A new cadinane sesquiterpenoid glucoside with cytotoxicity from Abelmoschus sagittifolius

Computational assessment of the radical scavenging activity of cleomiscosin

Coumarinolignans such as cleomiscosin A (CMA), cleomiscosin B (CMB), and cleomiscosin C (CMC) are secondary metabolites that were isolated from diverse plant species. Cleomiscosins (CMs) have numerous interesting biological activities, including noteworthy cytotoxicity of cancer cell lines along with hepatoprotective and assumed antioxidant activities. In this present study, the antioxidant properties of three cleomiscosins were investigated with a focus on the structure-activity relationship using thermodynamic and kinetic calculations with the M06-2X/6-311++G(d,p) method. The results show that CMs, including CMA, CMB, and CMC, are weak antioxidants in apolar environments, with k overall of 7.52 × 102 to 6.28 × 104 M-1 s-1 for the HOO˙ radical scavenging reaction in the gas phase and 3.47 × 102 to 6.44 × 104 M-1 s-1 in pentyl ethanoate. Remarkably, the difference in the fusion of phenylpropanoid structure with coumarin via two ortho-hydroxyl groups (CMA and CMB) does not cause any noticeable effect on their antioxidant activity, while the presence of a methoxy substitute on the aromatic ring of phenylpropanoid units (CMC) increases the reaction rate to about 61 to 84 times faster than that of CMA. In contrast, the studied CMs exhibit a good antioxidant capacity in polar environments, with a k overall range from 4.03 × 107 to 8.66 × 107 M-1 s-1, 102-103 times faster than that of Trolox, equal to that of ascorbic acid and resveratrol. The angular fusion of the phenylpropanoid and coumarin structures, as well as the methoxy substitution on the aromatic ring of the phenylpropanoid unit of the studied CMs, do not have any considerable effect on their antioxidant activity under the studied conditions.

A new pregnane glycoside from Marsdenia tenacissima and its cytotoxic and NO inhibitory activities

The Marsdenia tenacissima, has been used as traditional Chinese medicine for six hundred years. Our chemical investigation on the stem of Marsdenia tenacissima led to the isolation of one new pregnane glycoside, namely, marsdeoside J (compound 1) and twelve known compounds. The structure of the new compound was elucidated by spectroscopic analysis including 1D and 2D NMR, HRESIMS, IR, and UV. The absolute configurations of the sugar moiety were identified by comparing the specific optical rotations and Rf values with those of the commercially available standards and the data reported in the literature. Compound 1 showed cytotoxicities against five human cancer cell lines, with IC50 values ranging from 6.5 to 18.1 μM and certain inhibitory activities on NO production.

A Potent Antioxidant Sesquiterpene, Abelsaginol, from Abelmoschus sagittifolius: Experimental and Theoretical Insights

The sesquiterpenoid compound abelsaginol (AS) was successfully isolated from Abelmoschus sagittifolius for the first time. The compound was identified using NMR and MS data. The antioxidant activity of AS was also evaluated both theoretically and experimentally. AS was found to be a weak HOO^• radical scavenger in organic solvents such as pentyl ethanoate and dimethyl sulfoxide (k _overall = ∼ 10² M^-1 s^-1), in a good agreement with the results of the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assay. However, AS exhibited good HOO^• antiradical activity in water at pH 7.40 (k _overall = 9.00 × 10⁶ M^-1 s^-1) through the single-electron transfer mechanism of the anion state. Further calculations also demonstrated that AS could exert good to moderate activity against CH₃O^•, CH₃OO^•, CCl₃OO^•, NO₂, and SO₄ ^•- radicals, with k _f values from 4.00 × 10³ to 1.52 × 10⁷ M^-1 s^-1. However, AS exerted much lower activity against HO^•, CCl₃O^•, NO, O₂ ^•-, and N₃ ^• radicals under the studied conditions. In general, the activity of AS in water at pH 7.40 is higher than that of Trolox or butylated hydroxytoluene, which are common reference antioxidants. Thus, in an aqueous physiological milieu, AS is a promising natural antioxidant.

Cadinane Sesquiterpenoids and Their Glycosides from Alangium chinense That Inhibit Spontaneous Calcium Oscillations

Nine new cadinane sesquiterpenoids, alanenses A-I (1-9), were isolated from the leaves of Alangium chinense together with three previously reported analogues (10-12). The structures of these molecules were elucidated by interpretation of spectroscopic and spectrometric data. Absolute configurations were established by the comparison of experimental and calculated ECD data, chemical degradation studies for sugar moieties, and a single-crystal X-ray diffraction analysis. Compounds 1 and 2 were isolated as racemates, and enantiopurification was achieved by chiral HPLC. Compounds 3-5 are glycosylated cadinanes bearing a β-d-glucose unit, while compounds 6-9 incorporate a hydroxymethyl group in either the free form or additional ring fusion. The structure of compound 11 was originally misassigned and later revised using additional NMR data. The corrected structure is here supported by X-ray single-crystal analysis. Compounds 1 and 2 inhibit spontaneous calcium channel oscillations at low micromolar concentrations.

Natural Bioactive Cinnamoyltyramine Alkylamides and Co-Metabolites

Natural products are a vital source for agriculture, medicine, cosmetic and other fields. Among them alkylamides are a broad and expanding group found in at least 33 plant families. Frequently, they possess a simple carbon skeleton architecture but show broad structural variability and important properties such as immunomodulatory, antimicrobial, antiviral, larvicidal, insecticidal and antioxidant properties, amongst others. Despite to these several and promising biological activities, up to today, only two reviews have been published on natural alkylamides. One focuses on their potential pharmacology application and their distribution in the plant kingdom and the other one on the bioactive alkylamides specifically found in Annona spp. The present review is focused on the plant bioactive cinnamoyltyramine alkylamides, which are subject of several works reported in the literature. Furthermore, the co-metabolites isolated from the same natural sources and their biological activities are also reported.

Complete chloroplast genomes of three important species, Abelmoschus moschatus, A. manihot and A. sagittifolius: Genome structures, mutational hotspots, comparative and phylogenetic analysis in Malvaceae

Abelmoschus is an economically and phylogenetically valuable genus in the family Malvaceae. Owing to coexistence of wild and cultivated form and interspecific hybridization, this genus is controversial in systematics and taxonomy and requires detailed investigation. Here, we present whole chloroplast genome sequences and annotation of three important species: A. moschatus, A. manihot and A. sagittifolius, and compared with A. esculentus published previously. These chloroplast genome sequences ranged from 163121 bp to 163453 bp in length and contained 132 genes with 87 protein-coding genes, 37 transfer RNA and 8 ribosomal RNA genes. Comparative analyses revealed that amino acid frequency and codon usage had similarity among four species, while the number of repeat sequences in A. esculentus were much lower than other three species. Six categories of simple sequence repeats (SSRs) were detected, but A. moschatus and A. manihot did not contain hexanucleotide SSRs. Single nucleotide polymorphisms (SNPs) of A/T, T/A and C/T were the largest number type, and the ratio of transition to transversion was from 0.37 to 0.55. Abelmoschus species showed relatively independent inverted-repeats (IR) boundary traits with different boundary genes compared with the other related Malvaceae species. The intergenic spacer regions had more polymorphic than protein-coding regions and intronic regions, and thirty mutational hotpots (≥200 bp) were identified in Abelmoschus, such as start-psbA, atpB-rbcL, petD-exon2-rpoA, clpP-intron1 and clpP-exon2.These mutational hotpots could be used as polymorphic markers to resolve taxonomic discrepancies and biogeographical origin in genus Abelmoschus. Moreover, phylogenetic analysis of 33 Malvaceae species indicated that they were well divided into six subfamilies, and genus Abelmoschus was a well-supported clade within genus Hibiscus.

The Chemistry and Health Benefits of Dietary Phenolamides

Phenolamides, also known as hydroxycinnamic acid amides or phenylamides, have been reported throughout the plant kingdom, while a few of these amine-conjugated hydroxycinnamic acids are unique in foods. The current knowledge of their specific functions in plant development and defense is readily available as is their biosynthesis; however, their functionality in humans is still largely unknown. Of the currently known phenolamides, the most common are avenanthramides, which are unique in oats and similar to the well-known drug Tranilast, which possess anti-inflammatory, antioxidant, anti-itch, and antiatherogenic activities. While recent data have brought to light more information regarding the other known phenolamides, such as hordatines, dimers of agmatine conjugated to hydroxycinnamic acid, and kukoamines, spermine-derived phenolamides, the information is still severely limited, leaving their potential health benefits to speculation. Herein, to highlight the importance of dietary phenolamides to human health, we review and summarize the four major subgroups of phenolamides, including their chemical structures, dietary sources, and reported health benefits. We believe that the studies on phenolamides are still in the infancy stage and additional health benefits of these phenolamides may yet be identified.

Advances in the chemistry and pharmacological potential of coumarinolignans

Coumarinolignans (CLs) are a group of non-conventional lignans having coumarins and phenyl propanes as two C₆C₃ units linked commonly through a dioxane bridge. The research findings during Jan 2008-May 2018 on this group of secondary metabolites describing their occurrence, structural characteristics, large-scale preparation, synthesis, derivatives, pharmacological activities, and structure-activity relationship are presented in this review. Around 38 CLs have been isolated from 40 plant species belonging to 20 different families during the review period. Reports on the syntheses of CL derivatives are also discussed. The majority of the reported CLs have shown potential anti-inflammatory activities, especially against pro-inflammatory cytokines. The other pharmacological effects exhibited by CLs such as hepatoprotective, anticancer, etc., are also covered in this review comprehending the lacunae in their development into drugs. This article is a continuation of our earlier work on coumarinolignans (Begum SA, Sahai M, Ray AB (2010) Non-conventional lignans: coumarinolignans, flavonolignans, and stilbenolignans. In: Kinghorn AD, Falk H, Kobayashi J (eds) Progress in the chemistry of organic natural products, Springer, Verlag/Wien, p 1-70).