Juan Celidonio Ruiz Macedo’s research while affiliated with Universidad Nacional de la Amazonía Peruana and other places

Ethnopharmacological relevance An extensive ethnopharmacological survey was carried out in the Peruvian Amazonian district of Loreto with informants of various cultural origins from the surroundings of Iquitos (capital city of Loreto) and from 15 isolated riverine Quechua communities of the Pastaza River. A close attention was paid to the medical context and plant therapy, leading to the selection of 35 plant species (45 drugs). The extracts were tested for antiviral activity against HCV with counting of Huh-7 cellular death in case of toxicity, and cytotoxicity was evaluated in HepG2 cells. Aim of the study The aim of the study was to inventory the plants used against hepatitis in Loreto, then to evaluate their antiviral activity and to suggest a way to improve local therapeutic strategy against viral hepatitis, which is a fatal disease that is still increasing in this area. Materials and methods An ethnographic survey was carried out using “participant-observation” methodology and focusing on bioprospecting of plant therapy against hepatitis including associated remedies. The 45 selected drugs were extracted with methanol and tested in vitro for anti-HCV activity in 96-well plate, using HCV cell culture system with immunofluorescent detection assisted by automated confocal microscopy. Toxicity of plant extracts was also evaluated in microplates on hepatic cells by immunofluorescent detection, for the Huh-7 nuclei viability, and by UV-absorbance measurement of MTT formazan for cytotoxicity on HepG2 cells. Results In vitro assay revealed interesting activity of 18 extracts (50% infection inhibition at 25 μg/mL) with low cytotoxicity for 15 of them. Result analysis showed, that at least 30% of HCV virus were inhibited at 25 μg/mL for 60% of the plant extracts. Moreover, the ethnomedical survey showed that drugs used with low and accurate dosing as targeted therapy against hepatitis are usually more active than species indicated with more flexible dosing to alleviate symptoms of hepatic diseases. Conclusion Togeteher with bibliographic data analysis, this study supported the traditional medicinal uses of many plants and contributed to a better understanding of the local medical system. It also permitted to refine the therapeutic plant indications regarding patient's liver injury and vulnerability. Only 2 of the 15 most active plant species have already been studied for antiviral activity against hepatitis suggesting new avenues to be followed for the 13 other species.

Ethnopharmacological relevance: The plant species reported here are used in contemporary phytotherapies by native and neo-urban societies from the Iquitenian surroundings (district of Loreto, Peruvian Amazon) for ailments related to microbial infections. Inhabitants of various ethnic origins were interviewed and 81 selected extracts were evaluated for their antimicrobial properties against a panel of 36 sensitive and multi-resistant bacteria or yeast. Medicinal plant researches in the Peruvian Amazon are now significant, but none of them has focused on an exhaustive listing of identified species tested on so many microbes with standardized experiments (to obtain MIC value). Aim of the study: The aim of the study was to inventory the plants used against infections in the Loreto, an Amazonian region of Peru. It led to the new identification of secondary metabolites in two plant species. Materials and methods: Ethnographic survey was carried out using "participant-observation" methodology and focus on bioprospecting of antimicrobial remedies. Selected plant extracts and antimicrobial drugs were tested in vitro with agar dilution method on 35 bacteria strains and 1 yeast to evaluate their Minimal Inhibitory Concentration (MIC). Microdilution methods using 96-well microtiter plates were used for the determination of MIC from isolated compounds, and cytotoxicity in HepG2 cells from some selected extracts were also evaluated. Activity-guided isolation and identification of compounds were performed by various chromatographic methods and structural elucidations were established using HRMS and NMR spectroscopy. Results: This study outlined antimicrobial activities of 59 plant species from 33 families (72 single plant extracts and 2 fermented preparations), 7 mixtures, and one insect nest extract against 36 microorganisms. Of the 59 species analysed, 12 plants showed relevant antibacterial activity with MIC ≤0.15 mg/mL for one or several of the 36 micro-organisms (Aspidosperma excelsum, Brosimum acutifolium, Copaifera paupera, Erythrina amazonica, Hura crepitans, Myrciaria dubia, Ocotea aciphylla, Persea americana, Spondias mombin, Swartzia polyphylla, Virola pavonis, Vismia macrophylla). Examination by bioautography of E. amazonica, M. dubia and O. aciphylla extracts allowed the phytochemical characterization of antimicrobial fractions and compounds. Conclusion: This study suggested an a posteriori correlation of the plant extract antimicrobial activity with the chemosensory cues of the drugs and attested that those chemosensory cues may be correlated with the presence of antimicrobial compounds (alkaloids, tannins, saponosids, essential oil, oleoresin …). It also led to the first isolation and identification of three secondary metabolites from E. amazonica and M. dubia.

Objetivo: Determinar el efecto antibacteriano del extracto de Stevia rebaudiana (S. rebaudiana) frente a Streptococcus sanguinis (S. sanguinis) y Actinomyces viscosus (A. viscosus). Métodos: Se desarrolló la prueba de sensibilidad en placa de agar con discos, para lo cual se cultivaron las cepas de S. sanguinis y A. viscosus en placas de agar tripticasa soya (TSA) y agar sangre respectivamente, incubando a 37 °C por 48 horas a S. sanguinis y por 7 días en condiciones de anaerobiosis a A. viscosus. Las cepas bacterianas fueron estandarizadas a una escala de 0,5 de Mc Farland, y tomando inóculos de 100 μL fueron sembradas en diez placas de agar sangre y TSA, luego sobre cada placa se colocaron los discos de papel secante de 6 mm de diámetro de forma equidistante, cargados con 10 μL de las diferentes concentraciones del extracto, para luego ser incubados. Resultados: Las concentraciones de 15, 30, 50, 60 y 120 mg/ml presentaron un halo de inhibición promedio de 6,8±0,258; 8,2±1,15; 8,2±1,13; 8,3±0,823; 8,1±0,80 mm respectivamente, para las bacterias de S. sanguinis. Las concentraciones de 15, 30, 50, 60 y 120 mg/ml presentaron un halo de inhibición promedio de 7,2±0,75; 9,65±2,15; 9,20±2,03; 7,95±1,09; 8,05±0,96 mm respectivamente, para las bacterias de A. viscosus. La prueba de Kruskal Wallis determinó que existe diferencia estadísticamente significativa con p<0,05 de los promedios entre las concentraciones de A. viscosus. Conclusiones: El extracto de S. rebaudiana no presenta efecto antibacteriano para S. sanguinis, pero si presenta efecto antibacteriano sobre A. viscosus para las concentraciones de 30 y 50 mg/ml.

Deforestation of primary forests in developing countries is unquestionable, particularly, in tropical regions like Peru. Even extractors already use flooded forests. Consequently, populations of plants of commercial value have declined, putting their genetic diversity at risk (FAO 1993: 10–30; Namkoong et al. 1996). In the Peruvian Amazon, this problem is alarming, because the flooded alluvial plains represent more than 12% of the territory, with more than 60,000 km² (Kvist and Nebel 2005), with the aggravating circumstance that the exuberant forest that it presents, develops in very poor soils (Higuchi et al. 2005), as occurs in the forests of the Nanay River. The water in this river is black and very poor in silt, so the additional supply of nutrients is almost zero during the flood. To these areas, Burga (2007) mentions that it is a meandering plain characterized by the presence of ridges and semilunar bars, encompassing flatlands with slopes of less than 2%, where restinga and lowland are observed.

Minimum inhibitory concentration (MIC) of active plants (mg/mL)