Novel cytotoxic annonaceous acetogenins from Annona muricata

The Emerging Role of Natural Products in Cancer Treatment

The exploration of natural products as potential agents for cancer treatment has garnered significant attention in recent years. In this comprehensive review, we delve into the diverse array of natural compounds, including alkaloids, carbohydrates, flavonoids, lignans, polyketides, saponins, tannins, and terpenoids, highlighting their emerging roles in cancer therapy. These compounds, derived from various botanical sources, exhibit a wide range of mechanisms of action, targeting critical pathways involved in cancer progression such as cell proliferation, apoptosis, angiogenesis, and metastasis. Through a meticulous examination of preclinical and clinical studies, we provide insights into the therapeutic potential of these natural products across different cancer types. Furthermore, we discuss the advantages and challenges associated with their use in cancer treatment, emphasizing the need for further research to optimize their efficacy, pharmacokinetics, and delivery methods. Overall, this review underscores the importance of natural products in advancing cancer therapeutics and paves the way for future investigations into their clinical applications.

Laherradurin Inhibits Tumor Growth in an Azoxymethane/Dextran Sulfate Sodium Colorectal Cancer Model In Vivo

Colorectal cancer (CRC) is the third most common neoplasia in the world. Its mortality rate is high due to the lack of specific and effective treatments, metastasis, and resistance to chemotherapy, among other factors. The natural products in cancer are a primary source of bioactive molecules. In this research, we evaluated the antitumor activity of an acetogenin (ACG), laherradurin (LH), isolated from the Mexican medicinal plant Annona macroprophyllata Donn.Sm. in a CRC murine model. The CRC was induced by azoxymethane-dextran sulfate sodium (AOM/DSS) in Balb/c mice and treated for 21 days with LH or cisplatin. This study shows for the first time the antitumor activity of LH in an AOM/DSS CRC model. The acetogenin diminished the number and size of tumors compared with cisplatin; the histologic studies revealed a recovery of the colon tissue, and the blood toxicity data pointed to less damage in animals treated with LH. The TUNEL assay indicated cell death by apoptosis, and the in vitro studies exhibited that LH inhibited cell migration in HCT116 cells. Our study provides strong evidence of a possible anticancer agent for CRC.

Annonaceous Acetogenins Synergistically Inhibit Hepatocellular Carcinoma with Sorafenib

Sorafenib was first approved as the standard treatment for advanced hepatocellular carcinoma (HCC). Despite providing an advantage in terms of patient survival, sorafenib has shown poor clinical efficacy and severe side effects after long-term treatment. Thus, combination treatment is a potential way to increase the effectiveness and reduce the dose-limiting toxicity of sorafenib. Extracts of the seeds of Annona montana have shown synergistic antitumor activity with sorafenib, and seven annonaceous acetogenins, including three new acetogenins, muricin P (2), muricin Q (3), and muricin R (4), were isolated from the extracts by bioguided fractionation and showed synergy with sorafenib. The structures of these compounds were determined using spectroscopic and chemical methods. Annonacin (1) and muricin P (2), which reduced intracellular ATP levels and promoted apoptosis, exhibited synergistic cytotoxicity with sorafenib in vitro. In vivo, annonacin (1) displayed synergistic antitumor activity by promoting tumor cell apoptosis. Moreover, the potential mechanism of annonacin (1) was predicted by transcriptomic analysis, which suggested that SLC33A1 is a potential target in HCC. Annonacin (1) might be a novel candidate for combination therapy with sorafenib against advanced HCC.

Larvicidal property and active compound profiling of Annona squamosa leaf extracts against two species of diptera, Aedes aegypti and Anopheles stephensi

Background & objectives

Vector control measures are important in lowering the spread of infections spread by mosquito. Synthetic pesticides used to suppress vector populations during the larval stage have had adverse impacts on people and the environment. The early III instar larvae of Aedes aegypti and Anopheles stephensi were the targets of the current experiment, which assessed the larvicidal ability of petroleum ether, chloroform, methanol, and aqueous extracts of Annona squamosa leaves.

Methods

Using the standard World Health Organization (WHO) larval bioassay test, leaf extracts were evaluated for their activity against Ae. aegypti and An. stephensi to determine lethal doses. Phytochemical analysis and gas chromatography-mass spectrometry (GC-MS) were carried out to identify larvicidal components in the extract. Further analysis using a scanning electron microscope (SEM) was done to check the extracts toxicity for both mosquito larvae.

Results

The larvicidal active components were identified by GC-MS as tetradecanoic acid, cis-vaccenic acid, and 2,4-di-tert-butylphenol etc. Methanol leaf extracts of A. squamosa (ASME) exhibited strong larvicidal activity against the early 3rd instar larvae of Ae. aegypti and An. stephensi with Lethal concentration (LC50) values of 51.450 ppm and 107.121 ppm. Cell damages to the larva post exposure to ASME were examined.

Interpretation & conclusion

This finding showed that the ASME has better larvicidal activity and its components that may be used to kill larvae as larvicides. The extracts toxicity towards damage of midgut of larva further suggests that this plant methanol leaf extracts could be effective in larval growth control approaches.

Annona muricata: Comprehensive Review on the Ethnomedicinal, Phytochemistry, and Pharmacological Aspects Focusing on Antidiabetic Properties

Plants have played an important role over the centuries in providing products that have been used to help combat ailments and diseases. Many products originating from fresh, dried-plant materials, or extracts are utilized as community remedies in traditional practices or even in modern medicine. The Annonaceae family contains different types of bioactive chemical properties, such as alkaloids, acetogenins, flavonoids, terpenes, and essential oil, meaning the plants in this family are potential therapeutic agents. Belonging to the Annonaceae family, Annona muricata Linn. has recently attracted the attention of scientists for its medicinal value. It has been utilized as a medicinal remedy since ancient times to treat and improve various diseases, for example, diabetes mellitus, hypertension, cancer, and bacterial infections. This review, therefore, highlights the important characteristic and therapeutic effect of A. muricata along with future perspectives on its hypoglycemic effect. The most-common name is soursop, referring to its sour and sweet flavors, while in Malaysia, this tree is commonly called 'durian belanda'. Furthermore, A. muricata contains a high content of phenolic compounds in the roots and leaves. In vitro and in vivo studies have shown that A. muricata has the pharmacological effects of anti-cancer, anti-microbial, antioxidant, anti-ulcer, anti-diabetic, anti-hypertensive, and wound healing. With regard to its anti-diabetic effect, mechanisms of inhibiting glucose absorption via α-glucosidase and α-amylase activity inhibition, increasing glucose tolerance and glucose uptake by peripheral tissues, and stimulating insulin release or acting like insulin were deeply discussed. There is still a significant research gap, and future studies are required to conduct detailed investigations and gain a better molecular understanding of A. muricata's anti-diabetic potential, especially by using the metabolomics approach.

Photothermal combined with intratumoral injection of annonaceous acetogenin nanoparticles for breast cancer therapy

ACGs (annonaceous acetogenins) possess excellent antitumor activity, but their serious accompanying toxicity has prevented their application in the clinic. To address this problem, we therefore constructed an intratumoral drug delivery system integrating chemotherapy and photothermal therapy. The PEGylation of polydopamine nanoparticles (PDA-PEG NPs) possessed an excellent biocompatibility with size of 70.96 ± 2.55 nm, thus can be used as good photothermal materials in the body. Moreover, PDA-PEG NPs can kill half of cancer cells under NIR (near-infrared) laser irradiation, and the survival rate of 4T1 cells is only 1% when ACG NPs and PDA-PEG NPs are combined. In vivo distribution studies showed that the 0.1 mg/kg ACGs NPs + PDA-PEG NPs + NIR group had the highest tumor inhibition rate, which was significantly superior to that of the 0.1 mg/kg ACGs NPs intratumoral injection group (82.65% vs. 59.08%). Altogether, the combination of PDA-PEG NPs + NIR with chemotherapy drugs may provide a feasible and effective strategy for the treatment of superficial tumors.

Pharmacological Activities of Soursop (Annona muricata Lin.)

Soursop (Annona muricata Lin.) is a plant belonging to the Annonaceae family that has been widely used globally as a traditional medicine for many diseases. In this review, we discuss the traditional use, chemical content, and pharmacological activities of A.muricata. From 49 research articles that were obtained from 1981 to 2021, A.muricata’s activities were shown to include anticancer (25%), antiulcer (17%), antidiabetic (14%), antiprotozoal (10%), antidiarrhea (8%), antibacterial (8%), antiviral (8%), antihypertensive (6%), and wound healing (4%). Several biological activities and the general mechanisms underlying the effects of A.muricata have been tested both in vitro and in vivo. A.muricata contains chemicals such as acetogenins (annomuricins and annonacin), alkaloids (coreximine and reticuline), flavonoids (quercetin), and vitamins, which are predicted to be responsible for the biological activity of A.muricata.

Current Situation and Perspectives of Fruit Annonaceae in Mexico: Biological and Agronomic Importance and Bioactive Properties

The Annonaceae family is one of the oldest angiosperms. The genus Annona is the one with the most species and, together with Asimina, the only ones that contain edible fruits. In the last 10 years, interest in these fruit species has increased, mainly due to their nutritional properties and their application in the treatment of human diseases. Mexico is the center of origin for most of them. However, at present much of the basic agronomic information, postharvest handling of the fruits, and their potential as new crops for areas with poor soils in organic matter or semi-dry climates is unknown. It is considered that these custard apple species may be an option to change towards instead of crops that have lost profitability and sustainability. A review of the current state of knowledge in different areas of the species A. muricata, A. macroprophyllata, A. reticulata, A. squamosa, and A. cherimola was carried out and to focus research efforts on the topics of greatest interest and on those where is required to achieve a sustainable production and use of these resources in Mexico. However, knowledge about the cultivation and potential uses of these species is needed to increase their commercialization; the integration of interdisciplinary and interinstitutional groups is required.

Synthesis and Cytotoxic Property of Annonaceous Acetogenin Glycoconjugates

Background

Annonaceous acetogenins (ACGs) are secondary metabolites produced by the Annonaceae family and display potent anticancer activity against various cancer cell lines. Squamocin and bullatacin are two examples of ACGs that show promising antitumor activity; however, preclinical data are not sufficient partly due to their being highly lipophilic and poorly soluble in water. These compounds also display high toxicity to normal cells. Due to these disadvantageous properties, the therapeutic potential of squamocin and bullatacin as antitumor agents has not been fully evaluated.

Methods

In order to enhance their water solubility and potentially improve their cancer targeting, squamocin and bullatacin were conjugated to a glucose or galactose to yield glycosylated derivatives by direct glycosylation or the Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) reaction (the click reaction). The synthesized compounds were evaluated for their anticancer property against HeLa, A549 and HepG2 cancer cell lines using MTT assay.

Results

Nine glycosyl derivatives were synthesized and structurally characterized. Most of them show comparable in vitro cytotoxicity against HeLa, A549 and HepG2 cancer cell lines as their parent compounds squamocin and bullatacin. It appears that the type of sugar residue (glucose or galactose), the position at which the sugar residue is attached, and whether or not a linking spacer is present do not affect the potency of these derivatives much. The solubility of galactosylated squamocin 13 in phosphate buffer saline (PBS, pH = 7) is greatly improved (1.37 mg/mL) in comparison to squamocin (not detected in PBS).

Conclusion

The conjugation of a glucose or galactose to squamocin and bullatacin yields glycosyl derivatives with similar level of anticancer activity in tested cell lines. Further studies are needed to demonstrate whether or not these compounds show reduced toxicity to normal cells and their therapeutic potential as antitumor agents.

Molecular docking and antiviral activities of plant derived compounds against zika virus

Zika virus (ZIKV), a recently emerged pathogen of the genus flavivirus causes Guillain-Barré syndrome and microcephaly in fetus and newborns . Until date, there are no licensed vaccine or approved drug to treat ZIKV infection. Thus, in this study, 5550 phytochemicals retrieved from various databases were subjected for molecular docking in Discovery studio V.4.0 against the ZIKV helicase protein and envelope protein domain III. In addition, in silico ADMET and Density function theory studies were performed to retain the final hit compounds. Further, four of the identified compounds (eleutheroside B, neoandrographolide, apigenin, and madecassic acid) were tested for in vitro cytotoxicity and antiviral activities against ZIKV. Except madecassic acid, the other three compounds reduced ZIKV infection at non-cytotoxic concentrations. Hence, this study encourages the screening of more phytochemicals against druggable targets of ZIKV to identify new promising drug candidates.

Acetogenins from Annonaceae family. Their potential biological applications

The aim of this contribution has been to continue with the knowledge about newly isolated acetogenins from Annonaceae family for the last fifteen years. This review will report classification, extraction, isolation, elucidation of the structure, biological activities and mechanism of action of such interesting natural products. In fact, out of the 532 compounds reviewed, 115 previously non-described annonaceous acetogenins have been added to the list of isolated compounds from 2005 to May 2019.

Annonaceous acetogenin mimic AA005 suppresses human colon cancer cell growth in vivo through downregulation of Mcl-1

Annonaceous acetogenins are a well-established family of natural products with significant bioactivities, especially high cytotoxic and antitumor activities. AA005 is an annonaceous acetogenin mimic that has shown significant cytotoxicity against a variety of cancer cell lines, but its in vivo antitumor effects have not been demonstrated so far, and its anticancer mechanisms remain ambiguous. In this study, we investigated the effects of AA005 on human colon cancer cell lines in vivo. Human colon carcinoma cell line SW620 xenograft nude mice were treated with AA005 (5 mg/kg/day, i.p.) for 21 days. AA005 administration markedly inhibited the tumor growth via promoting nuclear translocation of apoptosis-inducing factor (AIF) and inducing AIF-dependent cell death. Subsequent studies in human colon carcinoma cell lines SW620 and RKO in vitro revealed that after the colon cancer cells exposed to AA005, downregulation of a B-cell lymphoma 2 family protein, myeloid cell leukemia-1 (Mcl-1), was an early event due to the inhibition of Mcl-1 mRNA level and protein synthesis in a time-dependent manner. Intriguingly, knockdown of Mcl-1 using small interfering RNA markedly accelerated the nuclear translocation of AIF and upregulation of receptor interacting protein-1, and enhanced AA005-mediated lethality, whereas ectopic expression of Mcl-1 substantially attenuated AA005-mediated lethality in the colon cancer cells. Finally, silencing Mcl-1 expression markedly enhanced AA005-induced lethality in SW620 xenograft nude mice, demonstrating a pivotal role of Mcl-1 downregulation in mediating the in vivo antitumor effects of AA005. Taken together, this study demonstrates for the first time the anticancer effects of AA005 against human colon cancer cell lines in vivo, which is mediated through the downregulation of Mcl-1.

Potential therapeutic applications of the genus Annona: Local and traditional uses and pharmacology

ETHNO-PHARMACOLOGICAL RELEVANCE

Annona species (Annonaceae) have long been used as traditional herbal medicines by native peoples in tropical areas. In different countries they are used against a large variety of illnesses, such as parasitic and infectious diseases, cancer, diabetes, peptic ulcers, and mental disorders.

AIM OF THE STUDY

This review aims to achieve a comprehensive understanding of the research conducted so far on the local and traditional uses, pharmacological activities, mechanism of actions of active compounds, toxicity, and possible interactions with other drugs of the Annona species. Through analysis of these findings, evidences supporting their applications in ethno-medicines are described. We discuss the possible research opportunities and stand out the weak points in our knowledge that deserves further investigation.

MATERIAL AND METHODS

Information on ethno-medicinal uses and pharmacological activities of the Annona genus was collected. The main scientific biomedical literature databases (Cochrane, PubMed, Scopus, Lilacs, SeCiMed, Elsevier, SpringerLink, Google Scholar, SciFinder) were consulted. The search covered all the literature available until September 2017. National and regional databases of Herbal Medicine and Complementary and Alternative Medicine were also revised in order to explore further data. For a better understanding of the therapeutic importance of these species, we have classified the pharmacological activities within each group of disorders. The International Classification of Diseases (ICD), used from WHO Member States, was chosen as the reference classification.

RESULTS

From among the 27 species revised, four species are highlighted for their important pharmacological activities in most of the groups of illnesses: A. muricata, A. squamosa, A. senegalensis, and A. cherimola. Many investigations have been performed with extracts from the leaves, bark, fruit and seeds and have shown a wide range of pharmacological activities, such as antiprotozoal, antitumoural, antidiabetic, hepato-protective, anti-inflammatory and anxiolytic activities. The chemistry on the annonaceous acetogenins (ACGs) has been extensively investigated due to their potent antitumoural activity. Many of the assays were carried out with the isolated acetogenins in different lines of tumour culture cells and were found effective at very low doses even in multidrug-resistant tumours, and hence constitute promising compounds in the treatment of different types of cancers. No studies were found with extracts rich in acetogenins in the clinical field.

CONCLUSIONS

The experimental results from the pharmacological research enable the validation of their traditional uses in several of the groups of diseases in the countries of origin and reveal these plants to be a valuable source for therapeutic molecules. However, more toxicity assays and clinical trials would be necessary to establish optimal and safe doses of consumption on the application of these medicinal plants.

Anticancer Properties of Graviola (Annona muricata): A Comprehensive Mechanistic Review

Graviola (Annona muricata) is a small deciduous tropical evergreen fruit tree, belonging to the Annonaceae family, and is widely grown and distributed in tropical and subtropical regions around the world. The aerial parts of graviola have several functions: the fruits have been widely used as food confectionaries, while several preparations, especially decoctions of the bark, fruits, leaves, pericarp, seeds, and roots, have been extensively used in traditional medicine to treat multiple ailments including cancers by local communities in tropical Africa and South America. The reported therapeutic benefits of graviola against various human tumors and disease agents in in vitro culture and preclinical animal model systems are typically tested for their ability to specifically target the disease, while exerting little or no effect on normal cell viability. Over 212 phytochemical ingredients have been reported in graviola extracts prepared from different plant parts. The specific bioactive constituents responsible for the major anticancer, antioxidant, anti-inflammatory, antimicrobial, and other health benefits of graviola include different classes of annonaceous acetogenins (metabolites and products of the polyketide pathway), alkaloids, flavonoids, sterols, and others. This review summarizes the current understanding of the anticancer effects of A. muricata and its constituents on diverse cancer types and disease states, as well as efficacy and safety concerns. It also includes discussion of our current understanding of possible mechanisms of action, with the hope of further stimulating the development of improved and affordable therapies for a variety of ailments.

Emerging therapeutic potential of graviola and its constituents in cancers

Cancer remains a leading cause of death in the USA and around the world. Although the current synthetic inhibitors used in targeted therapies have improved patient prognosis, toxicity and development of resistance to these agents remain a challenge. Plant-derived natural products and their derivatives have historically been used to treat various diseases, including cancer. Several leading chemotherapeutic agents are directly or indirectly based on botanical natural products. Beyond these important drugs, however, a number of crude herbal or botanical preparations have also shown promising utility for cancer and other disorders. One such natural resource is derived from certain plants of the family Annonaceae, which are widely distributed in tropical and subtropical regions. Among the best known of these is Annona muricata, also known as soursop, graviola or guanabana. Extracts from the fruit, bark, seeds, roots and leaves of graviola, along with several other Annonaceous species, have been extensively investigated for anticancer, anti-inflammatory and antioxidant properties. Phytochemical studies have identified the acetogenins, a class of bioactive polyketide-derived constituents, from the extracts of Annonaceous species, and dozens of these compounds are present in different parts of graviola. This review summarizes current literature on the therapeutic potential and molecular mechanism of these constituents from A.muricata against cancer and many non-malignant diseases. Based on available data, there is good evidence that these long-used plants could have both chemopreventive and therapeutic potential. Appropriate attention to safety studies will be important to assess their effectiveness on various diseases caused or promoted by inflammation.

Acetogenins and alkaloids during the initial development of Annona muricata L. (Annonaceae)

In plants, the presence and distribution of specialized metabolites during the early stages of development are not documented enough, even though their biosynthesis is one of the most important strategies for survival. In this study, five alkaloids and four acetogenins were detected in Annona muricata L. during early development seedling, including three phases of root emergence and three of seedling formation. Hexane and alkaloid extracts were obtained from each organ, which were analyzed in a gas-mass chromatograph and in a high-performance liquid chromatograph coupled with a photodiode array UV detector (HPLC-DAD). This research shows the presence of the acetogenins cis-uvarimicin IV, mosinone, muricina B, and cis-annonacin-10-one, as well as of the alkaloids reticuline, coreximine, anonaine, asimilobine, and nornuciferine, both groups with a variable organ-specific distribution, related with the formation of organs and tissues.

Annonaceae: Breaking the Wall of Inflammation

Inventories of tropical forests have listed Annonaceae as one of the most diverse plant families. For centuries, it is employed in traditional medicines to cure various pathological conditions including snakebite, analgesic, astringent, diarrhea, dysentery, arthritis pain, rheumatism, neuralgia, and weight loss etc. Phytochemical analysis of Annonaceae family have reported the occurrence of alkaloids, flavonoids, triterpenes, diterpenes and diterpene flavone glycosides, sterols, lignans, and annonaceous acetogenin characteristically affiliated with Annonaceae sp. Numerous past studies have underlined the pleotropic pharmacological activities of the crude extracts and isolated compounds from Annonaceae species. This review is an effort to abridge the ethnobotany, morphology, phytochemistry, toxicity, and particularly focusing on the anti-inflammatory activity of the Annonaceae species.

Folate-modified Annonaceous acetogenins nanosuspensions and their improved antitumor efficacy

Annonaceous acetogenins (ACGs) are a large family of fatty acid derived natural products that are exclusively isolated from the Annonaceae species. Many members of this diverse family have a broad spectrum of biological activities, the most impressive of which is anticancer activity. However, their poor solubility and severe toxicity restrict their clinical application, and their complicated composition hinders their formulation and drug delivery. In this study, β-cyclodextrin was modified with folic acid (FA) and then combined with soybean lecithin to prepare FA-modified ACGs nanosuspensions (FA-ACGs-NSps). The obtained FA-ACGs-NSps had a high drug payload of 57.59% and average particle size of 199.5 nm, and they exhibited sustained drug release within 142 hours. In comparison with ACGs-NSps, FA-ACGs-NSps showed significantly enhanced cytotoxicity and higher cell uptake toward folate receptor-positive 4T1 cell lines. An in vivo study demonstrated that FA-ACGs-NSps more effectively accumulated in tumors and enhanced the antitumor therapeutic efficacy with less toxicity in 4T1 tumor bearing mice. Therefore, FA-ACGs-NSps may be a promising drug delivery system for ACGs to improve their therapeutic window and may be suitable for clinical application to treat folate-positive tumors.

Novel Annonaceous acetogenins from Graviola (Annona muricata) fruits with strong anti-proliferative activity

Five bioactive Annonaceous acetogenins, including three new compounds, annonamuricins A (1), B (2), and C (3), one registered but no spectral data reported compounds, annonamuricin D (4), and one known compound annonacin (5) were isolated from Graviola fruit (Annona muricata) and further determined through bioassay-guided fractionation. All five compounds are C35 Anonnonaceous acetogenins with a mono-tetrahydrofuran ring and four hydroxyls. Their structures were elucidated using spectral methods as well as chemical modification after isolation via chromatographic techniques and HPLC purification. These acetogenins demonstrated potent anti-proliferative activities against human prostate cancer PC-3 cells.

Herbal remedies and functional foods used by cancer patients attending specialty oncology clinics in Trinidad

Background

Cancer is a major disease worldwide, and many patients use complementary and alternative treatments. The purpose of this study was to identify the herbal remedies and functional foods used as complementary medicine by prostate, breast and colorectal cancer patients at speciality care facilities in Trinidad. We also sought to determine how patients rated the efficacy of these modalities compared with conventional treatment.

Methods

A descriptive, cross-sectional survey was conducted using an interviewer-administered pilot-tested de novo questionnaire during the period June to August 2012 at two speciality treatment centres on the island. Data was analysed using χ² analyses.

Results

Among the 150 patients who reported use of herbal remedies/functional foods, soursop (Annona muricata L.) was the most popular; with 80.7 % using the leaves, bark, fruit and seeds on a regular basis. Other common herbal remedies/functional foods included wheatgrass (Triticum aestivum L.), saffron (Crocus sativus L.) and Aloe vera (L.) Burm. f. The most commonly used functional foods were beetroot (Beta vulgaris L.), carrots (Daucus carata L.) and papaya (Carica papaya L.) used by 43.3 % of patients; and these were mostly blended as a mixture. Herbal remedies and functional foods were used on a daily basis and patients believed that this modality was equally (32.0 %) or more efficacious (14.7 %) than conventional treatment.

Conclusions

This survey identified the most common herbal remedies and functional foods used among prostate, breast and colorectal cancer patients in Trinidad. Although functional foods rarely pose a problem, herbs may interact with conventional chemotherapy and physicians need to inform patients regarding probable herb-drug interactions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1380-x) contains supplementary material, which is available to authorized users.

Annonaceous acetogenins (ACGs) nanosuspensions based on a self-assembly stabilizer and the significantly improved anti-tumor efficacy

Annonaceous acetogenins (ACGs) have exhibited antitumor activity against various cancers. However, these substances' poor solubility has limited clinical applications. In this study, hydroxypropyl-beta-cyclodextrin (HP-β-CD) and soybean lecithin (SPC) were self-assembled into an amphiphilic complex. ACGs nanosuspensions (ACGs-NSps) were prepared with a mean particle size of 144.4nm, a zeta potential of -22.9mV and a high drug payload of 46.17% using this complex as stabilizer. The ACGs-NSps demonstrated sustained release in vitro and good stability in plasma as well as simulated gastrointestinal fluid, and met the demand of both intravenous injection and oral administration. The ACGs-NSps demonstrated significantly increased cytotoxicity against Hela and HepG2 cancer cell lines compared to ACGs in solution (in vitro cytotoxicity assay). An in vivo study with H22-tumor bearing mice demonstrated that nanosuspensions significantly improved ACGs' antitumor activity. When orally administered, ACGs-NSps achieved a similar tumor inhibition rate at 1/10th the dose of ACGs in an oil solution (47.94% vs. 49.74%, p>0.05). Improved therapeutic efficacy was further achieved when the ACGs-NSps were intravenously injected into mice (70.31%). With the help of nanosuspension technology, ACGs may be an effective antitumor drug for clinic use.

Acetogenins from Annonaceae

In recent decades, annonaceous acetogenins have become highly studied plant secondary metabolites in terms of their isolation, structure elucidation, synthesis, biological evaluation, mechanism of action, and toxicity. The aim of the present contribution is to summarize chemical and biological reports published since 1997 on annonaceous acetogenins and synthetic acetogenin mimics. The compounds are considered biologically in terms of their cytotoxicity for cancer cell lines, neurotoxicity, pesticidal effects, and miscellaneous activities.

Four cytotoxic annonaceous acetogenins from the seeds of Annona squamosa

Four new annonaceous acetogenins (ACGs), squamocin-I (1), II (2) and III (3) and squamoxinone-D (4), together with seven known ACGs (5-11), were isolated from the seeds of Annona squamosa. The structures of all isolates were elucidated and characterised by spectral and chemical methods. Compounds 1-4 were evaluated for their cytotoxicities against Hep G2, SMMC 7721, BEL 7402, BGC 803 and H460 human cancer cell lines. Compound 1 exhibited better potent activity than the positive compound and compound 3 shows selectively cytotoxical activity against H460 with IC50 values of 0.0492 μg/ml.

Annona muricata (Annonaceae): A Review of Its Traditional Uses, Isolated Acetogenins and Biological Activities

Annona muricata is a member of the Annonaceae family and is a fruit tree with a long history of traditional use. A. muricata, also known as soursop, graviola and guanabana, is an evergreen plant that is mostly distributed in tropical and subtropical regions of the world. The fruits of A. muricata are extensively used to prepare syrups, candies, beverages, ice creams and shakes. A wide array of ethnomedicinal activities is contributed to different parts of A. muricata, and indigenous communities in Africa and South America extensively use this plant in their folk medicine. Numerous investigations have substantiated these activities, including anticancer, anticonvulsant, anti-arthritic, antiparasitic, antimalarial, hepatoprotective and antidiabetic activities. Phytochemical studies reveal that annonaceous acetogenins are the major constituents of A. muricata. More than 100 annonaceous acetogenins have been isolated from leaves, barks, seeds, roots and fruits of A. muricata. In view of the immense studies on A. muricata, this review strives to unite available information regarding its phytochemistry, traditional uses and biological activities.

Isolation of three new annonaceous acetogenins from Graviola fruit (Annona muricata) and their anti-proliferation on human prostate cancer cell PC-3

Bioassay-guided fractionation of the fruit powder of Graviola (Annona muricata) was continued to be conducted and yielded three more novel bioactive compounds: C-35 annonaceous acetogenins, muricins M and N, and C-37 annonaceous acetogenins, muricenin. They all contain a mono-tetrahydrofuran ring and four hydroxyl groups. The structures were elucidated by spectral methods and chemical modification after isolation via open column chromatographic separation and HPLC purification. Especially, murices M and N demonstrated more potent anti-proliferative activities against human prostate cancer PC-3 cells.

Synergistic interactions among flavonoids and acetogenins in Graviola (Annona muricata) leaves confer protection against prostate cancer

Phytochemical complexity of plant extracts may offer health-promoting benefits including chemotherapeutic and chemopreventive effects. Isolation of 'most-active fraction' or single constituents from whole extracts may not only compromise the therapeutic efficacy but also render toxicity, thus emphasizing the importance of preserving the natural composition of whole extracts. The leaves of Annona muricata, commonly known as Graviola, are known to be rich in flavonoids, isoquinoline alkaloids and annonaceous acetogenins. Here, we demonstrate phytochemical synergy among the constituents of Graviola leaf extract (GLE) compared to its flavonoid-enriched (FEF) and acetogenin-enriched (AEF) fractions. Comparative quantitation of flavonoids revealed enrichment of rutin (~7-fold) and quercetin-3-glucoside (Q-3-G, ~3-fold) in FEF compared to GLE. In vivo pharmacokinetics and in vitro absorption kinetics of flavonoids revealed enhanced bioavailability of rutin in FEF compared to GLE. However, GLE was more effective in inhibiting in vitro prostate cancer proliferation, viability and clonogenic capacity compared to FEF. Oral administration of 100mg/kg bw GLE showed ~1.2-fold higher tumor growth-inhibitory efficacy than FEF in human prostate tumor xenografts although the concentration of rutin and Q-3-G was more in FEF. Contrarily, AEF, despite its superior in vitro and in vivo efficacy, resulted in death of the mice due to toxicity. Our data indicate that despite lower absorption and bioavailability of rutin, maximum efficacy was achieved in the case of GLE, which also comprises of other phytochemical groups including acetogenins that make up its natural complex environment. Hence, our study emphasizes on evaluating the nature of interactions among Graviola leaf phytochemcials for developing favorable dose regimen for prostate cancer management to achieve optimal therapeutic benefits.

Annonaceous acetogenin mimic AA005 induces cancer cell death via apoptosis inducing factor through a caspase-3-independent mechanism

BACKGROUND

Annonaceous acetogenins are a family of natural products with antitumor activities. Annonaceous acetogenin mimic AA005 reportedly inhibits mammalian mitochondrial NADH-ubiquinone reductase (Complex I) and induces gastric cancer cell death. However, the mechanisms underlying its cell-death-inducing activity are unclear.

METHODS

We used SW620 colorectal adenocarcinoma cells to study AA005 cytotoxic activity. Cell deaths were determined by Trypan blue assay and flow cytometry, and related proteins were characterized by western blot. Immunofluorescence and subcellular fractionation were used to evaluate AIF nuclear translocation. Reactive oxygen species were assessed by using redox-sensitive dye DCFDA.

RESULTS

AA005 induces a unique type of cell death in colorectal adenocarcinoma cells, characterized by lack of caspase-3 activation or apoptotic body formation, sensitivity to poly (ADP-ribose) polymerase inhibitor Olaparib (AZD2281) but not pan-caspase inhibitor Z-VAD.fmk, and dependence on apoptosis-inducing factor (AIF). AA005 treatment also reduced expression of mitochondrial Complex I components, and leads to accumulation of intracellular reactive oxygen species (ROS) at the early stage. Blocking ROS formation significantly suppresses AA005-induced cell death in SW620 cells. Moreover, blocking activation of RIP-1 by necroptosis inhibitor necrotatin-1 inhibits AIF translocation and partially suppresses AA005-induced cell death in SW620 cells demonstrating that RIP-1 protein may be essential for cell death.

CONCLUSIONS

AA005 may trigger the cell death via mediated by AIF through caspase-3 independent pathway. Our work provided new mechanisms for AA005-induced cancer cell death and novel clues for cancer treatment via AIF dependent cell death.

Three new anti-proliferative Annonaceous acetogenins with mono-tetrahydrofuran ring from graviola fruit (Annona muricata)

Bioassay-guided fractionation of the fruit powder of graviola (Annona muricata) yielded three novel compounds: muricins J, K, and L. The compounds are all C35 Annonaceous acetogenins with a mono-tetrahydrofuran ring and four hydroxyls. Their structures were elucidated by spectral methods and chemical modification after isolation via chromatographic techniques and HPLC purification. These three acetogenins demonstrated an antiproliferative against human prostate cancer PC-3 cells.

In vitro anthelmintic activity of aqueous leaf extract of Annona muricata L. (Annonaceae) against Haemonchus contortus from sheep

Despite the overall progress of sheep farming in Brazil, infections with the gastrointestinal parasite Haemonchus contortus represent one the most important problems in sheep production, aggravated by the increasing resistance of nematodes to traditional anthelmintic drugs caused by inadequate sheep flock management by breeders. Ethnopharmacological data indicate Annona muricata as a promising alternative for the control of gastrointestinal nematodes because of its general anthelmintic properties. The aim of this work was to evaluate the in vitro anthelmintic effects of A. muricata aqueous leaf extract against eggs, infective larvae and adult forms of parasitic nematode H. contortus. At higher doses, A. muricata extract showed 84.91% and 89.08% of efficacy in egg hatch test (EHT) and larval motility test (LMT), respectively. In the adult worm motility test, worms were completely immobilized within the first 6-8h of nematode exposition to different dilutions of extract. Phytochemical analysis indicated the presence of phenolic compounds in A. muricata aqueous leaf extract that may be responsible for the anthelmintic effects observed. Moreover those results validate the traditional use of A. muricata as a natural anthelmintic and then the pharmacological potential of its compounds for future in vivo investigations.

Six cytotoxic annonaceous acetogenins from Annona squamosa seeds

Custard apple (Annona squamosa L.) is an edible tropical fruit, and its seeds had been used in south China as a folk medicine to treat "malignant sore" (cancer) and as an insecticide. Phytochemical investigation of the ethanol fraction of custard apple seeds led to the isolation of six new annonaceous acetogenins: annosquacins A-D (1-4), annosquatin A (5) and annosquatin B (6). Their structures were elucidated by spectroscopic analysis. Compounds 1-4 are adjacent bistetrahydrofuran annonaceous acetogenins. Compounds 5 and 6 are non-adjacent bistetrahydrofuran annonaceous acetogenins and the first examples in which the tetrahydrofuran ring system is located between C-9 and C-20. The absolute configurations of 1-6 were defined by the application of the Mosher method. Compounds 1-6 exhibited potent cytotoxic activity in vitro against five human tumour cell lines. Compounds 5 and 6 showed a high selectivity toward the MCF-7 and A-549 cell line respectively.

Graviola: a novel promising natural-derived drug that inhibits tumorigenicity and metastasis of pancreatic cancer cells in vitro and in vivo through altering cell metabolism

Pancreatic tumors are resistant to conventional chemotherapies. The present study was aimed at evaluating the potential of a novel plant-derived product as a therapeutic agent for pancreatic cancer (PC). The effects of an extract from the tropical tree Annona Muricata, commonly known as Graviola, was evaluated for cytotoxicity, cell metabolism, cancer-associated protein/gene expression, tumorigenicity, and metastatic properties of PC cells. Our experiments revealed that Graviola induced necrosis of PC cells by inhibiting cellular metabolism. The expression of molecules related to hypoxia and glycolysis in PC cells (i.e. HIF-1α, NF-κB, GLUT1, GLUT4, HKII, and LDHA) were downregulated in the presence of the extract. In vitro functional assays further confirmed the inhibition of tumorigenic properties of PC cells. Overall, the compounds that are naturally present in a Graviola extract inhibited multiple signaling pathways that regulate metabolism, cell cycle, survival, and metastatic properties in PC cells. Collectively, alterations in these parameters led to a decrease in tumorigenicity and metastasis of orthotopically implanted pancreatic tumors, indicating promising characteristics of the natural product against this lethal disease.

Antiproliferative acetogenins from a Uvaria sp. from the Madagascar dry forest

Investigation of the endemic Madagascan plant Uvaria sp. for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of two new acetogenins. The structures of these two compounds were elucidated on the basis of analysis of their 1D and 2D NMR spectra, circular dichroism, and mass spectrometric data, together with chemical modification. The two acetogenins display weak antiproliferative activity against the A2780 ovarian cancer, the A2058 melanoma, and the H522 lung cancer cell lines.

Cytotoxic bistetrahydrofuran annonaceous acetogenins from the seeds of Annona squamosa

Three new bistetrahydrofuran annonaceous acetogenins (1-3) were isolated from a 95% EtOH extract of Annona squamosa seeds. Four known annonaceous acetogenins, uvarigrandin A (4), bullatacin (5), squamostatin-A (6), and squamostatin-D (7), were also isolated. Their structures were elucidated by spectroscopic analyses, and the absolute configurations of the carbinol centers of 1-3 were defined by application of the Mosher method. These compounds all exhibited significant cytotoxic activity in vitro against five human tumor cell lines.

Antiproliferative activity, antioxidant capacity and tannin content in plants of semi-arid northeastern Brazil

The objective of this study was to evaluate antiproliferative activity, antioxidant capacity and tannin content in plants from semi-arid northeastern Brazil (Caatinga). For this study, we selected 14 species and we assayed the methanol extracts for antiproliferative activity against the HEp-2 (laryngeal cancer) and NCI-H292 (lung cancer) cell lines using the (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazole) (MTT) method. In addition, the antioxidant activity was evaluated with the DPPH (2,2-diphenyl-2-picrylhydrazyl) assay, and the tannin content was determined by the radial diffusion method. Plants with better antioxidant activity (expressed in a dose able to decrease the initial DPPH concentration by 50%, or IC₅₀) and with higher levels of tannins were: Poincianella pyramidalis (42.95 ± 1.77 µg/mL IC₅₀ and 8.17 ± 0.64 tannin content), Jatropha mollissima (54.09 ± 4.36µg/mL IC₅₀ and 2.35 ± 0.08 tannin content) and Anadenanthera colubrina (73.24 ± 1.47 µg/mL IC₅₀ and 4.41 ± 0.47 tannin content). Plants with enhanced antiproliferative activity (% living cells) were Annona muricata (24.94 ± 0.74 in NCI-H292), Lantana camara (25.8 ± 0.19 in NCI-H292), Handroanthus impetiginosus (41.8 ± 0.47 in NCI-H292) and Mentzelia aspera (45.61 ± 1.94 in HEp-2). For species with better antioxidant and antiproliferative activities, we suggest future in vitro and in vivo comparative studies with other pharmacological models, and to start a process of purification and identification of the possible molecule(s) responsible for the observed pharmacological activity. We believe that the flora of Brazilian semi-arid areas can be a valuable source of plants rich in tannins, cytotoxic compounds and antioxidant agents.

Protective effects of Annona muricata Linn. (Annonaceae) leaf aqueous extract on serum lipid profiles and oxidative stress in hepatocytes of streptozotocin-treated diabetic rats

Extracts from various morphological parts of Annona muricata Linn. (Annonaceae) are widely used medicinally in many parts of the world for the management, control and/or treatment of a plethora of human ailments, including diabetes mellitus (DM). The present study was undertaken to investigate the possible protective effects of A. muricata leaf aqueous extract (AME) in rat experimental paradigms of DM. The animals used were broadly divided into four (A, B, C and D) experimental groups. Group A rats served as 'control' animals and received distilled water in quantities equivalent to the administered volumes of AME and reference drugs' solutions intraperitoneally. Diabetes mellitus was induced in Groups B and C rats by intraperitoneal injections of streptozotocin (STZ, 70 mg kg(-1)). Group C rats were additionally treated with AME (100 mg kg(-1) day(-1), p.o.) as from day 3 post STZ injection, for four consecutive weeks. Group D rats received AME (100 mg kg(-1) day(-1) p.o.) only for four weeks. Post-euthanization, hepatic tissues were excised and processed biochemically for antioxidant enzymes and lipid profiles, such as catalase (CAT), reactive oxygen species (ROS), glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), thiobarbituric acid reactive substances (TBARS), triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL) and low density lipoprotein (LDL), respectively. Treatment of Groups B and C rats with STZ (70 mg kg(-1) i. p.) resulted in hyperglycaemia, hypoinsulinaemia, and increased TBARS, ROS, TC, TG and LDL levels. STZ treatment also significantly decreased (p<0.05) CAT, GSH, SOD, GSH-Px activities, and HDL levels. AME-treated Groups C and D rats showed significant decrease (p<0.05) in elevated blood glucose, ROS, TBARS, TC, TG and LDL. Furthermore, AME treatment significantly increased (p<0.05) antioxidant enzymes' activities, as well as serum insulin levels. The findings of this laboratory animal study suggest that A. muricata extract has a protective, beneficial effect on hepatic tissues subjected to STZ-induced oxidative stress, possibly by decreasing lipid peroxidation and indirectly enhancing production of insulin and endogenous antioxidants.

Novel cytotoxic monotetrahydrofuranic Annonaceous acetogenins from Annona montana

Four new monotetrahydrofuranic Annonaceous acetogenins, montalicins G (1) and H (2) and monlicins A (3) and B (4), and two new linear acetogenins, (+)-monhexocin (5) and (-)-monhexocin (6), as well as three known compounds, murisolin (7), 4-deoxyannomontacin (8), and muricatacin (9), were isolated from the seeds of Annona montana by high performance liquid chromatographic (HPLC) method. The absolute stereochemical structures of new isolates were elucidated and characterized by spectral and chemical methods. Interestingly, these compounds show special cytotoxicity against human hepatoma cells, Hep G2.

Acetogenins from Annonaceae: recent progress in isolation, synthesis and mechanisms of action

The aim of the present review is to summarise the knowledge about newly isolated acetogenins (ACGs) in the last six years. It will also report the total syntheses that have allowed either the confirmation or the revision of some structures, together with the biological activities and mechanism of action of such interesting natural products. In fact, of the 417 isolated compounds reviewed, over 176 have been added during the period from 1998 to 2004.

Cancer—an ayurvedic perspective

An integrated approach is needed to manage cancer using the growing body of knowledge gained through scientific developments. Thousands of herbal and traditional compounds are being screened worldwide to validate their use as anti-cancerous drugs. The science of Ayurveda is supposed to add a step on to the curative aspects of cancers that have resemblance with clinical entities of arbuda and granthi mentioned in Sushrutha samhita. Hence, an attempt is made in this review to discuss about the pathology and therapeutic management of various cancers described in Ayurveda. Review of literature on anticancer drugs of plant origin revealed identification of newer ayurvedic drugs that are not mentioned in the ancient texts. These new findings add up to ayurvedic science that has been developed through ages. In addition, details of experimental and clinical studies conducted on single and compound ayurvedic preparations for their anticancer efficacy strongly emphasize ayurvedic therapy as a scientifically driven one and not simply unconventional.