María del Carmen Recio

Screening methods for natural products with antimicrobial activity: A review of the literature

Diffusion and dilution methods have been employed to study the antimicrobial activity of medicinal plants. A number of modifications have been made in the technique in order to obtain better results. Since some factors (culture medium composition, microorganisms tested, extractive method, pH, solubility of the sample in the culture medium, etc.) can change results, it is difficult using these methods to standardize a procedure for the study of antimicrobial plants. Bioautography is another method for studying antimicrobial activity. With it, previously chromatographed principles are diffused to the agar. The results can also change according to the method employed. All the various techniques are reviewed here and, in order to unify the different criteria and parameters, standard methods to study the antimicrobial activity of medicinal plants are proposed.

Anti‐inflammatory and antioxidant properties of Helichrysum italicum

The anti‐inflammatory and antioxidant activities of the aerial part of Helichrysum italicum extracts have been established in various in‐vivo and in‐vitro experimental models. The results obtained on the acute oedemas induced by 12‐O‐tetradecanoylphorbol 13‐acetate (TPA) and ethyl phenylpropiolate in the mouse ear, by serotonin and phospholipase A2 (PLA2) in the mouse paw, on chronic inflammation induced by repeated application of TPA in the mouse ear and on the delayed‐type hypersensitivity induced by sheep red blood cells suggest that said anti‐inflammatory activity is due to the effects of compounds expressed via a corticoid‐like mechanism. In addition, the antioxidant activity of the extracts seems to be implicated in this anti‐inflammatory activity, as the former inhibits enzymatic and non‐enzymatic lipid peroxidation and has free‐radical scavenger properties. We conclude that the anti‐inflammatory activity of Helichrysum italicum can be explained by multiple effects, including inflammatory enzyme inhibition, free‐radical scavenging activity and corticoid‐like effects.

Antimicrobial activity of selected plants employed in the Spanish mediterranean area

Eighty-one plants from the Spanish Mediterranean area employed as antimicrobial agents in folk medicine have been identified. The in vitro antimicrobial activity of chloroform and methanol extracts of the plants were studied using the agar dilution method against six selected microorganisms. Thirty extracts had activity against some of the microorganisms tested. Bioautography showed that the antimicrobial activity is probably due to flavonoids, terpenoids and phenolic acids.

Anti-inflammatory effects of south american Tanacetum vulgare

In recent years the role of phenolic compounds and sesquiterpene lactones, particularly parthenolide, in the anti‐migraine and anti‐inflammatory effects of Tanacetum parthenium (Asteraceae) has attracted much attention. However, the closely‐related cosmopolitan species T. vulgare has remained outside the mainstream of research in this field.

Pharmacological Properties of Shikonin - A Review of Literature since 2002

The naphthoquinone shikonin is the main active principle of Zicao, a traditional Chinese herbal medicine made from the dried root of Lithospermum erythrorhizon. Studies carried out over the past 30 years have provided a scientific basis for the use of Zicao which has been long employed in folk medicine to treat a variety of inflammatory and infectious diseases. In particular, shikonin has been shown to possess many diverse properties, including antioxidant, anti-inflammatory, antithrombotic, antimicrobial, and wound healing effects. The fact that shikonin shows so many beneficial properties has increased the interest in this molecule dramatically, especially in the past few years. The aim of this review is to provide an update of the new data published on shikonin, whose wide spectrum of pharmacological effects as well as pharmacokinetic properties and toxicity make it a highly interesting target molecule.

In vivo activity of pseudoguaianolide sesquiterpene lactones in acute and chronic inflammation.

The pseudoguaianolide sesquiterpene lactones 4-alpha-O-acetyl-pseudoguaian-6beta-olide (1), hymenin (2), ambrosanolide (3), tetraneurin A (4), parthenin (5), hysterin (6) and confertdiolide (7) were evaluated for their ability to affect the inflammation responses induced by different agents. All the compounds showed activity against the 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced mouse ear edema. The ethyl phenylpropiolate (EPP)-induced mouse ear edema was inhibited by compounds 3, 5 and 7. However, when sesquiterpene-lactones were assayed on the arachidonic acid (AA)-induced mouse ear edema, none of them were active. The only sesquiterpene lactone orally active against the paw mouse edema induced by carrageenan was 7, which gave a 46% edema inhibition after 3 h. On the other hand, compounds 3, 5 and 7 reduced the serotonin-induced paw edema in mice, although compound 7 was inactive in presence of cycloheximide. In addition, the sesquiterpene lactones were assayed against the chronic inflammation induced by repeated application of TPA on mouse ear. Confertdiolide was the most active compound; it reduced the edema by 87% and had a more moderate effect against the leukocyte recruitment (36% reduction in myeloperoxidase (MPO) levels). A histological study of ear the samples treated with 7 presented no detectable morphological lesions such as those treated with dexamethasone. On the oxazolone-induced delayed type hypersensitivity (DTH) only compounds 4 and 5 were active 24 h after the challenge. Compound 5 affected polymorphonuclear leukocyte infiltration (69% reduction in MPO levels). The results suggest that the especial chemical structure and spatial conformation of confertdiolide may facilitate its anti-inflammatory effect.

Effect of triterpenoids on the inflammation induced by protein kinase C activators, neuronally acting irritants and other agents.

In order to establish the mode of the anti-inflammatory activity of triterpenoids, 11 naturally occurring compounds were assayed on mouse ear oedema induced by the protein kinase C activators, mezerein, 12-O-tetradecanoylphorbol-13-acetate (TPA), two 12-deoxyphorbol-13-monoesters (13-tetradecanoate (DPT) and 13-phenylacetate (DPP)) and bryostatin 1, and by resiniferatoxin, xylene and arachidonic acid. The effects on bradykinin-induced paw oedema and on the rat skin inflammation caused by hydrogen peroxide were also examined. The oedema induced by mezerein and DPT was reduced to different extents by the triterpenoids administered epicutaneously (0.5 mg per ear). Against DPT-induced oedema, lupane and oleanane derivatives were the most effective compounds. Oleananes and lupanes possessing a carboxyl group were active against bryostatin 1-induced oedema. Most of the triterpenoids were ineffective against the neurogenic inflammation caused by resiniferatoxin and xylene. Many triterpenoids, especially oleanane and lupane alcoholic derivatives, were active against the plantar oedema induced by bradykinin and on the intradermal inflammation induced by hydrogen peroxide. In conclusion, the anti-inflammatory activity of triterpenoids may depend on inhibition of protein kinase C, without any involvement of neurogenic inflammatory mechanisms.

Anti-inflammatory activity of flavonoids from Cayaponia tayuya roots.

ETHNOPHARMACOLOGICAL RELEVANCE Taiuiá or tayuya (Cayaponia tayuya, Cucurbitaceae) is a climbing, lignified plant with a large swollen root that has traditionally been used as an anti-inflammatory and anti-rheumatic agent in the folk medicine of Brazil, Peru, and Colombia. THE AIM OF THE STUDY We have assayed the pharmacological properties of a flavonoid fraction obtained from the butanol extract of Cayaponia tayuya roots using two models of topical mouse ear oedema, paying special attention to its influence on the induction on pro-inflammatory enzymes and peptidic mediators. MATERIAL AND METHODS The in vivo experiments involved both the acute oedema induced by a single application of TPA and the subchronic inflammation brought on by repeated applications of TPA. The effects on the induction of pro-inflammatory enzymes and peptidic mediators in RAW 264.7 macrophages were analyzed with the aid of Western blot analysis. RESULTS The extract was identified as a mixture of flavonoids in which vicenin-2, spinosin, isovitexin, and a mixture of swertisin and isoswertisin were found. In acute TPA-induced oedema in mouse ears, the flavonoid-enriched fraction (at a dose of 0.5mg/ear) inhibited the oedema by 66% (4.2+/-0.6 mg vs. 12.3+/-1.4 mg, P<0.01) while in the subchronic model, the inhibition reached 37% at a dose of 0.5mg/ear x 7 applications (7.5+/-0.6 mg vs. 11.9+/-1.3mg, P<0.05). When assayed in vitro, the flavonoid showed no toxicity at 33.45 microg/mL on RAW 264.7 macrophages. Although the nitric oxide production in these cells was moderately reduced (42%) at 33.45 microg/mL, the flavonoid-enriched fraction had no effect on TNF-alpha production. In addition, at 22.30 microg/mL, the test sample inhibited both iNOS and COX-2 expression by 98% and 49%, respectively. CONCLUSION These results indicate that the anti-inflammatory activity of flavonoids from tayuya roots most likely stems from their inhibition of the induction of the enzymes COX-2 and iNOS.

Intestinal anti-inflammatory activity of ellagic acid in the acute and chronic dextrane sulfate sodium models of mice colitis.

ETHNOPHARMACOLOGICAL RELEVANCE Pomegranate (Punica granatum L.; Lythraceae) has traditionally been used for the treatment of various inflammatory diseases, including ulcerative colitis (UC). Because its fruits and extracts are rich in ellagitannins, which release ellagic acid when hydrolyzed, consumption of pomegranate products is currently being widely promoted for their potential health effects, including the prevention of inflammatory diseases and cancer. To evaluate the anti-inflammatory effects of ellagic acid on dextran sulfate sodium (DSS)-induced acute and chronic experimental colitis in two different strains of mice and to elucidate its possible mechanisms of action. MATERIALS AND METHODS In the acute UC model, female Balb/C mice were treated with DSS (5%) for seven days while concomitantly receiving a dietary supplement of ellagic acid (2%). In the chronic UC model, female C57BL/6 mice received four week-long cycles of DSS (1% and 2%) interspersed with week-long recovery periods along with a diet supplemented with ellagic acid (0.5%). RESULTS In acute model of UC, ellagic acid ameliorated disease severity slightly as observed both macroscopically and through the profile of inflammatory mediators (IL-6, TNF-α, and IFN-γ). In the chronic UC model, ellagic acid significantly inhibited the progression of the disease, reducing intestinal inflammation and decreasing histological scores. Moreover, mediators such as COX-2 and iNOS were downregulated and the signaling pathways p38 MAPK, NF-κB, and STAT3 were blocked. CONCLUSIONS Our study reinforces the hypothetical use of ellagic acid as an anti-inflammatory complement to conventional UC treatment in chronic UC patients and could be considered in the dietary prevention of intestinal inflammation and related cancer development.

Topological virtual screening: a way to find new compounds active in ulcerative colitis by inhibiting NF-κB

Ulcerative colitis and Crohn’s disease are chronic, immune-mediated inflammatory diseases of the gastrointestinal tract. Nuclear Factor Kappa B (NF-κB) is a transcription factor that plays a key role in regulating expression of multiple inflammatory and immune genes. In this study, a Topological Virtual Screening study has been carried out to achieve a model capable of finding new compounds active in ulcerative colitis by inhibiting NF-κB. Different topological indices were used as structural descriptors, and their relation to biological activity was determined using linear discriminant analysis. A topological model consisting of two discriminant functions was built up. The first function focused in the discrimination between NF-κB active and inactive compounds, and the second one in distinguishing between compounds active and inactive on ulcerative colitis. The model was then applied sequentially to a large database of compounds with unknown activity. Twenty-eight of such compounds were predicted to be active and selected for in vitro and in vivo testing.