Phytochemical Profile and Anticancer Potential of Endophytic Microorganisms from Liverwort Species, Marchantia polymorpha L.

Liverwort endophytes could be a source of new biologically active substances, especially when these spore-forming plants are known to produce compounds that are not found in other living organisms. Despite the significant development of plant endophytes research, there are only a few studies describing liverwort endophytic microorganisms and their metabolites. In the presented study, the analysis of the volatile compounds obtained from thallose liverwort species, Marchantia polymorpha L., and its endophytes was carried out. For this purpose, non-polar extracts of plant material and symbiotic microorganisms were obtained. The extracts were analyzed using gas chromatography coupled to mass spectrometry. Compounds with the structure of diketopiperazine in the endophyte extract were identified. Liverwort volatile extract was a rich source of cuparane-, chamigrane-, acorane-, and thujopsane-type sesquiterpenoids. The cytotoxicity of ethyl acetate extracts from endophytic microorganisms was evaluated on a panel of cancer (FaDu, HeLa, and SCC-25) cell lines and normal (VERO), and revealed significant anticancer potential towards hypopharyngeal squamous cell carcinoma and cervical adenocarcinoma.

Classifying natural products from plants, fungi or bacteria using the COCONUT database and machine learning

Natural products (NPs) represent one of the most important resources for discovering new drugs. Here we asked whether NP origin can be assigned from their molecular structure in a subset of 60,171 NPs in the recently reported Collection of Open Natural Products (COCONUT) database assigned to plants, fungi, or bacteria. Visualizing this subset in an interactive tree-map (TMAP) calculated using MAP4 (MinHashed atom pair fingerprint) clustered NPs according to their assigned origin (https://tm.gdb.tools/map4/coconut_tmap/), and a support vector machine (SVM) trained with MAP4 correctly assigned the origin for 94% of plant, 89% of fungal, and 89% of bacterial NPs in this subset. An online tool based on an SVM trained with the entire subset correctly assigned the origin of further NPs with similar performance (https://np-svm-map4.gdb.tools/). Origin information might be useful when searching for biosynthetic genes of NPs isolated from plants but produced by endophytic microorganisms.

Dynamic Changes in Endophytic Microorganisms and Metabolites During Natural Drying of Licorice

The method of drying licorice is an important factor affecting the quality of the final product. To determine the best processing method of licorice postharvest, we investigated the interaction of increasing aridity between the endophytic microorganisms and the accumulation of metabolites. Samples from the roots of licorice growing along an aridity gradient during the natural drying process were collected, and the metabolic components, the content of the main active substances and the dynamic changes of the endophytic microbial community were assessed. The glycyrrhizic acid and liquiritin contents decreased slightly or remained flat during natural drying, whereas those of liquiritigenin and isoliquiritigenin increased slightly. Moreover, the Shannon index of endophytic microbial diversity of licorice was the highest in the fresh period and showed a downward trend during the drying process. When the licorice were fresh, Cladosporiaceae and Burkholderiaceae were the dominant family present, but after drying, Nectriaceae and Enterobacteriaceae were the dominant families. A similar trend was also found in which the differential metabolites of licorice were reduced during natural drying. Furthermore, correlation analysis between dominant families and differential metabolites showed that there was a correlation between the two. Therefore, fresh processing is an effective drying method to ensure the quality of licorice. This study revealed the relationship of endophytic microbiota and changes in the licorice metabolites during different stages of drying, which provided a scientific basis for the drying method of licorice.