Antimicrobial activity of flavonoids from Piper lanceaefolium and other Colombian medicinal plants against antibiotic susceptible and resistant strains of Neisseria gonorrhoeae.

BACKGROUND: The successful treatment of Neisseria gonorrhoeae (NG) infections is increasingly problematic because of the resistance of this pathogen to multiple antimicrobial agents. This development underscores the need for new antimicrobial sources. In the current study, 21 crude methanol extracts, from 19 plants used in Colombian traditional medicine for cutaneous infections, were screened for antimicrobial activity against NG. METHODS: Extracts were screened by disc susceptibility assay. In addition, the minimum inhibitory concentrations of active compounds from P. lanceaefolium were assayed using a panel of 26 NG strains comprising 12 antibiotic-resistant phenotypes. RESULTS: In all, 71% of the crude extracts exhibited antibacterial activity against the antibiotic susceptible NG strain WHO V, whereas 10% of the extracts inhibited penicillinase-producing NG strain GC1-182. The crude extract of Piper lanceaefolium was the only extract to show significant activity without ultraviolet (UV) light activation. Preliminary screening identified 3 compounds in this plant possessing antimicrobial activity: the flavonoids 5,7-dihydroxyflavanone (pinocembrin), 2',4',6'-trihydroxychalcone (pinocembrin chalcone), and the prenylated benzoic acid derivative cyclolanceaefolic acid methyl ester. Pinocembrin and pinocembrin chalcone inhibited 100% of the NG panel at 64 µg/mL and 128 µg/mL, respectively, whereas cyclolanceaefolic acid methyl ester inhibited 44% of the strains at 128 µg/mL. CONCLUSIONS: This is the first report of the antibacterial activity of Columbian plants against NG. The activity of the 2 flavonoids, pinocembrin, and pinocembrin chalcone, toward both susceptible and resistant NG strains makes them promising candidates for further research.

Antifungal activity of benzoic acid derivatives from Piper lanceaefolium.

Bioactivity-guided fractionation of a methanol extract from the leaves of Piper lanceaefolium resulted in the isolation of four new benzoic acid derivatives (1-4), together with taboganic acid, pinocembrin, and pinocembrin chalcone. Lanceaefolic acid methyl ester (3) and pinocembrin chalcone displayed activity against Candida albicans with a minimal inhibitory concentration value of 100 microg/mL in both cases.

Antiviral and antimicrobial activities of Colombian medicinal plants.

Strong antiviral and antimicrobial activities were detected in methanolic extracts of 24 plants used medicinally in the treatment of skin infections in four different regions of Colombia. Thirteen extracts displayed activity against herpes simplex virus (HSV) whereas none was active against poliovirus. The antiviral activity was indicated by a total inhibition of viral cytopathic effects (CPE) at a non-cytotoxic concentration of the extract. The most potent extract was obtained from Byrsonima verbascifolia (L.) HBK. which showed anti-HSV activity at a concentration as low as 2.5 microg/ml. Antimicrobial screening was conducted using the disc diffusion assay against Klebsiella pneumoniae, Escherichia coli, Streptococcus faecalis, Mycobacterium phlei, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhimurium and the human pathogenic yeast, Candida albicans. Anti-Candida activity was observed for Piper lanceaefolium HBK. and Juglans neotropica Diels. Twenty-two extracts displayed activity against Gram-positive bacteria whereas none was active against the Gram-negative species. We concluded that these Colombian medicinal plants represent an untapped source of potentially useful antivirals and are worthy of further study.

An ethnobotanical study of the traditional medicine of the Mestizo people of Suni Miraño, Loreto, Peru.

Research on the ethnobotany of Mestizos in Suni Miraño in 1994 documented 60 plant species used for medicinal purposes. Some cultural data on traditional healing and etiology were also collected. Of these 60 species, 31 were submitted to antibacterial and antifungal assays in the presence and absence of UV light and a number of species were shown to be active.

Studies on the pharmacological activity of Amazonian Euphorbiaceae.

Plant material from 34 Amazonian species of the family Euphorbiaceae were collected and extracts prepared. Sixteen of these species have a documented use as a medicinal agent. The extracts were tested for their ability to inhibit the growth of the bacteria, Escherichia coli and Staphylococcus aureus; the yeasts, Saccharomyces cerevisiae and Candida albicans; the dermatophytic fungi, Microsporum canis, Microsporum fulvum, Microsporum gypseum and Trichophyton gallinae; the viruses, Sindbis virus and murine cytomegalovirus; and tumours induced on potato discs by Agrobacterium tumefaciens. They were also examined for their toxicity to brine shrimp, Artemia salina. The results are discussed with respect to ethnobotanical information available for some of the species.

Monoamine oxidase inhibitors in South American hallucinogenic plants Part 2: Constituents of orally-active Myristicaceous hallucinogens.

Alkaloid constituents in Myristicaceous bark and leaf samples and in purportedly hallucinogenic preparations derived from Myristicaceous sources were qualitatively and quantitatively analyzed using TLC, GC, alkaloid precipitation tests and GC/MS. Fourteen of the 27 bark and leaf samples analyzed contained detectable amounts of alkaloids. The major bases were N,N-dimethyltryptamine (DMT) and/or 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT); much smaller amounts of tryptamine and/or N-methyl-tryptamine (NMT) were also usually present. beta-Carbolines were not detected in the bark or leaf samples. Considerable variation in alkaloid profiles was found, extending to different collections of the same species. Fourteen of the 20 Virola samples contained alkaloids; none of the 6 Iryanthera species had detectable alkaloids. Osteophloem platyspermum contained an indolic base, identified as N-methyl-tryptophan methyl ester. Seven samples of an orally-ingested drug made from Virola spp. were analyzed. All except one contained substantial amounts of tryptamines; the types and proportions of tryptamines present varied greatly between samples. Samples of Yanomama snuff including various admixtures were analyzed and all components but one contained tryptamines. The drug samples having the highest concentrations of alkaloids contained 15-20 mg/g dry wt while the Myristicaceous bark and leaf samples had much lower concentrations ranging from 0.04 to 0.25 mg/g dry wt. beta-Carbolines were detected as trace constituents in only two of the Myristicaceous drug samples. Four Myristicaceous paste samples were bioassayed in self-experiments. Two of the samples were devoid of detectable hallucinogenic or physiological activity, while some degree of oral activity was detected in two other samples. The activity of a number of tryptamine derivatives as monoamine oxidase inhibitors (MAOI) was investigated using an in vitro enzyme assay. Activity was measured using single compounds and mixtures of compounds and the results were compared to the activity of samples of orally-ingested Myristicaceous pastes. Tryptamine derivatives had significantly less MAOI activity than the activity of beta-carboline derivatives measured in a previous study. Some structural correlations for MAOI activity were found for the tryptamine derivatives. Samples of orally-ingested Myristicaceous pastes were assayed for MAOI activity. The inhibition elicited by the paste samples was closely matched by mixtures of tryptamine standards having comparable proportions and concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)

An ethnopharmacological examination of Virola elongata bark: a South American arrow poison.

The use of the resin of Virola elongata as an arrow poison was investigated. Aqueous and methanolic extracts of the dried bark were not observed to have toxic effects when administered intraperitoneally to mice. In an attempt to determine if the hallucinogenic indole alkaloid constituents of the bark, which form the basis for the alternate use of this material as a ceremonial snuff, could also be responsible for its use as an arrow poison, alkaloidal and non-alkaloidal extracts were compared with respect to their behavioral effects on mice. The non-alkaloidal extract was more effective in producing an observable alteration in behavior. This consisted of a marked reduction in spontaneous locomotor activity. The extract was fractionated and 13 of the major constituents assayed for their ability to reduce spontaneous locomotor activity. Most of this biological activity of the extract was attributable to the presence of the bis-tetrahydrofuran lignans, epi-sesartemin, sesartemin, epi-yangambin and yangambin. Each of these compounds was also observed to reduce isolation induced aggression when administered to mice.

Monoamine oxidase inhibitors in South American hallucinogenic plants: tryptamine and beta-carboline constituents of ayahuasca.

Ayahuasca is a hallucinogenic beverage derived by boiling the bark of the Malpighiaceous liana Banisteriopsis caapi together with the leaves of various admixture plants, viz. Psychotria viridis, Psychotria carthagenensis , or Diplopterys cabrerana . B. caapi contains harmine, harmaline, and tetrahydroharmine while the admixtures contain N,N-dimethyltryptamine (DMT). DMT, a potent hallucinogen, is inactive orally due to degradation by visceral monoamine oxidase (MAO). The beta-carbolines, however, are highly active reversible inhibitors of MAO and may protect the DMT from deamination by MAO and render it orally active. This mechanism has been proposed to underlie the oral activity of ayahuasca but has not been experimentally confirmed. In the present study the constituents of the admixture plants and the alkaloids of eight ayahuasca samples from Peru were qualitatively and quantitatively analyzed using two-dimensional thin-layer chromatography (TLC), high pressure liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). Several B. caapi cultivars were quantitatively compared for variations in alkaloid content. Three admixture plants used rarely in the manufacture of ayahuasca were also screened for alkaloids. A selected sample of beta-carbolines were screened for activity as MAO inhibitors using an in vitro assay system, and structure/activity relationships were compared. Inhibition observed with single compounds was compared with the activity of selected samples of ayahuasca which were screened in the system and also with the activity of mixtures of beta-carbolines. The levels of DMT and beta-carbolines found in the ayahuasca samples examined in the present study were an order of magnitude greater than the levels reported in a previous study. Ayahuasca was found to be an extremely effective inhibitor of MAO in vitro and the degree of inhibition was directly correlated with the concentration of MAO-inhibiting beta-carbolines. Inhibition experiments using mixtures of beta-carbolines indicated that their effects in combination are additive, rather than synergistic or antagonistic. Implications of the results in understanding the pharmacology of ayahuasca are discussed.

Anti-reproductive and other medicinal effects of Tropaeolum tuberosum.

Tropaeolum tuberosum is an edible-tuber-producing cultigen of the Andes mountains. Historical beliefs relating to the effects of this species on human reproductive potential continue to the present day. T. tuberosum subsp. tuberosum contains p-methoxybenzylglucosinolate as its major secondary metabolite. The putative anti-aphrodisiac activity of T. tuberosum was examined in male rats fed a diet containing tubers of this taxon. Experimental animals and controls showed equal capability in impregnating females, although animals fed T. tuberosum showed a 45% drop in their blood levels of testosterone/dihydrotestosterone. This decrease appears to be related to the presence of isothiocyanates in the tubers. Feeding studies of female guinea pigs and in vitro studies to test the 17 beta-estradiol binding inhibition of plant extracts and of pure isothiocyanates failed to substantiate any estrogenic activity of these taxa. However, preliminary results suggest that N, N-di-(methoxy-4-benzyl)thiourea competitively inhibits estradiol binding and may have estrogenic activity. The antibiotic, insecticidal, nematocidal and diuretic properties of isothiocyanates substantiate several of the uses of T. tuberosum in Andean folk medicine.