Medicinal importance, pharmacological activities, and analytical aspects of hispidulin: A concise report

Hispidulin: A novel natural compound with therapeutic potential against human cancers

Cancer is one of the most devastating disease and leading cause of death worldwide. The conventional anticancer drugs are monotarget, toxic, expensive and suffer from drug resistance. Development of multi-targeted drugs from natural products has emerged as a new paradigm to overcome aforementioned conventionally encountered obstacles. Hispidulin (HIS), is a biologically active natural flavone with versatile biological and pharmacological activities. The anticancer, antimutagenic, antioxidative and anti-inflammatory properties of HIS have been reported. The aim of this review is to summarize the findings of several studies over the last few decades on the anticancer activity of HIS published in various databases including PubMed, Google Scholar, and Scopus. HIS has been shown to reduce the growth of cancer cells by inducing apoptosis, arresting cell cycle, inhibiting angiogenesis, invasion and metastasis via modulating multiple signaling pathways implicated in cancer initiation and progression. Multitargeted anticancer activity of HIS remains the strongest point for developing it into potential anticancer drug. We also highlighted the natural sources, anticancer mechanism, cellular targets, and chemo-sensitizing potential of HIS. This review will provide bases for design and conduct of further pre-clinical and clinical trials to develop HIS into a lead structure for future anticancer therapy.

Protective Effects of Polyphenols against Ischemia/Reperfusion Injury

Myocardial infarction (MI) is a leading cause of morbidity and mortality across the world. It manifests as an imbalance between blood demand and blood delivery in the myocardium, which leads to cardiac ischemia and myocardial necrosis. While it is not easy to identify the first pathogenic cause of MI, the consequences are characterized by ischemia, chronic inflammation, and tissue degeneration. A poor MI prognosis is associated with extensive cardiac remodeling. A loss of viable cardiomyocytes is replaced with fibrosis, which reduces heart contractility and heart function. Recent advances have given rise to the concept of natural polyphenols. These bioactive compounds have been studied for their pharmacological properties and have proven successful in the treatment of cardiovascular diseases. Studies have focused on their various bioactivities, such as their antioxidant and anti-inflammatory effects and free radical scavenging. In this review, we summarized the effects and benefits of polyphenols on the cardiovascular injury, particularly on the treatment of myocardial infarction in animal and human studies.

Current Perspectives of the Applications of Polyphenols and Flavonoids in Cancer Therapy

The development of anticancer therapies that involve natural drugs has undergone exponential growth in recent years. Among the natural compounds that produce beneficial effects on human health, polyphenols have shown potential therapeutic applications in cancer due to their protective functions in plants, their use as food additives, and their excellent antioxidant properties. The possibility of combining conventional drugs-which are usually more aggressive than natural compounds-with polyphenols offers very valuable advantages such as the building of more efficient anticancer therapies with less side effects on human health. This review shows a wide range of trials in which polyphenolic compounds play a crucial role as anticancer medicines alone or in combination with other drugs at different stages of cancer: cancer initiation, promotion, and growth or progression. Moreover, the future directions in applications of various polyphenols in cancer therapy are emphasized.

Hispidulin alleviates imiquimod-induced psoriasis-like skin inflammation by inhibiting splenic Th1/Th17 cell population and keratinocyte activation

Psoriasis is a chronic inflammatory skin disease characterized by hyperproliferation and abnormal differentiation of epidermal keratinocytes accompanied by increased infiltration of immune cells. Previous studies have demonstrated that hispidulin (4',5,7-trihydroxy-6-methoxyflavone, HPD) has various pharmacological benefits such as anti-fungal, anti-inflammation, and anti-allergic effects. This study investigated the effectiveness of HPD to treat psoriasis using an imiquimod (IMQ)-induced mouse model and activated keratinocytes. IMQ was topically applied to the back skin of mice for six consecutive days, and the mice were orally administered HPD. Based on the histological observation and immunological analysis, oral administration of HPD suppressed psoriatic characteristics including skin thickness, psoriasis area severity index, transepidermal water loss, and neutrophil infiltration. HPD alleviated pathologically increased levels of immunoglobulin G2a, myeloperoxidase, and tumor necrosis factor-α. Splenic Th1 and Th17 cell populations were also reduced by HPD in the murine model. In addition, in activated keratinocytes, HPD inhibited gene expression of Th1- and Th17-associated cytokines and chemokines, and phosphorylation of mitogen-activated protein kinases and nuclear factor-κB. In summary, HPD alleviates psoriasis skin inflammation in vivo and in vitro. Therefore, we suggest that HPD would be a potent therapeutic candidate for the treatment of psoriasis.

The pharmacological and biological roles of eriodictyol

Eriodictyol is a flavonoid in the flavanones subclass. It is abundantly present in a wide range of medicinal plants, citrus fruits, and vegetables that are considered to have potential health importance. Having the considerable medicinal properties, eriodictyol has been predicted to clarify the mode of action in various cellular and molecular pathways. Evidence for the existing therapeutic roles of eriodictyol includes antioxidant, anti-inflammatory, anti-cancer, neuroprotective, cardioprotective, anti-diabetic, anti-obesity, hepatoprotective, and miscellaneous. Therefore, this review aims to present the recent evidence regarding the mechanisms of action of eriodictyol in different signaling pathways in a specific disease condition. In view of the immense therapeutic effects, eriodictyol may serve as a potential drug source to enhance community health standards.

Hispidulin Inhibits Neuroinflammation in Lipopolysaccharide-Activated BV2 Microglia and Attenuates the Activation of Akt, NF-κB, and STAT3 Pathway

Microglia, resident innate immune cells in central nervous system, regulates neuroinflammation and is associated with a variety of neuropathologies. The present study investigated the antineuroinflammatory effects of hispidulin (HPD), a naturally flavone compound, in lipopolysaccharide- (LPS-) stimulated BV2 microglia cells. The expression levels of nitric oxide (NO), reactive oxygen species (ROS), and pro-inflammatory factors were determined by the Griess method, flow cytometry, and enzyme-linked immunosorbent assay (ELISA). Western blotting was used to measure various transcription factors such as Akt, nuclear factor-kappa B (NF-κB), and signal transducer and activator of transcription 3 (STAT3) activities. Our experimental results demonstrated that HPD increased cell viability and reduced apoptosis in LPS-treated BV2 microglia cells. Moreover, HPD significantly reduced the levels of NO, ROS, inducible nitric oxide synthase (iNOS), cyclooxygenase- (COX-) 2, tumor necrosis factor- (TNF-) α, interleukin- (IL-) 1β, IL-6, and prostaglandin E2 (PGE2) in a dose-dependent manner. Phosphorylation of NF-κB/IκB, Akt, and STAT3 proteins expression by HPD was suppressed in LPS-induced BV2 microglial cells. We concluded that HPD may inhibit neuroinflammatory responses by inhibiting NF-κB pathway activation and ROS formation. These results propose that HPD has potential as anti-inflammatory agents against microglia-mediated neuroinflammatory disorders.

Effect of Terpenoids and Flavonoids Isolated from Baccharis conferta Kunth on TPA-Induced Ear Edema in Mice

In this study, we isolated from the aerial parts of Baccharis conferta Kunth (i) a new neoclerodane, denominated "bacchofertone"; (ii) four known terpenes: schensianol A, bacchofertin, kingidiol and oleanolic acid; and (iii) two flavonoids: cirsimaritin and hispidulin. All structures were identified by an exhaustive analysis of nuclear magnetic resonance (NMR) and mass spectroscopy (MS). Extracts from aerial parts were screened for anti-inflammatory activity in the mice ear edema model of 12-O-tetradecanoylforbol-13-acetate mice. Dichloromethane extract (BcD) exhibited 78.5 ± 0.72% inhibition of edema, followed by the BcD2 and BcD3 fractions of 71.4% and 82.9% respectively, at a dose of 1 mg/ear. Kingidiol and cirsimaritin were the most potent compounds identified, with a median effective dose of 0.12 and 0.16 mg/ear, respectively. A histological analysis showed that the topical application of TPA promoted intense cell infiltration, and this inflammatory parameter was reduced with the topical application of isolated compounds.

Targeting PI3K/Akt/mTOR signaling pathway by polyphenols: Implication for cancer therapy

Cancer is one of the biggest challenges facing medicine and its cure is regarded to be the Holy Grail of medicine. Therapy in cancer is consisted as various artificial cytotoxic agents and radiotherapy, and recently immunotherapy. Recently much attention has been directed to the use of natural occurring agents in cancer therapy. One of the main group of agents utilized in this regard is polyphenols which are found abundantly in berries, fruits and vegetables. Polyphenols show to exert direct and indirect effects in progression of cancer, angiogenesis, proliferation and enhancing resistance to treatment. One of the cellular pathways commonly affected by polyphenols is PI3K/Akt/mTOR pathway, which has far ranging effects on multiple key aspects of cellular growth, metabolism and death. In this review article, evidence regarding the biology of polyphenols in cancer via PI3K/Akt/mTOR pathway is discussed and their application on cancer pathophysiology in various types of human malignancies is shown.

Flavone Hispidulin Stimulates Glucagon-Like Peptide-1 Secretion and Ameliorates Hyperglycemia in Streptozotocin-Induced Diabetic Mice

SCOPE

Loss of functional β-cell mass is central for the deterioration of glycemic control in diabetes. The incretin hormone glucagon-like peptide-1 (GLP-1) plays a critical role in maintaining glycemic homeostasis via potentiating glucose-stimulated insulin secretion and promoting β-cell mass. Agents that can directly promote GLP-1 secretion, thereby increasing insulin secretion and preserving β-cell mass, hold great potential for the treatment of T2D.

METHODS AND RESULTS

GluTag L-cells, INS832/13 cells, and mouse ileum crypts and islets are cultured for examining the effects of flavone hispidulin on GLP-1 and insulin secretion. Mouse livers and isolated hepatocytes are used for gluconeogenesis. Streptozotocin-induced diabetic mice are treated with hispidulin (20 mg kg^-1 day^-1 , oral gavage) for 6 weeks to evaluate its anti-diabetic potential. Hispidulin stimulates GLP-1 secretion from the L-cell line, ileum crypts, and in vivo. This hispidulin action is mediated via activation of cyclic adenosine monophosphate/protein kinase A signaling. Hispidulin significantly improves glycemic control in diabetic mice, concomitant with improved insulin release, and β-cell survival. Additionally, hispidulin decreases hepatic pyruvate carboxylase expression in diabetic mice and suppresses gluconeogenesis in hepatocytes. Furthermore, hispidulin stimulates insulin secretion from β-cells.

CONCLUSION

These findings suggest that Hispidulin may be a novel dual-action anti-diabetic compound via stimulating GLP-1 secretion and suppressing hepatic glucose production.

Health Benefits of Quassin from Quassia amara: A Comprehensive Review of their Ethnopharmacological Importance, Pharmacology, Phytochemistry and Analytical Aspects

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Medicinal plants have been indispensable to human life as they are used in food, cosmetics, medicines, nutraceuticals, perfumery, beverages and many more sectors. The medicinal plant contains various important classes of phytochemicals and broadly they are categorized into either primary or secondary metabolite. A large number of modern medicines are mainly derived from plant and other natural sources. Medicinal properties of plants are mainly due to the presence of their secondary metabolite and good examples are salicylic acid, morphine, quinine, vincristin and vinblastine. In spite of the great discovery of allopathic medicine, plant pure phytoconstituents play an important role in the modern medicine. Various plant based medicine are available in the market and people are using it on the basis of the belief that it is safer compared to the allopathic medicine. Furthermore, based on these believes, people use most of the traditional medicines in their routine life for the treatment of numerous disorders and this is called self-medication. Quassia amara plant belongs to Simaroubaceae family which is one of the best examples of the self-medicated plant. Traditionally Quassia amara has antimalarial, stomachic, antianaemic, antibiotics, cytotoxic and antiamoebic activity. Its reproductive, insecticidal, larvicidal and vermifuge properties have been also reported in the literature. Quassinoids are the important phytoconstituents of this plant and are the main bitter principles of Quassia amara too. Quassin is a white crystalline substance and is widely used in Chinese herbal medicine for their bitter taste. The purpose of this review is to gain an understanding of the Quassin and Quassia amara and to present information and knowledge regarding this phytoconstituent. Medicinal uses, pharmacological importance and various bioanalytical methods of Quassin and Quassia amara have been presented in this review. The benefit of this review is to get better understanding and ideas of Quassin and Quassia amara research findings in various disciplines. Furthermore, there is a need to perform more scientific investigation to explore the other beneficial properties of Quassia amara and Quassin.

Bioaffinity Fishing Procedure Using Secretory Phospholipase A2 for Screening for Bioactive Components: Modulation of Pharmacological Effect Induced by sPLA2 from Crotalus durissus terrificus by Hispidulin from Moquiniastrum floribundum

Bioaffinity capturing of molecules allows the discovery of bioactive compounds and decreases the need for various stages in the natural compound isolation process. Despite the high selectivity of this technique, the screening and identification methodology depends on the presence of a protein to capture potential ligands. However, some proteins, such as snake secretory phospholipase A2 (sPLA2), have never been investigated using this approach. The purpose of this study was to evaluate the use of a new method for screening natural compounds using a bioaffinity-guided ultrafiltration method on Crotalus durissus terrificus sPLA2 followed by HPLC-MS to identify the compounds, and this method could be used to discover new anti-inflammatory compounds from the various organisms originating from biodiversity. Different extracts were selected to evaluate their ability to inhibit sPLA2 activity. The extracts were incubated with sPLA2 and the resulting mixture was ultrafiltrated to elute unbound components. The resulting compounds were identified by HPLC-MS. We identified hispidulin as one of the components present in the Moquiniastrum floribundum leaf and evaluated the ability of this isolated compound to neutralize the inflammatory activity of sPLA2 from Crotalus durissus terrificus.

Natural Products Diversity in Plant-Insect Interaction between Tithonia diversifolia (Asteraceae) and Chlosyne lacinia (Nymphalidae)

The chemical ecology of plant-insect interactions has been driving our understanding of ecosystem evolution into a more comprehensive context. Chlosyne lacinia (Lepidoptera: Nymphalidae) is an olygophagous insect herbivore, which mainly uses host plants of Heliantheae tribe (Asteraceae). Herein, plant-insect interaction between Tithonia diversifolia (Heliantheae) and Chlosyne lacinia was investigated by means of untargeted LC-MS/MS based metabolomics and molecular networking, which aims to explore its inherent chemical diversity. C. lacinia larvae that were fed with T. diversifolia leaves developed until fifth instar and completed metamorphosis to the adult phase. Sesquiterpene lactones (STL), flavonoids, and lipid derivatives were putatively annotated in T. diversifolia (leaves and non-consumed abaxial surface) and C. lacinia (feces, larvae, pupae, butterflies, and eggs) samples. We found that several furanoheliangolide-type STL that were detected in T. diversifolia were ingested and excreted in their intact form by C. lacinia larvae. Hence, C. lacinia caterpillars may have, over the years, developed tolerance mechanisms for STL throughout effective barriers in their digestive canal. Flavonoid aglycones were mainly found in T. diversifolia samples, while their glycosides were mostly detected in C. lacinia feces, which indicated that the main mechanism for excreting the consumed flavonoids was through their glycosylation. Moreover, lysophospholipids were predominately found in C. lacinia samples, which suggested that they were essential metabolites during pupal and adult stages. These findings provide insights into the natural products diversity of this plant-insect interaction and contribute to uncovering its ecological roles.

Clerodendrum petasites S. Moore: The therapeutic potential of phytochemicals, hispidulin, vanillic acid, verbascoside, and apigenin

Clerodendrum petasites S. Moore has been prescribed in Thai traditional medicine for over 30 years for the treatment of ailments including asthma, inflammation, fever, cough, vomiting, and skin disorders. The phytochemicals from this plant have been identified as phenolic acids, flavones, flavone glycosides, glycosides, phenylpropanoid, and diterpenoid. The pharmacological activities both in vitro and in vivo have mostly been reported from crude extracts and not from pure compounds. This review, therefore, brings together information on the specific phytochemicals found in C. petasites in order to provide a guide to the natural bioactive compounds that are potentially used in medicines together with mechanisms underlying their pharmacological uses. All relevant information was searched for the terms of plant name, naturally-occurring compounds, and traditional uses from reliable databases, such as PubMed, Science Direct and Google Scholar, along with Thai traditional medicine textbooks. There was no specific timeline set for the search and this review selected to report only mechanisms studied by using standard compounds for their biological activities. Four dominant compounds comprising hispidulin, vanillic acid, verbascoside, and apigenin, have robust evidence to support their medical effects. Hispidulin was discovered to be possibly responsible for the treatment of cancer, osteolytic bone diseases, and neurological diseases. Other compounds were also found to tentatively support the uses in inflammation and neurological diseases. C. petasites extracts may provide an option as complimentary medicine, and or for the pharmacological development of new drugs derived from the phytochemicals found within.

Phytochemical composition and larvicidal activity of essential oils from herbal plants

The essential oils (EOs) of Plectranthus amboinicus showed the highest larvicidal activity among four herbal plants studied and β-caryophyllene might be the major component responsible for its differential toxicity to the larvae of Culex quinquefasciatus and Aedes Aegypti. Mosquitoes act as vectors for many life-threatening diseases, including malaria, dengue fever, and Zika virus infection. Management of mosquitoes mainly relies on synthetic insecticides, which usually result in the rapid development of resistance; therefore, alternative mosquito control strategies are urgently needed. This study characterized the major component of essential oils (EOs) derived from the vegetative parts of four herbal plants and their larvicidal activity toward important mosquito vectors. The EOs were extracted by hydro-distillation and subjected to gas chromatography-mass spectrometry (GC-MS) analysis and a larvicidal activity assay toward Aedes aegypti, Ae. albopictus and Culex quinquefasciatus. In total, 14, 11, 11 and 9 compounds were identified from the EOs of Plectranthus amboinicus, Mentha requienii, Vitex rotundifolia and Crossostephium chinense, respectively. The EOs derived from four herbal plants exhibited remarkable larvicidal activity against the three mosquito species. In particular, the EOs of P. amboinicus showed the highest larvicidal activity, and the larvae of Cx. quinquefasciatus were more sensitive to the P. amboinicus EOs than that of Ae. Aegypti. Although carvacrol (61.53%) was the predominant constituent of the P. amboinicus EOs, its precursors, γ-terpinene (8.51%) and p-cymene (9.42%), exhibited the most larvicidal activity toward Ae. aegypti and Cx. quinquefasciatus. However, β-caryophyllene (12.79%) might be the major component responsible for the differential toxicity of the P. amboinicus EOs, as indicated by the significant differences in its LC₅₀ values toward both mosquitoes. Information from these studies will benefit the incorporation of EOs into integrated vector management.

UPLC-HRMS and NMR applied in the evaluation of solid-phase extraction methods as a rational strategy of dereplication of Phyllanthus spp. aiming at the discovery of cytotoxic metabolites

The classical approach to drug discovery from natural products (NP's) requires strenuous and complex purification steps for the isolation and structural elucidation. Modern strategies as dereplication aim to accelerate the identification of known compounds present in a crude or partially purified extract. In this work, we investigated the influence of the solid-phase extraction (Oasis, Plexa, and Agilent C18 cartridges with and without organic modifiers) chemical profile obtained by UPLC-QTOF-MS and NMR and cytotoxicities of aqueous extracts from Phyllanthus niruri and P. amarus. Our results showed differences between the SPE cartridges and the mass recovered. P. niruri showed higher mass recovery than P. amarus indicating a higher amount of secondary metabolites. The UPLC-QTOF-MS analysis revealed that P. niruri crude extract presents higher contents of phenolic compounds than P. amarus. According to NMR analysis, P. niruri contained more tyrosine, corilagin, and glycosidic residues while P. amarus, presented higher content of ellagic acid. The different stationary phases, as well as mobile phases for exploratory SPE, enabled the exploitation of the different chemical functionalities within the Phyllanthus species. The SPE (MeOH:H₂O 70:30 with C18 cartridges) samples showed greater in vitro cytotoxicity than the crude extracts, with IC₅₀ ranging from 8.01 to 94.92 μg mL^-1 against the tumor lines tested. The solid phase extraction allowed the concentration of molecules with desirable physicochemical characteristics, which might increase the hit of therapeutically useful substances.

Glyphaea brevis - In vitro antioxidant and in silico biological activity of major constituents and molecular docking analyses

Previous studies have revealed that leaf extracts of Glyphaea brevis possess antioxidant activity but the bioactivity and mechanisms of action of its major constituents remain unknown. This study evaluated in vitro antioxidant and free radical scavenging activities of Glyphaea brevis twigs and leaves, and probable toxicity profile, pharmacological activities and mechanisms of action of major phytoconstituents in silico. Phytochemical screening detected saponins, tannins, steroids, anthraquinones, flavonoids, terpenoids and phenolics in the extracts. HPLC fingerprinting revealed major compounds as ferulic, catechuic and coumaric acids. Twig extract contained more flavanols compared to the leaf extract while the leaf extract had more flavonol content. Extract of the twigs demonstrated higher ORAC, TEAC and FRAP compared to the leaf extract. In silico analyses predicted low acute toxicity risk and pharmacological activities which are in agreement with traditional use of the plant in the management of diseases such as dyspepsia, ulcers, chest pains, diarrhea, dysentery and sleeping sickness. The molecular docking studies revealed that coumaric acid and ferulic acid have the best binding for all proteins tested. In summary, Glyphaea brevis twigs possess higher antioxidant activity than the leaves and major constituents showed low toxicological potential and promising biological activities which support its ethnomedical use.

Intravasation of SW620 colon cancer cell spheroids through the blood endothelial barrier is inhibited by clinical drugs and flavonoids in vitro

Mechanisms how colorectal cancer (CRC) cells penetrate blood micro-vessel endothelia and metastasise is poorly understood. To study blood endothelial cell (BEC) barrier breaching by CRC emboli, an in vitro assay measuring BEC-free areas underneath SW620 cell spheroids, so called "circular chemorepellent induced defects" (CCIDs, appearing in consequence of endothelial retraction), was adapted and supported by Western blotting, EIA-, EROD- and luciferase reporter assays. Inhibition of ALOX12 or NF-κB in SW620 cells or BECs, respectively, caused attenuation of CCIDs. The FDA approved drugs vinpocetine [inhibiting ALOX12-dependent 12(S)-HETE synthesis], ketotifen [inhibiting NF-κB], carbamazepine and fenofibrate [inhibiting 12(S)-HETE and NF-κB] significantly attenuated CCID formation at low μM concentrations. In the 5-FU-resistant SW620-R/BEC model guanfacine, nifedipine and proadifen inhibited CCIDs stronger than in the naïve SW620/BEC model. This indicated that in SW620-R cells formerly silent (yet unidentified) genes became expressed and targetable by these drugs in course of resistance acquisition. Fenofibrate, and the flavonoids hispidulin and apigenin, which are present in medicinal plants, spices, herbs and fruits, attenuated CCID formation in both, naïve- and resistant models. As FDA-approved drugs and food-flavonoids inhibited established and acquired intravasative pathways and attenuated BEC barrier-breaching in vitro, this warrants testing of these compounds in CRC models in vivo.