Use of a modified microplate bioassay method to investigate antibacterial activity in the Peruvian medicinal plant Peperomia galioides

A versatile microplate bioassay for quick and sensitive determination of antibacterial activity was developed for use in screening medicinal plants and identification of their active principles. This assay can be used to determine minimum inhibitory concentrations for small quantities of organic or water-soluble plant extracts. Bioassay-guided fractionation of the stem and leaves of Peperomia galioides using this method found fractions containing grifolin and grifolic acid, which inhibited growth of Staphylococcus aureus and Staphylococcus epidermidis.

Anti-inflammatory and analgesic activity of Peperomia pellucida (L.) HBK (Piperaceae)

An aqueous extract of the aerial part of Peperomia pellucida (L.) HBK (Piperaceae) was tested for anti-inflammatory (paw edema induced by carrageenin and arachidonic acid) and analgesic activity (abdominal writhes and hot plate) in rats and mice, respectively. Oral administration of 200 and 400 mg/kg of the aqueous extract exhibited an anti-inflammatory activity in the carrageenin test, which was based on interference with prostaglandin synthesis, as confirmed by the arachidonic acid test. In the abdominal writhing test induced by acetic acid, 400 mg/kg of the plant extract had the highest analgesic activity, whereas in the hot-plate test the best dose was 100 mg/kg. The LD(50) showed that Peperomia pellucida (5000 mg/kg) presented low toxicity.

Ethanol extract of Peperomia pellucida (Piperaceae) promotes fracture healing by an anabolic effect on osteoblasts

ETHNOPHARMACOLOGICAL RELEVANCE

The whole plant or some part of Peperomia pellucida (L.) HBK is used in some parts of Cameroon as a treatment for fracture healing.

AIM OF THE STUDY

To evaluate the effect of ethanolic extracts of Peperomia pellucida (L.), a Cameroonian medicinal plant on bone regeneration following bone and marrow injury, and determine the mode of action.

MATERIALS AND METHODS

Ethanol extract of Peperomia pellucida was administered at 100 and 200mg/kg doses orally to adult female Sprague-Dawley rats having a drill hole injury (0.8mm) in the femur diaphysis. Vehicle (gum-acacia in distilled water) was given to the control group. After 12 days of treatment, animals were euthanized and femur bones collected. Confocal microscopy of calcein labeling at the drill hole site was performed to evaluate bone regeneration. 3-D microarchitecture of drill hole site was analyzed by micorocomputed tomography. Osteogenic effects of the extract were evaluated by assessing mineralized nodule formation of bone marrow stromal cells and expression of osteogenic genes (mRNA level of type-1 collagen, bone morphogenetic protein-2 and osteocalcin genes) in the femur.

RESULTS

Ethanol extract from Peperomia Pellucida (L.) dose-dependently induced bone regeneration at the fracture site. At 200mg/kg dose, the extract significantly increased mineral deposition compared to controls. The extract also improved microarchitecture of the regenerating bone evident from increased bone volume fraction, trabecular thickness, trabecular number, and decreased trabecular separation and structure model index. In addition, the extract increased the formation of mineralized nodules from the bone marrow stromal cells. Furthermore, the extract induced the expression of osteogenic genes in the femur including type 1 collagen, osteocalcin and BMP-2, compared to control.

CONCLUSION

Ethanolic extract of P. pellucid (L.) accelerates fracture repair in rats via stimulatory effects on osteoblast differentiation and mineralization, thereby justifying its traditional use.

Natural radioactivity determination in samples of Peperomia pellucida commonly used as a medicinal herb

The concentration of (238)U, (232)Th, (230)Th, (226)Ra, (228)Ra and (210)Pb were determined in samples of Peperomia pellucida and in the surrounding soil, by alpha spectrometry and gross alpha and beta counting. The radionuclide activity concentrations ranged from 4.3 to 38 Bq kg(-1), 1.7-124 Bq kg(-1), 2.1-38 Bq kg(-1), 8.5-37 Bq kg(-1), 3.2-46 Bq kg(-1), 39-93 Bq kg(-1), respectively. In the plant extractions and infusions as used for consumption, the mean recoveries were from 23% to 60% in maceration and 24-75% in infusion.

Enhanced effects and mechanisms of Syngonium podophyllum-Peperomia tetraphylla co-planting on phytoremediation of low concentration uranium-bearing wastewater

To improve the remediation efficiency of plants on low concentration uranium-bearing wastewater and clarify its strengthening mechanism, Syngonium podophyllum-Peperomia tetraphylla co-planting system was established, the enhanced effects of plants interaction on uranium removal were investigated, the chemical forms, valence states, and subcellular distribution of uranium in plants were confirmed, and the mechanisms of alleviating uranium stress by plants interaction were revealed. In Syngonium podophyllum-Peperomia tetraphylla co-planting system, the total amount of ethanol-extracted uranium and deionized water-extracted uranium with higher toxicity in their roots were reduced by 10.30% and 7.17%, respectively, which reduced the toxicity of uranium to plants. Plants interaction can inhibit the reduction of U(VI) in the root of Peperomia tetraphylla, which is conducive to the transport of uranium from roots to shoots. In addition, uranium in plants mainly existed in the cell wall (54.44%-66.52%) and the soluble fraction (23.85%-32.89%). These results indicated that Syngonium podophyllum and Peperomia tetraphylla co-planting can enhance their effects of uranium removal by alleviating uranium stress with the cell wall immobilization and vacuole compartmentation, improving biomass of plants, increasing bioaccumulation factor and translocation factor of uranium.

Pellucidin A promotes antinociceptive activity by peripheral mechanisms inhibiting COX-2 and NOS: In vivo and in silico study

Peperomia pellucida (PP) belongs to the Peperomia genus, which has a pantropic distribution. PP is used to treat a wide range of symptoms and diseases, such as pain, inflammation, and hypertension. Intriguingly, PP extract is used by different tropical countries for its anti-inflammatory and antinociceptive effects. In fact, these outcomes have been shown in animal models, though the exact bioactive products of PP that exert such results are yet to be discovered. To determine and elucidate the mechanism of action of one of these compounds, we evaluated the antinociceptive effect of the novel dimeric ArC2 compound, Pellucidin A by using in vivo and in silico models. Animals were then subjected to chemical, biphasic and thermal models of pain. Pellucidin A induced an antinociceptive effect against chemical-induced pain in mice, demonstrated by the decrease of the number of writhes, reaching a reduction of 43% and 65% in animals treated with 1 and 5 mg/kg of Pellucidin A, respectively. In the biphasic response (central and peripheral), animals treated with Pellucidin A showed a significant reduction of the licking time exclusively during the second phase (inflammatory phase). In the hot-plate test, Pellucidin A did not have any impact on the latency time of the treated animals. Moreover, in vivo and in silico results show that Pellucidin A’s mechanism of action in the inflammatory pain occurs most likely through interaction with the nitric oxide (NO) pathway. Our results demonstrate that the antinociceptive activities of Pellucidin A operate under mechanism(s) of peripheral action, involving inflammatory mediators. This work provides insightful novel evidence of the biological properties of Pellucidin A, and leads to a better understanding of its mechanism of action, pointing to potential pharmacological use.

Obtainment of the spray-dried extracts of Peperomia pellucida L. (H.B.K.) using different atomization temperatures: physicochemical characterization and technological development for pharmaceutical applications

Spray-dried extracts are prepared as powders or granules after solvent removal, which can be obtained in the presence or absence of pharmaceutical adjuvants. This work aimed to optimize the process of obtaining dried extracts of Peperomia pellucida L. (HBK) by spray drying. The characterization of the extract was performed by thermal analysis, specific surface area, particle size and high performance liquid chromatography (HPLC); then, capsules were developed for antimicrobial treatment, evaluating four bench lots by the determination of the angle of repose and time of flow, scanning electron microscopy, porosity and physicochemical quality control. There were no significant differences between the extracts obtained by spray drying at atomization temperatures of 140 °C, 160 °C and 180 °C, which was confirmed by thermal analysis. Specific surface area varied inversely with the mean particle size. Regarding the marker content by HPLC, no significant differences were found between the samples, although the flavonoid fraction was more stable at 160 °C. Bench lots (I to IV) were developed using the diluents Flowlac®, Starch® 1500, microcrystalline cellulose 250 and Cellactose® 80. Based on the results, the bench lot I, containing Flowlac®, was selected. The results of physicochemical quality control demonstrated that the selected formulation meets the pre-established parameters, and proving to be economically viable.

Modelling the current and future distribution potential areas of Peperomia abyssinica Miq., and Helichrysum citrispinum Steud. ex A. Rich. in Ethiopia

BACKGROUND

The aim of this study is to investigate how climate change influences the distribution of economically and environmentally important species of P. abyssinica and H. citrispinum in Ethiopia. The species distribution modeling intends to forecast species' ecological niche ranges and habitat suitability by employing a variety of environmental parameters as predictors, which is vital for conservation planning and restoration success. Six representative concentration pathways (RCP 2.6, 4.5, and 8.5 for the years 2050 and 2070) with the same resolution of 2.5 min that shows the emission scenarios were used for the prediction. To predict the current and future distributions of H. citrispinum and P. abyssinica 56 and 45 occurrence records from National Herbarium, Addis Ababa University, GBIF, and available literatures were used respectively.

RESULTS

The MaxEnt model predicted habitat suitability for H. citrispinum species with an Area Under Curve (AUC) value of 0.961 ± 0.027, and 0.809 ± 0.045 for P. abyssinica, indicating excellent discriminatory ability or accuracy under the current climate scenario. The Future distribution of suitable habitat for both H. citrispinum and P. abyssinica plant species was accurately predicted with AUC values of 0.960 ± 0.017 and 0.780 ± 0.35, respectively under future climatic scenarios. The jackknife test result indicates that environmental variables such as topographic position index (92.5%), precipitation of the driest quarter (3%) and precipitation in the coldest quarter (1.8%) are associated with the distributions of H. citrispinum, while topographic position index (36.6%), precipitation of driest quarter (21.4%), precipitation of warmest quarter (16.2%) and precipitation seasonality (13.9%) were found to be limiting environmental variables for P. abyssinica under current and future climatic conditions in Ethiopia. The prediction map and interception calculation for both present and projected (in the 2050s and again in the 2070s) climate change scenarios indicate significant habitat loss, decreased, and fragmentation under all RCPs (2.6, 4.5, and 8.5) scenarios for P. abyssinica while habitat gain, and increasing for H. citrispinum in Ethiopia.

CONCLUSIONS

Topographic position index (TPI) is the most impactful predictor variable on the distribution of the two species. Consequently, potentially habitable areas (with diverse aspects and slopes) are increasing for H. citrispinum while decreasing for P. abyssinica.

Two isopentenyl resorcinols from Peperomia tetraphylla

Two isopentenyl resorcinols, peperobtusin B and peperobtusin C, have been isolated from Peperomia tetraphylla. Their structures were determined on the basis of spectroscopic methods, especially ¹H NMR, ¹³C NMR, 2D NMR, and HR-TOF-MS. Two compounds were evaluated for cytostatic activity against G₂, A 549, Hela and HCT 116 cells, but cytostatic activity of both compounds is weak.