Annonaceae: bio-resource for tomorrow's drug discovery

Research Progress on Sesquiterpene Compounds from Artabotrys Plants of Annonaceae

Artabotrys, a pivotal genus within the Annonaceae family, is renowned for its extensive biological significance and medicinal potential. The genus's sesquiterpene compounds have attracted considerable interest from the scientific community due to their structural complexity and diverse biological activities. These compounds exhibit a range of biological activities, including antimalarial, antibacterial, anti-inflammatory analgesic, and anti-tumor properties, positioning them as promising candidates for medical applications. This review aims to summarize the current knowledge on the variety, species, and structural characteristics of sesquiterpene compounds isolated from Artabotrys plants. Furthermore, it delves into their pharmacological activities and underlying mechanisms, offering a comprehensive foundation for future research.

In-vitro antimalarial activity of methanolic leaf- and stem-derived extracts from four Annonaceae plants

OBJECTIVE

Plants in the Annonaceae family are known for having abundant biologically active secondary metabolites. They have been used in alternative drugs for various diseases in several countries, for instance, the bark of Cananga odorata (Lam.) Hook and Thomson is used for Ophthalmic inflammation and wound healing in Malaysia. Extracts from the leaves and stems of four Annonaceae plants, namely Uvaria longipes (Craib) L.L.Zhou, Y.C.F.Su & R.M.K.Saunders, Dasymaschalon sp., Artabotrys burmanicus A.DC, and Marsypopetalum modestum (Pierre) B.Xue & R.M.K.Saunders were investigated for growth inhibitory activity against blood-stage Plasmodium falciparum growth in vitro and for non-specific cytotoxicity against normal peripheral blood mononuclear cells (PBMCs). Antimalarial activity was assessed by invasion inhibition assay and the percentage of infected red blood cells on blood smears were determined. Cytotoxicity was tested by culturing PBMCs with the extracts, and viabilities were determined by Annexin V/propidium iodide staining.

RESULTS

A. burmanicus stem extract and M. modestum leaf extract were capable of inhibiting growth of P. falciparum when used at 200 µg/mL compared to chloroquine. The extracts at effective concentrations, did not affect the viability of PBMCs. These results support further need for characterization of active compounds from specific Annonaceae plants in order to exploit their components for potential malaria treatment.

Fissistigma oldhamii (Hemsl.) Merr.: Ethnomedicinal, Phytochemistry, and Pharmacological Aspects

The species Fissistigma oldhamii (Hemsl.) Merr. (Annonaceae) has long been used as a traditional herbal medicine in China to treat diverse human diseases. Decoctions from the roots of the plant (Guā Fù Mù) are used to treat body pain and inflammatory pathologies, such as rheumatic syndromes, sciatica, and osteoarthritis. The phytochemical content of the plant and the associated pharmacological activities have been analyzed. Seventy natural products were identified in the different parts of the plants, namely, the roots, stems, leaves, fruits, and seeds. The compounds comprise many tri- and tetracyclic alkaloids (aporphine-type), anthraquinones, terpenoids, flavonoids, and others. The pharmacological properties of these molecules were analyzed to point out the anti-inflammatory, antioxidant, anticancer, and/or antimicrobial effects, together with the underlying modulated pathways and molecular targets in some cases. The panel of phytoconstituents present in F. oldhamii extracts is large, with the majority of bioactive products identified in the roots and stems. Multiple molecules can contribute to the anti-inflammatory properties of the extracts. Network pharmacology analyses of the phytoconstituents are needed to better delineate the effective components and their targets.

Antibacterial activities of seven ethnomedicinal plants from family Annonaceae

Serious threat to human health caused by bacterial infection persists as a global concern. It becomes more serious when the burden of multidrug-resistance bacteria is in the increasing trend. To overcome, researches have been conducted to develop antibacterial agents from plant-derived bioactive compounds. This review article focuses on the antibacterial activities of plant extracts from seven Annonaceae members, namely Annona muricata, Annona reticulata, Annona squamosa, Cananga odorata, Annona hypoglauca, Polyalthia longifolia, and Xylopia aethiopica. First, ethnomedical uses of the aforementioned plants are discussed and followed by the screening results of related phytochemicals. Among many secondary metabolites contained in the extracts of Annonaceae spp., anonaine, nornuciferine, and liriodenine are common and bioactive. The extracts were reported to have bacteriostatic and bactericidal properties against a wide spectrum of bacteria, including multidrug-resistant Escherichia coli, Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, Enterobacter aerogenes, Enterobacter cloacae, Salmonella choleraesuis, Salmonella typhimurium, and Shigella dysenteriae. We conclude that investigation on the extracts from Annonaceae spp. could contribute to the development of antibacterial agents that could be used against multidrug-resistant bacteria.

Natural Products from Annonaceae as Potential Antichagasic Agents

Chagas disease, a neglected tropical disease, is endemic in 21 Latin American countries and particularly prevalent in Brazil. Chagas disease has drawn more attention in recent years due to its expansion into non-endemic areas. The aim of this work was to computationally identify and experimentally validate the natural products from an Annonaceae family as antichagasic agents. Through the ligand-based virtual screening, we identified 57 molecules with potential activity against the epimastigote form of T. cruzi. Then, 16 molecules were analyzed in the in vitro study, of which, six molecules displayed previously unknown antiepimastigote activity. We also evaluated these six molecules for trypanocidal activity. We observed that all six molecules have potential activity against the amastigote form, but no molecules were active against the trypomastigote form. 13-Epicupressic acid seems to be the most promising, as it was predicted as an active compound in the in silico study against the amastigote form of T. cruzi, in addition to having in vitro activity against the epimastigote form.

Structure-Activity Relationships of Thiophene Carboxamide Annonaceous Acetogenin Analogs: Shortening the Alkyl Chain in the Tail Part Significantly Affects Their Growth Inhibitory Activity against Human Cancer Cell Lines

In a previous study, we found that the thiophene carboxamide solamin analog, which is a mono-tetrahydrofuran annonaceous acetogenin, showed potent antitumor activity through the inhibition of mitochondrial complex I. In this study, we synthesized analogs with short alkyl chains instead of the n-dodecyl group in the tail part. We evaluated their growth inhibitory activities against human cancer cell lines. We found that the alkyl chain in the tail part plays an essential role in their activity.

Bioprospecting of Natural Compounds from Brazilian Cerrado Biome Plants in Human Cervical Cancer Cell Lines

Cervical cancer is the third most common in Brazilian women. The chemotherapy used for the treatment of this disease can cause many side effects; then, to overcome this problem, new treatment options are necessary. Natural compounds represent one of the most promising sources for the development of new drugs. In this study, 13 different species of 6 families from the Brazilian Cerrado vegetation biome were screened against human cervical cancer cell lines (CCC). Some of these species were also evaluated in one normal keratinocyte cell line (HaCaT). The effect of crude extracts on cell viability was evaluated by a colorimetric method (MTS assay). Extracts from Annona crassiflora, Miconia albicans, Miconia chamissois, Stryphnodendron adstringens, Tapirira guianensis, Xylopia aromatica, and Achyrocline alata showed half-maximal inhibitory concentration (IC₅₀) values < 30 μg/mL for at least one CCC. A. crassiflora and S. adstringens extracts were selective for CCC. Mass spectrometry (Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (ESI FT-ICR MS)) of A. crassiflora identified fatty acids and flavonols as secondary compounds. One of the A. crassiflora fractions, 7C24 (from chloroform partition), increased H2AX phosphorylation (suggesting DNA damage), PARP cleavage, and cell cycle arrest in CCC. Kaempferol-3-O-rhamnoside and oleic acid were bioactive molecules identified in 7C24 fraction. These findings emphasize the importance of investigating bioactive molecules from natural sources for developing new anti-cancer drugs.

A Systematic Review of Plants With Antibacterial Activities: A Taxonomic and Phylogenetic Perspective

Background: Antimicrobial resistance represents a serious threat to human health across the globe. The cost of bringing a new antibiotic from discovery to market is high and return on investment is low. Furthermore, the development of new antibiotics has slowed dramatically since the 1950s' golden age of discovery. Plants produce a variety of bioactive secondary metabolites that could be used to fuel the future discovery pipeline. While many studies have focused on specific aspects of plants and plant natural products with antibacterial properties, a comprehensive review of the antibacterial potential of plants has never before been attempted. Objectives: This systematic review aims to evaluate reports on plants with significant antibacterial activities. Methods: Following the PRISMA model, we searched three electronic databases: Web of Science, PubMed and SciFinder by using specific keywords: "plant," "antibacterial," "inhibitory concentration." Results: We identified a total of 6,083 articles published between 1946 and 2019 and then reviewed 66% of these (4,024) focusing on articles published between 2012 and 2019. A rigorous selection process was implemented using clear inclusion and exclusion criteria, yielding data on 958 plant species derived from 483 scientific articles. Antibacterial activity is found in 51 of 79 vascular plant orders throughout the phylogenetic tree. Most are reported within eudicots, with the bulk of species being asterids. Antibacterial activity is not prominent in monocotyledons. Phylogenetic distribution strongly supports the concept of chemical evolution across plant clades, especially in more derived eudicot families. The Lamiaceae, Fabaceae and Asteraceae were the most represented plant families, while Cinnamomum verum, Rosmarinus vulgaris and Thymus vulgaris were the most studied species. South Africa was the most represented site of plant collection. Crude extraction in methanol was the most represented type of extraction and leaves were the main plant tissue investigated. Finally, Staphylococcus aureus was the most targeted pathogenic bacteria in these studies. We closely examine 70 prominent medicinal plant species from the 15 families most studied in the literature. Conclusion: This review depicts the current state of knowledge regarding antibacterials from plants and provides powerful recommendations for future research directions.

Antitumour activity of Annona muricata L. leaf methanol extracts against Ehrlich Ascites Carcinoma and Dalton's Lymphoma Ascites mediated tumours in Swiss albino mice

The use of plants as a source of sedative or treatment for cancer is reasonably widespread worldwide. Annona muricata Linn exhibits a vast array of medicinal and ethno-pharmaceutical benefits, attributed by different plant parts. The activity of this plant is regarded to the bio-production of secondary metabolites like alkaloids, phenols, flavonoids, and most unique group of compounds, namely, annonaceous acetogenins. Whilst this plant is gaining popularity as an anticancer treating plant, this study was undertaken to verify the plausible anticancer effect of leaf methanol extracts of A. muricata (LEAM). Acute toxicity study was carried to obtain safe dose in mice models using haematological, biochemical, and histological evaluations in Swiss albino mice. In-vitro cytotoxicity towards Dalton’s Lymphoma Ascites (DLA) and Ehrlich Ascites Carcinoma (EAC) cell lines were determined by trypan blue exclusion method. In-vivo antitumour activity of LEAM (100, 200, and 500mg/kg b.wt.) was evaluated using DLA induced solid carcinoma and EAC induced ascites carcinoma models and its comparison with standard drug Cisplatin. Acute toxicity studies did not exhibit significant variations in treated mice suggesting diminutive side effects of LEAM. Statistical analysis revealed the IC₅₀ values for DLA and EAC cell lines as 85.56 ± 5.28 and 68.07 ± 7.39 µg/mL, respectively, indicating better cytotoxic activity against EAC than DLA cells. LEAM decreased the tumour burden in dose-dependent manner. In comparison, with different concentrations tested, treatment with LEAM (200 mg/kg b.wt. and 500 mg/kg b.wt.) significantly reduced the solid tumour volume development by 58.11% and 65.70%, respectively. While lifespan was prolonged up to 51.43% in 500 mg/kg b.wt. LEAM treated ascites tumour-induced mice. This study thus indicates that LEAM possesses potent cytotoxic and antineoplastic activity and calls for more methodical safety assessments and other end-points of anti-tumourigenesis.

Abbreviations: LEAM: Leaf methanol extract of Annona muricata; DLA: Dalton’s Lymphoma Ascites; EAC: Ehrlich Ascites Carcinoma; IC₅₀: Half maximal inhibitory concentration; CPCSEA: Committee for the Purpose of Control Supervision of Experiments on Animal; IAEC: Institutional Animal Ethics Committee; ARRIVE: Animal Research: Reporting In-vivo Experiments; DMSO: Dimethyl sulphoxide; LD₅₀: Lethal Dose, 50%; SD: Standard Deviation; Hb: Haemoglobin; RBC: Red blood cells; WBC: White blood cells; HCT: Hematocrit; MCV: Mean cell volume; MCH: Mean cell haemoglobin; MCHC: Mean cell haemoglobin concentration; SALP: Serum alkaline phosphatase; SGPT: Serum glutamic pyruvic transaminase; SGOT: Serum glutamic oxaloacetic transaminase; ATP: Adenosine triphosphate; EGFR: Epidermal Growth Factor Receptor

Syntheses of C2'-Fluorinated Analogs of Solamin

The details of the total syntheses of C2'-fluorinated analogs of solamin, an antitumor annonaceous acetogenin, are described. Fluorine was enantioselectively introduced at the C2'-position by organocatalytic α-fluorination of the aldehyde according to a previously reported method. C2'-fluorinated solamin and its C2'-diastereomer were synthesized by the Sonogashira coupling of a tetrahydrofuran fragment and fluorine-containing γ-lactone fragments.

Anti-inflammatory properties of Xylopia aethiopica leaves: Interference with pro-inflammatory cytokines in THP-1-derived macrophages and flavonoid profiling

ETHNOPHARMACOLOGICAL RELEVANCE

Ethnopharmacological surveys on Guinea-Bissauan flora reveal that several species are used to treat or ameliorate the symptomatology of conditions with an inflammatory background. As such, extracts obtained from a series of plants recorded in those surveys were screened for their anti-inflammatory properties, a hydroethanolic extract obtained from the leaves of Xylopia aethiopica (Dunal) A. Rich, (Annonaceae), used on the treatment of headache, muscular pain and rheumatic pain, scoring positively and being further investigated.

AIM OF THE STUDY

In order to identify species with anti-inflammatory properties, extracts were screened for their ability to interfere with LPS-induced TNF-α levels. Since significant effects were recorded upon treatment with the extract of the leaves obtained from X. aethiopica, further assays were conducted to elucidate additional mechanisms underlying its anti-inflammatory potential. Since little is known on the chemical composition of the plant, we also aimed to characterise its phenolic profile.

MATERIALS AND METHODS

Interference with cytokines was evaluated by ELISA assay, through the quantification of TNF-α and IL-6 levels in the culture medium collected from LPS-activated THP-1-derived-macrophages. Inhibition of 5-lipoxygenase was assessed based on the oxidation of linoleic acid to 13-hydroperoxylinoleic acid. Characterization of the phenolic profile was attained by HPLC-DAD.

RESULTS

Evaluation of TNF-α levels in LPS-challenged THP-1 macrophages evidenced a significant inhibition (>90%) upon treatment with the hydroethanolic extract obtained from X. aethiopica leaves at a concentration of 500 μg/mL. Additional anti-inflammatory effects were recorded, including a significant decrease on IL-6 levels at 250 and 500 μg/mL. The extract proved to be active towards 5-LOX, leading to significant inhibition at concentrations ranging from 16 to 250 μg/mL (IC₅₀ = 85 μg/mL). Phenolic profiling allowed the identification and quantitation of eight constituents, including caffeoylquinic acids (1-3), mono-O-glycosylated flavonols (5-8), and the mono-O-glycosyl flavone luteolin-7-O-glucoside (4). The main phenolic constituent, kaempferol-3-O-rutinoside (8), was found to significantly contribute to the anti-inflammatory effects, namely through the inhibition of 5-LOX. However, no effects on the decrease of TNF-α and IL-6 levels caused by this phenolic compound were found.

CONCLUSION

The anti-inflammatory effects of X. aethiopica leaves are demonstrated experimentally, thus substantiating its use in folk Medicine. Relevantly, the observed anti-inflammatory properties can stimulate further studies in order to fully unveil the therapeutic potential of the plant, namely as a source of phenolic compounds with a significant ability to interfere with conventional inflammatory targets.

Antitubercular and Cytotoxic Chlorinated seco-Cyclohexenes from Uvaria alba

Two new chlorine-containing polyoxygenated seco-cyclohexenes, albanols A (1) and B (2), along with the oxepinone metabolite grandiuvarone (3) were isolated from the endemic Philippine Annonaceae plant Uvaria alba. Both new compounds exhibited modest antitubercular activity. Compound 1 showed cytostatic activity (ranging from 1-50 μM) against HeLa cells and weak antiproliferative activity against HUVEC and K-562 cells with GI₅₀ values of 106 and 81 μM, respectively.

Propolis Diterpenes as a Remarkable Bio-Source for Drug Discovery Development: A Review

Propolis is one of the complex, but valuable, bio-sources for discovering therapeutic compounds. Diterpenes are organic compounds composed of four isoprene units and are known for their biological and pharmacological characteristics, such as antibacterial, anticancer, and anti-inflammatory activities. Recently, advancements have been made in the development of antibacterial and anticancer leads from propolis-isolated diterpenes, and scrutiny of these compounds is being pursued. Thus, this review covers the progress in this arena, with a focus on the chemistry and biological activities of propolis diterpenes. It is anticipated that important information, in a comprehensive and concise manner, will be delivered here for better understanding of natural product drug discovery research.

Cell cycle arrest and apoptosis induction by methanolic leaves extracts of four Annonaceae plants

Background

Uvaria longipes (Craib) L.L.Zhou, Y.C.F.Su & R.M.K.Saunders, Artabotrys burmanicus A.DC, Marsypopetalum modestum (Pierre) B.Xue & R.M.K.Saunders and Dasymaschalon sp. have been used for traditional medicine to treat cancer-like symptoms in some ethnic groups of Thailand and Laos.

Methods

We evaluated the anti-cancer activity of these Annonaceae plants against several human cancer cell lines. The apoptosis induction was detected by Annexin/propidium iodide (PI) staining. Phytochemical screening was tested by standard protocols and bioactive compounds were determined by HPLC.

Results

The crude extracts from leaves of U. longipes, Dasymaschalon sp., A. burmanicus, and M. modestum showed particular effects that were found to vary depending on the cancer cell line, suggesting that the effect was in a cell-type specific manner. Interestingly, the induction of apoptotic cell death was prominent by the leaves-derived crude extract of M. modestum. This crude was, therefore, subjected to cell cycle analysis by PI staining. Results showed that this crude extract arrested cell cycle and increased the percentage of cells in the SubG1 phase in some cancer cell lines. The phytochemical screening tests indicated that all crude extracts contained tannins and flavonoids. HPLC of flavonoids using standards identified rutin as an active compound in U. longipes and Dasymaschalon sp., whereas quercetin was found in U. longipes and M. modestum.

Conclusions

These crude extracts provide a new source for rutin and quercetin, which might be capable of inducing cancer cell apoptotic death in a cell-type specific manner. This suggests, by analyzing the major bioactive compounds, the potential use of these crudes for chemotherapy in the future.

Bio-efficacy of medicinal plants used for the management of diabetes mellitus in Gabon: An ethnopharmacological approach

BACKGROUND/AIM

People suffering of diabetes increased significantly worldwide. Population, in Sub-Saharan Africa and mainly in Gabon, rely on medicinal plants to manage diabetes, as well in rural as in urban areas. This study aimed to survey a wide range of Gabonese plants for their antidiabetic activity.

MATERIALS AND METHODS

This study focused on the identification of medicinal plants used in the local treatment of diabetes mellitus. Ethnobotanical investigations were carried out in rural and urban areas of three provinces of Gabon using a semi-structured interview.

RESULTS

About 50 plant species belonging to 31 families and 50 genera were recorded, a majority of which have been documented previously to have medicinal properties. Most have documented antidiabetic properties with characterized therapeutic chemical compounds. Of the plant parts used for treatment, stem barks were employed most frequently (50%), followed by leaves (26%); the remaining 24% comprised roots, fibers, fruit, bulbs, flowers, rhizom, skin, and stem. Regarding the mode of preparation, decoction was the most widely used (58%), followed by maceration (18%) and infusion (14%). Almost all the plant products were administered orally (98%).

CONCLUSIONS

Taken in concert, this study highlights the possibility of exploiting traditional knowledge of specific medicinal plants for the inexpensive treatment and management of diabetes.

Mechanistic Study of Tetrahydrofuran- acetogenins In Triggering Endoplasmic Reticulum Stress Response-apotoposis in Human Nasopharyngeal Carcinoma

For past three decades, numerous studies have elucidated the antiproliferative effects of acetogenins in hopes of developing a new class of clinical anticancer agents. However, clear and definitive action mechanisms of acetogenins were less clarified. In the present study, three tetrahydrofuran (THF)-containing acetogenins were found to have potent and selective antiproliferative activity against human nasopharyngeal carcinoma (NPC) cell lines and their methotrexate-resistant counterparts. The THF-containing acetogenins induced G₂/M phase arrest, mitochondrial damage and apoptosis, and increased cytosolic and mitochondrial Ca²⁺ in NPCs. Microarray analysis of NPC-TW01 cells treated with squamostatin A, a non-adjacent bis-THF acetogenin, demonstrated an increased endoplasmic reticulum (ER)-stress response (ESR). Enhanced ESR in squamostatin A-treated cells was confirmed by real-time PCR, Western blot and shRNA gene knockdown experiments. Although our results showed that squamostatin A-induced ESR was independent of extracellular Ca²⁺, the presence of extracellular Ca²⁺ enhanced the antiproliferative effect of acetogenins. In vivo analyses demonstrated that squamostatin A showed good pharmacokinetic properties and significantly retarded NPC tumor growth in the xenograft mouse model. Conclusively, our work demonstrates that acetogenins are effective and selective inducers of the ESR that can block NPC proliferation, and illustrate a previously unappreciated antitumor mechanism of acetogenins that is effective against nasopharyngeal malignancies.

New Caledonia: A ' Hot Spot' for Valuable Chemodiversity: Part 2: Basal Angiosperms and Eudicot Rosids

The flora of New Caledonia encompasses more than 3000 plant species and almost 80% are endemic. New Caledonia is considered as a 'hot spot' for biodiversity. With the current global loss of biodiversity and the fact that several drugs and pesticides become obsolete, there is an urgent need to increase sampling and research on new natural products. In this context, we review the chemical knowledge available on New Caledonian native flora from economical perspectives. We expect that a better knowledge of the economic potential of plant chemistry will encourage the plantation of native plants for the development of a sustainable economy which will participate in the conservation of biodiversity. In the second part of this review, we focus on the results exposed in 60 scientific articles and describe the identification of 225 original compounds from basal angiosperms and eudicot rosids. We discuss the economic potential of plants and molecules from medicinal and industrial perspectives. This review also highlights several plants and groups, such as Amborella sp., Piperaceae, or Phyllanthaceae, that are unexplored in New Caledonia despite their high chemical interest. Those plants are considered to have priority in future chemical investigations.

Composition and cytotoxic activity of essential oils from Xylopia aethiopica (Dunal) A. Rich, Xylopia parviflora (A. Rich) Benth.) and Monodora myristica (Gaertn) growing in Chad and Cameroon

Background

Cancer has become a global public health problem and the search for new control measures is urgent. Investigation of plant products such as essential oils from Monodora myristica, Xylopia aethiopica and Xylopia parviflora might lead to new anticancer therapy. In this study, we have investigated the antineoplastic activity of essential oils from fruits of these plants growing in Chad and Cameroon.

Methods

The essential oils obtained by hydrodistillation of fruits of Monodora myristica, Xylopia aethiopica and Xylopia parviflora collected in Chad and Cameroon were analyzed by GC-FID and GC-MS and investigated for their antiproliferative activity against the breast cancer cell line (MCF7).

Results

Overall, monoterpenes were mostly found in the six essential oils. Oils from X. aethiopica and X. parviflora from Chad and Cameroon mainly contain β-pinene at 24.6%, 28.2%, 35.7% and 32.9% respectively. Monodora myristica oils from both origins contain mainly α-phellandrene at 52.7% and 67.1% respectively. The plant origin did not significantly influence the chemical composition of oils. The six essential oils exerted cytotoxic activity against cancer (MCF-7) and normal cell lines (ARPE-19), with more pronounced effect on neoplastic cells in the majority of cases. The highest selectivity was obtained with the essential oils of X. parviflora from Chad and Cameroon (5.87 and 5.54) which were more cytotoxic against MCF-7 than against normal cell line (ARPE-19) with IC₅₀ values of 0.155 μL/mL and 0.166 μL/mL respectively.

Conclusions

Essential oils from fruits of Monodora myristica, Xylopia aethiopica and Xylopia parviflora have shown acceptable antineoplastic potency, and might be investigated further in this regard.

Rational approaches, design strategies, structure activity relationship and mechanistic insights for anticancer hybrids

A Hybrid drug which comprises the incorporation of two drug pharmacophores in one single molecule are basically designed to interact with multiple targets or to amplify its effect through action on another bio target as one single molecule or to counterbalance the known side effects associated with the other hybrid part(.) The present review article offers a detailed account of the design strategies employed for the synthesis of anticancer agents via molecular hybridization techniques. Over the years, the researchers have employed this technique to discover some promising chemical architectures displaying significant anticancer profiles. Molecular hybridization as a tool has been particularly utilized for targeting tubulin protein as exemplified through the number of research papers. The microtubule inhibitors such as taxol, colchicine, chalcones, combretasatin, phenstatins and vinca alkaloids have been utilized as one of the functionality of the hybrids and promising results have been obtained in most of the cases with some of the tubulin based hybrids exhibiting anticancer activity at nanomolar level. Linkage with steroids as biological carrier vector for anticancer drugs and the inclusion of pyrrolo [2,1-c] [1,4]benzodiazepines (PBDs), a family of DNA interactive antitumor antibiotics derived from Streptomyces species in hybrid structure based drug design has also emerged as a potential strategy. Various heteroaryl based hybrids in particular isatin and coumarins have also been designed and reported to posses' remarkable inhibitory potential. Apart from presenting the design strategies, the article also highlights the structure activity relationship along with mechanistic insights revealed during the biological evaluation of the hybrids.

Potent inhibition of human neutrophil activations by bractelactone, a novel chalcone from Fissistigma bracteolatum

Fissistigma bracteolatum is widely used in traditional medicine to treat inflammatory diseases. However, its active components and mechanisms of action remain unclear. In this study, (3Z)-6,7-dihydroxy-4-methoxy-3-(phenylmethylidene)-5-(3-phenylpropanoyl)-1-benzofuran-2(3H) (bractelactone), a novel chalcone from F. bracteolatum, showed potent inhibitory effects against superoxide anion (O₂·⁻) production, elastase release, and CD11b expression in formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP)-induced human neutrophils. However, bractelactone showed only weak inhibition of phorbol myristate acetate-caused O₂·⁻ production. The peak cytosolic calcium concentration ([Ca²⁺](i)) was unaltered by bractelactone in FMLP-induced neutrophils, but the decay time of [Ca²⁺](i) was significantly shortened. In a calcium-free solution, changes in [Ca²⁺](i) caused by the addition of extracellular Ca²⁺ were inhibited by bractelactone in FMLP-activated cells. In addition, bractelactone did not alter the phosphorylation of p38 MAPK, ERK, JNK, or AKT or the concentration of cAMP. These results suggest that bractelactone selectively inhibits store-operated calcium entry (SOCE). In agreement with this concept, bractelactone suppressed sustained [Ca²⁺](i) changes in thapsigargin-activated neutrophils. Furthermore, bractelactone did not alter FMLP-induced formation of inositol 1,4,5-triphosphate. Taken together, our results demonstrate that the anti-inflammatory effects of bractelactone, an active ingredient of F. bracteolatum, in human neutrophils are through the selective inhibition of SOCE.

Inhibition of proliferation and induction of G1-phase cell-cycle arrest by dFMGEN, a novel genistein derivative, in lung carcinoma A549 cells

Genistein (GEN) is a molecule of great interest as a potent chemopreventive agent against atherosclerosis and cancer. However, the bioavailability of GEN is very low in vivo. Our previous study showed that a GEN derivative, 7-difluoromethyl-5,4'-dimethoxygenistein (dFMGEN) has a better bioavailability than GEN in vivo. In this study, we further evaluated the efficacy of dFMGEN as a candidate for cancer therapy. We demonstrated that dFMGEN treatment decreased the viability of A549 cells in a concentration- and time-dependent manner and induced cell-cycle arrest at the G(1) phase. G(1) phase arrest was correlated with a significant reduction of Cdk4 and cyclin D1 protein level. Further studies showed that cyclin-dependent kinase (Cdk)4 and cyclin D1 protein-level decrease was caused by Cdk inhibitors p15, p21, and p27 level increase, and decreased protein level directly suppressed Rb protein phosphorylation and E2F-1 expression, then cell-cycle progression was arrested. Finally, we also found that dFMGEN has a dosage effect in suppressing tumor growth in vivo, and that dFMGEN was well tolerated by animals. In summary, our results suggest that dFMGEN has therapeutic potential for the treatment of human lung cancer.