Flavonoids, alkaloids from the seeds of Crotalaria pallida and their cytotoxicity and anti-inflammatory activities

Advances in the synthesis of rearranged homoisoflavonoids

Rearranged homoisoflavonoids constitute a unique group of natural products, renowned for their structural diversity and complexity. These compounds, derived from modifications in the 3-benzylchroman skeleton, are categorized into four subclasses: brazilin, caesalpin, protosappanin, and scillascillin homoisoflavonoids. This review examines the advancements in the total synthesis of these complex structures, aiming to highlight the challenges and opportunities encountered. A comparative analysis of the strategies employed thus far to synthesize these compounds provides a comprehensive understanding of the progress in this field.

Asymmetric Synthesis of Scillascillin-Type Homoisoflavonoid

The first asymmetric synthesis of a scillascillin-type homoisoflavonoid was reported. Key reactions for the asymmetric synthesis of benzocyclobutene include catalytic reductive desymmetrization of malonic ester and an intramolecular C-H activation of the methyl group.

A molecular networking-based isolation of gardneria alkaloids from Gardneria distincta and their anti-inflammatory activity

Gardneria distincta P. T. Li is traditionally applied as a herbal medicine for treatment various ailments, and is mainly distributed in Southwestern China. Under the guided separation of MS/MS-based molecular networking, eight undescribed oxindole alkaloids, gardistines A-H, as well as 17 known alkaloids were discovered from the whole parts of Gardneria distincta. Structural elucidation of these undescribed alkaloids was performed by various spectroscopic methods. Gardistine A is a rare oxindole gardneria alkaloid bearing an ester carbonyl group attached to C-18, which is the second reported alkaloid of oxindole gardneria-type. All of the identified monoterpene indole alkaloids were investigated for their anti-inflammatory activity in LPS-induced RAW 264.7 cells. Gardistines A-B and akuammidine demonstrated significant inhibitory effects on the expressions of nitric oxide, tumor necrosis factor alpha, and interleukin-6 at 20 μM.

Revisiting the Domestication Process of African Vigna Species (Fabaceae): Background, Perspectives and Challenges

Legumes are one of the most economically important and biodiverse families in plants recognised as the basis to develop functional foods. Among these, the Vigna genus stands out as a good representative because of its relatively recent African origin as well as its outstanding potential. Africa is a great biodiversity centre in which a great number of species are spread, but only three of them, Vigna unguiculata, Vigna subterranea and Vigna vexillata, were successfully domesticated. This review aims at analysing and valorising these species by considering the perspective of human activity and what effects it exerts. For each species, we revised the origin history and gave a focus on where, when and how many times domestication occurred. We provided a brief summary of bioactive compounds naturally occurring in these species that are fundamental for human wellbeing. The great number of wild lineages is a key point to improve landraces since the domestication process caused a loss of gene diversity. Their genomes hide a precious gene pool yet mostly unexplored, and genes lost during human activity can be recovered from the wild lineages and reintroduced in cultivated forms through modern technologies. Finally, we describe how all this information is game-changing to the design of future crops by domesticating de novo.

Isolation and structure elucidation of anti-tyrosinase compounds from the seeds of Crotalaria pallida

Three new compounds, crotalariapallins A-C (1-3), were isolated from the 95% EtOH extract of the seeds of Crotalaria pallida. Their structures were established based on extensive spectroscopic methods, including HRESIMS, UV, 1D and 2D NMR. All compounds were evaluated for their inhibitory activities to tyrosinase. These compounds showed different degrees of inhibitory activities, among them, compound 3 exhibited the strongest inhibition activity (IC₅₀ = 0.42 mM).

A Comprehensive Review on Chemotaxonomic and Phytochemical Aspects of Homoisoflavonoids, as Rare Flavonoid Derivatives

Homoisoflavonoids (3-benzylidene-4-chromanones) are considered as an infrequent flavonoid class, possessing multi-beneficial bioactivities. The present study gives an overview on phytochemical aspects of homoisoflavonoids, including utilized plant species, parts, extracts, and separation techniques. Overall, these compounds have mainly been isolated and identified from bulbs and rhizomes of the plants belonging to Asparagaceae and Fabaceae families, particularly the genera of Ophiopogon, Dracaena, Scilla, Polygonatum, and Caesalpinia.

The complete chloroplast genome sequences and phylogenetic analysis of Crotalaria pallida (Leguminosae)

The complete chloroplast genome of Crotalaria pallida was obtained using the high-throughput sequencing technology in this article. The complete chloroplast genomes of this species were 152,658 bp in length, consisting of a large single-copy region (LSC) of 83,652 bp and a small single-copy region (SSC) of 18,028 bp, which were separated by a pair of inverted repeat (IRs) regions of 25,489 bp. The chloroplast genome contained 111 unique genes, including 77 protein-coding genes, 30 tRNA genes, and four rRNA genes. The phylogenomic relationship analysis suggested that C. pallida was closely related to Lupinus in the family of Leguminosae.

Crotalaria spectabilis as a source of pyrrolizidine alkaloids and phenolic compounds: HPLC-MS/MS dereplication and monocrotaline quantification of seed and leaf extracts

INTRODUCTION

Crotalaria spectabilis is an important species used as a pre-plant cover for soybean crops to control the proliferation of endoparasitic nematodes. Species from the Crotalaria genus are known for presenting pyrrolizidine alkaloids (PAs) in their composition, however, C. spectabilis is still considered chemically under-explored.

OBJECTIVE

The goal of this manuscript is the development and validation of a method for PAs and flavonoids identification and quantification of C. spectabilis seeds and leaves, a toxic plant used for nematode proliferation control in soil, especially in soybean crops.

MATERIALS AND METHODS

Seeds and leaves extracts were analysed by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) for the identification of the compounds.

RESULTS

PAs and phenolic compounds could be identified in both samples based on the MS/MS fragmentation pattern. Molecular formulas of the annotated compounds were confirmed by ultra-high-performace liquid chromatography-quadrupole time-of-flight (UHPLC-QToF), and monocrotaline could also be confirmed by standard comparison. The quantification of monocrotaline was performed by HPLC-MS/MS, resulting in 123 times higher monocrotaline content in seeds than in the leaves, which could explain its efficiency in combating nematode proliferation in soil.

CONCLUSION

This was the first report of phenolic compounds in C. spectabilis. The current study highlights the importance of C. spectabilis for nematode control due to the presence of toxic PAs, and the employment of analytical techniques for identification and quantification of compounds present in the extracts.

Divergent Photocatalytic Reactions of α-Ketoesters under Triplet Sensitization and Photoredox Conditions

The long-lived triplet excited states of transition metal photocatalysts can activate organic substrates via either energy- or electron-transfer pathways, and the rates of these processes can be influenced by rational tuning of the reaction conditions. The characteristic reactive intermediates generated, however, are distinct and can exhibit very different reactivity patterns. This mechanistic diversity available to photocatalytic reactions might thus offer an opportunity to engineer divergent reactions that give markedly different chemical outcomes under superficially similar conditions. Herein, we show that the photocatalytic reactions of benzoylformate esters with alkenes can be directed toward either Paternò-Büchi cycloadditions or allylic functionalization reactions under conditions favoring energy transfer or electron transfer, respectively. These studies provide a framework for designing other divergent photocatalytic methods that produce different sets of reaction outcomes under photoredox and triplet sensitization conditions.

Naturally Occurring Homoisoflavonoids: Phytochemistry, Biological Activities, and Synthesis (Part II)

This review documents all the new homoisoflavonoids (HIFs) that have been reported since 2007, whose total number has grown from 159 in 2007 to 295 at the present time. This review contains their structures, biological sources, plant parts they are obtained from, and, if reported, their optical rotations and melting points. The same classification is followed as an earlier review to ease reference to both reviews. This review takes note of the recent revision of plant families that were known to contain HIFs that have now been merged into one big family, Asparagaceae. Homoisoflavonoids also occur in Fabaceae and others. Two taxa, Ophiopogoan japonicus (Asparagaceae) and Caesalpinia sappan (Fabaceae), have been the source of many HIFs. These are briefly summarized. The biological properties of HIFs are also reviewed under the topics such as antioxidant, anti-inflammatory, antimicrobial, antidiabetic, and cytotoxic. The review also surveys the total synthesis of natural HIFs. All new compounds are classified and tabulated following the same style as the previous review.

Dedicated to Professor Andrew Paul Krapcho on the occasion of his 87th Birthday.

Chemical Constituents of Vigna luteola and Their Anti-inflammatory Bioactivity

Seventy-three compounds were identified from the methanol extract of V. luteola, and among these, three new (1–3) were characterized by spectroscopic and mass spectrometric analyses. The isolated constituents were assessed for anti-inflammatory potential evaluation, and several purified principles exhibited significant superoxide anion and elastase inhibitory effects.

Rapid determination of 3', 4'-dimethoxy flavonol-3-β-d-glucopyranoside in rat plasma by LC-MS/MS method followed by protein precipitation

A reliable liquid chromatography/tandem mass (LC-MS/MS) method was developed for quantitation of 3', 4'-dimethoxy flavonol-3-β-d-glucopyranoside (DF3G) in rat plasma using pantoprazole as the internal standard. An Agilent C18 column (100 mm × 3 mm, 3.5 μm) was performed for chromatographic separation with the mobile phase composed of methanol-water (containing formic acid) at a flow rate of 0.4 mL/min. A triple-quadrupole mass spectrometry equipped with an electrospray ionization (ESI) source in positive ion mode was applied to quantitative analysis by multiple reacting monitoring (MRM). The MRM precursor-product ion transition of DF3G and Pantoprazole (IS) were m/z 461.1 → 299.2 and 383.9 → 200.2, respectively. Calibration curves were recovered in a concentration range of 1-500 ng/mL for plasma with a limit of lower quantification (LLOQ) of 1 ng/mL. The intra-day and inter-day precision were not >10%. The accuracy of DF3G ranged from -10% to 0.53% in quality control (QC) samples at three concentrations. DF3G was not degraded during the analysis and the storage period. All the data were validated in accordance with the FDA bioanalytical method validation guideline. The LC-MS/MS method was successfully employed in the pharmacokinetic study of the DF3G after oral administration and intravenous injection in rats.