Saponins from the flower buds of Buddleja officinalis

Molecular networking unveils anti-SARS-CoV-2 constituents from traditionally used remedies

ETHNOPHARMACOLOGICAL RELEVANCE

Plants and fungi have a long tradition in ethnopharmacology for the treatment of infectious diseases including viruses. Many of these natural products have also been used to combat SARS-CoV-2 infections or symptoms of the post- and long-COVID form, owing to the scarcity of clinically approved therapeutics.

AIM OF THE STUDY

The ongoing threat posed by SARS-CoV-2, along with the rapidly evolving new variants, requires the development of new antiviral compounds. The aim of this study was to identify anti-SARS-CoV-2 herbal and fungal extracts used in traditional medicine against acute respiratory infection, inflammation, and related symptoms. Additionally, we sought to characterize their bioactive constituents.

MATERIALS AND METHODS

The antiviral activity and cell cytotoxicity of 179 herbal and fungal extracts were evaluated using two SARS-CoV-2 infection assays in Caco-2 cells. 19 plant extracts with and without anti-SARS-CoV-2 activity underwent detailed dereplication using molecular networking.

RESULTS

Extracts from Angelica sinensis (Oliv.) Diels roots, Annona squamosa L. seeds, Azadirachta indica A. Juss. fruits, Buddleja officinalis Maxim. flowers, Burkea africana Hook. bark and Clinopodium menthifolium (Host) Stace aerial parts showed a potent anti SARS-CoV-2 activity (IC50 < 5 μg/ml) with only moderate cytotoxicity (CC50 > 60 μg/ml, Caco-2). By performing the dereplication with a bioactivity-featured molecular network (MN) on the extract library level, rather than on the level of individual extracts, we could pinpoint compounds characteristic for active extracts. Thus, a straight-forward identification of potential anti-SARS-CoV-2 natural compounds was achieved prior to any fractionation or isolation efforts.

CONCLUSIONS

A sophisticated hyphenation of empirical knowledge with MS-based bioinformatics and automated compound annotation was applied to decipher the chemical space of the investigated extracts. The correlation with experimentally assessed anti-SARS-CoV-2 activities helped in predicting compound classes and structural elements relevant for the antiviral activities. Consequently, this accelerated the identification of constituents from the investigated mixtures with inhibitory effects against SARS-CoV-2.

Buddleja officinalis Maxim.: A review of its botany, ethnopharmacology, phytochemistry, pharmacology, and therapeutic potential for ophthalmic diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Buddleja officinalis Maxim. (B. officinalis), commonly known as "Menghua" "Yangerduo" is a widely recognized traditional herbal medicine in China, Korea, and Vietnam. For thousands of years, it has been used to treat dry eye disease, conjunctivitis, keratitis, eye ulcers, eye pain, cough, asthma, hemoptysis, and other medical conditions.

AIM OF THE REVIEW

This review article aims to provide a concise summary of the botany, ethnopharmacology, phytochemistry, pharmacology, medicinal potential, and application of B. officinalis in treating ophthalmic diseases and critically evaluates the existing literature to establish a scientific basis for its reasonable utilization and further investigation.

MATERIALS AND METHODS

The information reviewed in this study was collected from various electronic resources, including the Web of Science, PubMed, and Google Scholar.

RESULTS

To date, 80 structurally diverse compounds have been isolated and characterized from B. officinalis, primarily flavonoids, phenylethanoids, triterpenoids, and monoterpenes. Extracts and compounds derived from B. officinalis have been reported to possess broad pharmacological effects including anti-dry eye disease, anti-inflammation, anti-oxidation, anti-diabetes, anti-obesity, improving osteoporosis and treatment of skin diseases. This review provides a reference for the future studies on of B. officinalis.

CONCLUSIONS

As a natural medicinal plant, B. officinalis is worthy of further development in botany, ethnopharmacology, phytochemistry, pharmacology, and therapeutic potential for ophthalmic diseases. Although some components have demonstrated multiple pharmacological activities, their mechanisms of action remain unclear. Further studies on the underlying molecular basis and mechanism of action are warranted.

The development and validation of a sensitive HPLC-MS/MS method for the quantitative and pharmacokinetic study of the seven components of Buddleja lindleyana Fort

Buddleja lindleyana Fort., a traditional Chinese medicine, has demonstrated anti-inflammatory, immunomodulatory, antidementia, neuroprotective, antibacterial, and antioxidant effects. Its flowers, leaves, and roots have been used as traditional Chinese medicines. A simple and rapid high-performance liquid chromatography method coupled with mass spectrometry (HPLC-MS/MS) was applied in the multicomponent determination of Buddleja lindleyana Fort., and the discrepancies in the contents from ten different habitats were analyzed. The present study simultaneously determined the concentrations of seven chemical compounds of Buddleja lindleyana Fort. extract in rat plasma via HPLC-MS/MS, which was applied in the pharmacokinetic (PK) study of Buddleja lindleyana Fort. A C18 column was used for chromatographic separation, and ion acquisition was achieved by multiple-reaction monitoring (MRM) in negative ionization mode. The optimized mass transition ion-pairs (m/z) for quantization were 591.5/282.8 for linarin, 609.4/300.2 for rutin, 284.9/133.0 for luteolin, 300.6/151.0 for quercetin, 268.8/116.9 for apigenin, 283.0/267.9 for acacetin, 623.3/160.7 for acteoside, and 252.2/155.8 for sulfamethoxazole (IS). A double peak appeared in the drug–time curve of apigenin, which was associated with entero-hepatic recirculation. There were discrepancies in the contents of seven chemical compounds from 10 batches of Buddleja lindleyana Fort., which were associated with the growth environments. Herein, the pharmacokinetic parameters of seven analytes in Buddleja lindleyana Fort. extract are summarized. The maximum plasma concentration (C_max) of linarin, rutin, luteolin, quercetin, apigenin, acacetin and acteoside were 894.12 ± 9.34 ng mL⁻¹, 130.76 ± 18.33 ng mL⁻¹, 77.37 ± 25.72 ng mL⁻¹, 20.15 ± 24.85 ng mL⁻¹, 146.42 ± 14.88 ng mL⁻¹, 31.92 ± 17.58 ng mL⁻¹, and 649.78 ± 16.42 ng mL⁻¹, respectively. The time to reach C_max for linarin, rutin, luteolin, quercetin, apigenin, acacetin, and acteoside were 10, 5, 5, 5, 180, 10 and 10 min, respectively. This is the first report on the simultaneous determination of seven active components for 10 different growing environments and the pharmacokinetic studies of seven active components in rat plasma after the oral administration of Buddleja lindleyana Fort. extract. This study lays the foundation for a better understanding of the absorption mechanism of Buddleja lindleyana Fort., and the evaluation of its clinical application.

Quality control and pharmacokinetics of Buddleja lindleyana Fort by HPLC-MS/MS.

Glycosides from Buddleja officinalis with their protective effects on photoreceptor cells in light-damaged mouse retinas

A new phenylethanoid, hebitol IV (1), along with fifteen known glycosides (2-16), were isolated from water extract of the flower buds of Buddleja officinalis. Their structures were elucidated on the basis of 1 D-NMR, 2 D-NMR and MS data. Molecular docking showed the potential activities of the natural products against VEGFR-2. Bioassay results revealed that the compounds 10 and 14 exhibited strong inhibitory activity against VEGFR-2 with IC₅₀ values of 0.51 and 0.32 μM, respectively. Moreover, the potential retinal protective effects of 10 and 14 were then investigated in the mouse model featuring bright light-induced retinal degeneration. The results demonstrated remarkable photoreceptor protective activities of 10 and 14 in vivo.

Extraction, Purification, Characterization, and Antiangiogenic Activity of Acidic Polysaccharide from Buddleja officinalis

Firstly, optimal parameters of crude polysaccharide from Buddleja officinalis were obtained as follows: ratio of water to raw material of 26 : 1, ultrasonic power of 240 W, ultrasonic time of 45 min, and ultrasonic temperature of 62°C. Secondly, acidic polysaccharide (APBOM) from Buddleja officinalis was successfully acquired with the yield of 9.57% by using DEAE-52 cellulose and Sephadex G-100 gel column chromatography. Then, we found that total polysaccharide content of APBOM was 94.37% with a sulfuric acid group of 1.68%, uronic acid content of 17.41%, and average molecular weight of 165.4 kDa. Finally, APBOM was confirmed to have significant antiangiogenic effects.

Mimengosides J and K: two new neuroprotective triterpenoids from the fruits of Buddleja lindleyana

Two new 11-methoxyl substituted triterpenoids, named as mimengosides J (1) and K (2), along with seven known compounds, were isolated from the fruits of Buddleja lindleyana. Their structures were elucidated on the basis of spectroscopic analysis. In addition, the new ones were evaluated for protective effects against damage of SH-SY5Y cells induced by 1-methyl-4-phenylpyridinium ion (MPP⁺) and the results indicated that those may be one of the candidate compositions of Buddleja lindleyana for the treatment of neurodegenerative disease.

Bioactive Secondary Metabolites from the Aerial Parts of Buddleja macrostachya

A new iridoid glycoside, buddlemacroside A (1) and 15 known compounds, including 6-α-L-(4″- O-trans-p-coumaroyl)rhamnopyranosylcatalpol (2), 6-α-L-(2″-caffeoyl)rhamnopyranosylcatalpol (3), salidroside (4), echipuroside A (5), darendoside A (6), decaffeoylacteoside (7), acteoside (8), martynoside (9), 8-hydroxylinalool 3- O-β-D-glucopyranoside (10), 9- O-α-L-rhamnopyranosyl-4-hydroxy-cinnamic acid (11), apigenin (12), acacetin-7- O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside (13), mimengoside C (14), buddlejasaponin Ia (15), and buddejasaponin I (16) were isolated from a methanol extract of the aerial parts of Buddleja macrostachya Benth. Their chemical structures were elucidated by extensive spectroscopic analyses, including MS and NMR spectra as well as by comparison with the data reported in the literature. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging test showed that compounds 3 and 7-9 possess significant scavenging capacity, with SC50 values ranging from 6.9-19.6 μM. Compound 8 was shown to have potent inhibitory effect against the release of malondialdehyde (MDA) - the major product of the cellular lipid peroxidation, with IC50 value of 2.3 μM. Compounds 12 and 16 significantly inhibited nitrite production in LPS-stimulated BV2 microglia, with IC50 values of 14.2 and 11.4 μM, respectively. Furthermore, compound 16 showed cytotoxicity toward three human cancer cell lines, including SK-LU-1, MCF7, HepG2, with IC50 values in the range of 6.5-8.0 μM.

Optimization of the Extraction Conditions for Buddleja officinalis Maxim. Using Response Surface Methodology and Exploration of the Optimum Harvest Time

The Box-Behnken design was used to evaluate the effects of the methanol concentration (60-100%), liquid to solid ratio (20:1 to 40:1 mL/g) and extraction time (20-40 min) on the yield of 11 constituents from Buddleja officinalis Maxim using ultrasound-assisted extraction. The Derringer's desirability function approach showed that the modified optimum extraction conditions were: 76% methanol concentration, 33 min extraction time and a 34:1 mL/g solvent to solid ratio. Under these conditions, the experimentally measured yields of the compounds were in good agreement with the predicted values. An accurate and sensitive method was also established using high-performance liquid chromatography with diode-array detection for the simultaneous determination of the 11 compounds in Buddleja officinalis. The newly developed method was used to determine the amounts of bioactive components in Buddleja officinalis during four different growth stages. According to these results, we recommend that the full blossom stage is the best time for harvesting this plant to obtain the highest yield of crude materials.

Activation of AMPK by Buddleja officinalis Maxim. Flower Extract Contributes to Protecting Hepatocytes from Oxidative Stress

The Buddleja officinalis Maxim. flower is used in traditional Chinese and Korean medicine to treat inflammation, vascular diseases, headache, and stroke, as well as enhance liver function. This research investigated the effects of B. officinalis Maxim. flower extract (BFE) on hepatotoxicity. The cytoprotective effects and mechanism of BFE against severe mitochondrial dysfunction and H₂O₂ production in hepatotoxicity induced by coadministration of arachidonic acid (AA) and iron were observed in the HepG2 cell line. In addition, we performed blood biochemical, histopathological, and histomorphometric analyses of mice with carbon tetrachloride- (CCl₄-) induced acute liver damage. BFE inhibited the AA + iron-mediated hepatotoxicity of HepG2 cells. Moreover, it inhibited mitochondrial dysfunction, H₂O₂ production, and glutathione depletion mediated by AA + iron in the same cells. Meanwhile, the cytoprotective effects of BFE against oxidative stress were associated with the activation of AMP-activated protein kinase (AMPK). In particular, based on the histopathological observations, BFE (30 and 100 mg/kg) showed clear hepatoprotective effects against CCl₄-induced acute hepatic damage. Furthermore, it inhibited 4-hydroxynonenal and nitrotyrosine immunoreactivity in hepatocytes. These results provide evidence that BFE has beneficial hepatoprotective effects against hepatic damage via the activation of AMPK pathway. Accordingly, BFE may have therapeutic potential for diverse liver disorders.

Cytotoxic triterpenoid saponins from Lysimachia clethroides

Seven oleanane-type triterpenoid saponins, named clethroidosides A-G (1-7), an ursane-type triterpenoid saponin, clethroidoside H (8), and six known saponins were isolated from the aerial parts of Lysimachia clethroides. The structures of the saponins were elucidated on the basis of physical data analysis (1D and 2D NMR, HR-ESIMS) and chemical evidence. The cytotoxic activities of compounds 1-14 were evaluated against five human tumor cell lines (HT-29, HePG2, BGC-823, A549, and A375). Compounds 3, 4, 6, and 11-13 exhibited moderate cytotoxic activity, with IC50 values of 0.75-2.62 μM, while compound 5 showed selective cytotoxic activity.

Chemical study and medical application of saponins as anti-cancer agents

Saponins are a group of naturally occurring plant glycosides, characterized by their strong foam-forming properties in aqueous solution. The presence of saponins has been reported in more than 100 families of plants out of which at least 150 kinds of natural saponins have been found to possess significant anti-cancer properties. There are more than 11 distinguished classes of saponins including dammaranes, tirucallanes, lupanes, hopanes, oleananes, taraxasteranes, ursanes, cycloartanes, lanostanes, cucurbitanes and steroids. Due to the great variability of their structures, saponins always display anti-tumorigenic effects through varieties of antitumor pathways. In addition, there are a large amount of saponins that still either remain to be trapped or studied in details by the medicinal chemists. This article reviews many such structures and their related chemistry along with the recent advances in understanding mechanism of action and structure-function relationships of saponins at the molecular and cellular levels. These aglycones have been described and their classification and distribution have been listed in the review. Some special saponins with strong antitumor effects have also been exhibited. Ginsenosides, belonging to dammaranes, have been found beneficial targeted on inhibition of tumor angiogenesis by suppressing its inducer in the endothelial cells of blood vessels, and then on prevention of adhering, invasion, and metastasis of tumor cells. Dioscin, one of the steroidal saponins, and its aglycone diosgenin also have been extensively studied on its antitumor effect by cell cycle arrest and apoptosis. Other important molecules discussed include oleanane saponins such as avicins, platycodons, saikosaponins, and soysaponins along with tubeimosides.

Pancreatic lipase-inhibiting triterpenoid saponins from Gypsophila oldhamiana

Three new triterpenoid saponins, gypsosaponins A-C (1-3), were isolated from the roots of Gypsophila oldhamiana (Caryophyllaceae). Their structures were established as 3-O-beta-D-galactopyranosyl-(1-->2)-[beta-D-xylopyranosyl-(1-->3)]-beta-D-glucuronopyranosyl quillaic acid 28-O-alpha-L-arabinopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-fucopyranoside (1), 3-O-beta-D-galactopyranosyl-(1-->2)-[beta-D-xylopyranosyl-(1-->3)]-methyl-beta-D-glucuronopyranosyl gypsogenin 28-O-beta-D-glucopyranosyl-(1-->3)-[beta-D-xylopyranosyl-(1-->4)]-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-fucopyranoside (2), and 23-O-beta-D-glucopyranosyl gypsogenic acid 28-O-beta-D-glucopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->6)]-beta-D-glucopyranoside (3), on the basis of various spectroscopic analyses and chemical degradations. The biological activities of 1-3 were examined inhibitory activity against pancreatic lipase, which showed inhibition of 58.2%, 99.2% and 50.3% at concentration of 1 mg/ml, respectively.

Triterpenoids

This review covers the isolation and structure determination of triterpenoids including squalene derivatives, lanostanes, cycloartanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, uranes, hopanes, isomalabaricanes and saponins. The literature from January to December 2004 is reviewed and 243 references are cited.

Chromatographic determination of plant saponins—An update (2002–2005)

The developments during 2002-2005 in the methods used for saponin analyses in plant material are presented. There were number of papers published on isolation and identification of new saponins by chromatographic techniques. Some new developments can be found in separation techniques or solid and mobiles phases used. Separation of individual saponins is still complicated and time consuming. This is due to the fact that in most of the plant species saponins occur as a multi-component mixture of compounds of very similar polarities. Thus, to isolate single compound for structure elucidation or biological activity testing, a combination of different chromatographic techniques has to be used, e.g. first separation of the mixture to simpler sub-fractions on reversed phase C18 has to be followed by further purification on normal phase Silica gel column. Especially difficult is determination of saponins in plant material as these compounds do not possess chromophores and their profiles cannot be registered in UV. Most HPLC methods apply not only specific registration at 200-210 nm, but these methods are not applicable for determination of many saponins in plant material at levels lower than 200-300 mg/kg. Some new or improved techniques for quantification of saponins in plant material were published in reviewed period. These include further progress in the application of evaporative light scattering detection (ELSD) for saponin profiling and quantification, which is also not only specific but also more sensitive in comparison to 200-210 nm detection. Some progress in development of new applications for liquid chromatography-electrospray mass spectrometry (LC/ESI/MS) for saponin determination has also been done. This method gives highest sensitivity and on line identification of separated saponins and should be recommended for specialized analyses of extracts and pharmaceutical formulas like the validation of a new assay. From non-chromatographic techniques for saponin determination, a sensitive and compound specific ELISA tests for some saponins were developed.

Buddlin, a new compound from Buddleja asiatica

A new compound, named buddlin (1), was isolated from the whole plant of Buddleja asiatica. Its structure was elucidated from spectral evidence.