Progress of studies on natural products for glioblastoma therapy.

Glioblastoma (GBM) is the most common, malignant, and lethal primary brain tumor in adults. Up to now, the chemotherapy approaches for GBM are limited. Therefore, more studies on identifying and exploring new chemotherapy drugs or strategies overcome the GBM are essential. Natural products are an important source of drugs against various human diseases including cancers. With the better understanding of the molecular etiology of GBM, the development of new anti-GBM drugs has been increasing. Here, we summarized recent researches of natural products for the GBM therapy and their potential mechanisms in details, which will provide new ideas for the research on natural products and promote developing drugs from nature products for GBM therapy.

ß-acetoxyisovalerylalkannin suppresses proliferation and induces ROS-based mitochondria-mediated apoptosis in human melanoma cells.

ß-acetoxyisovalerylalkannin (ß-AIVA) is one of shikonin/alkannin derivative, which were mainly extracted from Boraginaceae family. The effects of ß-AIVA on human melanoma A375 cells and U918 cells were investigated in vitro. The CCK-8 assay showed that ß-AIVA inhibited proliferation of cells. Results from flow cytometry, ROS assay and JC-1 assay showed that ß-AIVA increased late apoptosis rate, induced the production of ROS and promoted mitochondrial depolarization in cells. ß-AIVA regulated expressions of BAX and Bcl-2 proteins, and increased the expression of cleaved caspase-9 and cleaved caspase-3. These findings suggest that ß-AIVA may be a potential therapeutic drug for treating melanoma.

Diverse terpenoid glycosides with in vitro cytotoxicity from Glechoma longituba.

Terpenoids are the largest class of all known natural products, possessing structural diversity and numerous biological activities. Ten previously undescribed terpenoid glycosides, glechlongsides A-J (1-10), were isolated from the ethanol extract of the whole plant of Glechoma longituba, including diterpenoid glycoside and pentacyclic triterpenoid saponin. The structures of these compounds were characterized by extensive analysis of 1D and 2D NMR as well as HRESIMS spectra. In addition, glechlongsides F-I (6-9) exhibited weak cytotoxicity against human cancer cell lines BGC-823, Be1, HCT-8, A2780, and A549 with IC50 values ranging from 3.77 to 30.95 µM, respectively.

Prenylaromadendrane-type diterpenoids from the gum resin of Boswellia sacra flueck and their cytotoxic effects.

Two new prenylaromadendrane-type diterpenoids, and three known analogues, were isolated from the ethanol extract of the gum resin of B. sacra Flueck. The structures of the new compounds were elucidated using 1 D and 2 D NMR spectroscopic analyses, mass spectrometric data, circular dichroism spectra, and comparison with the other compounds in the literature. One diterpenoid represents the first example of an acetoxyl-substituted prenylaromadendranoid in frankincense. All compounds exhibited notable cytotoxicity against human malignant glioma (U87-MG) cell line, with inhibitory rates exceeding that of the positive control 5-fluorouracil. However, nitric oxide inhibition induced by lipopolysaccarides was not observed in primary mouse peritoneal macrophages.

Four new polyprenylated acylphloroglucinol derivatives from Hypericum beanii.

Two new polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperbeanins P-Q (1-2), and two new biosynthetic precursors, hyperbeanins R-S (3-4), were isolated from Hypericum beanii, together with three known analogs (5-7). Compound 1 was one of type A PPAPs featured with unusual bicyclo[5.3.1]hendecane core. The structures of isolates were established by NMR spectroscopic methods, experimental electronic circular dichroism (ECD) spectra and comparisons with known compounds. Compounds 5 and 6 showed obvious hepatoprotective activity at 10 µM against paracetamol-induced HepG2 cell damage.

[Chemical constituents of triterpenoids from Euphorbia resinifera].

The combination of normal-phase silica gel column chromatography, octadecyl silica(ODS) column chromatography, semi-preparative high performance liquid chromatography(HPLC), etc. was employed to isolate and purify the chemical components from Euphorbia resinifera, and 7 triterpenoids were separated from the ethanol extract of the medicinal materials. Their structures were identified by various spectroscopy methods as cycloartan-1,24-diene-3-one(1), cycloartan-1,24-diene-3-ol(2), 3ß-hydroxy-lanosta-8,24-diene-11-one(3), lnonotusane C(4), eupha-8,24-diene-3ß-ol-7,11-dione(5), eupha-24-methylene-8-ene-3ß-ol-7,11-dione(6), and eupha-8,24-diene-3ß,11ß-diol-7-one(7). Compounds 1 and 2 are new compounds, and compound 3 is obtained from nature for the first time.

[Chemical constituents from Hypericum curvisepalum].

This study explored the chemical constituents of the aerial part of Hypericum curvisepalum. Sixteen compounds were isolated from the 95% ethanol extract of H. curvisepalum with various chromatographic techniques, including a new prenylated phenyl polyketide, mysorenone D(1). Other compounds were mysorenone-A(2), mysorenone-C(3), mysorenone-B(4), peplidiforone A(5), 4-methoxy-3-(2-methylbut-3-en-2-yl)-6-phenyl-2H-pyran-2-one(6), hyperenone-A(7), 4-(3,3-dimethylallyl)oxy-6-phenyl-α-pyrone(8), peplidiforone B(9), elegaphenone(10), hypercohin A(11), hyperisampsin G(12), spathulenol(13), quercetin(14), ß-sitosterol(15), and ß-amyrin(16).

Structural Revision of Hyperibrin B and Hyperscabrones H and I by Biosynthetic Considerations, NMR Analysis, and Chemical Synthesis.

Previously, Gao et al. reported the isolation and structural determination of three natural products, hyperibrin B (HB), hyperscabrone H (HH), and hyperscabrone I (HI), from Hypericum scabrum. HB and HH had different NMR spectroscopic data, but they were assigned identical structures. Furthermore, these compounds should be derived from bicyclic polyprenylated acylphloroglucinols (BPAPs) via degradation, but the assigned structural features of the prenyl and prenylmethyl groups being cis and meta-substituted on the cyclohexanone core were not consistent with their biosynthetic origin. In this note, we revise the structures of HB, HH, and HI via NMR and MS spectroscopic analyses and biosynthetic considerations. We also complete a total synthesis of the revised structure of HB as well as its analogue, hyperibrin A, to further confirm the revision. The revised structures of HB, HH, and HI have not been reported.

Chemoproteomics-based target profiling of sinomenine reveals multiple protein regulators of inflammation.

Although sinomenine (SIN) has been used to treat several inflammation-related diseases in the clinic for decades, the detailed anti-inflammatory mechanism remains elusive. Here, we present a chemoproteomic study that supports a polypharmacological mode of action for SIN to inhibit inflammation. Notably, functional validation revealed multiple new protein regulators whose knockdown could significantly affect inflammation.

Hypseudohenrins I - K: three new polycyclic polyprenylated acylphloroglucinol derivatives from Hypericum pseudohenryi.

Three previously unidentified polycyclic polyprenylated acylphloroglucinols (PPAPs) derivatives, hypseudohenrins I-K (1-3), along with a known analogue hyphenrone X (4), were isolated from the aerial part of Hypericum pseudohenryi. The structures of the new compounds were elucidated by NMR spectroscopy and ECD calculation. The anti-inflammatory activity of the compounds was evaluated. Compounds 1-3 showed mild anti-inflammatory activity while hyphenrone X showed prominent anti-inflammatory activity.[Formula: see text].

Two new polycyclic polyprenylated acylphloroglucinols derivatives from Hypericum acmosepalum.

Polycyclic polyprenylated acylphloroglucinols (PPAPs) were mainly obtained from the plants of Hypericum genus of Guttiferae family, and possessed intriguing chemical structures and appealing biological activities. Two new PPAPs derivatives, hyperacmosin C (1) and hyperacmosin D (2) were isolated from H. acmosepalum. Their structures were established by NMR, HREIMS, and experimental electronic circular dichroism spectra. Besides, compound 1 showed significant hepatoprotective activity at 10 µM against paracetamol-induced HepG2 cell damage and compound 2 could moderately increase the relative glucose consumption.

Ten undescribed cembrane-type diterpenoids from the gum resin of Boswellia sacra and their biological activities.

Ten undescribed cembrane-type diterpenes boscartins AL-AU, as well as five known analogues were isolated from Boswellia sacra Flueck. The relative configurations of these boscartins were established by extensive spectroscopic analysis of NMR spectra, IR and MS. The absolute configurations of boscartin AL, boscartin AN and isoincensole oxide were unequivocally assigned by single crystal X-ray diffraction. Meanwhile, the absolute configurations of boscartin AM, boscartin AP and boscartin AQ were determined by an empirical in situ formed Rh-complex ECD method. Biological evaluations showed that four compounds exhibited obvious hepatoprotective activities against paracetamol-induced HepG2 cell damage at 10 µM. Regarding neuroprotective activity, some isolates displayed moderate to evident protective effects against glutamate-induced toxicity in primary cultured fetal rat cortical neurons or oxygen-glucose deprivation toxicity in SK-N-SH Cells at 10 µM.

Hyperacmosins H-J, three new polycyclic polyprenylated acylphloroglucinol derivatives from Hypericum acmosepalum.

Three new polycyclic polyprenylated acylphloroglucinol derivatives, hyperacmosins H-J (1-3), with four known compounds (4-7), were isolated from the air-dried aerial parts of Hypericum acmosepalum. Especially, compounds 1 and 2 were identified as methylated polycyclic polyprenylated acylphloroglucinol derivatives (mPPAPs). Their structures were established by NMR, HRESIMS and experimental electronic circular dichroism (ECD) spectra. The hepatoprotective activity of seven compounds were evaluated. Compounds 1 and 5 exhibited hepatoprotective activity against paracetamol-induced HepG2 cell damage.[Formula: see text].

Hyperascyrins L - N, rare methylated polycyclic polyprenylated acylphloroglucinol derivatives from Hypericum ascyron.

Seven natural compounds, including new compounds hyperascyrins L-N (1-3) and four known compounds (4-7), were acquired from the aerial parts of Hypericum ascyron, that were all identified as methylated polycyclic polyprenylated acylphloroglucinol derivatives (mPPAPs). The structures of these compounds were established by NMR spectroscopy, experimental and calculated electronic circular dichroism (ECD) data. The neuroprotective activities and hepatoprotective activity of these compounds (10 µM) were evaluated. Compounds 1, 2 and 3 exhibited neuroprotection activity. Compounds 1 and 3 show hepatoprotective activity.

Methylated Polycyclic Polyprenylated Acylphloroglucinol Derivatives from Hypericum ascyron.

Hyperascyrins A-H (1-11) and four known compounds (12-15) were acquired from the air-dried aerial parts of Hypericum ascyron and were all identified as methylated polycyclic polyprenylated acylphloroglucinol derivatives. Their structures were established by NMR spectroscopy, experimental and calculated electronic circular dichroism (ECD) data, and comparison with established compounds. Compounds 8 and 9 showed protection against paracetamol-induced HepG2 cell damage at 10 µM. The neuroprotective activities of all compounds (10 µM) were evaluated, and compounds 1 and 8 exhibited mild neuroprotection against glutamate-induced toxicity in SK-N-SH cells.

[Chemical constituents of Hypericum perforatum].

A chemical investigation on the aerial parts of Hypericum perforatum resulted in the isolation of a new phloroglucinol derivatives (1), and seven known compounds (2-8). The structures of the compounds were elucidated by means of spectroscopic methods (MS, IR, 1D NMR, and 2D NMR) as 3-methyl-4,6-di (3- methyl-2-butenyl)-3-(4-methyl-3-pentenyl)-2-(2-ethyl-1-oxobutyl)-cyclohexanone (1)，hyperforin (2)，(2R,3R,4S,6R)-3-methyl-4,6-di(3-methyl-2-butenyl)-2-(2-methyl-1-oxo-propyl)-3-(4-methyl-3-pentenyl)-cyclohexanone (3)，hyperscabrin B (4)，hyperscabrin C (5)，furohyperforin isomer 1 (6)，furoadhyperforin (7)，and furohyperforin (8). Compound 1 was a new compound, and compounds 3-5 were obtained from H. perforatum for the first time.

Synthesis and antitumor activities of sinomenine derivatives on rings A and C.

A series of new sinomenine derivatives were designed, synthesized, and evaluated in tumor inhibitory activity, such as human triple negative breast cancer cell line (MDA-MB-231), glioma cell line (A172), human lung cancer cell line (A549), human colon cancer cell line (HCT-8). The modifications were carried out on rings A and C of the sinomenine by esterificating on phenolic hydroxyl with good yields. The highlight of this work was that the synthetic procedures were concise and sinomenine derivatives demonstrated promising antitumor activities.

Synthesis and antitumor activity of novel substituted uracil-1'(N)-acetic acid ester derivatives of 20(S)-camptothecins.

A series of novel substituted uracil-1'(N)-acetic acid esters (6-20) of camptothecins (CPTs) were synthesized by the acylation method. These new compounds were evaluated for in vitro antitumor activity against tumor cell lines, A549, Bel7402, BGC-823, HCT-8 and A2780. In vitro results showed that most of the derivatives exhibited comparable or superior cytotoxicity compare to CPT (1) and topotecan (TPT, 2), with 12 and 13 possessing the best efficacy. Four compounds, 9, 12, 13 and 16, were selected to be evaluated for in vivo antitumor activity against H22, BGC-823 and Bel-7402 in mice. In vivo testing results indicated that 12 and 13 had antitumor activity against mouse liver carcinoma H22 close to Paclitaxel and cyclophosphamide. 12 had similar antitumor activity against human gastric carcinoma BGC-823 in nude mice compared to irinotecan (3) and possessed better antitumor activity against human hepatocarcinoma Bel-7402 in nude mice than 2. It is also discovered that 12 showed a similar mechanism but better inhibitory activity on topoisomerase I (Topo I) compared to 2. These findings indicate that 20(S)-O-fluorouracil-1'(N)-acetic acid ester derivative of CPTs, 12, could be developed as an antitumor drug candidate for clinical trial.

Polyisoprenylated benzoylphloroglucinol derivatives from Hypericum scabrum.

Four new polyisoprenylated benzoylphloroglucinol derivatives, hyperscabrones J-M (1-4), were isolated from the air-dried aerial parts of Hypericum scabrum. Their structures were elucidated by spectroscopic methods and were subsequently confirmed by comparing with data of known compounds. The absolute configuration of the bicyclo[3.3.1]nonane-2,4,9-trione core was defined by the experimental and calculated electronic circular dichroism (ECD) spectra. The evaluation of their hepatoprotective activities against paracetamol-induced HepG2 cell damage showed that compounds 2 and 4 exhibited significant hepatoprotection at 10µM.

Polycyclic Polyprenylated Acylphloroglucinol Congeners from Hypericum scabrum.

Twenty polycyclic polyprenylated acylphloroglucinols (PPAPs), including the new compounds hyperscabrones A-I (1-9), were isolated from the air-dried aerial parts of Hypericum scabrum. These compounds comprise seven different structural types. All structures were determined by NMR spectroscopic methods and both experimental and calculated electronic circular dichroism (ECD) spectra. The evaluation of their neuroprotective effects on glutamate-induced toxicity in SK-N-SH cells showed that compounds 4-7 exhibited significant neuroprotection at 10 µM. Additionally, compounds 3, 4, 7, and 9 showed moderate hepatoprotective activities against paracetamol-induced HepG2 cell damage at 10 µM.