Anti-inflammatory and cytotoxic neoflavonoids and benzofurans from Pterocarpus santalinus

Ethnopharmacologically important highly subsidized Indian medicinal plants: Systematic review on their traditional uses, phytochemistry, pharmacology, quality control, conservation status and future prospective

ETHNOPHARMACOLOGICAL RELEVANCE

India has an extensive reservoir of traditional wisdom and a diverse range of medicinal plants that enrich its heritage. Plants have actively been used for healthcare practices globally since the time immemorial. Medicinal uses of plants have been well recognized in India, evident from plant species documented in different traditional medicinal systems such as Ayurveda (1400-1800 species), Siddha (500-900 species), Unani (400-700 species), Homeopathy (about 372 species), and Sowa-Rigpa (about 250 species), etc. AIM OF THE STUDY: The primary purpose of this review is to provide systematic updated information on thirteen medicinal plants prioritized by the Indian government (providing75 % subsidy on cultivation cost) based on the availability and market demand of these plants. Updated information regarding the traditional uses, phytochemistry, pharmacology, quality control, and conservation status of these plants will help in understanding their pharmacological and commercial importance. This will also help in developing new strategies for their conservation.

MATERIAL AND METHODS

Online databases such as SciFinder, Web of Science, Pubmed, and Google Scholar were used to collect the electronically available literature on targeted thirteen plants. Also, different Indian government official websites such as AYUSH (https://www.ayush.gov.in); NMPB (National Medicinal Plants Board) (https://nmpb.nic.in); e.charak (https://echarak.in) were used for collecting information related to the amount of subsidy, trade and price related information of these plants.

RESULTS

To promote medicinal plant cultivation, the Indian government provides subsidies for cultivating some traditionally important medicinal plants. These plants are divided into three categories according to the subsidy provided to farmers, i.e., 30%, 50%, and 75% of the cost of cultivation. Thirteen medicinal plants which are provided 75% subsidy are Aconitum ferox Wall., Aconitum heterophyllum Wall., Aquilaria agallocha Roxb., Berberis aristata DC., Commiphora wightii (Arn.) Bhandari, Nardostachys jatamansi (D.Don) DC., Oroxylum indicum (L.) Benth. ex Kurz, Picrorhiza kurroa Royle ex Benth., Podophyllum hexandrum Royle, Pterocarpus santalinus L.f., Santalum Album L., Saussurea costus (Falc.) Lipsch., and Swertia chirayita (Roxb.) H.Karst. The literature survey reveals the enormous traditional medicinal importance, wide geographical distribution, diverse range of natural products, and broad spectrum of pharmacological activities of these plants.

CONCLUSION

A comprehensive literature survey revealed that although remarkable progress has been made in isolation, bioactivity evaluation, quality assessment, and conservation, there is still a lot of scope for further scientific interventions. Scientific validation of traditionally claimed medicinal potential is lacking for various bioactivities. Some of the bioactivities are performed just on extracts/fractions, so there is a need for proper phytochemical studies to identify active constituents responsible for the specific bioactivity. Further, quality assessment methods using both targeted and non-targeted tools are required to evaluate the quality of these highly-priced medicinal plants and their adulterants. Ultimately, to encourage the cultivation of these endangered medicinal plant species, it is imperative to implement proper legislation and employ in-situ and ex-situ conservation tools.

Anti-inflammatory and Antiphytopathogenic Fungal Activity of 2,3-seco-Tirucallane Triterpenoids Meliadubins A and B from Melia dubia Cav. Barks with ChemGPS-NP and In Silico Prediction

Two new rearranged 2,3-seco-tirucallane triterpenoids, meliadubins A (1) and B (2), along with four known compounds, 3-6, were isolated from the barks of Melia dubia Cav. Compound 2 exhibited a significant inflammatory inhibition effect toward superoxide anion generation in human neutrophils (EC50 at 5.54 ± 0.36 μM). It bound to active sites of a human inducible nitric oxide synthase (3E7G) through interactions with the residues of GLU377 and PRO350, which may benefit in reducing the neutrophilic inflammation effect. The ChemGPS-NP interpretation combined with bioactivity assay and in silico prediction results suggested 2 to be an agent for targeting iNOS with different mechanisms as compared to a selected set of current approved drugs. Moreover, compounds 1 and 2 showed remarkable inhibition against the rice pathogenic fungus Magnaporthe oryzae in a dose-dependent manner with IC50 values of 137.20 ± 9.55 and 182.50 ± 18.27 μM, respectively. Both 1 and 2 displayed interactions with the residue of TYR223, a key active site of trihydroxynaphthalene reductase (1YBV). The interpretation of 1 and 2 in the ChemGPS-NP physical-chemical property space indicated that both compounds are quite different compared to all members of a selected set of reference compounds. In light of demonstrated biological activity and in silico prediction experiments, both compounds possibly exhibited activity against phytopathogenic fungi via a novel mode of action.

Three novel dalbergiphenol hybrids from the heartwood of Dalbergia cochinchinensis

A novel discovery of two hybrid benzodioxepin-dalbergiphenol epimers, named cochindalbergiphenols A-B (1-2), and a benzofuran-dalbergiphenol hybrid, named cochindalbergiphenol C (3), were isolated and identified from the heartwood of Dalbergia cochinchinensis. The structures of all the isolated compounds were identified through NMR and HRESIMS techniques, while the absolute configurations were determined by comparing the experimental and calculated ECD spectra. Compounds 1-3 exhibited potential protective effects against hypoxia/reoxygenation (H/R) induced injury in H9c2 cells.

Integrating Chemical Profiling, In Vivo Study, and Network Pharmacology to Explore the Anti-inflammatory Effect of Pterocarpus dalbergioides Fruits and Its Correlation with the Major Phytoconstituents

The purpose of this study is to explore the anti-inflammatory activity of Pterocarpus dalbergioides fruit extract (PFE) and the underlying mechanism. Chemical profiling using ultraperformance liquid chromatography/mass spectrometry identified 28 compounds in PFE (12 flavonoids, 5 fatty acids, 4 phenolic compounds, 3 alkaloids, 2 sesquiterpenes, and 2 xanthophylls). PFE (2 g/kg) significantly inhibited carrageenan-induced rat paw edema after 4 h of administration (42% inhibition). A network-based strategy and molecular docking studies were utilized to uncover the anti-inflammatory mechanism. Out of the identified compounds, 16 compounds with DL ≥ 0.18 and F ≥ 30% were selected using bioavailability (F) and drug-likeness (DL) metrics. The network analysis revealed that 90 genes are considered key targets for the selected compounds and linked to the anti-inflammatory effect. Among all compounds, linoleic acid was found to be the top-most active constituent as it targets maximum genes. Four targets (TNF, IL6, AKT1, and CCL2) among the top 10 genes were found to be the main target genes that may contribute to the anti-inflammatory potential of PFE. Furthermore, KEGG (Kyoto encyclopedia of genes and genomes) pathway analysis revealed that PFE might regulate inflammation through five pathways: neuroactive ligand-receptor interaction, lipid and atherosclerosis, fluid shear stress and atherosclerosis, TNF signaling pathway, and rheumatoid arthritis. The docking study predicted the significant binding affinity between the top four active constituents (linoleic acid, 9-octadecenoic acid, 11,12,13-trihydroxy-9-octadecenoic acid, and rhamnetin-3-O-rhamnoside) and the selected target proteins (TNF and AKT1). The findings highlight PFE as a promising drug lead for controlling inflammation.

Discovery of anti-SARS-CoV-2 secondary metabolites from the heartwood of Pterocarpus santalinus using multi-informative molecular networking

A pigment-depleted extract from the heartwood of Pterocarpus santalinus L. f. (PS-DE) showed promising anti-SARS-CoV-2 activity with an IC₅₀ of 29.9 μg/mL in Caco-2-F03 cells. To determine the potential active constituents within the extract prior to isolation, multi-informative molecular network (MN) was applied. Therefore, the extract was separated by high-performance counter-current chromatography (HPCCC) into 11 fractions which were subsequently tested for anti-SARS-CoV-2 activity and analysed by UPLC-tandem mass spectrometry (MS²). The resulting MN combines the bioactivity data of the fractions with the MS² data. The MN analysis led to the targeted isolation of seven compounds including one pterocarpan (7) reported for the first time as constituent of P. santalinus and four so far undescribed natural products (NPs) that belong to the compound classes of arylpropanes (9), isoflavanones (10) coumestans (16) and 3-arylcoumarins (17), respectively. In total, 15 constituents from the heartwood of P. santalinus and one synthetic isoflavonoid that is structurally related to the natural metabolites were tested for anti-SARS-CoV-2 activity. Thereby, the two pterocarpans (-)-homopterocarpin (5) and (-)-medicarpin (2), the stilbene (E)-pterostilbene (1) and the isoflavonoid 7-O-methylgenistein (11) showed a distinct antiviral activity with IC₅₀ values of 17.2, 33.4, 34.7, and 37.9 µM, respectively, and no cytotoxic effects against Caco-2-F03 cells (CC₅₀ > 100 µM). In addition, a structure-activity relationship (SAR) was proposed indicating structural requirements of pterocarpans for anti-SARS-CoV-2 activity. The herein presented results support the implementation of multi-informative molecular networks as powerful tool for dereplication and targeted isolation of bioactive NPs.

Biochemometry identifies suppressors of pro-inflammatory gene expression in Pterocarpus santalinus heartwood

The heartwood extract of the Ayurvedic medicinal plant Pterocarpus santalinus L. f. Has previously been shown to significantly suppress the expression of CX3CL1 and other pro-inflammatory molecules in IL-1-stimulated human endothelial cells. Here, we identify the pigment-depleted extract PSD as the most promising yet still complex source of metabolites acting as an inhibitor of CX3CL1 gene expression. For the target-oriented identification of the constituents contributing to the observed in vitro anti-inflammatory effect of PSD, the biochemometric approach ELINA (Eliciting Nature's Activities) was applied. ELINA relies on the deconvolution of complex mixtures by generating microfractions with quantitative variances of constituents over several consecutive fractions. Therefore, PSD was separated into 35 microfractions by means of flash chromatography. Their ¹H NMR data and bioactivity data were correlated by heterocovariance analysis. Complemented by LC-MS-ELSD data, ELINA differentiated between constituents with positive and detrimental effects towards activity and allowed for the prioritization of compounds to be isolated in the early steps of phytochemical investigation. A hyphenated high-performance counter-current chromatographic device (HPCCC+) was employed for efficient and targeted isolation of bioactive constituents. A total of 15 metabolites were isolated, including four previously unreported constituents and nine that have never been described before from red sandalwood. Nine isolates were probed for their inhibitory effects on CX3CL1 gene expression, of which four isoflavonoids, namely pterosonin A (1), santal (6), 7,3'-dimethylorobol (12) and the previously unreported compound pterosantalin A (2), were identified as pronounced inhibitors of CX3CL1 gene expression in vitro.

The structure characteristics, biosynthesis and health benefits of naturally occurring rare flavonoids

Rare flavonoids, a special subclass of naturally occurring flavonoids with diverse structures including pterocarpans, aurones, neoflavonoids, homoisoflavones, diphenylpropanes, rotenoids and 2-phenylethyl-chromones. They are mainly found in legumes with numerous health benefits. Rare flavonoids are regarded as minor flavonoids due to their very limited abundance in nature. This review gives an overview of the natural occurrences of rare flavonoids from previous literatures. Recent findings on the biosynthesis of rare flavonoids have been updated by describing their structural characteristics and classifications. Recent findings on the health benefits of rare flavonoids have also been compiled and discussed. Natural rare flavonoids with various characteristics from different subclasses from plant-based food sources are stated. They show a wide range of health benefits, including antibacterial, anticancer, anti-osteoporosis and antiviral activities. Studies reviewed suggest that rare flavonoids possessing different skeletons demonstrate different characteristic bioactivities by discussing their mechanism of actions and structure-activity relationships. Besides, recent advances on the biosynthesis of rare flavonoids, such as pterocarpans, rotenoids and aurones are well-known, while the biosynthesis of other subclasses remain unknown. The perspectives and further applications of rare flavonoids using metabolic engineering strategies also be expected.

Dalbergiones lower the inflammatory response in oral cells in vitro

Objectives

Periodontitis is a global health burden that underlines the demand for anti-inflammatory treatment. Dalbergia melanoxylon being a rich source of flavonoids has been widely used in traditional medicine but the potential anti-inflammatory activity of its dalbergiones remains to be shown.

Material and methods

We have isolated 3′-hydroxy-4,4′-dimethoxydalbergione, 4-methoxydalbergione, and 4′-hydroxy-4-methoxydalbergione from Dalbergia melanoxylon and tested their potential anti-inflammatory activity.

Results

All dalbergiones are potent inhibitors of an LPS-induced inflammatory response of RAW 264.7 macrophages. This is specified by IL1β and IL6 production, and the p65 nuclear translocation. Consistently, in primary macrophages, the dalbergiones caused an M1-to-M2 polarization switch indicated by the decreased ration of IL1β and IL6 versus arginase 1 and YM1 expression. To implement oral cells, we have used gingival fibroblasts exposed to IL1β and TNFα. Consistently, all dalbergiones reduced the expression of IL6 and IL8 as well as the nuclear translocation of p65.

Conclusion

These findings increase the accumulating knowledge on dalbergiones and extend it towards its capacity to lower the inflammatory response of oral cells.

Clinical relevance

These findings are another piece of evidence that supports the use of herbal medicine to potentially lower inflammatory events related to dentistry.

Chemical constituents from Pterocarpus santalinus and their inhibitory effects on nitric oxide production

A tropolone (2) and an acorane sesquiterpene (3), along with twenty previously known compounds were isolated from the heartwood of Pterocarpus santalinus. The structure of the isolated compounds was elucidated via 1D and 2D NMR spectroscopy and HRESIMS analysis. The absolute configuration of 3 was determined by comparison of the experimental and calculated ECD data. All compounds were evaluated for their inhibitory effects against nitric oxide production in LPS-stimulated RAW 264.7 macrophages.

Pterocarpus santalinus Selectively Inhibits a Subset of Pro-Inflammatory Genes in Interleukin-1 Stimulated Endothelial Cells

Based on the traditional use and scientific reports on the anti-inflammatory potential of red sandalwood, i.e., the heartwood of Pterocarpus santalinus L., we investigated its activity in a model of IL-1 stimulated endothelial cells. Endothelial cells were stimulated with IL-1 with or without prior incubation with a defined sandalwoodextract (PS), and analyzed for the expression of selected pro-inflammatory genes. The activity of NF-κB, a transcription factor of central importance for inflammatory gene expression was assessed by reporter gene analysis, Western blotting of IκBα, and nuclear translocation studies. In addition, microarray studies were performed followed by verification of selected genes by qPCR and supplemented by bioinformatics analysis. Our results show that PS is able to suppress the induction of E-selectin and VCAM-1, molecules that mediate key steps in the adhesion of leukocytes to the endothelium. It also suppressed the activity of an NF-κB reporter, IκBα phosphorylation and degradation, and the nuclear translocation of NF-κB RelA. In contrast, it stimulated JNK phosphorylation indicating the activation of the JNK signaling pathway. Gene expression profiling revealed that PS inhibits only a specific subset of IL-1 induced genes, while others remain unaffected. Most strongly suppressed genes were the signal transducer TRAF1 and the chemokine CX3CL1, whereas IL-8 was an example of a non-affected gene. Notably, PS also stimulated the expression of certain genes, including ones with negative regulatory function, e.g., members of the NR4A family, the mRNA destabilizing protein TTP as well as the transcription factors ATF3 and BHLHB40. These results provide mechanistic insight into the anti-inflammatory activity of PS, and suggest that it acts through the interplay of negative and positive regulators to achieve a differential inhibition of inflammatory gene expression.

Anti-Inflammatory Properties of Longifuran A, a New Benzofuran from the Stems of Amomum longiligulare

In this study, the following compounds were isolated from the dichloromethane fraction of the stems of Amomum longiligulare and then characterized: a new benzofuran, namely, longifuran A (1); five other phenolic compounds, namely, 4-methoxycinnamic acid (2), 2,5-dimethoxyphenol (3), eudesmic acid (4), 1,7-bis(4-hydroxyphenyl)-1,4,6-heptatrien-3-one (5), and 4,4'-dihydroxychalcone (6); and two triterpenoids, namely, 24-methylcycloartan-3β-ol (7) and 24-methylencycloartan-3β-ol (8). They were evaluated in terms of their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophages. Results indicated that 1 and 5 exhibited promising inhibitory activities against NO generation with IC₅₀ of 10.47±1.02 μM and 8.51±1.14 μM, respectively. Enzymatic assays demonstrated that they remarkably suppressed the secretion of two pro-inflammatory cytokines (i. e., IL-6 and TNF-α). They also dose-dependently inhibited the expression of inducible nitric oxide synthase and cyclooxygenase-2, two important enzymes modulating inflammation. Therefore, 1 and 5 could be targets for the development of new anti-inflammatory therapeutics.

Genus Pterocarpus: A review of ethnopharmacology, phytochemistry, biological activities, and clinical evidence

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Pterocarpus (Fabaceae) has about 46 species that are distributed over Asia, especially Indonesia, Africa, and several countries in America. Particularly, P. indicus and P. santalinus have been recorded as ancestor recipe in the old Indonesian book (Cabe puyang warisan nenek moyang). These plants have found application in traditional medicine, such as in the treatment of inflammatory diseases, gonorrhoea, infection, coughs, mouth ulcers, boils, diarrhoea, as well as in the management of pain (as an analgesic).

AIM OF THE REVIEW

The present review aimed to comprehensively summarise the current researches on the traditional and scientific applications of the genus Pterocarpus with regard to the phytochemical content, in vivo and in vitro bioactivities, as well as clinical evidence that may be useful for future drug development.

MATERIALS AND METHODS

Information about the Pterocarpus genus were obtained from local classic herbal literature and electronic databases, such as PubMed, Scopus, and Google Scholar. The scientific name of the species and its synonyms were checked with the information of The Plant List. Additionally, clinical trial results were obtained from the Cochrane library.

RESULTS

Several phytochemical constituents of the plants, e.g., flavonoids, isoflavonoids, terpenoids, phenolic acids, and fatty acids have been reported. There are about 11 species of Pterocarpus that have been scientifically studied for their biological activities, including anti-inflammatory, anti-microbial, analgesic, and anti-hyperglycemic. Of which, the anti-hyperglycemic activity of the extracts and phytochemicals of P. indicus and P. marsupium is particularly remarkable, allowing them to be further studied under clinical trial.

CONCLUSION

The present review has provided an insight into the traditional applications of the plants and some of them have been validated by scientific evidence, particularly their applications as anti-inflammatory and anti-microbial agents. In addition, the genus has demonstrated notable anti-diabetic activity in various clinical trials.

Melanoxylonin A-G, neoflavonoids from the heartwood of Dalbergia melanoxylon and their cardioprotective effects

Seven undescribed neoflavonoids, named melanoxylonins A-G, were isolated from the heartwood of Dalbergia melanoxylon, and all the non-toxic isolates were evaluated for their cardioprotective effect against ischemia/reoxygenation (I/R) injury in H9c2 cells. Of these, melanoxylonin A-D containing the 8-OH group showed better potent cardioprotective effects than the other four congeners. Molecular docking studies confirmed the capacity of melanoxylonin D to interact with the myeloperoxidase (MPO) protein. These results indicated that the potential cardioprotective effects of melanoxylonin D in H9c2 cells with I/R injury may be imparted through suppression of MPO. These results may provide a new medicinal usage of D. melanoxylon.

Traditional uses, phytochemistry and pharmacological attributes of Pterocarpus santalinus and future directions: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Pterocarpus santalinus, an ancient folk medicine, is endemic to the eastern ghats of south India, and the heartwood is prescribed since time immemorial for the mitigation of inflammatory disorders in traditional practice and ayurvedic system of medicines.

AIM OF THE STUDY

This review aims to provide collective pieces of information of the traditional uses, phytochemicals, and pharmacological facets of P. santalinus, with an intuition for promoting future research to explore its pharmaceutical potential as a therapeutic agent against modern maladies.

MATERIAL AND METHODS

Extensive literature search was performed to collate the data by using various electronic search engines. A network pharmacology-based approach is incorporated for validation of traditional claims orbiting around anti-inflammatory properties and directed its future exploration against obesity, ovarian inflammation, ovarian folliculogenesis, and inflammatory breast cancer.

RESULTS

In a nutshell, the present review encompasses the phytochemistry, pharmacology of this species intending to sensitize the scientific community for future research on this promising plant. Nearly 85 chemical constituents are reported from the plants wherein bark and leaves are enriched with the lupane and oleanane class of triterpene while sesquiterpenes and polyphenolic compounds are predominantly present in the heartwood of the plant. Although phytochemical investigations are being reported since the mid-twentieth century however there has been recent interest in the evaluation of biological activities such as anti-inflammatory, anti-oxidant, anti-cancer, anti-viral, etc. CONCLUSION: In conclusion, a systematic phytochemical analysis and pharmacological exploration in close collaboration for establishing the therapeutic potential of the chemical constituents present in P. santalinus is recommended to substantiate the traditional claims for bringing it into the mainstream pharmaceutical and commercial utilization.

Visible-light promoted oxidative cyclization of cinnamic acid derivatives using xanthone as the photocatalyst

We have developed an efficient photocatalytic synthesis of coumarin derivatives via a tandem double bond isomerization/oxidative cyclization of cinnamic acids.

Two New Compounds From the Heartwood of Dalbergia melanoxylon and Their Protective Effect on Hypoxia/Reoxygenation Injury in H9c2

A new neoflavonoid, named as (7 R)-(-)-3′,5-dihydroxy-4′,2,4-trimethoxy-dalbergiquinol (1) and a new phenanthrenedione, named as 3′,7-dihydroxy-3,6- dimethoxy-9-phenyl-1,4-phenanthrenedione (2), together with 4 known compounds, 5- O-methyldalbergiphenol (3), 3′,7-dihydroxy-4′,3,6-trimethoxy-9-phenyl-1,4-phenanthrenedione (4), (+)-obtusafuran (5), and melanoxin (6) were isolated from the heartwood of Dalbergia melanoxylon. Their structures were elucidated on the basis of chemical and spectral evidence, as well as by comparison with literature data. Moreover, compound 1 showed a protective effect on hypoxia/reoxygenation injury in H9c2 at 10.0 μM by decreasing lactate dehydrogenase and malondialdehyde activity and enhancing superoxide dismutase activity.

Antileishmanial compounds from Connarus suberosus: Metabolomics, isolation and mechanism of action

Leishmaniasis is a disease impacting public health worldwide due to its high incidence, morbidity and mortality. Available treatments are costly, lengthy and toxic, not to mention the problem of parasite resistance. The development of alternative treatments is warranted and natural products demonstrate promising activity. This study investigated the activity of Connarus suberosus extracts and compounds against Leishmania species. Several C. suberosus extracts were tested against L. amazonensis promastigotes. Active and inactive extracts were analyzed by UHPLC-MS and data evaluated using a metabolomics platform, revealing an unknown neoflavonoid (connarin, 3), isolated together with the pterocarpans: hemileiocarpin (1) and leiocarpin (2). The aforementioned compounds (1-3), together with the benzoquinones: rapanone (4), embelin (5) and suberonone (6) previously isolated by our group from the same species, were tested against: (i) L. amazonensis and L. infantum promastigotes, and (ii) L. amazonensis intracellular amastigotes, with the most active compound (3) also tested against L. infantum amastigotes. Cytotoxicity against murine peritoneal macrophages was also investigated. Compounds 2 and 3 presented an IC50 33.8 μM and 11.4 μM for L. amazonensis promastigotes; and 44.3 μM and 13.3 μM for L. infantum promastigotes, respectively. For L. amazonensis amastigotes, the IC50 of 2 was 20.4 μM with a selectivity index (SI) of 5.7, while the IC50 of 3 was 2.9 μM with an SI of 6.3. For L. infantum amastigotes, the IC50 of 3 was 7.7 μM. Compounds 2 and 3 presented activity comparable with the miltefosine positive control, with compound 3 found to be 2-4 times more active than the positive control, depending on the Leishmania species and form. The extracts and isolated compounds showed moderate toxicity against macrophages. Compounds 2 and 3 altered the mitochondrial membrane potential (ΔΨm) and neutral lipid body accumulation, while 2 also impacted plasma membrane permeabilization, culminating in cellular disorder and parasite death. Transmission electron microscopy of L. amazonensis promastigotes treated with compound 3 confirmed the presence of lipid bodies. Leiocarpin (2) and connarin (3) demonstrated antileishmanial activity. This study provides knowledge of natural products with antileishmanial activity, paving the way for prototype development to fight this neglected tropical disease.

Two new compounds from the heartwood of Dalbergia melanoxylon

A new neoflavonoid, named S(+)-3'-hydroxy-4',2,4,5-tetramethoxydalbergiquinol (1), and a new benzofuran, named (2S,3S)-5-hydroxy-6-methoxy-3-methyl-2-(4'-hydroxyphenyl)-2,3dihydrobenzofuran (4), together with two known neoflavonoids, were isolated from the heartwood of Dalbergia melanoxylon. Their structures were elucidated by a combination of spectroscopic methods and comparison with the literature. Compounds 1-4 were evaluated for inhibitory activity against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 6538, Salmonella enteri CMCC 50041 and Candida albicans ATCC 289065, which all exhibited inactive or weak activity.

Antitumour Property of Pterocarpus santalinus Seeds Against DMBA-Induced Breast Cancer in Rats

Breast cancer has been one of the most common form of malignancy globally among women, for more than a decade. Despite various preventive and treatment measures, it remains associated with high incidence and mortality rate. Pterocarpus santalinus Linn. f. has been extensively used in Indian medicine system Ayurveda, due to its various medicinal properties. However, despite various research works on the anticancer activity of P santalinus, no studies have been reported on animal model. Therefore, this study was aimed to decipher the antitumour activity of ethanolic seeds extract of P santalinus on DMBA (7,12-dimethylbenz(a)-anthracene)-induced breast cancer in rats. Fifty-five-days-old weighed (150 ± 10 g) female Charles Foster rats (12 females) were used for the study. The rats were divided into 3 groups of 4 rats each. 7,12-Dimethylbenz(a)-anthracene (single dose of 20 mg/mL dissolved in olive oil) was induced orally, to develop breast tumour. After the development of breast tumours (about 0.5 cm), the rats were treated with P santalinus ethanolic seeds extract (300 mg/kg body weight/day) orally for 5 weeks and then volume of tumour was measured. Oral administration of P santalinus extract resulted in about 49.5% tumour growth inhibition in the final week of treatment in DMBA + P santalinus group as compared with the DMBA group. Pterocarpus santalinus administration also significantly reduced (P < .0001) the serum malondialdehyde level from 58.81 ± 4.09 nmol/mL in DMBA group to 10.87 ± 1.20 nmol/mL in the DMBA + P santalinus group. Serum tumour necrosis factor-α level reduced significantly (P < .0001) from 80.43 ± 2.45 pg/mL in DMBA group to 28.30 ± 3.24 pg/mL in the DMBA + P santalinus group. The blood serum glucose level also reduced significantly (P < .0001) from 205.9 ± 22.22 mg/dL in DMBA group to 86.44 ± 8.36 in DMBA + P santalinus group. There was significant (P < .0001) improvement in the both the liver and kidney serum biomarkers level after P santalinus administration. The histological study of mammary tissues of rats shows that, in the DMBA group immature fibrocytes are completely replacing the normal adipocytes suggestive of fibroma molle, whereas in the DMBA + P santalinus group mature fibrocytes with multilayer glandular cells were seen denoting fibroadenoma. Thus, the P santalinus ethanolic seed extract possesses antitumorigenic, antioxidant and hypoglycaemic properties as well as hepato-renal protective effect. Hence, it may be concluded that P santalinus has therapeutic role against DMBA-induced breast cancer in rats and has a greater potential to develop as a chemotherapeutic agent in breast cancer treatment.

Neoflavonoids from the heartwood of Dalbergia melanoxylon

Three new neoflavonoids, named (1S,8R,9S)-1,5-dihydroxy-4,12-dimethoxy-8-vinyl-tricyclo[7.3.1.0^2,7]trideca-2,4,6,11-tetraen-10-one (1), 2,5,2',5'-tetrahydroxy-4-methoxybenzophenone (2) and 2,5,3'-trihydroxy-4-methoxybenzophenone (3), were isolated from the heartwood of Dalbergia melanoxylon. Their structures were established by spectroscopic methods, including UV, IR, HRMS, 1 D and 2 D-NMR. Compounds 1-3 were evaluated for inhibitory activity against three fungal strains Candida albicans, Mucor ramosissimus, Saccharomycopsis fermentans and seven bacterial strains Shigella dysenteriae, Salmonella enteri, Bacillus cereus, Staphylococcus epidermidis, Bacillus sphaericus, Staphylococcus aureus, Escherichia coli using the broth dilution method. However, none of compounds 1-3 showed potential antimicrobial activities in vitro.

Nickel catalyzed intramolecular oxidative coupling: synthesis of 3-aryl benzofurans

Recent research has been focused on the transition metal-catalyzed reactions. Herein we have developed nickel-catalyzed synthesis of 3-aryl benzofurans from ortho-alkenyl phenols via intramolecular dehydrogenative coupling. Notably, simple O2 gas served as an oxidant, without using any sacrificial hydrogen acceptor. The strategy enabled the synthesis of 3-aryl benzofurans in good to excellent yields.

Synthesis and biological activities of drugs for the treatment of osteoporosis

Osteoporosis is an asymptomatic progressive disease. With the improvement of people's living standard and the aging of population, osteoporosis and its fracture have become one of the main diseases threatening the aging society. The serious medical and social burden caused by this has aroused wide public concern. Osteoporosis is listed as one of the three major diseases of the elderly. At present, the drugs for osteoporosis include bone resorption inhibitors and bone formation promoters. The purpose of these anti-osteoporosis drugs is to balance osteoblast bone formation and osteoclast bone resorption. With the development of anti-osteoporosis drugs, new anti osteoporosis drugs have been designed and synthesized. There are many kinds of new compounds with anti osteoporosis activity, but most of them are concentrated on the original drugs with anti osteoporosis activity, or the natural products with anti-osteoporosis activity are extracted from the natural products for structural modification to obtain the corresponding derivatives or analogues. These target compounds showed good ALP activity in vitro and in vivo, promoted osteoblast differentiation and mineralization, or had anti TRAP activity, inhibited osteoclast absorption. This work attempts to systematically review the studies on the synthesis and bioactivity of anti-osteoporosis drugs in the past 10 years. The structure-activity relationship was discussed, which provided a reasonable idea for the design and development of new anti-osteoporosis drugs.

Screening for bioactive secondary metabolites in Sri Lankan medicinal plants by microfractionation and targeted isolation of antimicrobial flavonoids from Derris scandens

ETHNOPHARMACOLOGICAL RELEVANCE

Sri Lanka is known to have very diverse flora. Many of these species are used for plant-based remedies, which form the integral part of two Sri Lankan systems of traditional medicine, Ayurveda and Deshiya Chikitsa. Despite their widespread use, only a limited number of studies have probed into the scientific evidence for bioactivity of these medicinal plants. Such studies rarely progress to the identification of bioactive natural products.

AIM OF THE STUDY

The primary aim was to develop a bioactivity screening method and apply it to 50 Sri Lankan medicinal plants where antimicrobial properties could be relevant for its traditional use. The subsequent aim was the progression into defining and characterising potent isolates within targeted compound classes from such plants, i.e. Derris scandens and its antimicrobial flavonoids.

MATERIAL AND METHODS

The plant collection comprised 24 species of Fabaceae, 15 Rubiaceae, 7 Solanaceae and 4 Cucurbitaceae plants. These 50 species were collected based on their ethnopharmacological importance and use in Sri Lankan traditional medicine. Crude extracts from each species were initially subjected to radial disc diffusion and microdilution assays. Subsequently, aqueous extracts of all plants were microfractionated in deep well plates using reversed-phase HPLC. Fractions were tested for antibacterial and cytotoxic activities and masses of target bioactive compounds were identified using mass spectrometry. Bioactive compounds with the masses identified through microfractions were isolated from Derris scandens using reversed-phase HPLC. The isolated pure compounds were characterised using LC-MS and NMR.

RESULTS

Crude aqueous extracts from 19 species showed activity against Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) in the radial disc diffusion assay. Crude aqueous extracts from 34 plant species and organic extracts from 46 plant species were active against S. aureus (≤4 mg mL^-1) in the microdilution assay. Microfractionation demonstrated antibacterial activity for 19 plants and cytotoxicity for 6 plants. Furthermore, target bioactive compounds and their molecular ions were identified during microfractionation. Dalpanitin and vicenin-3, two of the flavonoids isolated from Derris scandens gave MICs of 23 μg mL^-1 against S. aureus. Dalpanitin also exhibited relevant MICs on Gram-negative bacteria (94 μg mL^-1 against Escherichia coli and Pseudomonas aeruginosa).

CONCLUSION

The microfractionation protocol developed in this study enabled time-efficient screening of many plants species, using a small quantity of sample material. In addition, microfractionation served as a guiding tool for identifying individual antimicrobial compounds. Through this process, flavonoids were isolated from Derris scandens, out of which dalpanitin and vicenin-3 showed activity in the low micromolar range. The high hit rate for in vitro antibacterial properties from this ethnopharmacologically guided sample collection gives credence to Sri Lankan traditional herbal medicine as a source for drug discovery.

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.

Enhancing bio-recovery of bioactive compounds extracted from Citrus medica L. Var. sarcodactylis: optimization performance of integrated of pulsed-ultrasonic/microwave technique

Abstract

This study mainly aimed to optimize a sustainable and green process for extracting bioactive compounds from Foshou fruit by using an integrated technique based on ultrasonic-microwave assisted extraction (UMAE). Response surface methodology (RSM) based on a Box–Behnken design was applied to determine optimal conditions. The following optimized UMAE processing parameters were obtained: sonication time (96.13 s), microwave power (305.28 W), and solid/solvent ratio (1:37). Based on a total phenolic compound extraction yield of 9.21 mg gallic acid (GA) equ/g dry weight (DW), a 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity with a half maximal inhibitory concentration (IC50) of 27.52 μg GA equ, and an antioxidant capacity detected by 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assay of 8.79 mg trolox equ/g DW. The optimized UMAE extract was superior to those obtained using microwave-assisted extraction (MAE) or conventional solvent extraction (CSE) methods. Scanning electron microscopy (SEM) analysis showed that the three extraction methods affected the sample tissue microstructure. Among them, UMAE caused the most marked structural disruption. UPLC-PDA-Q-TOF-MS analysis identified 67 phenolic compounds in the optimized UMAE extract of the Foshou fruit extract. This study indicated that the integrated UMAE technique is a suitable and safe technique to enhance the qualitative and quantitative extraction of phenolic compounds from Foshou fruit. These phenolic compounds can be used as a functional food ingredient in industrial production.

Graphical abstract

Three new sesquiterpenes from Pterocarpus santalinus

Three new sesquiterpenes of canusesnol K (1), canusesnol L (2) and 12, 15-dihydroxycurcumene (3), along with five known ones (4-8), were isolated from the heartwood extract of Pterocarpus santalinus. Their structures were established by extensive analyses of 1D and 2D NMR spectroscopy, including ¹H NMR, ¹³C NMR, HSQC, HMBC and NOESY, and HRESI-MS. The absolute configurations of the new compounds were established with Modified Mosher's method. The cytotoxic activities of all these compounds against HepG2 (human liver cancer), MCF-7 (human breast cancer), MDA-MB-231 (human breast cancer), and Hela (human cervical carcinoma) cancer cell lines were evaluated. Compound 1 exhibited moderate cytotoxic activity toward MDA-MB-231 cell lines.

Therapeutic Potential of Pterocarpus santalinus L.: An Update

Recently there has been increasing interest in plants and plant-derived compounds as raw food and medicinal agents. In Ayurveda, an Indian system of traditional medicine, a wide spectrum of medicinal properties of Pterocarpus santalinus is described. Many important bioactive phytocompounds have been extracted and identified from the heartwood of P. santalinus. Bioactive compounds typically occur in small amounts and have more subtle effects than nutrients. These bioactive compounds influence cellular activities that modify the risk of disease rather than prevent deficiency diseases. A wide array of biological activities and potential health benefits of P. santalinus have been reported, including antioxidative, antidiabetic, antimicrobial, anticancer, and anti-inflammatory properties, and protective effects on the liver, gastric mucosa, and nervous system. All these protective effects were attributed to bioactive compounds present in P. santalinus. The major bioactive compounds present in the heartwood of P. santalinus are santalin A and B, savinin, calocedrin, pterolinus K and L, and pterostilbenes. The bioactive compounds have potentially important health benefits: These compounds can act as antioxidants, enzyme inhibitors and inducers, inhibitors of receptor activities, and inducers and inhibitors of gene expression, among other actions. The present review aims to understand the pharmacological effects of P. santalinus on health and disease with "up-to-date" discussion.

Palladium-catalyzed bisarylation of 3-alkylbenzofurans to 3-arylalkyl-2-arylbenzofurans on water: tandem C(sp3)–H and C(sp2)–H activation reactions of 3-alkylbenzofurans

A protocol involving facile sequential C(sp³)–H and C(sp²)–H activation reactions of 3-alkylbenzofurans catalyzed by Pd(OAc)₂ in the presence of pivalic acid, silver salt, and tricyclohexylphosphine ‘on water’ was developed.

Chemical Constituents from Pterocarpus soyauxii

Three new benzofurans (1–3) and one new isoflavan (4), pteroyanin G, H, I and J, together with 21 known compounds, were isolated from the heartwood of Pterocarpus soyauxii. Their structures were determined by the NMR and MS spectral data in comparison with literature data. Compounds (1–25) did not show cytotoxicity against three human cancer cell lines, A549, Panc-28, and HCT-116 ( GI 50 > 50 μM).

Hybrids of the Benzofuran Core from Natural Products and the 2,4-Dihydroxy-5-isopropylbenzene Fragment as Potent Hsp90 Inhibitors: Design, Synthesis and Bioevaluation

Several chemical fragments have been confirmed as highly efficient cores for the design of Hsp90 inhibitors. Molecular hybridization of potent fragments has been widely used as a rational drug discovery strategy. In this study, a novel class of hybrids of benzofuran, a privileged core from natural products, and 2,4-dihydroxy-5-isopropyl phenyl, an efficient fragment in Hsp90 inhibitors, were designed and synthesized. Subsequent evaluation confirmed they inhibited cell proliferation and regulated the level of client proteins through Hsp90 inhibition. Some of the hybrids can serve as leads to obtain novel chemotypes of Hsp90 inhibitors. The methods reported here may expand the range of known structural types accommodated by the ATP binding site of Hsp90.