Ecklonia cava is edible seaweed that is found in Asian countries, such as Japan and Korea; and, its major components include fucoidan and phlorotannins. Phlorotannins that are isolated from E. cava are well-known to have an antioxidant effect and strong antiviral activity against porcine epidemic diarrhea virus (PEDV), which has a high mortality rate in piglets. In this study, the bioactive components were determined based on two different approaches: (i) bio-guided isolation using the antiviral activity against the H1N1 viral strain, which is a representative influenza virus that originates from swine and (ii) high-resolution mass spectrometry-based dereplication, including relative mass defects (RMDs) and HPLC-qTOFMS fragmentation analysis. The EC70 fraction showed the strongest antiviral activity and contained thirteen phlorotannins, which were predicted by dereplication. Ten compounds were directly isolated from E. cava extract and then identified. Moreover, the dereplication method allowed for the discovery of two new phlorotannins. The structures of these two isolated compounds were elucidated using NMR techniques and HPLC-qTOFMS fragmentation analysis. In addition, molecular modelling was applied to determine the absolute configurations of the two new compounds. The antiviral activities of seven major phlorotannins in active fraction were evaluated against two influenza A viral strains (H1N1 and H9N2). Six of the compounds showed moderate to strong effects on both of the viruses and phlorofucofuroeckol A (12), which showed an EC₅₀ value of 13.48 ± 1.93 μM, is a potential active antiviral component of E. cava.

Ten phenolic constituents, including three new macrocyclic glycosides (1–3), a new phenolic glycoside (5), a new biphenyl glycoside (6), and five known compounds (4, 7–10), were isolated from a 70% MeOH extract of the leaves of Heliciopsis terminalis by liquid chromatography-tandem mass spectrometry (LC-MS/MS)-guided molecular networking. The chemical structures of new compounds 1–3, 5 and 6 were established based on comprehensive spectroscopic data analysis, including 1D and 2D NMR and HRESIMS techniques. All isolated compounds (1–10) were evaluated for their stimulation of glucose uptake in differentiated 3T3-L1 adipocytes using 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-d-glucose (2-NBDG) as a fluorescent glucose analog. Compounds 3, 6 and 8 showed stimulatory effects on the uptake of 2-NBDG in 3T3-L1 adipocyte cells. Among them, compounds 3 and 6 activated the AMPK signaling pathway in differentiated C2C12 myoblasts.

Limacia scandens is traditionally used to treat depression and affective disorders in Malaysia. The chemical compositions have been reported to include bisbenzylisoquinoline and aporphine-type alkaloids in the genus Limacia Lour., but studies on the components of L. scandens have rarely been reported. Therefore, this study was conducted to determine new benzylisoquinoline alkaloid derivatives with autophagy regulation activity from this plant. Bioactivity-guided isolation was applied to various column chromatography methods using RP-18, Sephadex LH-20 open column chromatography, and preparative HPLC. The chemical structures of the isolated compounds were elucidated through spectroscopic data analysis, including NMR, HR-ESI-MS, and ECD data. In addition, isolated compounds were tested for autophagy-regulating activity in HEK293 cells expressing GFP-L3. Three new dimeric benzylisoquinoline alkaloids (1−3), one new 4-hydroxybenzoic acid-conjugated benzylisoquinoline alkaloid (4), and six known compounds (5−10) were isolated from the stems of L. scandens. All compounds (1–10) were screened for autophagy regulation in HEK293 cells stably expressing the GFP-LC3 plasmid. Among the isolated compounds, 1, 2, and 4 showed autophagic regulation activity that blocked the process of combining autophagosomes and lysosomes. They also inhibit the protein degradation process from the autolysosome as inhibitors of autophagy. Novel benzylisoquinoline alkaloids from L. scandens showed potent potency for the inhibition of autophagic flux. This study provides potential candidates for developing natural autophagy inhibitors for disease prevention and treatment.

Gymnema is a genus of the Apocynaceae with more than 50 species. Some of its species such as G. sylvestre and G. latifolium have been reported for their medicinal value. In this study, the genetic diversity of 20 samples of four species of Gymnema in Vietnam was evaluated using the Random Amplification of Polymorphic DNA (RAPD) and the internal transcribed spacer of nuclear ribosomal DNA (ITS-rDNA). Amplified bands obtained with primers UBC701, UBC709, and OPC4 were the highest polymorphic in RAPD analysis. The phylogenetic trees were built grouping the 20 samples into four clusters corresponding to the four Gymnema species according to morphological classification. A number of characteristic SNPs were identified for each species which can be used for authentication and differentiation. The results showed the consensus and usefulness of the two barcoding techniques in the molecular identification and characterization of the Gymnema genus.