Protoberberine Alkaloids and Cancer Chemopreventive Properties of Compounds from Alangium salviifolium

A Convenient Synthesis of Novel Isoxazolidine and Isoxazole Isoquinolinones Fused Hybrids

Isoxazolidine, isoxazole, and isoquinolinone rings are present in the structure of several natural products and/or pharmaceutically interesting compounds. In this work, facile and efficient pathways have been developed for the preparation of fused frameworks bearing those heterocycles. The successful approaches for both isoxazolidine/isoquinolinone and isoxazole/isoquinolinone hybrid syntheses relied initially on 1,3-dipolar cycloadditions of nitrones and nitrile oxides to indenone and 2-propargylbenzamide, respectively. The construction of the isoquinolinone lactam system followed by performing a selective Schmidt reaction for isoxazolidine derivatives (two steps overall), whereas the isoxazole lactams were reached via an Ullmann-type cyclisation (three steps overall). Key observations were made regarding the stereo- and regioselectivities of the reactions employed, and small libraries of the targeted hybrids were prepared, demonstrating the general applicability of these strategies.

Organocatalytic Asymmetric [4 + 2] Cyclization of Azadienes with Azlactones: Access to Chiral 3-Amino-δ-Lactams Derivatives

Herein, a series of chiral δ-lactam frameworks have been synthesized and catalyzed by chiral phosphoric acid (CPA) utilizing two kinds of open-chain aza-dienes and azlactones derived from amino acids. This powerful [4 + 2] annulation produces a broad substrate scope with functional group tolerance in yield up to 97% with up to 98:2 er. Moreover, a facile scale-up and straightforward conversion to diversely substituted products verify the synthetic utility of this method featuring good compatibility and high efficiency.

Novel Approach to the Construction of Fused Indolizine Scaffolds: Synthesis of Rosettacin and the Aromathecin Family of Compounds

Camptothecin-like compounds are actively employed as anticancer drugs in clinical treatments. The aromathecin family of compounds, which contains the same indazolidine core structure as the camptothecin family of compounds, is also expected to display promising anticancer activity. Therefore, the development of a suitable and scalable synthetic method of aromathecin synthesis is of great research interest. In this study, we report the development of a new synthetic approach for constructing the pentacyclic scaffold of the aromathecin family by forming the indolizidine moiety after synthesizing the isoquinolone moiety. Thermal cyclization of 2-alkynylbenzaldehyde oxime to the isoquinoline N-oxide, followed by a Reissert-Henze-type reaction, forms the key strategy in this isoquinolone synthesis. Under the optimum reaction conditions for the Reissert-Henze-type reaction step, microwave irradiation-assisted heating of the purified N-oxide in acetic anhydride at 50 °C reduced the formation of the 4-acetoxyisoquinoline byproduct to deliver the desired isoquinolone at a 73% yield after just 3.5 h. The eight-step sequence employed afforded rosettacin (simplest member of the aromathecin family) at a 23.8% overall yield. The synthesis of rosettacin analogs was achieved by applying the developed strategy and may be generally applicable to the production of other fused indolizidine compounds.

Genus Alangium - A review on its traditional uses, phytochemistry and pharmacological activities

The species from Alangium have been used as folk medicine to treat rheumatism, skin diseases, diabetes by the people of Southeast Asia. Previous phytochemical studies have shown this genus are rich sources of alkaloids, glycosides, and terpenoids, which have attracted considerable attention of many researchers due to their markedly diverse and complex architecture. The crude extracts as well as the monomeric compounds from the title genus possess anti-tumor, anti-inflammatory, antibacterial, anti-oxidant pharmacological activities. Besides, some isolates from Alangium exhibited the effects on skeletal, smooth muscle and the nervous system. As a large genus of medicinal plants, the medicinal value of Alangium has been widely reported, but there is no review that provide a systematic summary towards its chemical constituents and pharmacological activities, to our knowledge. This work aims to present a comprehensive overview on the traditional uses, phytochemistry, and pharmacological activities of medicinal plants in the genus Alangium, and to explore the evidence supporting its ethnopharmacological effectiveness.

Phallusialides A-E, Pyrrole-Derived Alkaloids Discovered from a Marine-Derived Micromonospora sp. Bacterium Using MS-Based Metabolomics Approaches

Integrating MS-based metabolomics approaches, LC-MS-PCA and molecular networking enabled the targeted isolation of five new pyrrole-derived alkaloids, phallusialides A-E (1-5), from a marine-derived Micromonospora sp. bacterium. The structures of 1-5 were elucidated by analysis of their HRMS, MS/MS, and NMR spectroscopic data. The absolute configuration of phallusialide A (1) was determined on the basis of comparisons of experimental and theoretically calculated ECD spectra. Compounds 1 and 2 exhibited antibacterial activity against methicillin resistant S. aureus (MRSA) and E. coli, with MIC values of 32 and 64 μg/mL, respectively, whereas 3-5 showed no antibacterial activity even at 256 μg/mL, yielding important SAR insights for this class of compounds.

Bioactive Pentacyclic Triterpene Ester Derivatives from Alnus viridis ssp. viridis Bark

Seven derivatives of pentacyclic triterpene acids (1-7) were isolated from the bark of Alnus viridis ssp. viridis using a combination of column chromatography and semipreparative HPLC. Compounds 1-3, 6, and 7 were determined to be new after spectroscopic data interpretation and were assigned as 27-hydroxyalphitolic acid derivatives (1-3), a 27-hydroxybetulinic acid derivative (6), and a 3-epi-maslinic acid derivative (7), respectively. Pentacyclic triterpenoids with a C-27 hydroxymethyl group have been found in species of the genus Alnus for the first time. These compounds were subjected to cytotoxicity testing against a number of cancer cell lines. Also, selected pentacyclic triterpenoids were selected as potential inhibitors of topoisomerases I and IIα for an in silico investigation.

Cytotoxic Triterpenoids from the Barks of Betula platyphylla var. japonica

Phytochemical investigation on the barks of Betula platyphylla var. japonica (Betulaceae) was carried out, resulting in the isolation and identification of three new triterpenoids, 27-O-cis-caffeoylcylicodiscic acid (1), 27-O-cis-feruloylcylicodiscic acid (2), and 27-O-cis-caffeoylmyricerol (3), along with six known triterpenoids, obtusilinin (4), winchic acid (5), 27-O-trans-caffeoylcylicodiscic acid (6), uncarinic acid E (7), myriceric acid B (8), and 3-O-trans-caffeoyloleanolic acid (9). The structures of the new compounds were elucidated by extensive spectroscopic methods, including 1D- and 2D-NMR, and HR-ESI-MS. All of the isolated compounds were evaluated for cytotoxicity against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and Bt549). Compounds 2, 6, 8, and 9 exhibited potent cytotoxicity against all of the tumor cells tested (IC₅₀  < 10.0 μm), while compounds 3, 4, 5, and 7 showed moderate cytotoxicity against all of the tumor cells tested (IC₅₀  < 20.0 μm).

Bioactive composition of Reevesia formosana root and stem with cytotoxic activity potential

Three lignanoids and three terpenoids, along with 40 known compounds were isolated from Reevesia formosana.

Cerasoidine, a Bis-aporphine Alkaloid Isolated from Polyalthia cerasoides during Screening for Wnt Signal Inhibitors

A new bis-aporphine alkaloid, cerasoidine (1), was isolated from the root extract of Polyalthia cerasoides together with the known bis-aporphine bidebiline E (2) during screening for compounds with Wnt signal inhibitory activities. The structure of cerasoidine (1) was established by X-ray analysis and shown by chiral HPLC analyses and electronic circular dichroism to be a 57:43 mixture of R(-)- and S(+)-atropisomers. Bidebiline E (2) exhibited inhibition of transcriptional activity of TCF/β-catenin with an IC50 value of 20.2 μM and was also found to inhibit Wnt signaling by decreasing nuclear β-catenin.

Chemistry and Pharmacognosy of the Genus Durio

Durio is well known as one of the sources of seasonal fruit production in Southeast Asia with its center of diversity in Borneo. Thailand, Indonesia, and Malaysia are the main Durio producers in the world. Besides having much information about the utilization and benefit from its timber and fruits as a food substance, traditionally some parts of this plant, such as leaves, bark and root, can also be used for medical purposes. This review deals with chemical constituents and the biological activities of Durio plants.

Synthesis of novel tetrahydrobenzazepine derivatives and their cytoprotective effect on human lymphocytes

Cytoprotective compounds such as amifostine play an important role in chemo- and radiotherapy due to their ability to reduce the side effects of these treatments. Our work was initiated with the intention to design, synthesise and test a new class of heterocyclic compounds that would have an antioxidative profile with the potential to be further developed as cytoprotective agents. The design was based on the privileged tetrahydrobenzazepine scaffold found in many natural products with a wide range of biological properties. This structure was further functionalised with moieties known to possess antioxidative features such as tertiary amine and styrene double bond. A series of eight tetrahydrobenzazepine derivatives of isoquinoline, 3,4-dihydro-β-carboline and pyridine were synthesised employing the Heck reaction as a key transformation. Some of the prepared compounds were tested for their in vitro effects on chromosome aberrations in peripheral human lymphocytes using the cytochalasin-B blocked micronucleus (MN) assay. Three tetrahydrobenzoazepine derivatives showed significant cytoprotective properties, comparable or even better to those of the radioprotective agent amifostine.

Bioactive cardinane sesquiterpenes from the stems of Alangium salviifolium

A dichloromethane extract of the stems of Alangium salviifolium afforded twelve cardinane sesquiterpenes, seven of which are new alangenes A-G (1-7) and five known compounds (8-12). Their structures were elucidated on the basis of spectroscopic techniques including UV, IR, and NMR spectroscopies, and mass spectrometry. Most of the tested compounds exhibited very potent aromatase inhibition properties, especially in the case of the cardinane sesquiterpenes 1, 5-8, and 10 (IC50 values of 0.09, 0.13, 0.30, 0.06, 2.05, and 1.19 μM, respectively), which are significantly better than that of the positive control (ketoconazole, IC50 of 2.4 μM). Compounds 1 and 4 exhibited selective cytotoxicity against the MOLT-3 cancer cell line with IC50 values of 7.9 and 2.1 μg mL(-1) , respectively.

Recent investigations of bioactive natural products from endophytic, marine-derived, insect pathogenic fungi and Thai medicinal plants

Living organisms in Thailand are very diverse due to the unique geographical location of Thailand. The diversity of Thai bioresources has proven to be a rich source of biologically active compounds. The present review covers bioactive substances from Thai endophytic, marine-derived, insect pathogenic fungi and medicinal plants. Many new compounds isolated from Thai bioresources have diverse skeletons belonging to various classes of natural products. These compounds exhibited an array of biological activities, and some are of pharmaceutical interest. Bioactive compounds from Thai bioresources have not only attracted organic chemists to develop strategies for total synthesis, but also attracted (chemical) biologists to investigate the mechanisms of action. The chemistry and biology of some selected compounds are also discussed in this review.

Phytochemical Investigations of Lonchocarpus Bark Extracts from Monteverde, Costa Rica

The acetone bark extracts of three species of Lonchocarpus from Monteverde, Costa Rica, L. atropurpureus, L. oliganthus, and L. monteviridis, were screened for antibacterial, cytotoxic, and antioxidant activities. L. orotinus extract was antibacterial against Bacillus cereus (MIC = 39 μg/mL), while L. monteviridis exhibited the most antioxidant activity. None of the Lonchocarpus extracts showed cytotoxic activity against MCF-7 cells. Fatty acids and atraric acid were isolated and purified from L. atropurpureus bark, fatty acids and loliolide from L. oliganthus bark, and leonuriside A and β-D-glucopyranos-1-yl N-methylpyrrole-2-carboxylate from L. monteviridis bark. Atraric acid showed cytotoxic and antimicrobial activities.

Triterpenoids

This review covers the isolation and structure determination of triterpenoids including squalene derivatives, lanostanes, holostanes, cycloartanes, cucurbitanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, onoceranes and saponins; 308 references are cited.

Anti-cancer potential of South Asian plants

Phyto-chemicals are increasingly being used in the treatment of cancer because of their availability, potential anti-cancer activity with less adverse effects when compared with chemotherapy. The variation of climate and geography in South Asian countries provides a nursing environment for the growth of versatile plant species, that are repeatedly drawing attention of the scientific community. In this review, we have focused on the anti-cancer potential of thirty plants, which are commonly found in Bangladesh, India, Nepal, Pakistan and Sri Lanka, with their mechanisms of action. In particular, we have discussed the bio-active components that display anti-cancer activity, which have been identified in these plants. This review may help researchers to profile plants with known anti-cancer effect of this region and further investigations of anti-cancer agents in medicinal plants from South Asia.