Identification of antitumor lignans from the seeds of morning glory (Pharbitis nil)

Pharbitidis Semen: A review of botany, traditional uses, phytochemistry, pharmacology, and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Pharbitidis Semen (the seeds of Ipomoea nil (L.) Roth or Ipomoea purpurea (L.) Roth), a popular traditional Chinese medicine, is also known as "Heichou" or "Baichou" (Chinese: , ). It can purge the bowels, promote diuresis, remove stagnated accumulation, and kill worms. It can be used for treating anasarca with constipation and oliguria; dyspnea and cough caused by retained fluid; abdominal pain because of intestinal parasitosis; ascariasis; and taeniasis.

AIMS

This review discusses the botany, ethnopharmacology, phytochemistry, pharmacological activities, toxicology, and quality control of Pharbitidis Semen, to obtain a complete understanding of its effects and provide a basis for further research and the development of new drugs.

MATERIALS AND METHODS

The literature on Pharbitidis Semen is mainly obtained from pharmacopoeias of different countries, masterpieces of traditional Chinese medicine, Master's and Ph.D. theses, and published articles obtained from literature retrieval websites, such as CNKI, PubMed, SciFinder, WanFang data, Web of Science, Springer, ScienceDirect, Wiley, ACS Publications, Taylor & Francis, J-STAGE, and Google Scholar. Its botany, ethnopharmacology, phytochemistry, pharmacological activities, toxicology, and quality control are discussed to understand its effects and provide a basis for further research.

RESULTS

Pharbitidis semen has been used ethnomedically in many tropical and subtropical countries as deobstruents, diuretics, and anthelmintics. About 170 chemical compounds, including terpenoids, phenylpropanoids, resin glycosides, fatty acids and other compounds, have been isolated. It has been reported to have different effects, including laxative, renal-protective, neuroprotective, insecticidal, antitumor, anti-inflammatory, and antioxidant. Moreover, a brief introduction to processing, toxicity, and quality control is provided.

CONCLUSIONS

The traditional efficacy of Pharbitidis Semen in diarrhea has been confirmed, but its bioactive and toxic ingredients are not entirely clear. It is necessary to strengthen the research and identification of effective parts or natural active components of Pharbitidis Semen, clarify the molecular mechanism of its toxicity and change rule of endogenous substances to make Pharbitidis Semen better used in clinical practice. Additionally, the imperfect quality standard is also a challenge that must be solved urgently. The study of modern pharmacology has broadened the application of Pharbitidis Semen and provided ideas for better utilization of this resource.

Identification and Evaluation of Apoptosis-Inducing Activity of Ipomone from Ipomoea nil: A Novel, Unusual Bicyclo-[3.2.1] Octanone Containing Gibberic Acid Diterpenoid

Ipomone (1), a novel diterpenoid along with seven known compounds (2-8), was isolated for the first time from the acidified hydroalcoholic extract of Ipomoea nil seeds. The structures of the isolated compounds were elucidated via comprehensive NMR spectroscopic data. The absolute configuration of 1 was ascertained through NOESY, NMR, and ECD analyses. Compound 1 was found to contain an unusual bicyclo-[3.2.1] octanone, which appeared first time in any natural product that might be an artifact resulting from the acid-catalyzed 1,2 alkyl shift/rearrangement. The novel compound was screened for cytotoxic activity against a panel of 12 human cancer cell lines and exhibited weak cytotoxicity with IC₅₀ values in the range of 34-86 μM (except for HEK-293 cells). Microscopic studies revealed that compound 1 induced apoptosis and autophagy in A549 cells. To further explore the signaling pathway involved, immunoblot analysis was performed that confirmed inhibition of apoptotic proteins PARP-1 and caspase-3 expression and upregulation of LC3B expression by compound 1. The compound was further subjected to molecular docking studies to evaluate its binding affinity with p110α, PARP-1, and caspase-3 proteins.

Active Compound of Pharbitis Semen (Pharbitis nil Seeds) Suppressed KRAS-Driven Colorectal Cancer and Restored Muscle Cell Function during Cancer Progression

Kirsten rat sarcoma viral oncogene homolog (KRAS)-driven colorectal cancer (CRC) is notorious to target with drugs and has shown ineffective treatment response. The seeds of Pharbitis nil, also known as morning glory, have been used as traditional medicine in East Asia. We focused on whether Pharbitis nil seeds have a suppressive effect on mutated KRAS-driven CRC as well as reserving muscle cell functions during CRC progression. Seeds of Pharbitis nil (Pharbitis semen) were separated by chromatography and the active compound of Pharbitis semen (PN) was purified by HPLC. The compound PN efficiently suppressed the proliferation of mutated KRAS-driven CRC cells and their clonogenic potentials in a concentration-dependent manner. It also induced apoptosis of SW480 human colon cancer cells and cell cycle arrest at the G2/M phase. The CRC related pathways, including RAS/ERK and AKT/mTOR, were assessed and PN reduced the phosphorylation of AKT and mTOR. Furthermore, PN preserved muscle cell proliferation and myotube formation in cancer conditioned media. In summary, PN significantly suppressed mutated KRAS-driven cell growth and reserved muscle cell function. Based on the current study, PN could be considered as a promising starting point for the development of a nature-derived drug against KRAS-mutated CRC progression.

New ent-kauran diterpene and antioxidant components from the seed of Ipomoea nil

One new ent-kauran diterpene, 7β,16β,17-trihydroxy ent-kauran 19-(6β)-olide (1), along with eight known compounds were isolated from the seed of Ipomoea nil. Isolates caffeoylquinic acid derivatives 5-9 were found for the first time in this species. All structures were identified from various spectroscopic data. trans-Caffeic acid 3, phenylpropanoid 4, and caffeoylquinic acid derivatives 5-9 could inhibit ROS generations induced in human keratinocyte HaCaT cells with IC₅₀ values of 0.94-28.40 μM. Compounds 3 and 5-9 also had DPPH free radical scavenging properties (IC₅₀ values, 14.86-68.27 μM), however, isolate 4 did not show inhibition effect. Generally, I. nil and its secondary metabolites 3-9 could be further applied for oxidative stress damage resulted in skin disorders.

New octadecanoid derivatives from the seeds of Ipomoea nil

Four new octadecanoid derivatives (1-4) including a pair of enantiomers (1/2), along with 12 known analogues (5-16), were isolatedfrom the seeds of Ipomoea nil. Their structures were determined by detailed spectroscopic analyses and comparison with reported data of structurally related compounds, with the absolute configurations of 1 and 2 being assigned by an in situ dimolybdenum ECD method. Our bioassays revealed that these isolates did not show ABTS radical scavenging activity while 10 and 13 displayed better α-glucosidase inhibitory activity than the positive control acarbose (IC₅₀ 167.7 ± 1.55 μmol·L^-1), with IC₅₀ of 92.73 ± 3.12 and 11.39 ± 2.18μmol·L^-1, respectively.

In vitro assessment of selected Korean plants for antioxidant and antiacetylcholinesterase activities

CONTEXT

Antiacetylcholinesterase (AChE) drugs have been a main therapeutic treatment for Alzheimer's disease because increased AChE levels play a key role in reducing neurotransmission.

OBJECTIVES

Extracts from 35 Korean plants were selected and screened for antioxidant and anti-cholinesterase activity to explore new sources derived from Korean natural resources that could be used as AD therapeutic agents.

MATERIALS AND METHODS

The antioxidant effect of extracts from 35 selected Korean plants was determined using two most common free radical scavenging assays using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS). Additionally, the effect of extracts, identified as antioxidants, on acetylcholinesterase inhibition was assessed by an acetylcholinesterase assay kit.

RESULTS

Out of 36 extracts of 35 plants tested, Oenothera biennis L. (9.09 μg/mL), Saururus chinensis (Lour.) Baill. (9.52 μg/mL) and Betula platyphylla var. japonica (9.85 μg/mL) showed strong DPPH scavenging activity. Twelve other extracts also exerted moderate free radical scavenging activities with IC50 values ranging from 10 to 50 μg/mL. Antioxidant capacity detected by ABTS assay was only significant in O. biennis (23.40 μg/mL), while the other extracts were weak or unable to reduce the production of ABTS. Based on the antioxidant activities of these plant extracts, 19 extracts with IC50 values less than 100 μg/mL in DPPH assay were selected for further AChE inhibition assay. Among the extracts tested, the IC50 value for Prunella vulgaris var. lilacina NAKAI (18.83 μg/mL) in AChE inhibitory activity was the lowest, followed by O. biennis (20.09 μg/mL) and Pharbitis nil Chosy (22.79 μg/mL).

CONCLUSIONS

Considering complex multifactorial etiology of AD, the extracts of P. vulgaris var. lilacina (aerial part), O. biennis (seed) and P. nil (seed) may be safe and ideal candidates for future AD modifying therapies.

Pharbitis Nil (PN) induces apoptosis and autophagy in lung cancer cells and autophagy inhibition enhances PN-induced apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Pharbitis Nil (PN) is used as a main component of the existing drug, DA-9701, which was developed to treat functional dyspepsia (FD) in Korea. PN extracts isolated from its seeds have been reported to have anticancer effects.

AIM OF THE STUDY

The purpose of this study was to investigate the underlying mechanism of the chemotherapeutic effects of PN in lung cancer cells.

MATERIALS AND METHODS

We performed MTT assays, colony formation assays, flow cytometry assays, Western blot analysis, reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence analysis, and cell counting assays to study the molecular mechanism of chemotherapeutic effects of PN in lung cancer cells.

RESULTS

Our results indicate that PN induced autophagy as well as apoptosis. PN inhibited cell proliferation and survival by inducing apoptosis in several lung cancer cell lines. PN-treated cells also exhibited induction of autophagy, as evidenced by increased protein expression levels and punctuate patterns of LC3 II. Moreover, activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), which plays an important role in autophagy activation, was shown to be related with PN-induced autophagy. Interestingly, pharmacological blockade of autophagy activation with wortmannin and inhibition of ERK1/2 phosphorylation by U0126 markedly enhanced PN-induced apoptosis and reduced cell viability, suggesting that autophagy induced by PN may have a cytoprotective effect by suppressing apoptosis. PN- induced apoptosis was regulated by signal transducer and activator of transcription 3 (STAT3) deactivation. Moreover, decrease of STAT3 activation in PN-treated cells was associated with reduced survivin expression, further demonstrating that PN-induced apoptosis was regulated by STAT3 deactivation.

CONCLUSION

We believe that PN, which is already proven to treat human patients with FD, might be a potential anticancer drug for human lung cancer. In addition, our data suggest that the combination of PN treatment with an autophagy inhibitor or traditional anticancer agents may be an effective anticancer therapy.

First total synthesis of quiquesetinerviusin A

The first total synthesis of the dihydrobenzofuran neolignan quiquesetinerviusin A and its related structure have been described. Phenolic coupling is the key step to constructing the dihydrobenzofuran skeleton with vanillin as the raw material. The hydroxyl group was protected with dihydropyran (DHP) and the ester group was reduced with diisobutylaluminium hydride (DIBAL-H) in order to obtain the crucial intermediate diol, which was then condensed with an acid ligand to give the desired compounds following removal of the protecting groups.

Pharbilignan C induces apoptosis through a mitochondria-mediated intrinsic pathway in human breast cancer cells

Pharbitidis Semen, the seed of Morning glory (Pharbitis nil), is a medicinal agent that has traditionally been used as a purgative in Korea. Pharbilignan C (PLC) is a dihydro[b]-benzofuran-type neolignan from Pharbitidis Semen, which reportedly exhibited the most potent cytotoxicity against human tumor cells. To further study the antiproliferative activity of PLC, its molecular mechanisms of action in two breast adenocarcinoma cells, MCF-7 and MDA-MB 231 cells were investigated. PLC inhibited the proliferation of MDA-MB 231 and MCF-7 cells, in order of sensitivity (IC50 of MDA-MB 231 cells: 7.0±2.0μM). PLC induced apoptosis in MDA-MB 231 cells with down regulation of Bcl-2 and up-regulation of Bax expression. It also decreased mitochondrial membrane potential accompanied with increasing initiator caspase, caspase-9 activation and executioner caspase, caspase-3 activation. This study demonstrates that PLC inhibited proliferation of MDA-MB 231 cells by inducing apoptosis via the mitochondria-mediated intrinsic pathway.

Polyhydroxytriterpenoids and Phenolic Constituents from Forsythia suspensa (Thunb.) Vahl Leaves

Forsythia suspensa (Thunb.) Vahl leaves have been consumed in China as a health-promoting functional tea for centuries. Three new polyhydroxytriterpenoid glycosides named suspensanosides A-C (1-3), seven known polyhydroxytriterpenoids (4-10), and 12 known phenolics (11-22) were identified from F. suspensa leaves. Compounds 1-10, 15-17, and 22 have not been found in the Forsythia genus previously, whereas compound 14 was first reported to be isolated from the leaves of F. suspensa. All isolates were tested for their antiproliferative activities on BGC-823 and MCF-7 human tumor cell lines, whereas all phenolics were further investigated for their antioxidant activities by a DPPH assay. The results clearly demonstrate that triterpenoids, especially ursane-type triterpenoids, and the diverse phenolic components are crucial for the beneficial effects of F. suspensa leaves.