like Parkinsonism.

Smooth muscle relaxant effect of kaurenoic acid, a diterpene from Copaifera langsdorffii on rat uterus in vitro.

The effect of kaurenoic acid, a diterpene isolated from the oleo-resin of the popular medicinal plant Copaifera langsdorffii (Leguminaceae), was analysed on rat uterine muscle responsiveness to various drugs in vitro. Cumulative concentration-response curves to acetylcholine and oxytocin were obtained before and after incubation of uterine segments with up to 160 microm of kaurenoic acid. The maximal contractile response (E(max)) evoked by these agonists was inhibited by kaurenoic acid in a concentration-related manner; at 160 microm, kaurenoic acid depressed the E(max) of oxytocin and acetylcholine by 83% and 91%, respectively. The relaxation caused by kaurenoic acid on oxytocin-induced contraction was unaffected in the presence of tetraethyl ammonium, a compound that blocks the calcium activated potassium channels. It was partially reversed by glibenclamide (10(-5) m), an ATP-sensitive potassium channel blocker. Also, kaurenoic acid at 160 microm concentration was found to inhibit significantly the CaCl(2)-evoked contractile responses in a medium of high potassium and zero calcium. Furthermore, kaurenoic acid was found to relax the sustained tonic contraction induced by acetylcholine, oxytocin, BaCl(2) and KCl in a concentration-dependent way. However, KCl-induced tonic contraction was only weakly inhibited by kaurenoic acid. These data indicate that the diterpene, kaurenoic acid, exerts a uterine relaxant effect acting principally through calcium blockade and in part, by the opening of ATP-sensitive potassium channels.

Investigation on the wound healing activity of oleo-resin from Copaifera langsdorffi in rats.

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.

Effects of nitric oxide synthase inhibitors and melatonin on the hyperglycemic response to streptozotocin in rats.

Recent studies evidence that peroxynitrite is spontaneously formed when nitric oxide (NO) and superoxide coexist and suggest that it is likely to be involved in the destruction of the pancreatic beta cells. We examined whether drugs that inhibit nitric oxide synthase (NOS) or scavenge peroxynitrite could abrogate STZ-induced hyperglycemia in rats. Blood glucose levels were measured before (0 h) and 24, 48, and 72 h following intraperitoneal administration of 60 mg/kg streptozotocin (STZ). The levels of blood sugar in STZ-treated control animals were significantly elevated at all time points of observation with a peak increase at 48 h. The hyperglycemic response of STZ was found to be significantly reduced in animals pretreated with aminoguanidine (50 mg/kg i.p.), an inducible isoform-selective NOS (iNOS) inhibitor with antioxidant property, and by melatonin (6 mg/kg i.p.), an antioxidant that also prevents peroxynitrite formation but not by Nw-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg i.p.), and 7-nitroindazole (7-NI, 50 mg/kg i.p.), the constitutive inhibitors of endothelial and neuronal NOS, respectively. These findings indicate the possible participation of iNOS-derived NO as well as oxygen free radicals in STZ-induced pancreatic beta cell destruction and compounds that act as scavengers of peroxynitrite may offer protection against such a damage.

Possible role of mast cells in cineole-induced scratching behavior in mice.

We examined the scratch (itch) inducing effect of 1,8-cineole (cineole), a monoterpene oxide present in many plant essential oils and the possible role of mast cells in the response. Subcutaneous injection of cineole (10, 20 and 40 microl/site) or the mast cell degranulating agent, compound 48/80 (25, 50 and 100 microg/site) into the rostral back of mice induced a scratching behavior. This response of cineole as well as that of 48/80 was markedly suppressed in mice subjected to mast cell desensitization by repeated injections of 48/80. The cineole-induced scratching was also significantly diminished in animals pretreated with diphenhydramine, the histamine H1-receptor antagonist or cyproheptadine, the dual histamine/serotonin-receptor antagonist. Furthermore, the scratch-inducing effect of cineole was greatly reduced in mice that received the opioid antagonist naloxone or the selective adenosine A1-receptor agonist, N6-cyclopentyladenosine (CPA), but not the more selective adenosine A2-receptor agonist, 5'-N-ethylcarboxamidoadenosine (NECA). The data suggest a likely role for mast cells in cineole-induced scratching behavior of mice, possibly involving adenosinergic and opioidergic mechanisms.

The cytotoxic and embryotoxic effects of kaurenoic acid, a diterpene isolated from Copaifera langsdorffii oleo-resin.

In this work, we studied the effects of kaurenoic acid, a diterpene isolated from the oleo-resin of Copaifera langsdorffii in developing sea urchin (Lytechinus variegatus) embryos, on tumor cell growth in microculture tetrazolium (MTT) test and on mouse and human erythrocytes in hemolysis assay. Continuous exposure of embryos to kaurenoic acid starting immediately after fertilization inhibited the first cleavage (IC(50): 84.2 microM) and progressively induced embryo destruction (IC(50): 44.7 microM and < 10 microM for blastulae and larvae stages, respectively). In MTT assay, kaurenoic acid at a concentration of 78 microM produced growth inhibition of CEM leukemic cells by 95%, MCF-7 breast and HCT-8 colon cancer cells by 45% each. Further, kaurenoic acid induced a dose-dependent hemolysis of mouse and human erythrocytes with an EC(50) of 74.0 and 56.4 microM, respectively. The destruction of sea urchin embryos, the inhibition of tumor cell growth and the hemolysis of mouse and human erythrocytes indicate the potential cytotoxicity of kaurenoic acid.