Exploring endophytic bacteria communities of Vanilla planifolia.

BACKGROUND: Rhizosphere bacterial community and endophytes are now known to influence plant health and response to environmental stress. Very few studies have reported the diversity of endophytic bacterial communities of Vanilla planifolia and their potential roles in promoting plant growth or contributing to aromatic quality. RESULTS: In this study, the composition and diversity of the Vanilla rhizosphere bacterial community were explored by analyzing rhizosphere soil and root tissue samples as well as green pods of three accessions of Vanilla planifolia grown on different types of substrates (compost and leaf litter). In addition, the endophytic bacterial diversity of roots and green pods as well as the evolution of endophytic bacteria after the curing process of vanilla green pods were analyzed based on a metabarcoding approach. The results showed that bacterial species richness and diversity were higher in the compost. The analysis of the soil bacterial composition displayed that Halomonas, Pseudoalteromonas, Enterobacter and Bradyrhizobium were the most abundant genera. Moreover, the results indicated that the soil bacterial community structure was linked to the host plant genotype. Regarding the roots endophytic bacteria composition, the genera Halomonas, Pseudoalteromonas, Bacillus and Carboxydocella genera were present in all samples, independently from the substrate nature. Several genera including Bacillus, Bradyrhizobium, Burkholderia and Halomonas were transmitted internally from the roots to the green pods. The curing process reduced the bacterial richness and bacterial diversity associated with the green pods. Halomonas, Pseudoalteromonas, Bacillus, and Carboxydocella are the dominant genera in the pods after the curing process. CONCLUSIONS: This study provides an overview of changes of the bacterial communities dynamics especially endophytic in the roots and the green pods. It highlighted bacterial genera (Halomonas, Pseudoalteromonas, Bacillus, and Carboxydocella) potentially implicated in the formation of aroma compounds of vanilla beans.

A 1H NMR-based metabolomic approach to study the production of antimalarial compounds from Psiadia arguta leaves (pers.) voigt.

Psiadia arguta (Asteraceae) is endemic to the island of Mauritius in the Indian Ocean. The species is traditionally used to treat various ailments, such as its use as an expectorant or for the treatment of bronchitis and asthma. Preliminary biological screenings have displayed the antimalarial (Plasmodium falciparum) and anticancer (HeLa human cell line) potential of P. arguta leaves. The phytochemical investigation of this plant has led to the isolation and characterization of sixteen compounds including five antiplasmodial molecules. The accumulation of the antiplasmodial compounds during the growth of the plant was studied by a 1H NMR-based metabolomic approach. In order to identify factors influencing the production of bioactive compounds, young plants of P. arguta were multiplied using in vitro culture techniques, and micro-propagated plants at different stages of development were acclimatized and followed for the experiments. The multivariate data analysis showed an accumulation of four bioactive compounds in the leaves of P. arguta when these plants were challenged with a biotic stress: labdan-13(E)-en-8α-ol-15-yl acetate, labdan-8α-ol-15-yl acetate, labdan-13(E)-ene-8α-ol-15-diol, and (8R,13S)-labdan-8,15-diol.

Antiplasmodial Diterpenoids from Psiadia arguta.

An ethyl acetate extract of Psiadia arguta leaves showed in vitro antiplasmodial activity against Plasmodium falciparum with IC50 values of 12.3 ± 2.4 µg/mL (3D7 strain) and 13.5 ± 3.4 µg/mL (W2 strain). Phytochemical investigation led to the isolation and characterization of 16 compounds including four new diterpenoids: labdan-8α-ol-15-yl-(formate) (1), labdan-8α-ol-15-yl-(2-methylbutanoate) (2), labdan-8α-ol-15-yl-(3-methylpentanoate) (3), and labdan-8α-ol-15-yl-(labdanolate) (4). The latter compounds were characterized by spectroscopic methods (1D and 2D NMR, HRMS, and IR). The in vitro antiplasmodial activities of all compounds were evaluated. The known compounds labdan-13( E)-en-8α-ol-15-yl acetate (5), labdan-8α-ol-15-yl acetate (6), 13- epi-sclareol (7), labdan-13( E)-ene-8α,15-diol (8), and (8 R,13 S)-labdane-8α,15-diol (9) exhibited antiplasmodial effects, with IC50 values of 29.1, 33.2, 35.0, 36.6, and 22.2 µM, respectively.

The genus Psiadia: Review of traditional uses, phytochemistry and pharmacology.

ETHNOPHARMACOLOGICAL RELEVANCE: The genus Psiadia Jacq. ex. Willd. belongs to the Asteraceae family and includes more than 60 species. This genus grows in tropical and subtropical regions, being especially well represented in Madagascar and the Mascarene Islands (La Réunion, Mauritius and Rodrigues). Several Psiadia species have been used traditionally for their medicinal properties in Africa and the Mascarene Islands. Based on traditional knowledge, various phytochemical and pharmacological studies have been conducted. However there are no recent papers that provide an overview of the medicinal potential of Psiadia species. Therefore, the aim of this review is to provide a comprehensive summary of the botany, phytochemistry and pharmacology of Psiadia and to highlight the gaps in our knowledge for future research opportunities. MATERIALS AND METHODS: The available information on traditional uses, phytochemistry and biological activities of the genus Psiadia was collected from scientific databases through a search using the keyword 'Psiadia' in 'Google Scholar', 'Pubmed', 'Sciencedirect', 'SpringerLink', 'Web of Science', 'Wiley' and 'Scifinder'. Additionally, published books and unpublished Ph.D. and MSc. dissertations were consulted for botanical information and chemical composition. RESULTS: Historically, species of the genus Psiadia have been used to treat a wide range of ailments including abdominal pains, colds, fevers, bronchitis, asthma, rheumatoid arthritis, skin infections and liver disorders among others. Phytochemical works led to the isolation of flavonoids, phenylpropanoids, coumarins and terpenoids. Furthermore, phytochemical compositions of the essential oils of some species have been evaluated. Crude extracts, essential oils and isolated molecules showed in vitro pharmacological activities, such as antimicrobial, anti-viral, anti-inflammatory, antiplasmodial and antileishmanial activities. Crude extracts of Psiadia dentata and Psiadia arguta have specifically been found to be potentially useful for inhibition of growth of Plasmodium falciparum. However, pharmacological data on this particular genus is quite limited. Further research is necessary to determine the active compounds and the underlying mechanisms.