Anti-inflammatory effect of Lithrea molleoides extracts and isolated active compounds

In vitro inhibitory effect of Hydrocotyle bonariensis Lam. extracts over Chlamydia trachomatis and Chlamydia pneumoniae on different stages of the chlamydial life cycle

Chlamydial infections in humans are widely distributed and are responsible for a variety of acute and chronic diseases. Both Chlamydia trachomatis and Chlamydia pneumoniae can lead to chronic conditions that have been linked to complications and sequelae. This study aimed to develop a culture method in order to detect in vitro antichlamydial activity of different extracts obtained from native Argentinian plants used as antimicrobials in local ethnomedicine and to evaluate their inhibitory activity over Chlamydia trachomatis and Chlamydia pneumoniae growth. The inhibitory activity over different stages of the chlamydial life cycle on cell culture was assessed: the entry, the inclusion developing after entry, and the exponential growth stage. Also, the capability of rendering the cell refractory to chlamydial infection by pre-incubation with the extracts was assayed. Inhibitory activity of water-based and organic-based extracts obtained from Hydrocotyle bonariensis Lam. (Araliaceae), Lithraea molleoides (Vell.) Engl. (Anacardiaceae) and Hybanthus parviflorus (Mutis ex L.f.) Baill. (Violaceae) were tested against five strains of Chlamydia trachomatis (L2/434/BU and four clinical isolates form both neonatal conjunctivitis and adult genital infections, genotypes D, E, and K) and against Chlamydia pneumoniae AR39. The Hydrocotyle bonariensis dichloromethane extract showed a broad inhibitory activity over the exponential growth stage of Chlamydia trachomatis and Chlamydia pneumoniae independently from the chlamydial strain and the cell line. These results suggest a high inhibitory potential on both Chlamydiae species. In order to characterize the Hydrocotyle bonariensis dichloromethane active extract, an ¹H-NMR was performed. The ¹H-NMR characterization showed a spectrum with characteristic signals of the fatty acid moiety of lipids or cerebrosides, volatile phenolics, phytosterols, methyl triterpenes signals, and glucose moiety of the cerebrosides.

Study of two isoforms of lipoxygenase by kinetic assays, docking and molecular dynamics of a specialised metabolite isolated from the aerial portion of Lithrea caustica (Anacardiaceae) and its synthetic analogs

Our investigation focused on the characterization and study of epicuticular leaf extracts (dichloromethane extract) and certain derivatives of Lithrea caustica (Molina) Hook and Arn. (Anacardiaceae) as inhibitors of 15 soybean and 5 human lipoxygenases (15-sLOX and 5-hLOX). From the epicuticular extract of leaves, the compound (Z)-3-(pentadec-10'-enyl)-catechol (Litreol) was isolated, and three hemisynthetic derivatives were prepared, as they are 3-pentadecylcatechol, (Z)-1,2-diacetyl-3-(pentadec-10'-enyl)-benzene and 1,2-diacetyl-3-pentadecylbenzene. The inhibitory activities for the four compounds against 15-sLOX and 5-hLOX were determined, being (Z)-3-(pentadec-10'-enyl)-catechol (IC₅₀ 54.77 μM and 2.09 μM, respectively) and 3-pentadecylcatechol (IC₅₀ 55.28 μM and 2.74 μM, respectively), the most interesting compounds assayed. The kinetic studies for (Z)-3-(pentadec-10'-enyl)-catechol and 3-pentadecylcatechol showed a mixed inhibition mechanism to 5-LOX. Finally, docking and molecular dynamics studies were performed to characterize and describe how the chemical structures could be correlated to the decreased 5-hLOX activity observed in the in vitro studies.

Animal Models of Inflammation for Screening of Anti-inflammatory Drugs: Implications for the Discovery and Development of Phytopharmaceuticals

Inflammation is one of the common events in the majority of acute as well as chronic debilitating diseases and represent a chief cause of morbidity in today's era of modern lifestyle. If unchecked, inflammation leads to development of rheumatoid arthritis, diabetes, cancer, Alzheimer's disease, and atherosclerosis along with pulmonary, autoimmune and cardiovascular diseases. Inflammation involves a complex network of many mediators, a variety of cells, and execution of multiple pathways. Current therapy for inflammatory diseases is limited to the steroidal and non-steroidal anti-inflammatory agents. The chronic use of these drugs is reported to cause severe adverse effects like gastrointestinal, cardiovascular, and renal abnormalities. There is a massive need to explore new anti-inflammatory agents with selective action and lesser toxicity. Plants and isolated phytoconstituents are promising and interesting sources of new anti-inflammatories. However, drug development from natural sources has been linked with hurdles like the complex nature of extracts, difficulties in isolation of pure phytoconstituents, and the yield of isolated compounds in minute quantities that is insufficient for subsequent lead development. Although various in-vivo and in-vitro models for anti-inflammatory drug development are available, judicious selection of appropriate animal models is a vital step in the early phase of drug development. Systematic evaluation of phytoconstituents can facilitate the identification and development of potential anti-inflammatory leads from natural sources. The present review describes various techniques of anti-inflammatory drug screening with its advantages and limitations, elaboration on biological targets of phytoconstituents in inflammation and biomarkers for the prediction of adverse effects of anti-inflammatory drugs. The systematic approach proposed through present article for anti-inflammatory drug screening can rationalize the identification of novel phytoconstituents at the initial stage of drug screening programs.

Anti-inflammatory action of an alkaloid, fraction and extract from Alchornea glandulosa in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Alchornea glandulosa (Euphorbiaceae) has traditionally been used in medicine for treating immune-mediated inflammatory diseases.

AIM OF STUDY

This work aimed to evaluate the anti-inflammatory effects of a methanolic extract of leaves from A. glandulosa (MEAG), as well as the ethyl acetate fraction (EAFAG) and isolated compound guanidine alkaloid N-1, N-2, N-3-triisopentenylguanidine (AG-1), in experimental in vivo models of inflammation in mice. We also investigated this extract's phenols, flavonoids and flavonol compounds.

MATERIALS AND METHODS

MEAG (extracted by maceration with methanol), EAFAG (fraction resulting from the partition of the methanolic extract with ethyl acetate) and AG-1 (alkaloid isolated by chromatographic methods) were analysed. MEAG and EAFAG were analysed by HPLC/DAD. The effects of MEAG (30, 100 and 300 mg/kg), EAFAG (30, 100 and 300 mg/kg) and AG-1 (5 and 30 mg/kg) were studied in the following experimental mouse models: paw oedema and myeloperoxidase (MPO) activity, croton-oil-induced ear oedema, leukocyte migration in a pleurisy model induced by carrageenan and zymosan induction of joint inflammation.

RESULTS

MEAG and EAFAG were analysed by LC/DAD, and phenolic acids (gallic acid and caffeic acid) and flavonoids (myricetin-3-O-α-rhamnopyranoside and quercetin) were detected. MEAG, EAFAG and AG-1 were used in the carrageenan-induced paw oedema model and showed maximum inhibitions of 60.10% (MEAG, 2 h, 300 mg/kg) and 66.21% (EAFAG, 2 h, 300 mg/kg). AG-1 at 5 mg/kg showed significant inhibition, ranging from 60.92% to 63.13%, at all evaluated times, and the 30 mg/kg dose showed inhibition of 42.12% (1 h) and 40.36% (2 h). MEAG (37%, 46.1% and 68.11%) and EAFAG (31%, 42.21% and 48.93%), at doses of 30, 100 and 300 mg/kg, respectively, significantly reduced the increase in MPO activity, and AG-1 (5 and 30 mg/kg) showed inhibition of 64.62% and 65.12%, respectively. In the pleurisy model, MEAG (300 mg/kg), EAFAG (300 mg/kg) and AG-1 (30 mg/kg) significantly reduced the migration of total leukocytes with maximal inhibition of 80.90%, 83.17% and 89.39%, respectively. In the croton oil model, pretreatment with MEAG (0.1, 0.3 and 1 mg/ear) increased the diameter of the right ear (30.32%, 48.87% and 53.09%, respectively). Finally, MEAG (100 and 300 mg/kg; 33.11% and 56.03%) and EAFAG (100 and 300 mg/kg; 36.89% and 50.53%) reduced zymosan-induced oedema formation.

CONCLUSIONS

To the best of our knowledge, these results are the first to demonstrate that A. glandulosa exhibits oral and topical anti-inflammatory activity. This study detected alkaloid and phenol/polyphenolic compounds in A. glandulosa, which may help to explain the ethnobotanical use of this plant in traditional medicine in Brazil to treat immune-mediated inflammatory diseases.

Potential usefulness of methyl gallate in the treatment of experimental colitis

Methyl gallate is a gallotannin widely distributed in nature. Previous studies have demonstrated its antioxidant, anti-inflammatory, antimicrobial and anti-tumor activities. In the present study, the activity of methyl gallate on experimental models of inflammatory bowel disease has been investigated. Experimental colitis was induced in Sprague-Dawley rats through the intracolonic instillation of an acetic acid solution (2 mL, 4% v/v). Methyl gallate (100 and 300 mg/kg, p.o.) and the reference drug mesalazine (100 mg/kg, p.o.) were tested. Methyl gallate induced a significant reduction in the colon weight/length ratio and macroscopic lesion score. Besides, the malondialdehyde content and the GSSG/GSH ratio were remarkably decreased. Furthermore, the administration of methyl gallate reduced the expression of COX₂, IL-6, TNFα and the severity of microscopic tissue damage induced by acetic acid, while the mean goblet cell density was significantly higher in both the group treated with methyl gallate and the one treated with mesalazine, in comparison with untreated animals. The Na⁺K⁺ATPase pump activity was recovered in treated groups (control: 827.2 ± 59.6, colitis: 311.6 ± 54.8, methyl gallate 100 mg/kg: 642.2 ± 175.0, methyl gallate 300 mg/kg: 809.7 ± 100.6, mesalazine: 525.3 ± 81.7). Methyl gallate was also found to induce a significant reduction in the castor oil-induced intestinal motility in Swiss mice, decreasing the peristalsis by 74.5 and 58.82% at 100 and 300 mg/kg p.o., respectively. This compound also antagonized the jejunum contractions induced by Ach and CaCl₂. This study demonstrates that methyl gallate exerts beneficial effects in a preclinical model of intestinal disorders.

Phytochemical screening and anti-inflammatory properties of Algerian Hertia cheirifolia methanol extract

CONTEXT

Hertia cheirifolia L. (Asteraceae) is traditionally used in Northern Africa to treat various inflammatory infections. However, few studies on this plant have been reported.

OBJECTIVE

The anti-inflammatory activity of methanol extract of H. cheirifolia leaves was investigated using different experimental models.

MATERIALS AND METHODS

Phytochemical analysis was performed to determine phenolic compounds. Acute toxicity of the extract (2000 mg/kg) was examined in Swiss albino mice for 14 days, before croton oil-induced ear oedema in mice, carrageenan-induced paw oedema in Swiss albino rats, cotton pellet-induced granuloma in rats and carrageenan-induced air pouch in mice were conducted. The IL-1β and TNF-α release from concanavalin A-stimulated monocytes was measured by ELISA.

RESULTS

Methanol extract of H. cheirifolia is rich in polyphenols and flavonoids. Cinnamic acid and rutin represent the major constituents. Methanol extract up to 2000 mg/kg did not produce any toxic effects. Topical application of 2 mg/ear of the extract produced 78.7% of inhibition on ear swilling. Oral pre-treatment of rats with 200 and 400 mg/kg of the extract inhibited paw oedema by 70% and 89%, respectively. At 200 mg/kg, granuloma dry and wet weights were reduced by 41.85% and 61.72%, respectively. Moreover, the treatment with methanol extract at 1 mg/kg exerted 62.7% of inhibition on leucocytes migrated into the ear pouch. TNF-α and IL-1β release was reduced by 69% and 78%, respectively, with 1 μg/mL of the extract.

CONCLUSION

Methanol extract of H. cheirifolia possesses a strong anti-inflammatory activity and may be considered an interesting source of effective anti-inflammatory compounds.

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.

Two new isoaurones derivatives from Callistephus chinensis flower

Two new isoaurones derivatives were obtained from Callistephus chinensis flower. Their structures were elucidated on the basis of extensive spectroscopic analyses. Both of the new compounds were evaluated cytotoxic activity. Phytochemical investigation of Callistephus chinensis flower led to the isolation of two new isoaurones derivatives (Z)-4',4,10-trihydroxy-siamaurone (1) and (E)-4',4,10-trihydroxy-siamaurone (2). The structures of these new compounds were identified by the interpretation of spectroscopic data (mainly 1D and 2D NMR) and by comparison with data reported in the literature. Both of the new compounds were evaluated for their cytotoxicity.

Anti-inflammatory R-prostaglandins from Caribbean Colombian soft coral Plexaura homomalla

OBJECTIVES

This study aims to evaluate the effect of prostaglandins isolated from soft coral Plexaura homomalla, collected in Colombian Caribbean Sea, on in vivo and in vitro inflammation models.

METHODS

Extracts from P. homomalla were fractionated and sequentially chromatographed to obtain the prostaglandins: (15R)-PGA2 (1), (15R)-PGA2 -Me (2), (15R)-O-Ac-PGA2 (3), (15R)-O-Ac-PGA2 -Me (4) and (15R)-PGE2 (5) in addition to three semi-synthetic prostaglandins obtained by transformations of the natural products. The anti-inflammatory properties of natural and semi-synthetic compounds were determined in vivo using 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear oedema model and in vitro leucocyte degranulation, myeloperoxidase (MPO) and elastase enzymatic activities from human polymorphonuclear cells (PMNs). The cell viability was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.

KEY FINDINGS

In the in vivo assay, (15R)-PGE2 (1) and (15R)-O-Ac-PGA2 (3) showed anti-inflammatory activity, as well as in vitro inhibition of elastase release from PMNs. In the PMNs degranulation assay, (15R)-PGE2 (5), was the most active compound in the inhibition of MPO release. Finally, all the tested prostaglandins showed moderate inhibition for elastase enzyme activity, whereas none of the prostaglandins exhibit significative inhibition on MPO activity.

CONCLUSION

(15R)-PGE2 (1) and (15R)-O-Ac-PGA2 (3) present significant inhibition on three important events related to the topical inflammatory response induced by TPA: the oedema formation, the PMNs degranulation, events that modulate MPO and elastase levels at inflammation site, and the inhibition of the enzyme activity.

Cnidoscolus chayamansa Mc Vaugh, an important antioxidant, anti-inflammatory and cardioprotective plant used in Mexico

ETHNOPHARMACOLOGICAL RELEVANCE

Cnidoscolus chayamansa Mc Vaugh (Euphorbiaceae) is commonly known as 'chaya' in Central America. In South East Mexico, because of its high nutritional values, is an important part of the diet of many indigenous communities. Chaya is also used as a traditional remedy for the treatment of diabetes, rheumatism, gastrointestinal disorders and inflammation-related diseases. Although Cnidoscolus chayamansa is one of most used and valued medicinal plants, only few studies on documenting its pharmacological properties can be found.

MATERIALS AND METHODS

Dried leaves of Cnidoscolus chayamansa were subjected to a successive maceration using Hex, EtOAc and EtOH. The antioxidant activities of the extracts were tested using the DPPH radical scavenging, Ferric reducing/antioxidant power and total phenolic content assays. To determine the anti-inflammatory activity, the TPA-induced mouse ear edema and the carrageenan-induced mouse paw edema assays were used. The cardioprotective effects of the EtOH extract was determined using the ischemia/reperfusion (I/R) rat model. Finally, the acute toxicity was determined using Lorke's method.

RESULTS

The results showed a similar anti-inflammatory activity (≈30%) for all extracts but only the EtOAc extract showed relevant activity when applied intraperitoneally. When tested for their antioxidant activity none of the extracts showed a significant activity suggesting that the antinflammatory activity is not related to a direct free radical scavenging of the extracts. Additionally, the EtOH extract showed a strong cardioprotective effect at 500mg/kg when given orally. Both the EtOAc and the EtOH extract have a LD50 >5g/kg, confirming their safety in acute oral administration.

CONCLUSIONS

All these results are relevant for a better understanding of the therapeutic used of Cnidoscolus chayamansa in the Mexican traditional medicine and highlights its cardioprotective potential.

Vitexin inhibits inflammatory pain in mice by targeting TRPV1, oxidative stress, and cytokines

The flavonoid vitexin (1) is a flavone C-glycoside (apigenin-8-C-β-D-glucopyranoside) present in several medicinal and other plants. Plant extracts containing 1 are reported to possess antinociceptive, anti-inflammatory, and antioxidant activities. However, the only evidence that 1 exhibits antinociceptive activity was demonstrated in the acetic acid-induced writhing model. Therefore, the analgesic effects and mechanisms of 1 were evaluated. In the present investigation, intraperitoneal treatment with 1 dose-dependently inhibited acetic acid-induced writhing. Furthermore, treatment with 1 also inhibited pain-like behavior induced by phenyl-p-benzoquinone, complete Freund's adjuvant (CFA), capsaicin (an agonist of transient receptor potential vanilloid 1, TRPV1), and both phases of the formalin test. It was also observed that inhibition of carrageenan-, capsaicin-, and chronic CFA-induced mechanical and thermal hyperalgesia occurred. Regarding the antinociceptive mechanisms of 1, it prevented the decrease of reduced glutathione levels, ferric-reducing ability potential, and free-radical scavenger ability, inhibited the production of hyperalgesic cytokines such as TNF-α, IL-1β, IL-6, and IL-33, and up-regulated the levels of the anti-hyperalgesic cytokine IL-10. These results demonstrate that 1 exhibits an analgesic effect in a variety of inflammatory pain models by targeting TRPV1 and oxidative stress and by modulating cytokine production.

Antinociceptive activity of aqueous extract and isolated compounds of Lithrea molleoides

ETHNOPHARMACOLOGICAL RELEVANCE

Lithrea molleoides (Vell.) Engl. (Anacardiaceae) is a medicinal plant commonly used in traditional medicine in South America.

AIM OF THE STUDY

In the present study, the in vivo antinociceptive effect of L. molleoides' aqueous extract and its isolated compounds has been investigated.

MATERIALS AND METHODS

Antinociceptive activity was evaluated through writhing, formalin and hot plate tests in mice. The phytochemical analysis was performed.

RESULTS

The extract produced significant inhibition on nociception induced by acetic acid (ED50: 8.7 mg/kg, i.p.) and formalin (ED50: 7.7 mg/kg, i.p.) administered intraperitoneally and also orally. Yohimbine diminished the activity of the extract in the acetic acid test meanwhile haloperidol enhanced its effect. Two majority compounds, shikimic and vanillic acid were active in chemical nociceptive models used in this work, producing the highest inhibition of the writhing response at a dose of 30 mg/kg i.p. (55.4% and 57.1%, respectively) meanwhile at 100 mg/kg p.o. produced a slight response (23.3% and 23.9%, respectively).

CONCLUSIONS

These results suggest that L. molleoides' aqueous extract produced antinociception possibly related to the presence of shikimic and vanillic acid. The adrenergic and dopaminergic systems seem to be involved in the mechanism of antinociception of the extract.