Deciphering anti-infectious compounds from Peruvian medicinal Cordoncillos extract library through multiplexed assays and chemical profiling.

High prevalence of parasitic or bacterial infectious diseases in some world areas is due to multiple reasons, including a lack of an appropriate health policy, challenging logistics and poverty. The support to research and development of new medicines to fight infectious diseases is one of the sustainable development goals promoted by World Health Organization (WHO). In this sense, the traditional medicinal knowledge substantiated by ethnopharmacology is a valuable starting point for drug discovery. This work aims at the scientific validation of the traditional use of Piper species ("Cordoncillos") as firsthand anti-infectious medicines. For this purpose, we adapted a computational statistical model to correlate the LCMS chemical profiles of 54 extracts from 19 Piper species to their corresponding anti-infectious assay results based on 37 microbial or parasites strains. We mainly identified two groups of bioactive compounds (called features as they are considered at the analytical level and are not formally isolated). Group 1 is composed of 11 features being highly correlated to an inhibiting activity on 21 bacteria (principally Gram-positive strains), one fungus (C. albicans), and one parasite (Trypanosoma brucei gambiense). The group 2 is composed of 9 features having a clear selectivity on Leishmania (all strains, both axenic and intramacrophagic). Bioactive features in group 1 were identified principally in the extracts of Piper strigosum and P. xanthostachyum. In group 2, bioactive features were distributed in the extracts of 14 Piper species. This multiplexed approach provided a broad picture of the metabolome as well as a map of compounds putatively associated to bioactivity. To our knowledge, the implementation of this type of metabolomics tools aimed at identifying bioactive compounds has not been used so far.

Metabotyping of Andean pseudocereals and characterization of emerging mycotoxins.

Pseudocereals are best known for three crops derived from the Andes: quinoa (Chenopodium quinoa), canihua (C. pallidicaule), and kiwicha (Amaranthus caudatus). Their grains are recognized for their nutritional benefits; however, there is a higher level of polyphenism. Meanwhile, the chemical food safety of pseudocereals remains poorly documented. Here, we applied untargeted and targeted metabolomics approaches by LC-MS to achieve both: i) a comprehensive chemical mapping of pseudocereal samples collected in the Andes; and ii) a quantification of their contents in emerging mycotoxins. An inventory of the fungal community was also realized to better know the fungi present in these grains. Metabotyping permitted to add new insights into the chemotaxonomy of pseudocereals, confirming the previously established phylotranscriptomic clades. Sixteen samples from Peru (out of 27) and one from France (out of one) were contaminated with Beauvericin, an emerging mycotoxin. Several mycotoxigenic fungi were detected, including Aspergillus sp., Penicillium sp., and Alternaria sp.

Comparison of the Phytochemical Variation of Non-Volatile Metabolites within Mother Tinctures of Arnica montana Prepared from Fresh and Dried Whole Plant Using UHPLC-HRMS Fingerprinting and Chemometric Analysis.

Arnica montana L. has been recognized for centuries as an herbal remedy to treat wounds and promote healing. It also has a long tradition of use in homeopathy. Depending on its medicinal utilization, standardization regulations allow different manufacturing processes, implying different raw materials, such as the whole arnica plant in its fresh or dried state. In this study, an untargeted metabolomics approach with UHPLC-HRMS/MS was used to cross-compare the phytochemical composition of mother tinctures of A. montana that were prepared from either fresh whole plant (fMT) matter or from oven-dried whole plant (dMT) matter. The multivariate data analysis showed significant differences between fMT and dMT. The dereplication of the HRMS and MS/MS spectra of the more discriminant compounds led to annotated quinic acid, dicaffeoyl quinic acids, ethyl caffeate, thymol derivatives and dehydrophytosphingosine, which were increased in fMT, while Amadori rearrangement products (ARP) and methoxyoxaloyl-dicaffeoyl quinic acid esters were enhanced in dMT. Neither sesquiterpene lactones nor flavonoids were affected by the drying process. This is the first time that a sphingosine, ethyl caffeate and ARP are described in A. montana. Moreover, putative new natural products were detected as 10-hydroxy-8,9-epoxy-thymolisobutyrate and an oxidized proline fructose conjugate, for which isolation and full structure elucidation will be necessary to verify this finding.

Patterns of Plumericin Concentration in Leaves of Himatanthus tarapotensis (Apocynaceae) and Its Interactions with Herbivory in the Peruvian Amazon.

We explored the concentration patterns of the bioactive metabolite plumericin produced by Himatanthus tarapotensis (Apocynaceae) under different edaphic conditions and variations in rainfall intensity, as well as its potential role in the chemical defense against insect herbivores. Values of plumericin concentration from leaves were obtained by High-Performance Liquid Chromatography, and evaluated as a function of differences in soil types, variation of precipitation, and variation of the abundance of insect herbivores, using first a Repeated Measures Correlation (rmcorr) and then a Generalized Linear Mixed Model (GLMM) analysis. Plumericin concentration is highly variable among plants, but with a significantly higher concentration in plants growing on clay soil compared to that of the white-sand soil habitat (p < 0.001). Plumericin concentration is not affected by precipitation. The caterpillar of Isognathus leachii (Lepidoptera: Sphingidae) is the most conspicuous herbivore of H. tarapotensis, and its presence is continuous but not related to plumericin concentration, probably because of its capacity to elude the chemical defense of this plant. Nevertheless, our multivariate model revealed that plumericin concentration is related to the abundance of Hymenoptera (Formicidae), and this relationship is significantly influenced by the soil parameters of carbon percentage, clay percentage, and phosphorous percentage (p < 0.001). Plumericin is a mediating agent in the interaction between H. tarapotensis and its natural environment. Variation in plumericin concentration would be induced by the abundance of Hymenoptera (Formicidae), probably as a chemical response against these insects, and by differences in soil nutrient availability.

Chemical fingerprinting of the Brazilian medicinal plant Calea pinnatifida (R. Br.) Less. (Asteraceae) collected at different altitudes.

Calea pinnatifida (R. Br.) Less. is a plant of Brazilian folk medicine. We evaluated the influence of environmental factors on the chemical profile of C. pinnatifida collected during the winter season. C. pinnatifida leaves, alongside soil samples, were collected from two sites of different altitude. Plant samples were sequentially extracted, while soil samples were subject to compositional analysis. Plant extracts were compared using HPTLC-UV, using chemometric analyses to compare samplings harvested at both altitudes. Two marker metabolites, calein A (1) and acetylportentol (2), were isolated from samples collected at the respective altitudes. The differing metabolic profiles observed may be a result of the influence of environmental factors.

Metabolomic approach of the antiprotozoal activity of medicinal Piper species used in Peruvian Amazon.

ETHNOPHARMACOLOGICAL RELEVANCE: In the Peruvian Amazon as in the tropical countries of South America, the use of medicinal Piper species (cordoncillos) is common practice, particularly against symptoms of infection by protozoal parasites. However, there is few documented information about the practical aspects of their use and few scientific validation. The starting point of this work was a set of interviews of people living in six rural communities from the Peruvian Amazon (Alto Amazonas Province) about their uses of plants from Piper genus: one community of Amerindian native people (Shawi community) and five communities of mestizos. Infections caused by parasitic protozoa take a huge toll on public health in the Amazonian communities, who partly fight it using traditional remedies. Validation of these traditional practices contributes to public health care efficiency and may help to identify new antiprotozoal compounds. AIMS OF STUDY: To record and validate the use of medicinal Piper species by rural people of Alto Amazonas Province (Peru) and annotate active compounds using a correlation study and a data mining approach. MATERIALS AND METHODS: Rural communities were interviewed about traditional medication against parasite infections with medicinal Piper species. Ethnopharmacological surveys were undertaken in five mestizo villages, namely: Nueva Arica, Shucushuyacu, Parinari, Lagunas and Esperanza, and one Shawi community (Balsapuerto village). All communities belong to the Alto Amazonas Province (Loreto region, Peru). Seventeen Piper species were collected according to their traditional use for the treatment of parasitic diseases, 35 extracts (leaves or leaves and stems) were tested in vitro on P. falciparum (3D7 chloroquine-sensitive strain and W2 chloroquine-resistant strain), Leishmania donovani LV9 strain and Trypanosoma brucei gambiense. Assessments were performed on HUVEC cells and RAW 264.7 macrophages. The annotation of active compounds was realized by metabolomic analysis and molecular networking approach. RESULTS: Nine extracts were active (IC50 ≤ 10 µg/mL) on 3D7 P. falciparum and only one on W2 P. falciparum, six on L. donovani (axenic and intramacrophagic amastigotes) and seven on Trypanosoma brucei gambiense. Only one extract was active on all three parasites (P. lineatum). After metabolomic analyses and annotation of compounds active on Leishmania, P. strigosum and P. pseudoarboreum were considered as potential sources of leishmanicidal compounds. CONCLUSIONS: This ethnopharmacological study and the associated in vitro bioassays corroborated the relevance of use of Piper species in the Amazonian traditional medicine, especially in Peru. A series of Piper species with few previously available phytochemical data have good antiprotozoal activity and could be a starting point for subsequent promising work. Metabolomic approach appears to be a smart, quick but still limited methodology to identify compounds with high probability of biological activity.

Mass Spectrometry Imaging of Specialized Metabolites for Predicting Lichen Fitness and Snail Foraging.

Lichens are slow-growing organisms supposed to synthetize specialized metabolites to protect themselves against diverse grazers. As predicted by the optimal defense theory (ODT), lichens are expected to invest specialized metabolites in higher levels in reproductive tissues compared to thallus. We investigated whether Laser Desorption Ionization coupled to Mass Spectrometry Imaging (LDI-MSI) could be a relevant tool for chemical ecology issues such as ODT. In the present study, this method was applied to cross-sections of thalli and reproductive tissues of the lichen Pseudocyphellaria crocata. Spatial mapping revealed phenolic families of metabolites. A quantification of these metabolites was carried out in addition to spatial imaging. By this method, accumulation of specialized metabolites was observed in both reproductive parts (apothecia and soralia) of P. crocata, but their nature depended on the lichen organs: apothecia concentrated norstictic acid, tenuiorin, and pulvinic acid derivatives, whereas soralia mainly contained tenuiorin and pulvinic acid. Stictic acid, tenuiorin and calycin, tested in no-choices feeding experiments, were deterrent for N. hookeri while entire thalli were consumed by the snail. To improve better knowledge in relationships between grazed and grazing organisms, LDI-MSI appears to be a complementary tool in ecological studies.

Overcoming deterrent metabolites by gaining essential nutrients: A lichen/snail case study.

Specialised metabolites in lichens are generally considered repellent compounds by consumers. Nevertheless, if the only food available is lichens rich in specialised metabolites, lichenophages must implement strategies to overcome the toxicity of these metabolites. Thus, the balance between phagostimulant nutrients and deterrent metabolites could play a key role in feeding preferences. To further understand lichen-gastropod interactions, we studied the feeding behaviour and consumption in Notodiscus hookeri, the land snail native to sub-Antarctic islands. The lichen Usnea taylorii was used because of its simple chemistry, its richness in usnic acid (specialised metabolite) and arabitol (primary metabolite) and its presence in snail habitats. Choice tests in arenas with intact lichens versus acetone-rinsed lichens were carried out to study the influence of specialised metabolites on snail behaviour and feeding preference. Simultaneously, usnic acid and arabitol were quantified and located within the lichen thallus using HPLC-DAD-MS and in situ imaging by mass spectrometry to assess whether their spatial distribution explained preferential snail grazing. No-choice feeding experiments, with the pure metabolites embedded in an artificial diet, defined a gradual gustatory response, from strong repellence (usnic acid) to high appetence (D-arabitol). This case study demonstrates that the nutritional activity of N. hookeri is governed by the chemical quality of the food and primarily by nutrient availability (arabitol), despite the presence of deterrent metabolite (usnic acid).

Intrathalline Metabolite Profiles in the Lichen Argopsis friesiana Shape Gastropod Grazing Patterns.

Lichen-gastropod interactions generally focus on the potential deterrent or toxic role of secondary metabolites. To better understand lichen-gastropod interactions, a controlled feeding experiment was designed to identify the parts of the lichen Argopsis friesiana consumed by the Subantarctic land snail Notodiscus hookeri. Besides profiling secondary metabolites in various lichen parts (apothecia, cephalodia, phyllocladia and fungal axis of the pseudopodetium), we investigated potentially beneficial resources that snails can utilize from the lichen (carbohydrates, amino acids, fatty acids, polysaccharides and total nitrogen). Notodiscus hookeri preferred cephalodia and algal layers, which had high contents of carbohydrates, nitrogen, or both. Apothecia were avoided, perhaps due to their low contents of sugars and polyols. Although pseudopodetia were characterized by high content of arabitol, they were also rich in medullary secondary compounds, which may explain why they were not consumed. Thus, the balance between nutrients (particularly nitrogen and polyols) and secondary metabolites appears to play a key role in the feeding preferences of this snail.

Which Specialized Metabolites Does the Native Subantarctic Gastropod Notodiscus hookeri Extract from the Consumption of the Lichens Usnea taylorii and Pseudocyphellaria crocata?

Notodiscus hookeri is the only representative of terrestrial gastropods on Possession Island and exclusively feeds on lichens. The known toxicity of various lichen metabolites to plant-eating invertebrates led us to propose that N. hookeri evolved means to protect itself from their adverse effects. To validate this assumption, the current study focused on the consumption of two lichen species: Usnea taylorii and Pseudocyphellaria crocata. A controlled feeding experiment was designed to understand how the snail copes with the unpalatable and/or toxic compounds produced by these lichen species. The occurrence of two snail ecophenotypes, represented by a mineral shell and an organic shell, led to address the question of a metabolic response specific to the phenotype. Snails were fed for two months with one of these lichens and the chemical profiles of biological samples of N. hookeri (i.e., crop, digestive gland, intestine, and feces) were established by HPLC-DAD-MS and compared to that of the lichens. N. hookeri appears as a generalist lichen feeder able to consume toxic metabolite-containing lichens, independently of the ecophenotype. The digestive gland did not sequester lichen metabolites. The snail metabolism might be based on four non-exclusive processes according to the concerned metabolites (avoidance, passive transport, hydrolysis, and excretion).

A new phthalide derivative from Peperomia nivalis.

One new phthalide (1) was isolated from aerial parts of Peperomia nivalis, along with known compounds (2 and 3), reported in this species for the first time. The structure of the new compound was characterised on the basis of 1D (1H and 13C NMR), 2D (COSY, HMQC, HMBC and NOESY) NMR and high-resolution mass spectral (HRMS) data. Compound 2 was isolated from a natural source for the first time but previously synthesised. Compounds 1-3 were evaluated for their anti-Helicobacter pylori and anti-Plasmodium falciparum activities. Compound 1 showed moderate activities against H. pylori (MIC 47.5 µM) and the F32-Tanzania strain of P. falciparum (IC50 8.5 µM). Compounds 2 and 3 exhibited weak anti-H. pylori activity (MIC 241.3 and 237.6 µM, respectively) and were inactive against P. falciparum.