A new alkylbenzoquinone from Embelia rowlandii Gilg. (Myrsinaceae)

Metabolomic Responses of Lettuce (Lactuca sativa) to Allelopathic Benzoquinones from Iris sanguinea Seeds

Weed management is important in modern crop protection. Chemical weed control using synthetic herbicides, however, suffers from resistance and ecotoxicity. Metabolomic investigation of allelopathy (or allelochemicals) may provide novel alternatives to synthetic herbicides. This study aimed to investigate the detailed metabolomic responses of plants to allelochemicals in Iris seed extracts. The seed extracts of Iris sanguinea showed the strongest growth inhibitory activity against alfalfa, barnyard grass, lettuce, and mustard. 3-Hydroxyirisquinone (3-[10(Z)-heptadecenyl]-2-hydroxy-5-methoxy-1,4-benzoquinone) was isolated as a major allelochemical from I. sanguinea seeds through bioassay-guided fractionation. The compound inhibited the growth of shoots and roots by browning root tips. Discriminant analysis identified 33 differentially regulated lettuce metabolites after treatment with 3-hydroxyirisquinone (3HIQ). Metabolic pathway analysis revealed that several metabolic pathways, including aromatic amino acid biosynthesis and respiratory pathways, were affected by the compounds. Differential responses of membrane lipids (accumulation of unsaturated fatty acids) and extensive formation of reactive oxygen species were observed in root tissues following treatment with 3HIQ. Overall, alkylbenzoquinone from I. sanguinea induced extensive metabolic modulation, oxidative stress, and growth inhibition. The metabolomic responses to allelochemicals may provide fundamental information for the development of allelochemical-based herbicides.

Embelin: an HPTLC method for quantitative estimation in five species of genus Embelia Burm. f

Background

The plants belonging to the genus Embelia, a significant tropical genus with many biological activities, are benefiting because of their robust medicinal properties. Embelin is one of the principal bioactive molecules responsible for the medicinal properties of the genus Embelia. The quantification of the embelin compound among different species in this genus has not yet been investigated, so still uncertain which species and which part should be accepted. The present study was intended to establish a speedy and precise high-performance thin-layer chromatographic (HPTLC) method for quantitative study of embelin in various plant parts of Embelia ribes, Embelia tsjeriam-cottam, Embelia basaal, Embelia adnata, and Embelia gardneriana.

Result

This research confirmed the method as per the International Conference on Harmonization (ICH) guidelines. We achieved separation on silica gel 60 F254 HPTLC plates using propanol: butanol: ammonia (7:3:7 v/v/v) as a mobile phase. Densitometry scanning performed for detection and quantification at 254 nm and 366 nm. Among the species investigated, the highest amount of embelin was found in E. ribes fruits.

Conclusion

Embelia ribes fruits are the best source of embelin. Embelin was first described in the endemic species, such as E. adnata and E. gardneriana. The method illustrated in this research may be applied for quantification of embelin and fingerprint analysis of other species within Embelia genus or described genera and chemo taxonomic studies of this genus.

Synthesis, Characterization and Biochemical Analysis of Azo-metal complex of Embelin with Second Group Transition Metals

Aim:

The objective of the work is to synthesize, characterize and biochemically analyze Azo-metal complex of Embelin with Second Group Transition Metals.

Background:

The genus Embelia is a well-known herb and has considerable importance in the field of pharmaceutical chemistry. The plant species has been used considerably as a traditional medicine in Ayurveda, old Chinese medicine, and Siddha for a long time. The dried berries of this plant, called “vidanga” have boundless biochemical properties, like anthelmintic, carminative, antibacterial, antibiotic, and hypoglycemic.

Objective:

Embelin, metal-embelin (EM) and azo-metal-embelin (EAM) complexes were synthesized, analysed for antioxidant and antimicrobial properties.

Method:

The metal-embelin (EM) complexes and metal-azo-embelin (EAM) complexes were synthesized by pure mixing of embelin, azo-embelin and metals viz, Tc, Ru, Rh, Pd, Ag and Cd. The embelin and EAN complexes were analysed by various spectroscopic techniques, viz, UV-visible, FTIR, NMR, TGA, MS and CHNS analysis.

Results:

The results authenticate the reaction between metals, and bidentate embelin occurs via quinonic and enolic oxygen atoms as [M (Emb) 2 (H2O)] 2H2O and [M (Emb-Azo)2 (H2O)2]. The antioxidant results show that the complexation between metals and compounds decreases the antioxidant potential significantly. In contrast, the antimicrobial activity shows that cobalt and nickel embelin complexes showed more than 74% growth inhibition against the concerned microbes in comparison to embelin alone.

Conclusion:

As the results are taken into consideration, the scavenging property of embelin shows the reduction in power upon complexation with metals and azo-metals. Also, embelin and its associates as metal-embelin and metal-azo-embelin can be used as antioxidant and antimicrobial agents significantly.

Alkenylbenzoquinones and other compounds from the fruit of Maesa lanceolata exhibited potent cytotoxic, antibacterial, and antiradical scavenging activities§

A phytochemical study of the methanol extract of the fruit of Maesa lanceolata resulted in the isolation of a new alkenylbenzoquinone (1), alongside the known compounds (Z)-2,5-dihydroxy-6-methyl-3-(pentadec-10'-enyl)-1,4-benzoquinone (2), 2,5-dihydroxy-6-methyl-3-(nonadec-14'-enyl)-1,4-benzoquinone (3), 2,5-dihydroxy-6-methyl-3-(tridecyl)-1,4-benzoquinone (4), (2S,3S,4R,2'R,9E)-[2'-hydroxytetraeicosanoyl]-2-aminooctadec-9-ene-1,3,4-triol (5), monopalmitin (glyceryl palmitate) (6), lupeol (7), and 3-O-(β-D-glucopyranoside)-β-sitosterol (8). The structures of the compounds were established by the means of spectroscopic (1 D- and 2 D-NMR) and spectrometric techniques (MS). The isolated compounds were assessed for their antibacterial, cytotoxic, and antiradical activities. Compound 2 showed moderate activity against Staphylococcus warneri (DSMZ 20036), while the other compounds were inactive. The two quinones 1 and 2 were significantly cytotoxic, with IC₅₀ values of 0.005 µM and 12.5 µM respectively, and were weakly active towards DPPH radical (IC₅₀ >250 µg/mL).

New Alkenylresorcinols with Cytotoxic and Antimicrobial Activities from the Leaves of Embelia schimperi

A phytochemical study of the methanol extract of the leaves of Embelia schimperi resulted in the isolation of three new alkenylresorcinols, 1:  - 3: , together with the known analogs 4:  - 7: . Their structures were established by a combination of spectroscopic techniques. Compounds 1:  - 7: exhibited moderate cytotoxic activity against human cervical cancer cells HeLa-S3 and more pronounced antimicrobial properties towards bacteria and filamentous fungi. The present study falls into an ongoing research project on the characterization of bioactive phenolic lipids from plants of the family Primulaceae.

Polyphenolic profiling of two Embelia spp. endemic to South Western Ghats of India by liquid chromatography coupled with tandem mass spectrometry analysis

This study for the first time illustrates a comprehensive picture of the phenolic composition of Embelia adnata and Embelia gardneriana by high-performance liquid chromatography coupled with mass spectrometry analysis with ESI in negative ionisation. The analysis was performed in the methanolic extracts of different parts of these two species separately and identifies 54 individual phenolic compounds present in them. Among this by individual 36 and 28 compounds were recorded from E. adnata and E. gardneriana, respectively, and in this, 10 compounds were common in both the two species. The detected compounds come under the classes flavonoids, flavonoid glycosides, isoflavonoids, benzenoids, coumarins, stilbens, chalcones, polyphenols, gallic acid derivatives, tannins and different derivatives of various organic acids.