Anti-inflammatory Flavan-3-ol-dihydroretrochalcones from Daemonorops draco

Medicinal plant resin natural products: structural diversity and biological activities

Covering: up to the mid of 2023Plants secrete defense resins rich in small-molecule natural products under abiotic and biotic stresses. This comprehensive review encompasses the literature published up to mid-2023 on medicinal plant resin natural products from six main contributor genera, featuring 275 citations that refer to 1115 structurally diverse compounds. The scope of this review extends to include essential information such as the racemic nature of metabolites found in different species of plant resins, source of resins, and revised structures. Additionally, we carefully analyze the reported biological activities of resins, organizing them based on the their structures. The findings offer important insights into the relationship between their structure and activity. Furthermore, this detailed examination can be valuable for researchers and scientists in the field of medicinal plant resin natural products and will promote continued exploration and progress in this area.

Flavonoids, gut microbiota, and host lipid metabolism

Flavonoids are widely distributed in nature and have a variety of beneficial biological effects, including antioxidant, anti-inflammatory, and anti-obesity effects. All of these are related to gut microbiota, and flavonoids also serve as a bridge between the host and gut microbiota. Flavonoids are commonly used to modify the composition of the gut microbiota by promoting or inhibiting specific microbial species within the gut, as well as modifying their metabolites. In turn, the gut microbiota extensively metabolizes flavonoids. Hence, this reciprocal relationship between flavonoids and the gut microbiota may play a crucial role in maintaining the balance and functionality of the metabolism system. In this review, we mainly highlighted the biological effects of antioxidant, anti-inflammatory and antiobesity, and discussed the interaction between flavonoids, gut microbiota and lipid metabolism, and elaborated the potential mechanisms on host lipid metabolism.

New flavan trimer from Daemonorops draco as osteoclastogenesis inhibitor

Dragon's blood is a red resin obtained from different plants and is considered highly efficacious and used in medicine owing its wound healing function. Two new compounds (7 and 8) were isolated from the dragon's blood of Daemonorops draco fruits, along with eight known compounds (1-6, 9, and 10). Their structures, including their absolute configurations, were elucidated by nuclear magnetic resonance (NMR), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and electronic circular dichroism (ECD) analysis. According to the spectroscopic data, 8 was determined to be a quinone methide derivative of flavan and 7 was deduced to be a flavan trimer. All compounds were evaluated for their anti-osteoclastogenesis activity, compound 1 and 7 exhibited anti-osteoclastogenesis activity with IC50 values of 31.3 and 36.8 μM, respectively.

Loureirin B protects against cerebral ischemia/reperfusion injury through modulating M1/M2 microglial polarization via STAT6 / NF-kappaB signaling pathway

The latest research indicates that modulating microglial polarization from M1 to M2 phenotype may be a coping therapy for ischemic stroke. The present study thereby evaluated the effects of loureirin B (LB), a monomer compound extracted from Sanguis Draconis flavones (SDF), on cerebral ischemic injury and the potential mechanisms. The middle cerebral artery occlusion (MCAO) model was established in male Sprague-Dawley rats to induce cerebral ischemia/reperfusion (I/R) injury in vivo, and BV2 cells were exposed to oxygen-glucose deprivation and reintroduction (OGD/R) to mimic cerebral I/R injury in vitro. The results showed that LB significantly reduced infarct volume, neurological deficits and neurobehavioral deficits, apparently improved histopathological changes and neuronal loss in cortex and hippocampus of MCAO/R rats, markedly decreased the proportion of M1 microglia cells and the level of pro-inflammatory cytokines, and increased the proportion of M2 microglia and the level of anti-inflammatory cytokines both in vivo and in vitro. In addition, LB evidently improved the p-STAT6 expression and reduced the NF-κB (p-p65) expression after cerebral I/R injury in vivo and in vitro. IL-4 (a STAT6 agonist) exhibited a similar impact to that of LB, while AS1517499 (a STAT6 inhibitor) significantly reversed the effect of LB on BV-2 cells after OGD/R. These findings point to the protection of LB against cerebral I/R injury by modulating M1/M2 polarization of microglia via the STAT6/NF-κB signaling pathway, hence LB may be a viable treatment option for ischemic stroke.

Perplexing Polyphenolics: The Isolations, Syntheses, Reappraisals, and Bioactivities of Flavonoids, Isoflavonoids, and Neoflavonoids from 2016 to 2022

Flavonoids, isoflavonoids, neoflavonoids, and their various subcategories are polyphenolics-an extensive class of natural products. These compounds are bioactive and display multiple activities, including anticancer, antibacterial, antiviral, antioxidant, and neuroprotective activities. Thus, these compounds can serve as leads for therapeutic agents or targets for complex synthesis; they are coveted and routinely isolated, characterized, biologically evaluated, and synthesized. However, data regarding the compounds' sources, isolation procedures, structural novelties, bioactivities, and synthetic schemes are often dispersed and complex, a dilemma this review aims to address. To serve as an easily accessible guide for researchers wanting to apprise themselves of the latest advancements in this subfield, this review summarizes seventy-six (76) articles published between 2016 and 2022 that detail the isolation and characterization of two hundred and forty-nine (249) novel compounds, the total and semisyntheses of thirteen (13) compounds, and reappraisals of the structures of twenty (20) previously reported compounds and their bioactivities. This article also discusses new synthetic methods and enzymes capable of producing or modifying flavonoids, isoflavonoids, or neoflavonoids.

Antifungal and wound healing promotive compounds from the resins of Dracaena cochinchinensis

Five new compounds (xuejieins A-E), including three new phenolic glycosides (1, 2, and 5) and two new flavonoids (10 and 11), together with six known compounds were isolated from the resins of Dracaena cochinchinensis (Chinese dragon's blood). The structures of the new compounds were confirmed by extensive spectroscopic methods and electronic circular dichroism (ECD) data analysis. Especially, the absolute configurations of the sugar moieties in compounds 1, 2, and 5 were clarified by GC analysis after acid hydrolysis. All isolated compounds have been tested for antifungal and wound healing promoting activities, The results showed that compound 9 shows significant antifungal activities against Botrytis cinerea, Magnaporthe grisea, Penicillium digitatum, and Sclerotinia sclerotiorum. In addition, compound 4 could significantly stimulate human keratinocytes (HaCAT) proliferation, mobility, and human umbilical vein vascular endothelial cells (HUVECs) tube formation at 40 μM.

Anti-inflammatory, pro-proliferative and antimicrobial potential of the compounds isolated from Daemonorops draco (Willd.) Blume

ETHNO-PHARMACOLOGICAL RELEVANCE

Daemonorops draco (D. draco) commonly known as "Dragon's blood" is one of the most used plants by Momok, Anak Dalam and Talang Mamak tribes from Indonesia as a remedy for wound healing.

AIM OF THE STUDY

This study aimed to identify the extract, fractions and compounds responsible for the anti-inflammatory and pro-proliferative activities of the D. draco resin. Additionally, the antimicrobial activity against two bacteria and one yeast species was analysed.

MATERIALS AND METHODS

Bio-guided isolation of compounds with anti-inflammatory, pro-proliferative and antimicrobial activities from the D. draco resin was carried out by measuring: the inhibition of NF-κB and activation of Nrf2 in THP-1, HaCaT, NIH-3T3 cells; cell proliferation in NIH-3T3 and HaCaT cells; and the antimicrobial effect on E. coli, S. aureus and C. albicans.

RESULTS

Guided isolation by bioassay gave rise to the isolation and characterisation by nuclear magnetic resonance and mass spectrometry of three compounds: 1 (Bexarotene), 2 (Taspine) and 3 (2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone). All compounds showed NF-κB inhibitory activity with IC₅₀ values of 0.10-0.13, 0.22-0.24 and 3.75-4.78 μM, respectively, while the positive control, Celastrol, had an IC₅₀ of 7.96 μM. Likewise, all compounds showed an activating effect of Nrf2 with EC₅₀ values of 5.34-5.43, 163.20-169.20 and 300.82-315.56 nM, respectively, while the positive control, CDDO-Me, had an EC₅₀ of 0.11 nM. In addition, concerning the pro-proliferative activity, compound 1 (IC₅₀ = 8.62-8.71 nM) showed a capacity of 100%, compound 2 (IC₅₀ = 166-171 nM) showed a capacity of 75%, and compound 3 (IC₅₀ = 469-486 nM) showed a capacity of 65%, while FSB 10% (positive control) had a pro-proliferative activity of 100% in the NIH3T3 cell lines (fibroblasts) and HaCaT (keratinocytes). Finally, all the compounds showed antimicrobial activity with MIC values of 0.12-0.16, 0.31-0.39 and 3.96-3.99 μM, respectively, in S. aureus, E. coli and C. albicans strains, while the positive control, Ofloxacin, had a MIC of 27.65 μM.

CONCLUSION

This study managed to isolate, for the first time, three compounds (Bexarotene, Taspine and 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone) from the resin of D. draco, with anti-inflammatory, and pro-proliferative as well as antimicrobial activities.

Eight new flavonoids from the fruits of Daemonorops draco

Eight new flavonoids daemoflavans A-H, including two dimeric proanthocyanidins (1 and 2), four flavans (3-6), two 2-arylbenzofurans (7 and 8), along with nine known compounds (9-17), were isolated from the fruit of Daemonorops draco. Their structures, including the absolute configurations, were elucidated by extensive spectroscopic data, ECD analysis, and X-ray crystal diffraction. Besides, the X-ray crystal data of a known compound dracoflavan B₁ (9) was firstly reported. Daemoflavan G (7) represents a rare example of C-5 methylated 2-arylbenzofuran in natural products. Among the known compounds, 15, 16, 17 were reported from this species for the first time. All the compounds were evaluated for their cytotoxicity against HepG2 cell line. Among them, compounds 1, 9 and 10 exhibited modest cytotoxic activity with IC₅₀ values of 12.4, 12.0 and 13.2 μM, respectively.

Bioactive flavonoid dimers from Chinese dragon's blood, the red resin of Dracaena cochinchinensis

Seven flavonoid dimers, biflavocochins A-G, together with six known compounds were isolated from the red resins of Dracaena cochinchinensis (Chinese dragon's blood). Their structures were elucidated based on extensive spectroscopic analysis. The absolute configurations of 1-7 was assigned by experimental and quantum chemical calculated ECD spectra, and that of 4 was further established by X-ray diffraction analysis using Cu Kα radiation. Compounds 1-3 are novel dimers of homoisoflavonoid and dihydrochalcone with a unique dibenzopyran ring. Compounds 2, 6, 7 exhibited moderate PTP1B inhibitory activities in an enzyme assay. Compound 1 showed neuroprotective effect on serum deficiency-induced cellular damage in PC12 cells.

Antioxidant Activity of Daemonorops draco Resin

Jernang resin is secretion of jernang rattan (Daemonorops draco, Arecaceae family) fruits which is endemic in Southeast Asia. This resin has various biological activities and empirically used as wound healing, headache medicines, and fever remedies by Anak Dalam ethnic group from Jambi. This study was performed to evaluate the antioxidant activity of nonpolar fraction of D. draco resin which collected from Jambi Province, Sumatera, Indonesia. Resin was extracted with n-hexane, ethyl acetate, and methanol respectively. The antioxidant properties of the extracts were then evaluated using 1,1-diphenyl-2picryl-hidrazyl radical scavenging assay. The most active extract was further fractionated using n-hexane and methanol and separated using column chromatography and preparative thin layer chromatography. Separation of the extract was conducted through antioxidant assay-guided fractionation. Characterization of the active fraction was carried out by infrared spectroscopy. The result shows that ethyl acetate extract provides higher antioxidant activity (IC50 = 27.61 µg/mL) compare to methanol and n-hexane extracts. N-hexane fraction of ethyl acetate extract used for further separation using column and preparative thin layer chromatography due to its antioxidant activity. Separation using column chromatography resulting in 9 fractions (F.1-9). Fraction F.5 provide high antioxidant activity (IC50 = 17.27 µg/mL) and further separated using preparative thin layer chromatography resulting two fractions with lower antioxidant activity F.5.1 (IC50 = 85.18 µg/mL) and F.5.2 (IC50 = 34.94 µg/mL). Characterization of fraction F.5.2 using infrared spectroscopy showed that component in fraction F.5.2 contains NH-substituted benzene.

Human disorders associated with inflammation and the evolving role of natural products to overcome

Inflammation is a biological function which triggered after the mechanical tissue disruption or from the responses by the incidence of physical, chemical or biological negotiator in body. These responses are essential act provided by the immune system during infection and tissue injury to maintain normal tissue homeostasis. Inflammation is a quite complicated process at molecular level with the involvement of several proinflammatory expressions. Several health problems are associated with prolonged inflammation, which effects nearly all major to minor diseases. The molecular and epidemiological studies jagged that the inflammation is closely associated with several disorders with their specific targets. It would be great achievement for human health around the world to overcome on inflammation. Mostly used anti-inflammatory drugs are at high risk of side effects and also expensive. Hence, the plant-based formulations gained a wide acceptance by the public and medical experts to treat it. Due to extensive dispersal, chemical diversity and systematically established biological potentials of natural products have induced renewed awareness as a gifted source for medications. However, today's urgent need to search for cheaper, more potent and safe anti-inflammatory medications to overcome on current situation. The goal of this review to compile an update on inflammation, associated diseases, molecular targets, inflammatory mediators and role of natural products. The entire text concise the involvement of various cytokines in pathogenesis of various human disorders. This assignment discussed about 321 natural products with their promising anti-inflammatory potential discovered during January 2009 to December 2018 with 262 citations.

Survey of natural products reported by Asian research groups in 2017

The new natural products reported in 2017 in peer-reviewed articles in journals with good reputations were reviewed and analyzed. The advances made by Asian research groups in the field of natural products chemistry in 2017 were summarized. Compounds with unique structural features and/or promising bioactivities originating from Asian natural sources were discussed based on their structural classification.