Lobelia chinensis: chemical constituents and anticancer activity perspective

LC-ESI-MS/MS-Based Comparative Metabolomic Study, Antioxidant and Antidiabetic Activities of Three Lobelia Species: Molecular Modeling and ADMET Study

The hydroethanol (70%) extracts of three Lobelia species (L. nicotianifolia, L. sessilifolia, and L. chinensis) were analyzed using LC-ESI-MS/MS. Forty-five metabolites were identified, including different flavonoids, coumarin, polyacetylenes, and alkaloids, which were the most abundant class. By applying Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) based on LC-ESI-MS/MS analysis, the three species were completely segregated from each other. In addition, the three Lobelia extracts were tested for their antioxidant activities using a DPPH assay and as antidiabetic agents against α-glycosidase and α-amylase enzymes. L. chinensis extract demonstrated significant antioxidant activity with an IC50 value of 1.111 mg/mL, while L. nicotianifolia showed mild suppressing activity on the α-glycosidase activity with an IC50 value of 270.8 μg/mL. A molecular simulation study was performed on the main compounds to predict their potential antidiabetic activity and pharmacokinetic properties. The molecular docking results confirmed the α-glycosidase inhibitory activity of the tested compounds, as seen in their binding mode to the key amino acid residues at the binding site compared to that of the standard drug acarbose. Furthermore, the predictive ADMET results revealed good pharmacokinetic properties of almost all of the tested compounds. The biological evaluation results demonstrated the promising activity of the tested compounds, aligned with the in silico results.

Alkaloids and Polyacetylenes from Hippobroma longiflora with Antiangiogenesis Properties

Four new alkaloids, hippobrines A-D (1-4), along with three new polyacetylenes, hippobrenes A-C (5-7), were isolated from Hippobroma longiflora. Compounds 1-3 possess an unprecedented carbon skeleton. All of the new structures were determined by analyzing their mass and NMR spectroscopic data. The absolute configurations of 1 and 2 were confirmed by single-crystal X-ray analyses, and the absolute configurations of 3 and 7 were deduced using their ECD spectra. Plausible biogenetic pathways of 1 and 4 were proposed. In regard to bioactivities, all compounds (1-7) exhibited weak antiangiogenic activity against human endothelial progenitor cells, with IC₅₀ values ranging from 21.1 ± 1.1 to 44.0 ± 2.3 μg/mL.

Beyond Alkaloids: Novel Bioactive Natural Products From Lobelia Species

In this work, we reviewed the progress in the phytochemical and biological investigations of bioactive components derived from medicinally valuable Lobelia species. In the last 60 years, Lobelia has garnered significant attention from the phytochemist from around the world, majorly due to the discovery of bioactive piperidine alkaloids (e.g., lobinaline and lobeline) in the early 1950s. Later, lobeline underwent clinical trials for several indications including the treatment of attention deficit hyperactivity disorder and a multicenter phase three trial for smoking cessation. Subsequently, several other alkaloids derived from different species of Lobelia were also investigated for their pharmacological characteristics. However, in the last few years, the research focus has started shifting to the characterization of the other novel chemical classes. The major shift has been noticed due to the structurally similar alkaloid components, which essentially share similar pharmacological, physicochemical, and toxicological profiles. In this review, we present an up-to-date overview of their progress with special attention to understanding the molecular mechanisms of the novel bioactive components.

Network Pharmacology-Based Dissection of the Anti-diabetic Mechanism of Lobelia chinensis

Diabetes mellitus (DM) is a chronic inflammatory disease, and the rapidly increasing DM is becoming a major problem of global public health. Traditional Chinese medicine (TCM) has a long history of treating diabetes. It has been developed and utilized because of its good efficacy and no toxic side effects. Lobelia chinensis is a traditional whole grass herbal. With the continuous deepening of pharmacological research on TCM, the active ingredients of L. chinensis are continuously revealed, which contained the alkaloids, flavonoids, flavonoid glycosides and amino acids that have the good effects of anti-inflammatory, anti-viral and anti-diabetic. In order to further explore the targets of active ingredients and its anti-diabetic mechanism, a feasible network pharmacology analysis model based on chemical, pharmacokinetic and pharmacological data was developed by network construction method to clarify the anti-diabetic mechanism of L. chinensis. The present study conducted by gas chromatography–mass spectrometer (GC/MS), which identified 208 metabolites of L. chinensis, of which 23 ingredients may have effective pharmacological effects after absorption, distribution, metabolism, and excretion (ADME) screening. Network pharmacological analysis on the active ingredients revealed that 5-hydroxymethylfurfural in L. chinensis affects the insulin resistance signaling pathway by acting on GSK3B, TNF, and MAPK1, acacetin affects the diabetic pathway by acting on INSR, DPP4, and GSK3B, that regulate type 2 diabetes, non-insulin-dependent DM, and inflammatory diseases. These results successfully indicated the potential anti-diabetic mechanism of the active ingredients of L. chinensis.

New strategy for identifying potential natural HIV-1 non-nucleoside reverse transcriptase inhibitors against drug-resistance: an in silico study

Non-nucleosides reverse transcriptase inhibitors (NNRTIs), specifically targeting the HIV-1 reverse transcriptase (RT), play a unique role in anti-AIDS agents due to their high antiviral potency, structural diversity, and low toxicity in antiretroviral combination therapies used to treat HIV. However, due to the emergence of new drug-resistant strains, the development of novel NNRTIs with adequate potency, improved resistance profiles and less toxicity is highly required. In this work, a novel virtual screening strategy combined with structure-based drug design was proposed to discover the potential inhibitors against drug-resistant HIV strains. Seven structure-variant RTs, ranging from the wild type to a hypothetical multi-mutant were regarded as target proteins to perform structure-based virtual screening. Totally 23 small molecules with good binding affinity were identified from the Traditional Chinese Medicine database (TCM) as potential NNRTIs candidates. Among these hits, (+)-Hinokinin has confirmed anti-HIV activity, and some hits are structurally identical with anti-HIV compounds. Almost all these hits are consistent with external experimental results. Molecular simulations analysis revealed that top 2 hits (Pallidisetin A and Pallidisetin B) bind stably and in high affinity to HIV-RT, which are ready to be experimental confirmed. These results suggested that the strategy we proposed is feasible, trustworthy and effective. Our finding might be helpful in the identification of novel NNRTIs against drug-resistant, and also provide a new clue for the discovery of HIV drugs in natural products.Communicated by Ramaswamy H. Sarma.

Chemical Profiling of Lobelia chinensis with High-Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry (HPLC/Q-TOF MS) Reveals Absence of Lobeline in the Herb

Lobelia chinensis is a kind of herbal medicine widely distributed and used in Asia. The chemical components of this herb, however, have not been well studied until now. Lobeline, as an essential and famous bioactive compound in Lobelia genus, has been assumed to be present in L. chinensis. In order to ascertain its presence and, more importantly, proper use of this herb, chemical profiling this herb with highly sensitive and high-resolution analytical mass spectrometry was applied. In this study, high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC/Q-TOF MS) method was employed to systematically profile the chemical constituents of L. chinensis for the first time. Comparative chemical profiling study of L. chinensis and Lobelia inflata was also conducted to provide evidence whether lobeline is present or not. Piperidine alkaloids except for lobeline, alkaloid-lignan hybrids, flavonoids, polyacetylenes, nonanedioic acid, and some new phytochemicals were successfully identified in L. chinensis simultaneously. Comparing to the chemical profiles of L. inflata, lobeline was found to be absent in L. chinensis. All of the secondary metabolites in L. chinensis were determined with the HPLC/Q-TOF MS method. The absence of lobeline in L. chinensis was confirmed after this extensive study.

Evaluating the cytotoxic effects of the water extracts of four anticancer herbs against human malignant melanoma cells

Malignant melanoma (MM) is the most dangerous type of skin cancer, killing more than 1,100 people each year in Canada. Prognosis for late stage and recurrent MM is extremely poor due to insensitivity to chemotherapy drugs, and thus many patients seek complementary and alternative medicines. In this study, we examined four commonly used anticancer herbs in traditional Chinese medicine, Hedyotis diffusa, Scutellaria barbata, Lobelia chinensis, and Solanum nigrum, for their in vitro antitumor effects toward human MM cell line A-375. The crude water extract of S. nigrum (1 g of dry herb in 100 mL water) and its 2-fold dilution caused 52.8%±13.0% and 17.3%±2.7% cytotoxicity in A-375 cells, respectively (P<0.01). The crude water extract of H. diffusa caused 11.1%±12.4% cytotoxicity in A-375 cells with no statistical significance (P>0.05). Higher concentrated formulation might be needed for H. diffusa to exert its cytotoxic effect against A-375 cells. No cytotoxicity was observed in A-375 cells treated with crude water extract of S. barbata and L. chinensis. Further high performance liquid chromatography-tandem mass spectroscopy analysis of the herbal extracts implicated that S. nigrum and H. diffusa might have adopted the same bioactive components for their cytotoxic effects in spite of belonging to two different plant families. We also showed that the crude water extract of S. nigrum reduced intracellular reactive oxygen species generation in A-375 cells, which may lead to a cytostatic effect. Furthermore, synergistic effect was achieved when crude water extract of S. nigrum was coadministered with temozolomide, a chemotherapy drug for skin cancer.

The anti-tubercular activity of Melia azedarach L. and Lobelia chinensis Lour. and their potential as effective anti-Mycobacterium tuberculosis candidate agents

Objective

To evaluate the anti-mycobacterial activity of Melia azedarach L. (M. azedarach) and Lobelia chinensis Lour. (L. chinensis) extracts against the growth of Mycobacterium tuberculosis (M. tuberculosis).

Methods

The anti-M. tuberculosis activity of M. azedarach and L. chinensis extracts were evaluated using different indicator methods such as resazurin microtiter assay (REMA) and mycobacteria growth indicator tube (MGIT) 960 system assay. The M. tuberculosis was incubated with various concentrations (50–800 μg/mL) of the extracts for 5 days in the REMA, and for 4 weeks in MGIT 960 system assay.

Results

M. azedarach and L. chinensis extracts showed their anti-M. tuberculosis activity by strongly inhibiting the growth of M. tuberculosis in a concentration-dependent manner in the REMA and the MGIT 960 system assay. Particularly, the methanol extract of M. azedarach and n-hexane extract of L. chinensis consistently exhibited their effects by effectively inhibiting the growth of M. tuberculosis in MGIT 960 system for 4 weeks with a single-treatment, indicating higher anti-M. tuberculosis activity than other extracts, and their minimum inhibitory concentrations were measured as 400 μg/mL and 800 μg/mL, respectively.

Conclusions

These results demonstrate that M. azedarach and L. chinensis extracts not only have unique anti-M. tuberculosis activity, but also induce the selective anti-M. tuberculosis effects by consistently inhibiting or blocking the growth of M. tuberculosis through a new pharmacological action. Therefore, this study suggests the potential of them as effective candidate agents of next-generation for developing a new anti-tuberculosis drug, as well as the advantage for utilizing traditional medicinal plants as one of effective strategies against tuberculosis.

Chemical Structure and Immunomodulating Activities of an α-Glucan Purified from Lobelia chinensis Lour

A neutral α-glucan, named BP1, with a molecular mass of approximately 9.45 kDa, was isolated from Lobelia chinensis by hot-water extraction, a Q-Sepharose Fast Flow column and Superdex-75 column chromatography. Its chemical structure was characterized by monosaccharide analysis, methylation analysis and analysis of its FT-IR, high performance gel permeation chromatography (HPGPC) and 1D/2D-NMR spectra data. The backbone of BP1 consists of →₆α-d-Glcp¹→6,3α-d-Glcp¹→(₆α-d-Glcp¹)x-6,3α-d-Glcp¹-(₆α-d-Glcp¹)y→. The side chains were terminal α-d-Glcp¹→ and α-d-Glcp¹→ (₆α-d-Glcp¹)z→₄α-d-Glcp¹→₃α-d-Glcp¹→₄α-d-Glcp¹→ (x + y + z = 5), which are attached to the backbone at O-3 of 3,6α-d-Glcp¹. The results of the effect of BP1 on mouse macrophage cell line RAW 264.7 indicate that BP1 enhances the cell proliferation, phagocytosis, nitric oxide production and cytokine secretion in a dose-dependent manner. Because the inhibitor of Toll-like receptor 4 blocks the BP1-induced secretion of TNF-α and IL-6, we hypothesize that α-glucan BP1 activates TLR4, which mediates the above-mentioned immunomodulating effects.

Preliminary assessment of two non-destructive instrumental techniques for quality evaluation of Lobelia chinensis Lour

Two non-destructive instrumental methods, infrared spectroscopy (IR) and X-ray diffraction (XRD), were studied for quality evaluation of Lobelia chinensis Lour. (L. chinensis). We obtained the IR spectra and XRD patterns of L. chinensis collected from different sources. The similarity of samples was analyzed by calculating the cosine coefficient. The cosine values were in the range of 0.83–0.90, indicating that the main components of L. chinensis samples are similar. Sample L1 and L6 showed a slightly lower similarity than that of L2, L3, L4, L5 detected by the two methods, which revealed that IR and XRD methods exhibited analogous detection ability for quality evaluation of L. chinensis. The two methods could be highly recommended as simple and rapid detection means for quality evaluation of L. chinensis.