Oxindole and Benzoxazinone Alkaloids from the Seeds of Persea americana (Avocado) and Their SIRT1 Stimulatory Activity.

Persea americana Mill. (Lauraceae), commonly known as avocado, is a well-known food because of its nutrition and health benefits. The seeds of avocado are major byproducts, and thus their phytochemicals and bioactivities have been of interest for study. The chemical components of avocado seeds were investigated by using UPLC-qTOF-MS/MS-based molecular networking, resulting in the isolation of seven new oxindole alkaloids (1-7) and two new benzoxazinone alkaloids (8 and 9). The chemical structures of the isolated compounds were identified by the analysis of NMR data in combination with computational approaches, including NMR and ECD calculations. Bioactivities of the isolated compounds toward silent information regulation 2 homologue-1 (SIRT1) in HEK293 cells were assessed. The results showed that compound 1 had the most potent effect on SIRT1 activation with an elevated NAD+/NADH ratio with potential for further investigation as an anti-aging agent.

Linderanidins A-F: Rare oligomeric flavonoids with an unusual C-3-C-4 linkage from the roots of Lindera erythrocarpa and their inhibitory activities on autophagy.

Autophagy is a crucial process for maintaining cellular homeostasis by degrading and recycling unnecessary or damaged cellular components. In the process of exploring autophagy regulators in plants, unique nine oligomeric flavonoids linked by the bonding of C-3 and C-4, consisting of three pairs of biflavonoids, linderanidins A-C [(+)-1/(-)-1, (+)-2/(-)-2, and (+)-3/(-)-3], and three trimeric A-type proanthocyanidins, linderanidins D-F (4-6), were isolated from the roots of Lindera erythrocarpa. The structures and absolute configurations of these compounds were determined using various techniques, such as 1D and 2D NMR, mass spectrometry, X-ray crystallography, and electronic circular dichroism. All isolates were evaluated for their ability to regulate autophagy, and compounds (±)-1-(±)-3, (-)-1-(-)-3, (+)-1-(+)-3 and 4 were found to inhibit autophagy by blocking the fusion process between autophagosome and lysosome in HEK293 cells. This study suggests that unique oligomeric flavonoids possessing a C-3-C-4 linkage derived from the roots of L. erythrocarpa are potent autophagy inhibitors.

Antiviral activity of CAVAC-1901, a combination of 3 standardized medicinal plants, against highly pathogenic influenza A virus in chickens.

Three different medicinal plants that consisted of the formulated mixture (CAVAC-1901) have been traditionally used for distinct medicinal purposes in different areas. Angelica dahurica has been used as an important ingredient of a prescription, Gumiganghwal-tang, for the common cold and influenza. Curcuma longa has been utilized for the treatment of asthma, and jaundice. Pinus densiflora (Korean red pine) has been used to improve memory and brain function for the treatment of vascular. Industrial livestock, which are characterized by dense breeding, are vulnerable to influenza infection, causing severe economic loss and social problems. However, there are no viable alternatives due to the risk of the occurrence of variants. Therefore, the aim of this study was to discover anti-influenza combinations of different medicinal plants with the concept of a multicomponent and multitarget (MCMT) strategy in traditional Chinese medicine (TCM). As part of a continuous project, 3 medicinal plants whose inhibitory activity against influenza A was previously reported at the compound level, and the inhibition of cytopathic effects (CPEs) by these formulated mixtures was evaluated against influenza A virus H1N1. A selected combination with an optimal ratio exhibiting synergistic activity was assessed for its antiviral activity in chickens against the highly pathogenic avian influenza (HPAI) H5N6. The selected combination (CAVAC-1901) showed potent inhibitory effects on the expression of neuraminidase and nucleoprotein, by RT-qPCR, Western blot, and immunofluorescence assays. The antiviral activity was more evident in chickens infected with H5N6. The sample-treated group (50 mg/kg/d) decreased mortality and virus titers in various organs. Our results indirectly suggest synergistic inhibitory activity of the combination of 3 different medicinal plants with different modes of action. Taken together, an optimally formulated mixture (CAVAC-1901) could serve as an effective alternative to current measures to minimize damage caused by HPAIs.

Unique guanidine-conjugated catechins from the leaves of Alchornea rugosa and their autophagy modulating activity.

Natural guanidines, molecules that contain the guanidine moiety, are structurally unique and often exhibit potent biological activities. A phytochemical investigation of the leaves of Alchornea rugosa (Lour.) Müll.Arg. by MS/MS-based molecular networking revealed eight undescribed guanidine-flavanol conjugates named rugonines A-H. The chemical structures of the isolated compounds were comprehensively elucidated by NMR spectroscopy, HRESIMS, and circular dichroism (CD) analysis. All isolated compounds were tested for autophagosome formation in HEK293 cells stably expressing GFP-LC3. The results revealed that compounds rugonines D-G showed potential autophagy inhibitory activity.

Triterpenoid saponins from the leaves and stems of Pericampylus glaucus and their insulin mimetic activities.

During an attempt to discover insulin mimetics, thirteen new triterpenoid saponins (1-13), including three phytolaccagenic acids (1, 2, and 12) and ten serjanic acids (3-11 and 13), as aglycones were isolated from a 70% ethanol extract of leaves and stems from Pericampylus glaucus. The chemical structures of compounds 1-13 were determined through spectroscopic data analysis, including NMR, IR, and HRESIMS. All isolated compounds (1-13) were evaluated using 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-d-glucose (2-NBDG) as a fluorescent-tagged glucose probe to determine their stimulatory effects on glucose uptake in differentiated 3 T3-L1 adipocyte cells. Consequently, four compounds (4, 7, 11, and 12) exhibited stimulatory effects on glucose uptake.

Flavanonol Glycosides from the Stems of Myrsine seguinii and Their Neuroprotective Activities.

The accumulation of amyloid beta (Aß) peptides is common in the brains of patients with Alzheimer's disease, who are characterized by neurological cognitive impairment. In the search for materials with inhibitory activity against the accumulation of the Aß peptide, seven undescribed flavanonol glycosides (1-7) and five known compounds (8-12) were isolated from stems of Myrsine seguinii by HPLC-qTOF MS/MS-based molecular networking. Interestingly, this plant has been used as a folk medicine for the treatment of various inflammatory conditions. The chemical structures of the isolated compounds (1-12) were elucidated based on spectroscopic data, including 1D and 2D nuclear magnetic resonance (NMR), high-resolution electrospray ionization mass spectrometry (HRESIMS) and electronic circular dichroism (ECD) data. Compounds 2, 6 and 7 showed neuroprotective activity against Aß-induced cytotoxicity in Aß42-transfected HT22 cells.

Phenolic Constituents of the Roots of Rhamnoneuron balansae with Senolytic Activity.

With the advent of senolytic agents capable of selectively removing senescent cells in old tissues, the perception of age-associated diseases has been changing from being an inevitable to a preventable phenomenon of human life. In the search for materials with senolytic activity from natural products, six new flavonostilbenes (1-6), three new phenylethylchromanones (7-9), three new phenylethylchromones (10-12), and four known compounds (13-16) were isolated from the roots of Rhamnoneuron balansae. The chemical structures of these isolated compounds were determined based on the interpretation of spectroscopic data, including 1D and 2D NMR, ECD, and HRMS. The absolute configuration of compound 1 was also determined by a Mosher ester analysis and ECD calculations. Compounds 6-8 were shown to selectively destroy senescent cells, and the promoter activity of p16INK4A, a representative senescence marker, was reduced significantly by compound 6. The present results suggest the potential activity of flavonostilbene and phenylethylchromanone skeletons from R. balansae as new senolytics.

Glucose Uptake-Stimulating Galloyl Ester Triterpenoids from Castanopsis sieboldii.

Using molecular networking-guided isolation, three new galloyl ester triterpenoids (1-3), two new hexahydroxydiphenic acid-conjugated triterpenoids (6 and 7), and four known compounds (4, 5, 8, and 9) were isolated from the fruits and leaves of Castanopsis sieboldii. The chemical structures of 1-3, 6, and 7 were elucidated on the basis of interpreting their NMR, HRESIMS, and ECD spectra. All compounds (1-9) were evaluated for their glucose uptake-stimulating activities in differentiated adipocytes using 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-d-glucose as a fluorescent-tagged glucose probe. Compounds 2 and 9 resulted in a 1.5-fold increase in glucose uptake. Among them, compound 2 from the fruits showed an upregulation of p-AMPK/AMPK ratio in differentiated C2C12 myoblasts to support the mechanism proposed of glucose uptake stimulation.

Antiviral activity of furanocoumarins isolated from Angelica dahurica against influenza a viruses H1N1 and H9N2.

ETHNOPHARMACOLOGICAL RELEVANCE: Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav. (Umbelliferae family) is an herbaceous, perennial plant native to northern and eastern Asia. The root of A. dahurica has traditionally been used under the name "Bai Zhi" as a medicinal plant for colds, dizziness, ulcers, and rheumatism. Moreover, it is also an important ingredient of various prescriptions, such as Gumiganghwal-Tang, for the common cold and influenza. AIM OF THE STUDY: Even though various biological activities of the root of A. dahurica have been reported along with its chemical components, the detailed mechanism of how it exerts anti-influenza activity at the compound level has not been studied. Therefore, we investigated the anti-influenza properties of furanocoumarins purified by bioactivity-guided isolation. MATERIALS AND METHODS: Bioactivity-guided isolation from a 70% EtOH extract of the root of A. dahurica was performed to produce four active furanocoumarins. The inhibition of cytopathic effects (CPEs) was evaluated to ascertain the antiviral activity of these compounds against influenza A (H1N1 and H9N2) viruses. The most potent compound was subjected to detailed mechanistic studies such as the inhibition of viral protein synthesis, CPE inhibition in different phases of the viral replication cycle, neuraminidase (NA) inhibition, antiapoptotic activity using flow cytometry, and immunofluorescence. RESULTS: The bioactivity-guided isolation produced four active furanocoumarins, isoimperatorin (1), oxypeucedanin (2), oxypeucedanin hydrate (3) and imperatorin (4) from the n-BuOH fraction. Among them, compound 2 (followed by compounds 1, 4 and 3) showed a significant CPE inhibition effect, which was stronger than that of the positive control ribavirin, against both H1N1 and H9N2 with an EC50 (µM) of 5.98 ± 0.71 and 4.52 ± 0.39, respectively. Compound 2 inhibited the synthesis of NA and nucleoprotein (NP) in a dose-dependent manner. In the time course assays, the cytopathic effects of influenza A-infected MDCK cells were reduced by 80-90% when treated with compound 2 for 1 and 2 h after infection and declined drastically 3 h after infection. The level of viral NA and NP production was markedly reduced to less than 20% for both proteins in compound 2 (20 µM)-treated cells compared to untreated cells at 2 h after infection. In the molecular docking analysis, compound 2 showed a stronger binding affinity for the C-terminus of polymerase acidic protein (PAC; -36.28 kcal/mol) than the other two polymerase subunits. Compound 2 also exerted an antiapoptotic effect on virus infected cells and significantly inhibited the mRNA expression of caspase-3 and Bax. CONCLUSION: Our results suggest that compound 2 might exert anti-influenza A activity via the inhibition of the early phase of the viral replication cycle, not direct neutralization of surface proteins, such as hemagglutinin and NA, and abnormal apoptosis induced by virus infection. Taken together, these findings suggest that furanocoumarins predominant in A. dahurica play a pivotal role in its antiviral activity. These findings can also explain the reasons for the ethnopharmacological uses of this plant as an important ingredient in many antiviral prescriptions in traditional Chinese medicine (TCM).

Antiviral Activities of Compounds Isolated from Pinus densiflora (Pine Tree) against the Influenza A Virus.

Pinus densiflora was screened in an ongoing project to discover anti-influenza candidates from natural products. An extensive phytochemical investigation provided 26 compounds, including two new megastigmane glycosides (1 and 2), 21 diterpenoids (3-23), and three flavonoids (24-26). The chemical structures were elucidated by a series of chemical reactions, including modified Mosher's analysis and various spectroscopic measurements such as LC/MS and 1D- and 2D-NMR. The anti-influenza A activities of all isolates were screened by cytopathic effect (CPE) inhibition assays and neuraminidase (NA) inhibition assays. Ten candidates were selected, and detailed mechanistic studies were performed by various assays, such as Western blot, immunofluorescence, real-time PCR and flow cytometry. Compound 5 exerted its antiviral activity not by direct neutralizing virion surface proteins, such as HA, but by inhibiting the expression of viral mRNA. In contrast, compound 24 showed NA inhibitory activity in a noncompetitive manner with little effect on viral mRNA expression. Interestingly, both compounds 5 and 24 were shown to inhibit nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression in a dose-dependent manner. Taken together, these results provide not only the chemical profiling of P. densiflora but also anti-influenza A candidates.

Oleanane hemiacetal glycosides from Gymnema latifolium and their inhibitory effects on protein tyrosine phosphatase 1B.

Gymnema sylvestre (Retz.) R. Br. ex Schult. has a long history to be used as an antidiabetic herbal medicine. Various varieties of G. sylvestre, have been studied intensively on their 3ß-hydroxy oleanane triterpenoid composition for hypoglycemic effects. It is also well-known that most species belonging to the same genus have similar chemical composition and biological activity. Thus, an extract of the Gymnema latifolium Wall. ex Wight, which showed considerable protein tyrosine phosphatase 1B (PTP1B) inhibitory activity (>70% inhibition at 30 µg/mL), was studied intensively. Extensive chemical investigation on the 70% EtOH of G. latifolium led to the isolation of four previously undescribed oleanane hemiacetal glycosides, gymlatinosides GL1-GL4, three previously undescribed oleanane glycosides, gymlatinosides GL5-GL7, and two known 3ß-hydroxy oleanane analogs. The structures of the previously undescribed compounds were elucidated using diverse spectroscopic methods. The hemiacetal structure of the glycoside portion was further elaborated precisely by HMBC and J resolved proton NMR. Gymlatinosides GL2 and GL3 showed considerable PTP1B inhibitory effect.

12,23-Dione dammarane triterpenes from Gynostemma longipes and their muscle cell proliferation activities via activation of the AMPK pathway.

The aging population is growing rapidly around the world and there is also an increase in sarcopenia, which is characterized by decreased muscle mass, strength and function in the elderly population. AMP-activated protein kinase (AMPK) is an essential sensor and regulator of glucose, lipid and energy metabolism throughout the body. Previous studies have shown that AMPK pathway activation by regular exercise and appropriate dietary control have beneficial effects on skeletal muscle. In the process of searching for new AMPK activators from medicinal plants, we isolated and characterized eight new 12,23-dione dammarane triterpenoids (1-3 and 5-9), as well as one known gypentonoside A from Gynostemma longipes. When all isolates were tested for their AMPK activation activities, seven compounds (1 and 3-8) were significantly activated AMPK phosphorylation in mouse C2C12 skeletal muscle cell lines. Since G. longipes contained a significant amount of active compound 1 (over 2.08% per dried raw plant), it suggested the potential of this plant to be developed as a functional food or botanical drug that enhances muscle proliferation by activating AMPK signaling pathways.

Insulin Mimetic Activity of 3,4- Seco and Hexanordammarane Triterpenoids Isolated from Gynostemma longipes.

As part of ongoing research to find new antidiabetic agents from medicinal plants, the chemical composition of Gynostemma longipes, an ethnomedicinal plant used to treat type 2 diabetes mellitus by local communities in Vietnam, was investigated. Ten new dammarane triterpenes, including two 3,4- seco-dammarane analogues, secolongipegenins S1 and S2 (1 and 2), a 3,4- seco-hexanordammarane, secolongipegenin S3 (3), two hexanordammarane glycosides, longipenosides ND1 and ND2 (4 and 5), and five other dammarane glycosides, longipenosides GL1-GL5 (6-10), were isolated from a 70% EtOH extract of the whole G. longipes plant. The structures of the new compounds were elucidated using diverse spectroscopic methods. All of the isolates were evaluated for their stimulatory activities on glucose uptake in differentiated 3T3-L1 adipocyte cells using 2-[ N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-d-glucose as a fluorescent-tagged glucose probe. The stimulant activities on glucose uptake by the test compounds were mediated via the activation of the AMPK pathway using differentiated mouse C2C12 skeletal myoblasts. Consequently, compounds 1, 2, and 4 enhanced glucose uptake and GLUT4 translocation significantly by regulating the AMPK signaling pathway.