Development of surrogate standards approach for the determination of polyphenols in Vernonia amygdalina Del

Extraction, detection, bioactivity, and product development of luteolin: A review

Luteolin is a kind of natural flavonoid, widely existing in a variety of plants, has been revealed to have a wide range of biological activities. In recent years, the research results of luteolin are abundant. Here we review the latest research results of luteolin in order to provide new ideas for further research and development of luteolin. In this paper, the focus of the search was published between 2010 and 2024 on the extraction and determination of luteolin, biological activities, and the development and application of luteolin products. A comprehensive search using the keyword "luteolin" was conducted in the PubMed, Web of Science and WIPO databases. Through the collection of related literature, this paper summarized a variety of extraction techniques of luteolin, including immersion extraction, solvent extraction, ultrasonic-assisted extraction, supercritical fluid extraction and so on. The determination methods include: thin layer chromatography (TLC), high performance liquid chromatography (HPLC), capillary electrophoresis (CE), electrochemical method (ED) and so on. In addition, the biological activities of luteolin, including antioxidant, anti-inflammatory, anti-tumor, antibacterial, analgesic and so on, were described. And luteolin as the main component of the product is being gradually developed, and has been used in the field of food, medicine and cosmetics. This paper provides a reference for further study of luteolin.

Vernonia amygdalina aqueous leaf extract modulates metformin pharmacokinetics, inhibits CYP3A4 and CYP2C9 enzymes in streptozotocin-induced diabetic rats

OBJECTIVES

Vernonia amygdalina Del. leaves are used in traditional Southeast Asia and Africa medicinal practices. Metformin is used for diabetes management. This study investigated the effect of a single dose of aqueous leaf extract of V. amygdalina on metformin pharmacokinetics in diabetic rats.

METHODS

Diabetic rats were randomly assigned to four groups, with six rats in each group. Group 1 was administered distilled water. Group 2 was administered V. amygdalina aqueous leaf extract alone. Group 3 was administered metformin alone. Group 4 was co-administered V. amygdalina extract plus metformin. Blood was collected at predetermined intervals, and plasma metformin levels were measured with liquid chromatography. The area under the curve (AUC0-t), maximum plasma concentration (Cmax), time to reach Cmax (Tmax), half-life (t1/2), and clearance (CL), were calculated based on noncompartment analysis. The effect of the extract on CYP2C9, CYP3A4, and UGT activities was determined using a Fluorometric Screening Kit.

RESULTS

The combined treatment altered the pharmacokinetic parameters of metformin. The Tmax increased from 90±0.18 min to 180±0.13 min and the Cmax, increased from 0.91±0.32 μg/mL to 2.153±0.28 μg/mL. Additionally, the AUC(0-t) increased from 118.25±1.37 μg min mL-1 to 301.006±1.96 μg min mL-1 and the t1/2 increased from 34.69±0.61 min to 101.321±0.55 min. However, the CL rate was decreased. The extract inhibited CYP3A4 and CYP2C9 enzyme activities.

CONCLUSIONS

The alteration of pharmacokinetic parameters by the extract suggests potential herb-drug interactions.

Polyphenols in edible plant leaves: an overview of their occurrence and health properties

Edible plant leaves (EPLs) constitute a major renewable functional plant biomass available all year round, providing an essential source of polyphenols in the global diet. Polyphenols form a large family of antioxidant molecules. They protect against the harmful effects of free radicals, strengthen immunity and stimulate the body's natural defenses thanks to their antibacterial and antiviral functions. This study refers to phenolic compounds from 50 edible plant leaves divided into four categories: green leafy vegetables, underutilized leafy vegetables, leafy spices and leafy drinks. It provides data on the identification, occurrence and pharmacological functions of polyphenols contained in EPLs, and provides a better understanding of trends and gaps in their consumption and study. Certain EPLs, such as moringa (Moringa oleifera Lam.), tea (Camellia sinensis L.) and several leafy spices of the Lamiaceae family, reveal important characteristics and therapeutic potential. The polyphenol composition of EPLs makes them functional plants that offer relevant solutions in the fight against obesity, the management of food insecurity and the prevention of chronic diseases.

Polyoxygenated Stigmastane-Type Steroids from Vernonia kotschyana Sch. Bip. ex Walp. and Their Chemophenetic Significance

Four polyoxygenated stigmastanes (1-4) alongside known analogues (7-8) and flavonoids (5-6) were isolated from a dichloromethane/methanol (1:1, v/v) extract of the whole plant of Vernonia kotschyana Sch. Bip. ex Walp. (Asteraceae). Their structures were determined by means of spectroscopic and spectrometric analysis. The relative stereochemistry of the new compounds was established and confirmed via biosynthesis evidence and cyclization of 1 under acidic conditions. A plausible biosynthetic pathway to the new compounds and the chemophenetic significance of the isolated constituents were also discussed. The crude extract, fractions, and compounds (1-3) were assessed for their antibacterial activity against five highly prevalent bacterial strains. The fractions and compounds showed low to moderate activity with minimal inhibitory concentrations (MICs) > 125 µg/mL.

An application of the standardised reference extract quantification strategy in the quality control of ginseng infusions by liquid chromatography with mass spectrometric detection

INTRODUCTION

Limited availability of individual standards is a bottleneck for quality control of functional foods and natural medicines. The use of standard mixtures or secondary standards is a possible alternative in this case. Earlier, an approach known as standardised reference extract (RE) strategy was introduced for HPLC-UV analysis of different plant materials; however, its application in HPLC-MS analysis has not been investigated.

OBJECTIVE

To establish an HPLC-MS-based RE method for determination of ginsenoside content in ginseng infusions using commercially available extract reference material of Panax quinquefolius L.

RESULTS

The developed HPLC-MS method was validated as precise (1.1%-9.4% intra-day variation; 1.6%-12.8% inter-day variation) and highly sensitive [limit of detection (LOD): 1-40 ng/mL; limit of quantification (LOQ): 4-120 ng/mL]. The stability of samples was satisfactory (5.7%-16.3%). The RE quantification method was compared with the external standard method, and the obtained difference was not significant, mostly in the range of 5%-10%. Matrix effects for the diluted samples of RE and ginseng infusions, determined via the standard addition method, were in the range of 85%-115% and 80%-126%, respectively, and were also positively correlated with the ginsenoside concentration. Eleven batches of ginseng infusions from different manufacturers were analysed using the established method.

CONCLUSION

The method for HPLC-MS-based ginsenoside quantification using RE as a secondary standard was established for the first time. The results of this study demonstrate that the application of the standardised RE strategy in HPLC-MS can minimise the matrix effect-related error in addition to the cost-effective quality control of herbal products, foods, and traditional medicines.

Tautomeric phytosterols from Vernonia amygdalina Delile and their anti-cervical cancer activity

Vernonia amygdalina Delile is generally used as green vegetables for cuisine in Nigeria and health tea or products in southeast of china. It was also used as folk medicine for the treatment of anti-helminth, febrifuge, digestive tonic and wounds. In this study, eleven undescribed phytosterols (1-2, 4-12) and six known analogues (3, 13-17) were isolated from the stems of V. amygdalina. Their structures including absolute configurations were elucidated by comprehensive spectroscopic methods (1D and 2D NMR, HRESIMS), X-ray diffraction and comparison of their ECD spectra. Besides, the tautomerism of phytosterols (1, 3-6, 12-17) with hemiacetal moiety were analyzed by solution NMR with different deuterated solvent and variable-temperature experiments. In addition, the cytotoxic activities of isolates against HeLa cells were evaluated. As a result, compound 10 exhibited the most potent anti-cervical cancer activity with the IC₅₀ of 22.44 μM. Mechanism studies indicated that 10 triggered HeLa cells apoptosis through activating caspase signaling pathway. Furthermore, 10 could arrest the cell cycle in S phase and suppress the activation of the PI3K/AKT/mTOR pathway, leading to the inhibition of HeLa cells proliferation.

The Role of Flavonoids as a Cardioprotective Strategy against Doxorubicin-Induced Cardiotoxicity: A Review

Doxorubicin is a widely used and promising anticancer drug; however, a severe dose-dependent cardiotoxicity hampers its therapeutic value. Doxorubicin may cause acute and chronic issues, depending on the duration of toxicity. In clinical practice, the accumulative toxic dose is up to 400 mg/m² and increasing the dose will increase the probability of cardiac toxicity. Several molecular mechanisms underlying the pathogenesis of doxorubicin cardiotoxicity have been proposed, including oxidative stress, topoisomerase beta II inhibition, mitochondrial dysfunction, Ca²⁺ homeostasis dysregulation, intracellular iron accumulation, ensuing cell death (apoptosis and necrosis), autophagy, and myofibrillar disarray and loss. Natural products including flavonoids have been widely studied both in cell, animal, and human models which proves that flavonoids alleviate cardiac toxicity caused by doxorubicin. This review comprehensively summarizes cardioprotective activity flavonoids including quercetin, luteolin, rutin, apigenin, naringenin, and hesperidin against doxorubicin, both in in vitro and in vivo models.

Protective effect of Vernonia amygdalina Delile against doxorubicin-induced cardiotoxicity

Doxorubicin has been used as an anticancer drug and has already indicated effective in the treatment of cancer. The incidence of cardiotoxicity due to doxorubicin was approximately 11%, resulting in the limited use of doxorubicin. Cardiac protection during doxorubicin therapy is needed because it can reduce the incidence of heart failure. Vernonia amygdalina (VA) is traditionally used by Indonesians as a traditional medicine and contains many secondary metabolites, including vernolide, vernodalol, vernoamygdalin, vernolepin, luteolin, luteolin 7-O-beta-glucoronoside and luteolin 7-O-glucoside. The pharmacological activity of VA has been widely studied, including its antimalarial, antidiabetic, anticancer, hepatoprotective, nephroprotective, and antioxidant activities. This research aimed to determine the antioxidant 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, total phenol, total flavonoid, and cardioprotective effects of Vernonia Amygdalina. Negative control was only intraperitoneal injection of doxorubicin (20 mg/kgbw) on the eight day while quercetin (85 mg/kgbw) and ethanol extract of Vernonia amygdalina (EEVA) 100, 200, 400 mg/kgbw dose are orally administered for eight consecutive days. Both quercetin and EEVA groups were also injected with doxorubicin (20 mg/kgbw) on the same day. On the following day, rats were injected with ketamine HCL 75 mg/kgbw and were dissected for heart blood collected. The blood collected 3 ml from each rat was analyzed for biochemical parameters. The analyzed biochemical parameters were Aspartate transaminase (AST), Alanine transaminase (ALT), Ureum, Creatinine, Creatinine kinase-MB (CK-MB), Lactate dehydrogenase (LDH), Troponin T, Brain natriuretic peptide (BNP), and antioxidant parameter Superoxide Dismutase (SOD). The result showed that EEVA antioxidant activity was 40.51 ± 4.89 μg/mL, total flavonoid was 3.79 ± 0.61 mg QE/g extract, and total phenol was 281.575 ± 1.069 mg GAE/g extract. Quercetin (85 mg/kgbw) and EEVA (400 mg/kgbw) reduce AST, ALT, Ureum, Creatinine, CK- MB, LDH, Troponin T, BNP significantly and increase rats' SOD level compared with negative control. So that, this study explicates that EEVA potentials as cardioprotective agent against doxorubicin by reducing biochemical parameters.

Secondary metabolite contents and antimicrobial activity of leaf extracts reveal genetic variability of Vernonia amygdalina and Vernonia calvoana morphotypes

Vernonia species (Asteraceae) are indigenous medicinal and food leaf vegetables commonly consumed in some African countries like Cameroon where they constitute a staple dish called "ndolé." Previous studies have demonstrated the nutritional importance of Vernonia, but there is little knowledge of their agronomic value and genetic potentials. Wide genetic variability in the genus has been established earlier through the study of its pollen. However, to the best of our understanding, no such study has been undertaken on the genetic variability of Vernonia with respect to its secondary metabolites. This study was therefore aimed at evaluating the genetic variability of Vernonia amygdalina (VAA and VALF) and V. calvoana (VCAB, VCAV, VCSB, and VCSV) morphotypes in 2016 based on secondary metabolite content and antimicrobial properties. This involved phytochemical analysis by HPLC/MS for the detection of alkaloids, flavonoids, phenols, and tannins in leaves from each of the six genotypes. Results showed that all tested genotypes are rich in phenols (18 analyzed), flavonoids, and tannins with, VAA richer in phenols (206.1 ± 3.12 µg/g of dry extract), followed by VCAV (197.9 ± 18.03 µg/g). The lowest level of flavonoid was found in VCSV (81.6 ± 7.21 µg/g), while the highest was from VCAB (132.8 ± 31.5 µg/g). VCSV (56.3 ± 4.08 µg/g) had the lowest level of tannins, while VCAB (97.8 ± 23.8 µg/g) had the highest levels. Assessment of antimicrobial activity of leaf extracts from the six genotypes was done by culture on Mueller Hinton (MH) agar and MH broth agar for bacteria and in Sabouraud dextrose agar and Sabouraud dextrose broth media for fungi, respectively. All morphotypes exhibited inhibitory activity on bacteria except VAA, with isoquercetin characteristic of VCSV. Chemotaxonomic analyses of Vernonia morphotypes highlighted the genetic diversity within species and variability of antimicrobial properties of ethanolic leaf extracts among morphotypes. These results provide baseline data in the valuation of genetic resources and the establishment of improvement programs.