Alkaloids from Alstonia scholaris and Ficus schwarzii

Alkaloids, which are the most studied secondary metabolites, are structurally diverse and well known for their biological activity. The aim of the present study is to perform phytochemical investigations on the alkaloidal composition of two selected plant species, namely, Ficus schwarzii (Moraceae) and Alstonia scholaris (Apocynaceae). (specimen from the West Coast of Peninsular Malaysia). The previously unexplored phytochemistry of F. schwarzii and the phytochemical variation of A. scholaris due to locality have motivated research into the two species collected from Peninsular Malaysia. Phytochemical investigation of the leaves of F. schwarzii yielded nine novel alkaloids, namely, schwarzinicines A−G (1−7), and schwarzificusines A and B (8 and 9). The schwarzinicine alkaloids represent the first examples of 1,4 diarylbutanoid−phenethylamine conjugates, while schwarzificusines A and B (8 and 9) represent a pair of new diastereomeric 1-phenyl-3-aminotetralins that are structurally related to the schwarzinicines alkaloids. The structures of alkaloids 1–9 were elucidated by detailed analysis of their HRMS and NMR data. Plausible biogenetic pathways that furnish the skeletons of the schwarzinicine and schwarzifiscusine alkaloids were proposed. Phytochemical investigation of the leaves, bark and flowers of A. scholaris cultivated on the West Coast of Peninsular Malaysia provided a total of 17 alkaloids, of which five are new, namely, alstoscholactine (10), alstolaxepine (11), N-formylyunnanensine (12), scholaphylline (13), and alstobrogaline (19). Alstoscholactine (10), alstolaxepine (11), and alstobrogaline (19) were established to contain novel ring systems. Alstoscholactine (10) represents a rearranged stemmadenine alkaloid with an unprecedented C-6-C-19 connectivity, while alstolaxepine (11) represents a 6,7-seco-angustilobine B-type alkaloid incorporating a rare γ-lactone-bridged oxepane ring system. On the other hand, alstobrogaline (19) is an unusual monoterpenoid indole alkaloid incorporating a third N atom, and possessing an aldimine as well as a nitrone function. N-Formylyunnanensine (12) is the N-formyl derivative of the known alkaloid yunnanensine, and it was isolated as a pair of unseparable E/Z-formamide rotamers. Scholaphylline (13) represents the first member of the secostemmadenine-secovallesamine-type bisindole alkaloid. The 12 known alkaloids obtained from Alstonia scholaris are 19,20-E-vallesamine (14), 19,20-Z-vallesamine (15), 19,20-E-vallesamine N-oxide (16), 6,7-secoangustilobine B (17), and 6,7-seco-19,20-epoxyangustilobine B (18), tetrahydroalstonine (20), picrinine (21), 16R-19,20-Z-isositsirikine (22), 16R-19,20-E-isositsirikine (23), scholaricine (24), N-demethylalstogustine N-oxide (25), and E/Z-vallesiachotamine (26)

The effect of heating on the antioxidants content in edible oil / Premanand a/l Krishnan

There are many types edible oils with various brand found in the market. The types of oils involved in the analysis for the antioxidants content were palm oil, olive oil, canola oil, sunflower oil, soy bean oil, corn oil, gingerly oil, rice bran oil, mixed oil and ayurvedic oil. The method used to evaluate the amount antioxidants in this study was 2, 2-diphenyl-1-picrylhydrazyl (DPPH). In this test, the scavenging of the DPPH radicals was followed by monitoring the decrease in absorbance at 515 nm. Heating the oil samples to various temperatures shows negative effect on the antioxidants content. The antioxidants content in all types of oils showed decreasing pattern when subjected to heat. The sample with highest antioxidants content at the temperature 180 oC is corn oil, followed by palm oil, sunflower oil, olive oil, canola oil, ayurvedic oil, rice bran oil, mixed oil, soy bean oil and lastly gingerly oil. Therefore, corn oil is the most suitable type of oil for high temperature cooking such as fryin

Alkaloids from Alstonia scholaris and Ficus schwarzii

Alkaloids, which are the most studied secondary metabolites, are structurally diverse and well known for their biological activity. The aim of the present study is to perform phytochemical investigations on the alkaloidal composition of two selected plant species, namely, Ficus schwarzii (Moraceae) and Alstonia scholaris (Apocynaceae). (specimen from the West Coast of Peninsular Malaysia). The previously unexplored phytochemistry of F. schwarzii and the phytochemical variation of A. scholaris due to locality have motivated research into the two species collected from Peninsular Malaysia. Phytochemical investigation of the leaves of F. schwarzii yielded nine novel alkaloids, namely, schwarzinicines A−G (1−7), and schwarzificusines A and B (8 and 9). The schwarzinicine alkaloids represent the first examples of 1,4 diarylbutanoid−phenethylamine conjugates, while schwarzificusines A and B (8 and 9) represent a pair of new diastereomeric 1-phenyl-3-aminotetralins that are structurally related to the schwarzinicines alkaloids. The structures of alkaloids 1–9 were elucidated by detailed analysis of their HRMS and NMR data. Plausible biogenetic pathways that furnish the skeletons of the schwarzinicine and schwarzifiscusine alkaloids were proposed. Phytochemical investigation of the leaves, bark and flowers of A. scholaris cultivated on the West Coast of Peninsular Malaysia provided a total of 17 alkaloids, of which five are new, namely, alstoscholactine (10), alstolaxepine (11), N-formylyunnanensine (12), scholaphylline (13), and alstobrogaline (19). Alstoscholactine (10), alstolaxepine (11), and alstobrogaline (19) were established to contain novel ring systems. Alstoscholactine (10) represents a rearranged stemmadenine alkaloid with an unprecedented C-6-C-19 connectivity, while alstolaxepine (11) represents a 6,7-seco-angustilobine B-type alkaloid incorporating a rare γ-lactone-bridged oxepane ring system. On the other hand, alstobrogaline (19) is an unusual monoterpenoid indole alkaloid incorporating a third N atom, and possessing an aldimine as well as a nitrone function. N-Formylyunnanensine (12) is the N-formyl derivative of the known alkaloid yunnanensine, and it was isolated as a pair of unseparable E/Z-formamide rotamers. Scholaphylline (13) represents the first member of the secostemmadenine-secovallesamine-type bisindole alkaloid. The 12 known alkaloids obtained from Alstonia scholaris are 19,20-E-vallesamine (14), 19,20-Z-vallesamine (15), 19,20-E-vallesamine N-oxide (16), 6,7-secoangustilobine B (17), and 6,7-seco-19,20-epoxyangustilobine B (18), tetrahydroalstonine (20), picrinine (21), 16R-19,20-Z-isositsirikine (22), 16R-19,20-E-isositsirikine (23), scholaricine (24), N-demethylalstogustine N-oxide (25), and E/Z-vallesiachotamine (26)

A comprehensive review on the chemical constituents, sesquiterpenoid biosynthesis and biological activities of Sarcandra glabra

Abstract Sarcandra glabra (Thunb.) Nakai is a perennial evergreen herb categorised within the Sarcandra Gardner genus under the Chloranthaceae family. Indigenous to tropical and subtropical regions of East Asia and India, this species is extensively distributed across China, particularly in the southern regions (Sichuan, Yunnan, and Jiangxi). In addition to its high ornamental value, S. glabra has a rich history of use in traditional Chinese medicine, evident through its empirical prescriptions for various ailments like pneumonia, dysentery, fractures, bruises, numbness, amenorrhea, rheumatism, and other diseases. Besides, modern pharmacological studies have revealed various biological activities, such as antitumour, anti-bacterial, anti-viral anti-inflammatory and immunomodulatory effects. The diverse chemical constituents of S. glabra have fascinated natural product researchers since the 1900s. To date, over 400 compounds including terpenoids, coumarins, lignans, flavonoids, sterols, anthraquinones, organic acids, and organic esters have been isolated and characterised, some featuring unprecedented structures. This review comprehensively examines the current understanding of S. glabra’s phytochemistry and pharmacology, with emphasis on the chemistry and biosynthesis of its unique chemotaxonomic marker, the lindenane-type sesquiterpenoids. Graphical Abstrac

Unusual phenethylamine-containing alkaloids from Elaeocarpus tectorius

From the leaves of Elaeocarpus tectorius (Lour.) Poir. four previously undescribed phenethylamine-containing alkaloids were isolated, namely, tectoricine, possessing an unprecedented isoquinuclidinone ring system incorporating a phenethylamine moiety, tectoraline, representing a rare alkamide incorporating two phenethylamine moieties, and tectoramidines A and B, representing the first naturally occurring trimeric and dimeric phenethylamine alkaloids incorporating an amidine function. The structures of these alkaloids were established by detailed spectroscopic analysis. The absolute configuration of tectoricine was determined by comparison of the experimental and calculated ECD spectra. Plausible biosynthetic pathways to the four alkaloids are proposed

Alstoscholactine and Alstolaxepine, Monoterpenoid Indole Alkaloids with γ-Lactone-Bridged Cycloheptane and Oxepane Moieties from Alstonia scholaris

Two new monoterpenoid indole alkaloids, alstoscholactine (1) and alstolaxepine (2), were isolated from Alstonia scholaris. Compound 1 represents a rearranged stemmadenine alkaloid with an unprecedented C-6-C-19 connectivity, whereas compound 2 represents a 6,7-seco-angustilobine B-type alkaloid incorporating a rare γ-lactone-bridged oxepane ring system. Their structures and absolute configurations were determined by spectroscopic analyses. Compound 1 was successfully semisynthesized from 19E-vallesamine. Compound 2 induced marked vasorelaxation in rat isolated aortic rings precontracted with phenylephrine

Pentacyclic and hexacyclic cucurbitacins from Elaeocarpus petiolatus

Four undescribed cucurbitacins, designated as petiolaticins A–D, and four known cucurbitacins were isolated from the bark and leaves of Elaeocarpus petiolatus (Jack) Wall. Their chemical structures were elucidated based on detailed analyses of the NMR and MS data. The absolute configuration of petiolaticin A was also determined by X-ray diffraction analysis. Petiolaticin A represents a cucurbitacin derivative incorporating a 3,4-epoxyfuranyl-bearing side chain, while petiolaticin B possesses a furopyranyl unit fused to the tetracyclic cucurbitane core structure. Petiolaticins A, B, and D were evaluated in vitro against a panel of human breast, pancreatic, and colorectal cancer cell lines. Petiolaticin A exhibited the greatest cytotoxicity against the MDA-MB-468, MDA-MB-231, MCF-7, and SW48 cell lines (IC50 7.4, 9.2, 9.3, and 4.6 μM, respectively). Additionally, petiolaticin D, 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one, and 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one 3-O-β-D-glucopyranoside were tested for their ability to inhibit cell entry of a pseudotyped virus bearing the hemagglutinin envelope protein of a highly pathogenic avian influenza virus. Petiolaticin D showed the highest inhibition (44.3%), followed by 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one (21.0%), and 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one 3-O-β-D-glucopyranoside showed limited inhibition (9.0%). These preliminary biological assays have demonstrated that petiolaticins A and D possess anticancer and antiviral properties, respectively, which warrant for further investigations

Preparation and Preliminary Structure–Activity Relationship Studies of Schwarzinicine A Analogs as Vasorelaxant Agents

Schwarzinicines A–D, a series of alkaloids recently discovered from Ficus schwarzii, exhibit pronounced vasorelaxant activity in rat isolated aorta. Building on this finding, a concise synthesis of schwarzinicines A and B has been reported, allowing further investigations into their biological properties. Herein, a preliminary exploration of the chemical space surrounding the structure of schwarzinicine A (1) was carried out aiming to identify structural features that are essential for vasorelaxant activity. A total of 57 analogs were synthesized and tested for vasorelaxant activity in rat isolated aorta. Both efficacy (Emax) and potency (EC50) of these analogs were compared. In addition to identifying structural features that are required for activity or associated with potency enhancement effect, four analogs showed significant potency improvements of up to 40.2-fold when compared to 1. Molecular dynamics simulation of a tetrameric 44-bound transient receptor potential canonical-6 (TRPC6) protein indicated that 44 could potentially form important interactions with the residues Glu509, Asp530, Lys748, Arg758, and Tyr521. These results may serve as a foundation for guiding further structural optimization of the schwarzinicine A scaffold, aiming to discover even more potent analogs