Squamocin-O(1) and squamocin-O(2), new adjacent bis-tetrahydrofuran acetogenins from the seeds of Annona squamosa

Acetogenins from the Stem of Uvaria rufa and Their Cytotoxic Activity

Four new adjacent bis-tetrahydrofuran acetogenins, bullacin C (7), uvarirufin (9), and uvariasolins III (12) and IV (13), along with 11 known acetogenins, were isolated from the stem of Uvaria rufa. Their structures were elucidated based on spectroscopic data analysis, including 1D and 2D NMR, HRESIMS, and MALDI-MS/MS of the lithium adducts. Absolute configurations were assigned using Mosher ester analysis and ECD measurements. Uvarirufin (9) possesses a unique C-39 skeleton among acetogenins. Most tested acetogenins exhibited cytotoxicity against human cancer cell lines (HCT 116, 22Rv1, MDA-MB-435, OVCAR3). Squamocin (8) and uvarirufin (9) were found to be the most potent, with an IC50 value of 1.2 μM for both in HCT 116 colon cancer cells. Additionally, a new application of Dragendorff's reagent is proposed herein for the TLC detection of acetogenins.

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.

HPLC-DAD method for the detection of five annopurpuricins in root samples of Annona purpurea

INTRODUCTION

Annona purpurea is a species known in Mexico as "cabeza de negro". In folk medicine A. purpurea root is used to treat patients with kidney diseases and cancer. Our recent studies demonstrated that this species contains five acetogenins named annopurpuricins A-E, which are active against tumoural cell lines in a subnanomolar range.

OBJECTIVE

To develop an analytical method using a high-performance liquid chromatography diode array detector (HPLC-DAD) to quantify annopurpuricins A-E in different A. purpurea root samples.

METHODOLOGY

To quantify the five annopurpuricins A-E a sample treatment was carried out, which consisted of fractionation by means of cold and hot maceration; using solvents of ascending polarity: hexane, dichloromethane, methanol and water. The resulting extracts were subject to HPLC-DAD analysis. The optimised chromatographic separation on a XBRIDGE C18 column achieved separation of all compounds in around 30 min.

RESULTS

The developed method was validated according to ICH (International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use) validation guide. The developed analytical method was found fast, economic, robust, sensitive, linear and precise. The dichloromethane extract of A. purpurea contains annopurpuricin A in quantities 2- to 25-fold higher than annopurpuricins B-E. This optimised method identified and quantified five annopurpuricins, highly bioactive molecules, in A. purpurea root.

CONCLUSIONS

The fingerprint of the dichloromethane extracts of A. purpurea was obtained at 210 nm. The results analysis allowed to quantify annopurpuricins A-E that are present in different collection batches of medium polarity extracts. After data analysis, annopurpuricin A could be establish as the metabolite marker of the root of the species.

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.

Comparative study of ultrasonic pretreatment and ultrasound assisted three phase partitioning for extraction of custard apple seed oil

Custard apple seed oil is a marketable product extracted from custard apple seed which is a potential agriculture waste. The present work aims to elucidate simultaneous extraction of the custard apple seed oil and proteins using three phase partitioning (TPP). The efficient oil extraction was executed by optimization of parameters including time, slurry ratio, salt concentration, and slurry to t-butanol ratio. Additionally, the application of ultrasound as process intensification tool for TPP was studied that reduces the time of conventional TPP and increases the yield by 2.53%. The work also comprises a comparative study of two modes of ultrasound application, namely ultrasound pre-treatment and simultaneous ultrasound assisted TPP. This work proves ultrasonic pre-treatment followed by TPP as a superior mode of ultrasound application that attributes 33.6 ± 0.56% (w/w) oil extraction with optimized pre-treatment time of 150 s, 30 W ultrasound power and 75% duty cycle. Extraction kinetics studied for conventional, Ultrasound assisted Three Phase Partitioning (UTPP), and Ultrasound Pre-treatment assisted Three Phase Partitioning (UPTPP) were observed to fit Peleg's model.

A Review on Annona squamosa L.: Phytochemicals and Biological Activities

Annona squamosa L. (Annonaceae) is a fruit tree with a long history of traditional uses. A. squamosa is an evergreen plant mainly located in tropical and subtropical regions. Srikayas, the fruits of A. squamosa, are extensively used to prepare candies, ice creams and beverages. A wide range of ethno-medicinal uses has been related to different portions of A. squamosa, such as tonic, apophlegmatisant, cool medicine, abortient and heart sedative. Numerous research projects on A. squamosa have found that it has anticancer, anti-oxidant, antidiabetic, antihypertensive, hepatoprotective, antiparasitic, antimalarial, insecticidal, microbicidel and molluscicidal activities. Phytochemistry investigations on A. squamosa have considered annonaceous acetogenins (ACGs), diterpenes (DITs), alkaloids (ALKs) and cyclopeptides (CPs) as the main constituents. Until 2016, 33 DITs, 19 ALKs, 88 ACGs and 13 CPs from this species were reported. On the basis of the multiple researches on A. squamosa, this review strives to integrate available information on its phytochemicals, folklore uses and bioactivities, hoping to promote a better understanding of its medicinal values.

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.

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.

Isodesacetyluvaricin, an Annonaceous acetogenin, specifically inhibits gene expression of cyclooxygenase-2

Cyclooxygenase-2 (COX-2) is an inducible isoform of the enzyme responsible for the synthesis of several inflammatory mediators. In a search for phytochemicals with anti-inflammatory activity, the COX-2 inhibitory activity of 15 typical Annonaceous acetogenins was examined. Isodesacetyluvaricin (1), from the Formosan tropical fruit tree Annona glabra, exhibited the most potent activity. Reverse transcription PCR was used to test the effect of 1 on epidermal growth factor-stimulated expression of COX-2 in cultures of A431 human epidermoid carcinoma cells. Three hours after exposure to 1 (5 μM), A431 cells had barely detectable levels of COX-2 mRNA. A corresponding but smaller decline in the COX-2 protein appeared on using Western blots. Lipopolysaccharide-stimulated expression of COX-2 in Raw 264.7 mouse leukemic monocyte-macrophages showed a similar decrease. Luciferase assays revealed that cells exposed to 1 had reduced activities of two COX-2 promoter-transcription factors: cAMP response element-binding factor and nuclear factor of activated T-cells. Compound 1 did not affect cell proliferation, as measured by a colorimetric assay, or intracellular store-operated calcium influx, as determined by fluorescence imaging. Thus, 1 may serve as a lead compound for targeting inflammatory diseases as well as angiogenesis and cancer metastasis.

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.

Anthelmintic acetogenin from Annona squamosa L. Seeds

Annona squamosa seeds extracts showed anthelmintic activity against Haemonchus contortus, the main nematode of sheep and goat in Northeastern Brazil. A compound 1 was isolated from ethyl acetate extract and inhibited the egg hatching of H. contortus at 25 mg ml(-1). The structure of 1 was determined as a C37 trihydroxy adjacent bistetrahydrofuran acetogenin based on spectroscopic analysis.

Antimicrobial and cytotoxic constituents from the seeds of Annona squamosa

Annotemoyin-1, Annotemoyin-2, squamocin and cholesteryl glucopyranoside were isolated from the seeds of Annona squamosa. These compounds and plant extracts showed remarkable antimicrobial and cytotoxic activities.

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.