Oligomeric phloroglucinols with hAChE inhibitory and antibacterial activities from tropic Rhodomyrtus tomentosa.

Alzheimer's diseases (AD) and other infectious diseases caused by drug-resistance bacteria have posed a serious threat to human lives and global health. With the aim to search for human acetylcholinesterase (hAChE) inhibitors and antibacterial agents from medicinal plants, 16 phloroglucinol oligomers, including two new phloroglucinol monomers (1a and 1b), four new phloroglucinol dimers (3a, 3b, 4b, and 5a), six new phloroglucinol trimers (6a, 6b, 7a, 7b, 8a, and 8b), and two naturally occurring phloroglucinol monomers (2a and 2b), along with two known congeners (4a and 5b), were purified from the leaves of tropic Rhodomyrtus tomentosa. The structures and absolute configurations of these new isolates were unequivocally established by comprehensive analyses of their spectroscopic data (NMR and HRESIMS), ECD calculation, and single crystal X-ray diffraction. Structurally, 3a/3b shared a rare C-5' formyl group, whereas 6a/6b possessed a unique C-7' aromatic ring. In addition, 7a/7b and 8a/8b were rare phloroglucinol trimers with a bis-furan and a C-6' hemiketal group. Pharmacologically, the mixture of 3a and 3b showed the most potent human acetylcholinesterase (hAChE) inhibitory activity with an IC50 value of 1.21 ± 0.16 µM. The molecular docking studies of 3a and 3b in the hAChE binding sites were performed, displaying good agreement with the in vitro inhibitory effects. In addition, the mixture of 3a and 3b displayed the most significant anti-MRSA (methicillin-resistant Staphylococcus aureus) with MIC and MBC values of both 0.50 µg/mL, and scanning electron microscope (SEM) studies revealed that they could destroy the biofilm structures of MRSA. The findings provide potential candidates for the further development of anti-AD and anti-bacterial agents.

Two new dammarane triterpenoid saponins from the leaves of Cyclocarya paliurus.

Two undescribed dammarane triterpenoid saponins, cypaliurusides O and P (1 and 2), were isolated from the ethanol extracts of the leaves of Cyclocarya paliurus. Bioactivity assay results showed that compound 1 has potential cytotoxic activities against selected human cancer cell lines in vitro, with IC50 values ranging from 14.55 ± 0.55 to 22.75 ± 1.54 µM. Compound 1 showed better antitumor activity against HepG2 cells with IC50 of 14.55 ± 0.55 µM. In addition, compound 2 showed no obvious antitumor activity.

Phloroglucinol derivatives rhotomensones A-G from Rhodomyrtus tomentosa.

Undescribed phloroglucinol derivatives, rhotomensones A-G, and a known derivative rhodomyrtosone B, were isolated from the leaves of Rhodomyrtus tomentosa. Rhotomensones A-D and G have unreported structural characteristics, in which rhotomensone A substitutes a benzene ring, rhotomensones B-D are bonded with a 2-methylbutanoyl group, and rhotomensone G has two fewer carbons. The structures of these compounds were determined by NMR spectroscopy, circular dichroism (CD) spectroscopy and X-ray crystallography. The inhibitory activities against α-glucosidase of rhotomensones E and F were evaluated in vitro, with IC50 values of 0.50 ± 0.14 mg/mL and 0.07 ± 0.02 mg/mL. Moreover, rhodomyrtosone B showed significant antibacterial activity against some bacteria, with MIC values ranging from 0.50 to 16.00 µg/mL.

Anti-hepatitis B virus activity and hepatoprotective effect of des(rhamnosyl) verbascoside from Lindernia ruellioides in vitro.

Although clinically approved hepatitis B virus (HBV) polymerase inhibitors (lamivudine-3TC, entecavir, etc.) serve as effective therapeutics, the virus can easily generate resistance to them. Therefore, the treatment of HBV infection remains a public health problem. Numerous studies have shown that natural products have prospective anti-HBV activity. The purpose of this study was to isolate and extract des(rhamnosyl) verbascoside from Lindernia ruellioides (Colsm.) Pennell and explore its anti-HBV and hepatoprotective effects. Anti-HBV activity was evaluated in HepG2.2.15 cells, a human hepatocellular carcinoma cell line with HBV-stable infection, and its protective effect was evaluated in HL-7702 cells, a normal human liver cell line. HepG2.2.15 cells maintained normal growth morphology within the selected concentration range of des(rhamnosyl) verbascoside. It also inhibited the expression of HBV antigens and HBV DNA in a dose- and time-dependent manner in vitro. Further, western blot experiments showed that it could downregulate HBV X protein (HBx) expression in a dose-dependent manner. In the H2 O2 -induced hepatocyte injury model, the cell-survival rate of the HL-7702 cells with the highest drug dose reached 85.25%, which was significantly improved compared with that of the model group. Most of the cells returned to normal morphology, showing polygonal or fusiform structures. Thus, it may be stated that des(rhamnosyl) verbascoside exhibits anti-HBV activity and hepatoprotective effects in vitro and may exert an anti-HBV effect via antigen inhibition, HBV DNA secretion, and HBx protein expression.

α-Glucosidase inhibitory and anti-inflammatory activities of dammarane triterpenoids from the leaves of Cyclocarya paliurus.

Diabetes mellitus is caused by chronic inflammation and affects millions of people worldwide. Cyclocarya paliurus leaves have been widely used in traditional folk tea as a remedy for diabetes, but the antidiabetic constituents remain to be further studied. The α-glucosidase inhibitory and anti-inflammatory activities were examined to evaluate their effects on diabetes mellitus, and bioassay-guided separation of C. paliurus leaves led to the identification of twenty dammarane saponins, including eleven new dammarane saponins (1-11). The structures of the isolates were elucidated by spectroscopic methods. Bioactivity assay results showed that compounds 1 and 2 strongly inhibited α-glucosidase activity, with IC50 values ranging from 257.74 µM, 282.23 µM, and strongly inhibited the release of NO, with IC50 values of 9.10 µM, 9.02 µM. Moreover, compound 2 significantly downregulated the mRNA expression of iNOS, COX-2, IL-1ß, NF-κB, IL-6 and TNF-α in LPS-mediated RAW 264.7 cells and markedly suppressed the protein expression of iNOS, NF-κB/p65, and COX-2. Dammarane glucoside 2 exhibited the strongest α-glucosidase inhibitory and anti-inflammatory activities. In addition, the structure-activity relationships (SARs) of the dammarane saponins were investigated. In summary, C. paliurus leaves showed marked α-glucosidase inhibitory and anti-inflammatory activities, and dammarane saponins are responsible for regulating α-glucosidase, inflammatory mediators, and mRNA and the protein expression of proinflammatory cytokines, which could be meaningful for discovering new antidiabetic agents.

Potential anti-diabetic isoprenoids and a long-chain δ-lactone from frangipani (Plumeria rubra).

A decoction of Plumeria rubra flowers has been used traditionally for the treatment of diabetes in China and Mexico. Chemical investigations on the bioactive constituents of these flowers led to the isolation of 30 compounds, including the four new compounds, one iridoiod (1), two triterpenoids (4, 5), and a long-chain δ-lactone (16). In addition, 26 known compounds (2, 3, 6-15, 17-30) are also reported. All of these compounds were identified on the basis of spectroscopic data interpretation and the absolute configurations of compound 4, 5, 16 were determined by Mosher's method. Compounds 1-4, 7, 8 and 16 showed moderate to significant inhibitory activities against α-glucosidase and protein tyrosine phosphatase 1B, with 4 having IC50 values of 19.45 µM and 0.21 µM, respectively.

Anti-Hepatitis B Virus Activity of Esculetin from Microsorium fortunei In Vitro and In Vivo.

Coumarins are widely present in a variety of plants and have a variety of pharmacological activities. In this study, we isolated a coumarin compound from Microsorium fortunei (Moore) Ching; the compound was identified as esculetin by hydrogen and carbon spectroscopy. Its anti-hepatitis B virus (HBV) activity was investigated in vitro and in vivo. In the human hepatocellular liver carcinoma 2.2.15 cell line (HepG2.2.15) transfected with HBV, esculetin effecting inhibited the expression of the HBV antigens and HBV DNA in vitro. Esculetin inhibited the expression of Hepatitis B virus X (HBx) protein in a dose-dependent manner. In the ducklings infected with duck hepatitis B virus (DHBV), the levels of DHBV DNA, duck hepatitis B surface antigen (DHBsAg), duck hepatitis B e-antigen (DHBeAg), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) decreased significantly after esculetin treatment. Summing up the above, the results suggest that esculetin efficiently inhibits HBV replication both in vitro and in vivo, which provides an opportunity for further development of esculetin as antiviral drug.

The caffeoyl phenylethanoid glycosides from Lindernia ruellioides and their anti-HBV effects.

Five caffeoyl phenylethanoid glycosides, including two new ones linderruelliosides A (1) and B (2), were isolated from the leaves and stems of Lindernia ruellioides. Their structures were elucidated on the basis of spectroscopic methods, including extensive NMR and MS spectra. In addition, all these compounds were tested for their anti-HBV activity. Compounds 1, 3, and 4 showed anti-HBV activities, with IC50 values of 54.87, 30.74, and 69.02 µM for HBsAg and 26.70, 5.17, and 7.08 µM for HBeAg, respectively.

Kadcoccinic Acids A-J, Triterpene Acids from Kadsura coccinea.

Eleven triterpene acids including 10 new compounds (kadcoccinic acids A-J, 1-10) were isolated from the stems of Kadsura coccinea. Except for 10, these compounds feature a rearranged lanostane skeleton with a 6/6/5/6 tetracyclic ring system, and compounds 1 and 2 are the first examples of 2,3-seco-6/6/5/6-fused tetracyclic triterpenoids. Their structures were established primarily by spectroscopic and spectrometric methods. Additionally, the absolute configuration of 3 was determined by single-crystal X-ray diffraction. Several of the compounds isolated were tested for their anti-HIV-1 and cytotoxic activities.

Structure and bioactivity of triterpenoids from the stems of Schisandra sphenanthera.

Two new triterpenoids, schisphendilactone A and B (1 and 2), together with three known triterpenoids, were isolated from the stems of Schisandra sphenanthera. Their structures were elucidated by spectroscopic methods, and the absolute configuration of 1 was determined by single-crystal X-ray diffraction. Compound 2 showed moderate inhibitory activity against SW480 cancer cell line, and compound 5 exhibited promising anti-HIV-1 activity with EC50 value of 0.52 µg ml(-1) and therapeutic index value of 117.12.

Kadcotriones A-C: tricyclic triterpenoids from Kadsura coccinea.

Three new triterpenoids, kadcotriones A-C (1-3), together with the biogenetically related lanostane-type triterpenoid (4), were isolated from Kadsura coccinea. Compound 1 features a 12,14ß-dimethyl 6/6/6-fused tricyclic skeleton, while 2 and 3 are characterized by a 6/6/5-ring system. Their structures were determined by NMR and electronic circular dichroism spectroscopic methods. Compounds 2 and 4 exhibited anti-HIV-1 activities with EC50 values of 30.29 and 54.81 µM, respectively.

Six new lignans from the leaves and stems of Schisandra sphenanthera.

Six new lignans, schisphenlignans F-K (1-6), together with ten known ones, were isolated from the leaves and stems of Schisandra sphenanthera. Their structures were elucidated on the basis of spectroscopic methods, including extensive NMR, MS and CD spectra. In addition, some compounds were tested for their acute activity on insulin sensitivity in 3T3-L1 differentiated adipocytes and anti-HIV-1 activity.

Kadcoccitones A and B, two new 6/6/5/5-fused tetracyclic triterpenoids from Kadsura coccinea.

A pair of new triterpenoid epimers, kadcoccitones A (1) and B (2), together with a new biogenetically related compound kadcoccitone C (3), were isolated from Kadsura coccinea. The epimers featured an unprecedented carbon skeleton with a 6/6/5/5-fused tetracyclic ring system unit and a C(9) side chain. Their structures were determined by spectroscopic data, ECD calculation, and single-crystal X-ray diffraction. Compounds 1 and 3 showed anti-HIV-1 activity with an EC(50) value of 47.91 and 32.66 µg/mL, respectively.

[Studies on the chemical constituents of Rubus parvifolius].

OBJECTIVE: To study the chemical constituents of Rubus parvifoliu. METHODS: The constituents were isolated by column chromatography and their structures were elucidated through spectroscopic analysis such as 1H-NMR, 13C-NMR, FT-IR, et al. RESULTS: Seven compounds were isolated from the roots of Rubus parvifolius L., they were identified as p-sitosterol (I), lauric acid (II), O-nitrophenol (III), beta-daucosterol (IV), euscaphic acid (V), camelliagenin A (VI) and(+) -catech in (VII). CONCLUSION: Compounds III and VII are isolated from the plant for the first time.