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Biomedical subjects

N Hermans

Publications and source records attributed to N Hermans.

12 recordsLinked to original sources
PubMed2006

Cytotoxicity and in vitro susceptibility of Entamoeba histolytica to Morinda morindoides leaf extracts and its isolated constituents.

An aqueous decotion (dried extract), an 80% MeOH extract from Morinda morindoides leaves, and 10 flavonoids and 4 iridoids isolated from the 80% MeOH extract were evaluated in vitro for their potential antiamoebic activity and their cytotoxic effect against MT-4 cells. Results indicated that the aqueous decoction and the 80% MeOH extract exhibited an interesting antiamoebic activity with IC(50) values of 3.1 +/- 1.7 and 1.7 +/- 0.6 microg/ml, respectively. Apigenin-7-O-glucoside and luteolin-7-O-glucoside exhibited a moderate antiamoebic activity with IC(50) values of 22.3 +/- 3.2 and 37.4 +/- 2.7 microg/ml, respectively. Kaempferol (IC(50) = 10.3 +/- 2.3 microg/ml), apigenin (IC(50) = 12.7 +/- 4.3 microg/ml), and luteolin (IC(50) = 17.8 +/- 4.3 microg/ml) showed a more pronounced activity than their corresponding glycosides. All tested iridoids displayed a very good activity with IC(50) values less than 10 microg/ml. The most active iridoids were epoxygaertneroside (IC(50) = 1.3 +/- 0.4 microg/ml) and methoxygaertneroside (IC(50) = 2.3. +/- 0.7), followed by gaertneroside and gaertneric acid with IC(50) values of 4.3 +/- 1.8 and 7.1 +/- 1.4 microg/ml, respectively. Except quercetin and quercetin-7,4'-dimethylether which have shown a cytotoxic effect with IC(50) ranging from 14 to 22 microg/ml. No correlation could be deduced between the observed antiamoebic and cytotoxic activity of these tested samples. A structure-activity relationship for isolated compounds is discussed. These findings support the medicinal report for the traditional use of Morinda morindoides leaves for the treatment of amoebiasis.

Amebicides↗
PubMed2005

[Adherence to guidelines in CHF therapy in Germany].

BACKGROUND AND OBJECTIVE: The MAHLER survey examined the impact of the European guidelines for the treatment of chronic heart failure (CHF). Especially, the trial addressed the question whether adherence to treatment guidelines leads to a reduction in the rate of CHF and cardiovascular (CV) hospitalization. The present sub-study presents the Germany specific data of the MAHLER study and compares the results with the results in other European countries. PATIENTS AND METHOD: The gobal adherence index (GAI) shows the proportion of correctly prescribed heart failure medications per patient. Class adherence indicators for angiotensin-converting enzyme (AC)-inhibitors, beta-blockers, spironolactone, diuretics and cardiac glycosides and general adherence indicators (GAI3 adherence to first three classes of heart failure medications, GAI5 adherence to five classes) were constructed. In the German sub-study, 251 patient were included, who were seen by 21 cardiologists in private practice (mean age 68,6 + 10,4 years; 173 man, 78 woman; 158 NYHA II; 91 NYHA III, 2 NYHA IV). RESULTS: Mean adherence to CHF therapy guidelines was 63 % for GAI3, 62 % for GAI5. Compared to the other MAHLER-study countries, Germany was on place two and three concerning GAI3 and GAI5, respectively. Strong adherence to treatment guidelines in Germany led to a reduction of CHF and CV hospitalization rate by 40 % (p < 0.033). Thus, the German data confirm the results of the international study indicating that a good GAI3 performance is an independent predictor of time to hospitalization. Hitherto, the relative risk for hospitalization was higher for CHF patients in Germany than for patients in all other European countries. CONCLUSIONS: In Germany like in other European countries, guideline adherence for CHF therapy leads to a reduction in hospitalization rate.

Aged↗
PubMed2004

In vitro antiplasmodial activity of callus culture extracts and fractions from fresh apical stems of Phyllanthus niruri L. (Euphorbiaceae): part 2.

The ethanolic extracts from fresh apical stems of Phyllanthus niruri L. (Euphorbiaceae) cultured on Murashige and Skoog (MS) medium supplemented with IBA/BAP/Coco nucifera L. milk for 1, 2, 4 and 6 months were phytochemically and biologically investigated and compared with intact plant part and whole plant extracts. Results from the in vitro antiplasmodial testing indicated that the EtOH extract of a 1-month-old callus culture (IC(50) = 16.3 +/- 2.5 microg/ml) exhibited a higher activity than the ethanolic extracts of the fresh apical stem (IC(50) = 18.2 +/- 2.4 microg/ml) and callus cultures of 2-, 4- and 6-months-old (25 microg/ml < IC(50) < 40 microg/ml). These activities were however lower than that displayed by the ethanolic extract of the whole plant (IC(50) < 3 microg/ml). The EtOH extract of 1-month-old callus culture (the most active) was fractionated with solvents of different polarities. Its CH(2)Cl(2) fraction rich in terpenic constituents (IC(50) = 9.2 +/- 3.4 microg/ml) exhibited a higher antiplasmodial activity than its isoamylic alcohol fraction obtained at pH 2-3 (IC(50) = 25.6 +/- 2.3 microg/ml) rich in flavonoids. The activity of these two fractions was lower than that displayed by the same fractions from the whole plant (2 microg/ml < IC(50) < 3 microg/ml). Alkaloidic fractions from the whole plant and 1-month-old callus culture of fresh apical stem were considered as inactive (IC(50) > 100 microg/ml).

Animals↗
PubMed2004

Proanthocyanidins in health care: current and new trends.

Polyphenolic compounds are widely distributed in higher plants and are an integral part of the human diet. Recent interest in these substances has been stimulated by their potential health benefits, which are believed to arise mainly from their antioxidant activity. In the past years, the antioxidant activity of flavonoids has been studied in detail. An important but often overlooked group of polyphenols is that of the proanthocyanidins. Therefore, the present review is focused mainly on the antioxidant activity of proanthocyanidins and its relevancy in vivo. The three most important mechanisms of their antioxidant action will be discussed, i.e. free radical scavenging activity, chelation of transition metals, and inhibition of enzymes. In addition, the protective role of proanthocyanidins against lipid peroxidation and peroxynitrite, as well as their antimicrobial properties will be discussed. To study the in vivo relevancy of the proanthocyanidin activities, the knowledge of their pharmacokinetic parameters is crucial. Although bioavailability and metabolism data on polyphenols in general and proanthocyanidins in particular are still largely unavailable, the first reports indicate that at least monomers and smaller oligomeric procyanidins are absorbed. There is also considerable scientific and public interest in the important role that antioxidants may play in health care, e.g. by acting as cancer chemopreventive and anti-inflammatory agents and by reducing risk of cardiovascular mortality. Each of these aspects will be discussed, with special attention to the role of proanthocyanidins on apoptosis, gene expression and transcription factors, such as NF-kappa B.

Animals↗
PubMed2003

Comparative study of eight well-known polyphenolic antioxidants.

Eight antioxidants from five different polyphenolic classes (cinnamic acids, benzoic acids, flavonoids, proanthocyanidins and stilbenes), and the water-soluble vitamin E derivative trolox were examined for their antioxidant activity in-vitro. In addition, the compounds were tested for their cytotoxicity on growing fibroblasts and their inhibition of the classical pathway of the complement system. Procyanidin C1 was shown to be a good scavenger of both DPPH(*) and HO(*), and a strong inhibitor of lipid peroxidation and the classical pathway of the complement system. Consequently, procyanidin C1 was classified as the most promising antioxidant in-vitro of all compounds tested. In contrast, genistein exhibited a very low antioxidant activity in both the lipid peroxidation and the DPPH(*) scavenging assay, a high cytotoxicity and a low complement-inhibiting activity.

Antioxidants↗
PubMed2002

Further evaluation of Rwandan medicinal plant extracts for their antimicrobial and antiviral activities.

A total of 45 Rwandan plant extracts, belonging to 37 different plant species out of 21 families, were investigated for their antibacterial, antifungal, and antiviral properties. The plants were selected on the base of their ethnomedicinal use against infections and autoimmune diseases. From all the plant extracts tested, only Clematis hirsuta (leaves) showed a pronounced antifungal activity against Candida albicans and the dermatophytes Trichophyton rubrum, Epidermophyton floccosum, and Microsporum canis. Seven plant extracts showed a high antiviral activity against the DNA-virus Herpes simplex type 1, while five and three plant extracts were highly active against the RNA-viruses Coxsackie and Polio, respectively. Only Macaranga kilimandscharica (leaves) showed an interesting anti-measles activity, whereas Eriosema montanum (leaves) and Entada abyssinica (leaves) were highly active against Semliki forest virus. Some plant extracts showed an antibacterial activity against Gram-positive bacteria and Mycobacterium fortuitum, but none of them were active against the Gram-negative bacteria tested.

Anti-Bacterial Agents↗
PubMed2002

Correlation between chemical composition and antibacterial activity of essential oils of some aromatic medicinal plants growing in the Democratic Republic of Congo.

The chemical composition of essential oils from 15 aromatic medicinal plant species growing in the Democratic Republic of Congo have been studied. More than 15 constituents in an amount higher than 0.1% were identified in each essential oil. 1,8-cineole, alpha and beta-pinene, p-cymene, myrcene, gamma-terpinene, alpha-terpineol and limonene were prevalent constituents in almost more than 10 selected plant species. Results from the antibacterial testing by the diffusion method indicate that all essential oils (5 microl per disc) inhibited the growth of selected bacteria at different extents. The most active antibacterial essential oils were those of the leaves of Eucalyptus camadulensis and Eucalyptus terticornis (12-30 mm zone diameter of inhibition). They showed particularly a most potent inhibition of Pseudomonas aeruginosa growth (15-16 mm), followed by Eucalyptus robusta (12 mm). Essential oils from the leaves of Eucalyptus alba, Eucalyptus citriodora, Eucalyptus deglupta, Eucalyptus globulus, Eucalyptus saligna, Eucalyptus robusta, Aframomum stipulatum, Cymbopogon citratus, Ocimum americanum and that of the seeds of Monodora myristica showed also a good antibacterial activity (10-18 mm). Eucalyptus propinqua, Eucalyptus urophylla and Ocimum gratissimum essential oils were the less active samples against the selected bacteria. No correlation between the amount of major constituents such as 1,8-cineol, alpha-pinene, p-cymene, cryptone or thymol and the antibacterial activity was observed.

Anti-Bacterial Agents↗
PubMed2002

Antiviral activity of Rwandan medicinal plants against human immunodeficiency virus type-1 (HIV-1).

Selected plants used in Rwandan traditional medicine for the treatment of infections and/or rheumatoid diseases were investigated for antiviral activity in vitro against human immunodeficiency virus type-1 (HIV-1). Of the 38 tested 80% ethanolic extracts, belonging to plants of 21 different families only the extracts from the leaves of Aspilia pluriseta (Asteraceae) and Rumex bequaertii (Polygonaceae) had interesting selectivity indices (SI = ratio of the 50% cytotoxic concentration to the 50% effective antiviral concentration) higher than 1. Further fractionation of the initially antivirally inactive ethanolic extract of Tithonia diversifolia, however, led to an aqueous fraction with a high anti-HIV-1 activity (SI > 461), indicating that the cytotoxicity of some plant components may mask the antiviral properties of the active plant substances in total plant extracts.

Anti-HIV Agents↗
PubMed2002

Complement modulating activity of Rwandan medicinal plants.

Forty-two ethanolic extracts of thirty-six Rwandan medicinal plants were investigated for their influence on complement-mediated hemolysis. The plants were selected on the base of their ethnomedicinal use in infections and autoimmune diseases. Eight plant extracts showed an inhibitory activity against the classical pathway of the complement system and ten plant extracts against the alternative pathway. Three plant extracts exhibited an interesting activity against both pathways, i.e. Aspilia pluriseta, Coleus kilimandschari, and Macaranga kilimandscharica (leaves and stem). Further study indicated that the complement inhibitory activity was not caused by chelation of bivalent cations or by direct action on the target erythrocytes.

Complement Activation↗
PubMed2001

Radical scavenging and xanthine oxidase inhibitory activity of phenolic compounds from Bridelia ferruginea stem bark.

Bridelia ferruginea Benth. (Euphorbiaceae) is a subtropical medicinal plant widely used in traditional African medicine against various diseases, including rheumatic pains. Seven of its constituents (3-O-methylquercetin (1), 3,7,3',4'-tetra-O-methylquercetin (rutisin, 2), myricetin (3), 3',4',5'-tri-O-methylmyricetin (ferrugin, 4), 3,3',4',5'-tetra-O-methylmyricetin (5), quercetin 3-O-glucoside (6), and a biflavanol gallocatechin-[4'-O-7]-epigallocatechin (7)) have been evaluated in-vitro in the xanthine-xanthine oxidase enzymatic system for inhibition of xanthine oxidase and radical scavenging activity. Results indicated that compounds 1, 3, 4 and 6 exhibited, at different levels, xanthine oxidase inhibiting and superoxide scavenging activity at micromolar concentrations, whereas compound 7 showed scavenging activity only. Compounds 2 and 5 were inactive in both cases. Study of the structure-activity relationship demonstrated that for flavonoids the xanthine oxidase inhibitory activity was reduced by methylation of the hydroxyl functionality at C-3 and in rings A and B. These results may partly explain and support the use of B. ferruginea stem bark for the treatment of rheumatic pains in traditional medicine.

Arthritis, Rheumatoid↗
PubMed2001

In-vivo antimalarial activity of Cassia occidentalis, Morinda morindoides and Phyllanthus niruri.

The ethanolic, dichloromethane and lyophilized aqueous extracts of Cassia occidentalis root bark, Morinda morindoides leaves and whole plants of Phyllanthus niruri were evaluated for their antimalarial actvity in vivo, in 4-day, suppressive assays against Plasmodium berghei ANKA in mice. No toxic effect or mortality was observed in mice treated, orally, with any of the extracts as a single dose, of 500 mg/kg body weight, or as the same dose given twice weekly for 4 weeks (to give a total dose of 4 g/kg). No significant lesions were observed, by eye or during histopathological examinations, in the hearts, lungs, spleens, kidneys, livers, large intestines or brains of any mouse. At doses of 200 mg/kg, all the ethanolic and dichloromethane extracts produced significant chemosuppressions of parasitaemia (of > 60% for C. occidentalis root bark and Ph. niruri whole plant, and of 30% for M. morindoides leaves) when administered orally. The most active ethanolic extract, that of Ph. niruri, reduced parasitaemia by 73%. The dichloromethane extracts of M. morindoides and Ph. niruri produced similar reductions (74% and 72% chemosuppression, respectively), whereas that of C. occidentalis was slightly less active (60% chemosuppression). Each lyophilized aqueous extract was less active than the corresponding ethanolic extract.

Administration, Oral↗