Alkaloids from Sri Lankan curry-leaf (Murraya koenigii) display melanogenesis inhibitory activity: Structures of karapinchamines A and B

Site-selective synthesis and pharmacological elucidation of novel semi-synthetic analogues of koenimbine as a potential anti-inflammatory agent

Koenimbine (1), a carbazole alkaloid isolated from Murraya koenigii, belongs to the Rutaceae family. Various pharmacological effects such as anti-diabetic, melanogenesis inhibition, anti-diarrheal, anti-cancer, and anti-inflammatory properties of koenimbine have already been reported. In the current study, we investigated the anti-inflammatory role of koenimbine (1) and its novel semi-synthetic derivative 8-methoxy-3,3,5-trimethylpyrano[3,2-a] carbazole-11(3H)-yl) (3-(trifluoromethyl) phenyl) methanone (1G) in both in vitro and in vivo biological systems. Our results demonstrated that the anti-inflammatory activity of 1G significantly lowered the production of NO, pro-inflammatory cytokines (IL-6, TNF-α & IL-1β), LTB4 following LPS stimulation in RAW 264.7 macrophages. Furthermore, 1G significantly attenuated the expression levels of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose dependent manner and also decreased the production of reactive oxygen species (ROS) in LPS-activated RAW 264.7 cells. In addition, the oral administration of 1G reduced the inflammatory response in carrageenan-induced paw edema in BALB/C mice. Moreover, it effectively reduced NO, IL-6, IL-1β & TNF-α levels, liver markers (AST, ALT), and kidney markers (BUN, CRE, and Urea). Also, 1G reverted the infiltration of inflammatory cells and tissue damage in lungs, liver and kidney enhanced the survival rate in LPS-challenged mice. 1G blocks NF-κB p65 from translocating into the nucleus and activating inflammatory gene transcription. These results illustrated that 1G suppresses the inflammatory effects both in-vitro and in-vivo studies via downregulating the nuclear factor kappa-B (NF-κB) signaling pathway. In conclusion, our results demonstrate that semi-synthetic derivative 1G can effectively attenuate the inflammatory response via NF-κB and MAPK signaling pathways; suggesting 1G is a potential novel anti-inflammatory drug candidate in treating inflammatory disorders.

Trends in carbazole synthesis - an update (2013-2023)

The interest of scientists in the carbazole core has risen steadily over the last 30 years, particularly over the last decade given its presence in several active pharmaceutical ingredients, functional materials and a wide range of biologically active natural products. The continuous development of more efficient, more (regio-)selective and "greener" methodologies to access the carbazole core is thus imperative. This review compares and evaluates synthetic strategies towards the carbazole core that have been reported since 2013, with a focus on their applicability towards the total synthesis of carbazole-containing natural products.

Phytochemistry and Biological Activities of Murraya Species

Murraya is a plant genus within the Rutaceae family comprising over 17 species, which are widely distributed in Asia, Australia, and the Pacific Islands. Furthermore, these species have been used in traditional medicine to treat fever, pain, and dysentery. Several reports have also extensively studied the leaves, seeds, stembark, and bark of Murraya from 1965 to 2023 to explore their natural product composition. Various phytochemical studies have revealed the isolation of 413 compounds recorded, comprising coumarins, terpenoids, flavonoids, and aromatics, as well as alkaloids, which constitute the largest proportion (46.9%). These isolated compounds have long been known to exhibit different bioactivities, such as cytotoxic and anti-inflammatory properties. Cytotoxic activity has been observed against HCT 116, HeLa, HepG2, and other cell lines. Previous studies have also reported the presence of antifungal, hepatoprotective, antihyperlipidemic, antidiarrheal, and antioxidant effects. Therefore, this review provides a comprehensive overview of Murraya species, highlighting their phytochemistry, biological activities, and potential as a source of active natural compounds.

Antiproliferative Activities of Diterpenes from Leaves of Isodon trichocarpus against Cancer Stem Cells

Two new diterpenes named trichoterpene I (1) and trichoterpene II (2) were isolated from the extract from the leaves of Isodon trichocarpus together with 19 known diterpenes. Their chemical structures were elucidated on the basis of chemical and physicochemical properties. Among them, oridonin (3), effusanin A (4), and lasiokaurin (9) with the α,β-unsaturated carbonyl moiety showed antiproliferative activities against breast cancer MDA-MB-231 and human astrocytoma U-251 MG cells [i.e., non-cancer stem cells (non-CSCs)] and their cancer stem cells (CSCs) isolated by sphere formation. In particular, compound 4 (IC₅₀ = 0.51 µM) showed a higher antiproliferative activity against MDA-MB-231 CSCs than against MDA-MB-231 non-CSCs. The antiproliferative activity toward CSCs of compound 4 was equal to adriamycin (positive control, IC₅₀ = 0.60 µM).

Chemical Structures of Phenylbutanoids From Rhizomes of Zingiber cassumunar

Zingiber cassumunar is widely distributed in Asia, and its rhizomes are used for asthma treatment in traditional medicine and as a spice. Five new phenylbutanoids, cassumunols I–M (1-5), were isolated from Z cassumunar rhizomes collected in Thailand, and their structures were characterized on the basis of physiochemical and chemical evidence.

Carbazole alkaloids with potential cytotoxic activities targeted on PCK2 protein from Murraya microphylla

From the 95% aqueous ethanol extract of Murraya microphylla, five pairs of new carbazole alkaloid enantiomers, (+/-)-microphylines N-R (1a/1b-5a/5b), were isolated, together with 20 known carbazole alkaloids. The structures of the new compounds were determined by the HRMS and NMR spectroscopic data, along with the calculated electronic circular dichroism (ECD) and Mo₂(AcO)₄-induced CD data. The known compound (+)-mahanine (21) showed significant cytotoxicities against Du145, HepG2, HeLa, and HCT-116 cell lines, and its possible mechanism was deduced to target on phosphoenolpyruvate carboxykinase 2 (PCK2) protein via surface plasmon resonance (SPR) and molecular docking.

A Review of the Anti-Cancer Potential of Murraya koenigii (Curry Tree) and Its Active Constituents

Murraya koenigii (MK) relates to the Rutaceae family and has many health benefits. To date, over eighty-eight carbazole alkaloids along with terpenoids, and other nutrients have been identified from different parts of this plant. This review presents accumulated information regarding the role of MK and its constituents in the prevention/treatment of cancer. Literature survey revealed that MK and its constituents target multiple deranged pathways associated with apoptosis, growth (JAK-STAT, mTOR), and cell cycle in a variety of cancerous cell lines (colon, lung, liver, skin, prostate, breast, etc.) and few animal models. Thus, the present review highlights the anticancer mechanism of MK and its phytoconstituents, and further future perspectives. The ameliorating effects of MK and its phytoconstituents against various cancers warrant its multi-institutional clinical trials as soon as possible. The prospects of relatively cheaper cancer drugs could then be brighter, particularly for the socio-economically feebler cancer patients of the world.

Accelerative effects of carbazole-type alkaloids from Murraya koenigii on neurite outgrowth and their derivative's in vivo study for spatial memory

Murraya koenigii is a medicinal plant that contains several carbazole-type alkaloids as its characteristic constituents. Blood-brain barrier permeable constituents of M. koenigii accelerated neurite outgrowth in PC-12 cells. Nine compounds were isolated from M. koenigii and their effects on neurite outgrowth were examined. Murrayamine-E (8) at 10 μM showed significant effect. Focusing on the carbazole skeleton, we synthesized derivatives to attenuate cytotoxicity. 9-Benzyl-9H-carbazol-4-ol (15) exhibited strong neurite outgrowth accelerative effect. In addition, the novel object recognition test and the Morris water maze test were performed to evaluate memory improvement of 15 in APdE9 mice. Compound 15 tended to improve spatial memory in the Morris water maze test. These results suggest that carbazole derivative 15 would be a seed compound for Alzheimer's disease drug.

In vitro and in vivo toxicity assessment of selenium nanoparticles with significant larvicidal and bacteriostatic properties

In the present study, we investigated the larvicidal and bacteriostatic activity of biosynthesized selenium nanoparticles using aqueous berry extract of Murraya koenigii (Mk-Se NPs). The synthesized Mk-Se NPs were characterized using UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. XRD analysis revealed the crystalline nature of Mk-Se NPs as hexagonal. The FTIR spectra of Mk-Se NPs exhibited a strong peak at 3441 cm^-1 corresponding to the OH group. SEM and TEM analysis showed that the Mk-Se NPs were spherical in shape with a size between 50 and 150 nm. EDX peaks confirm the presence of 73.38% of selenium and 26.62% of oxide in Mk-Se NPs. Mk-Se NPs showed significant larvicidal property against the 4th instar larvae of a dengue fever-causing vector Aedes aegypti with LC_50- - 3.54 μg mL^-1 and LC_90- - 8.128 μg mL^-1 values. Mk-Se NPs displayed anti-bacterial activity against Gram-positive (Enterococcus faecalis &Streptococcus mutans) and Gram-negative (Shigella sonnei &Pseudomonas aeruginosa) bacteria at 40 and 50 μg mL^-1. In addition, Mk-Se NPs reduced bacterial biofilm thickness extensively at 25 μg mL^-1. The high antioxidant property at 50 μg mL^-1 and low hemolysis activity till 100 μg mL^-1 proved the biocompatible nature of Mk-Se NPs. In vitro and in vivo toxicity assessment of Mk-Se NPs showed low cytotoxicity against RAW 264.7 macrophages and Artemia nauplii. Together, our results suggest the potential application of Mk-Se NPs as a nano-biomedicine.

Inhibition of melanin production by anthracenone dimer glycosides isolated from Cassia auriculata seeds

The methanol extract of Cassia auriculata seeds was found to inhibit melanogenesis in B16 melanoma 4A5 cells under conditions of theophylline stimulation. Two new phlegmacin-type anthracenone dimer glycosides, auriculataosides A and B, were isolated from the active methanol fraction, and their inhibitory effects were observed in the concentration range of 0.03 to 0.3 μM. Inhibition of microphthalmia-associated transcription factor, tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 protein expression was observed, suggesting that the inhibition of these factors is part of the mechanism of action underlying melanogenesis inhibition.

Inhibition of human prostate cancer (PC-3) cells and targeting of PC-3-derived prostate cancer stem cells with koenimbin, a natural dietary compound from Murraya koenigii (L) Spreng

BACKGROUND

Inhibition of prostate cancer stem cells (PCSCs) is an efficient curative maintenance protocol for the prevention of prostate cancer. The objectives of this study were to assess the efficiency of koenimbin, a major biologically active component of Murraya koenigii (L) Spreng, in the suppression of PC-3 cells and to target PC-3-derived cancer stem cells (CSCs) through apoptotic and CSC signaling pathways in vitro.

MATERIALS AND METHODS

The antiproliferative activity of koenimbin was examined using MTT, and the apoptotic detection was carried out by acridine orange/propidium iodide (AO/PI) double-staining and multiparametric high-content screening (HCS) assays. Caspase bioluminescence assay, reverse transcription polymerase chain reaction (RT-PCR), and immunoblotting were conducted to confirm the expression of apoptotic-associated proteins. Cell cycle analysis was investigated using flow cytometry. Involvement of nuclear factor-kappa B (NF-κB) was analyzed using HCS assay. Aldefluor™ and prostasphere formation examinations were used to evaluate the impact of koenimbin on PC-3 CSCs in vitro.

RESULTS

Koenimbin remarkably inhibited cell proliferation in a dose-dependent manner. Koenimbin induced nuclear condensation, formation of apoptotic bodies, and G0/G1 phase arrest of PC-3 cells. Koenimbin triggered the activation of caspase-3/7 and caspase-9 and the release of cytochrome c, decreased anti-apoptotic Bcl-2 and HSP70 proteins, increased pro-apoptotic Bax proteins, and inhibited NF-κB translocation from the cytoplasm to the nucleus, leading to the activation of the intrinsic apoptotic pathway. Koenimbin significantly (P<0.05) reduced the aldehyde dehydrogenase-positive cell population of PC-3 CSCs and the size and number of PC-3 CSCs in primary, secondary, and tertiary prostaspheres in vitro.

CONCLUSION

Koenimbin has chemotherapeutic potential that may be employed for future treatment through decreasing the recurrence of cancer, resulting in the improvement of cancer management strategies and patient survival.

Structures of Aromatic Glycosides from the Seeds of Cassia auriculata

A new benzocoumarin glycoside, cassiaglycoside I (1), a new naphthol glycoside, cassiaglycoside II (2), a new chromon glycoside, cassiaglycoside III (3), a new phenylethyl glycoside, cassiaglycoside IV (4), were isolated from the seeds of Cassia auriculata, together with seven known constituents. The chemical structures of four new constituents were characterized on the basis of chemical and physicochemical evidence.

POCl3-mediated cyclization of (+)-S-mahanimbine led to the divergent synthesis of natural product derivatives with antiplasmodial activity

POCl₃ mediated divergent synthesis of (+)-S-mahanimbine provides five natural and seven new natural derived unusual oxidative cyclised tetracyclic carbazole compounds (2–13). 1–13 were screened for the first time against Plasmodium falciparum and 2, 6 and 7 were proven the most potent (IC₅₀ values of 2.7, 4.5, and 3.2 μM respectively).

The Methanolic Extract from Murraya koenigii L. Inhibits Glutamate-Induced Pain and Involves ATP-Sensitive K+ Channel as Antinociceptive Mechanism

Murraya koenigii L. is a perennial shrub, belonging to the family Rutaceae. Traditionally, the leaves of this plant are extensively used in treatment of a wide range of diseases and disorders including pain and inflammation. Although researchers have revealed the antinociceptive effects of this plant's leaves during past few years, the mechanisms underlying these effects are still unknown. Therefore, the present study evaluated some antinociceptive mechanisms of the methanolic extract of M. koenigii (MEMK) leaves along with its antinociceptive potential using several animal models. The antinociceptive effects of MEMK were evaluated using formalin-induced licking and acetic acid-induced writhing tests at the doses of 50, 100, and 200 mg/kg. In addition, we also justified the possible participations of glutamatergic system and ATP-sensitive potassium channels in the observed activities. Our results demonstrated that MEMK significantly (p < 0.01) inhibited the pain thresholds induced by formalin and acetic acid in a dose-dependent manner. MEMK also significantly (p < 0.01) suppressed glutamate-induced pain. Moreover, pretreatment with glibenclamide (an ATP-sensitive potassium channel blocker) at 10 mg/kg significantly (p < 0.05) reversed the MEMK-mediated antinociception. These revealed that MEMK might have the potential to interact with glutamatergic system and the ATP-sensitive potassium channels to exhibit its antinociceptive activities. Therefore, our results strongly support the antinociceptive effects of M. koenigii leaves and provide scientific basis of their analgesic uses in the traditional medicine.

Chemical structures of constituents from the whole plant of Bacopa monniera

Two new dammarane-type triterpene oligoglycosides, bacomosaponins A and B, and three new phenylethanoid glycosides, bacomosides A, B1, and B2, were isolated from the whole plant of Bacopa monniera Wettst. The chemical structures of the new constituents were characterized on the basis of chemical and physicochemical evidence. In the present study, bacomosaponins A and B with acyl groups were obtained from the whole plant of B. monniera. This is the first report of acylated dammarane-type triterpene oligoglycosides isolated from B. monniera. In addition, dammarane-type triterpene saponins significantly inhibited the aggregation of 42-mer amyloid β-protein.

Gold catalysis in total synthesis – recent achievements

The most recent achievements of gold catalysed transformations applied in total synthesis of natural products are reviewed and analysed.

Chemical structures and hepatoprotective effects of constituents from Cassia auriculata leaves

An 80% aqueous acetone extract of Cassia auriculata leaves was found to show a protective effect on D-galactosamine-induced cytotoxicity in primary cultured mouse hepatocytes. From the 80% aqueous acetone extract, we isolated a new benzocoumarin glycoside, avaraoside I (1), and a new flavanol dimer, avaraol I (2), together with 29 known constituents. The structures of the new compounds were elucidated on the basis of chemical and physicochemical evidence. In addition, three isolated compounds, pseudosemiglabrin (15, 0.0011%), (2S)-7,4'-dihydroxyflavan(4β→8)-catechin (22, 0.00075%), and (2S)-7,4'-dihydroxyflavan(4β→8)-gallocatechin (23, 0.092%), displayed hepatoprotective effects equivalent to that of the hepatoprotective agent, silybin.

Koenimbin, a natural dietary compound of Murraya koenigii (L) Spreng: inhibition of MCF7 breast cancer cells and targeting of derived MCF7 breast cancer stem cells (CD44(+)/CD24(-/low)): an in vitro study

BACKGROUND

Inhibition of breast cancer stem cells has been shown to be an effective therapeutic strategy for cancer prevention. The aims of this work were to evaluate the efficacy of koenimbin, isolated from Murraya koenigii (L) Spreng, in the inhibition of MCF7 breast cancer cells and to target MCF7 breast cancer stem cells through apoptosis in vitro.

METHODS

Koenimbin-induced cell viability was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Nuclear condensation, cell permeability, mitochondrial membrane potential, and cytochrome c release were observed using high-content screening. Cell cycle arrest was examined using flow cytometry, while human apoptosis proteome profiler assays were used to investigate the mechanism of apoptosis. Protein expression levels of Bax, Bcl2, and heat shock protein 70 were confirmed using Western blotting. Caspase-7, caspase-8, and caspase-9 levels were measured, and nuclear factor kappa B (NF-κB) activity was assessed using a high-content screening assay. Aldefluor™ and mammosphere formation assays were used to evaluate the effect of koenimbin on MCF7 breast cancer stem cells in vitro. The Wnt/β-catenin signaling pathway was investigated using Western blotting.

RESULTS

Koenimbin-induced apoptosis in MCF7 cells was mediated by cell death-transducing signals regulating the mitochondrial membrane potential by downregulating Bcl2 and upregulating Bax, due to cytochrome c release from the mitochondria to the cytosol. Koenimbin induced significant (P<0.05) sub-G0 phase arrest in breast cancer cells. Cytochrome c release triggered caspase-9 activation, which then activated caspase-7, leading to apoptotic changes. This form of apoptosis is closely associated with the intrinsic pathway and inhibition of NF-κB translocation from the cytoplasm to the nucleus. Koenimbin significantly (P<0.05) decreased the aldehyde dehydrogenase-positive cell population in MCF7 cancer stem cells and significantly (P<0.01) decreased the size and number of MCF7 cancer stem cells in primary, secondary, and tertiary mammospheres in vitro. Koenimbin also significantly (P<0.05) downregulated the Wnt/β-catenin self-renewal pathway.

CONCLUSION

Koenimbin has potential for future chemoprevention studies, and may lead to the discovery of further cancer management strategies by reducing cancer resistance and recurrence and improving patient survival.

A rare glutamine derivative from the flower buds of daylily

A rare glutamine derivative, hemerocallisamine I (1), was isolated from the methanolic extract of the flower buds of daylily, together with a new pyrrole alkaloid hemerocallisamine II (2) and a new γ-lactam derivative, hemerocallisamine III (3). The chemical structures of the new compounds were elucidated on the basis of chemical and physicochemical evidence. For hemerocallisamine I (1), the absolute configuration was determined by Mo-Kα X-ray crystallographic analysis. This is the first report of a glutamine derivative with a pyrrole ring from natural plants.

Lignan dicarboxylates and terpenoids from the flower buds of Cananga odorata and their inhibitory effects on melanogenesis

The methanolic extract from the flower buds of Cananga odorata showed an inhibitory effect on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extract, two new lignan dicarboxylates, canangalignans I and II, three new terpenoids, canangaterpenes I, II, and III, and eight known compounds were isolated. The structures of these compounds were elucidated on the basis of chemical/physicochemical evidence. Several mono- and sesquiterpene analogues significantly inhibited melanogenesis. In particular, canangaterpene I and (3R,3aR,8aS)-3-isopropyl-8a-methyl-8-oxo-1,2,3,3a,6,7,8,8a-octahydroazulene-5-carbaldehyde exhibited a potent inhibitory effect on melanogenesis [inhibition (%): 34.7±4.2 (p<0.01), 45.5±5.7 (p<0.01) at 1 μM, respectively] without inducing cytotoxicity. Moreover, the biological effect of these compounds was much stronger than that of the reference compound, arbutin. Thus, these isolated terpenoid derivatives may be promising therapeutic agents for the treatment of several skin disorders.

Diarylheptanoids with inhibitory effects on melanogenesis from the rhizomes of Curcuma comosa in B16 melanoma cells

The methanolic extract from the dried rhizomes of Curcuma comosa cultivated in Thailand was found to inhibit melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extract, three new diarylheptanoids, diarylcomosols I-III, were isolated together with 12 known diarylheptanoids. Their chemical structures were elucidated on the basis of chemical and physicochemical evidence. The diarylheptanoids inhibited melanogenesis, and several structural requirements of the active constituents for the inhibition were clarified. In particular, (3R)-1,7-bis(4-hydroxyphenyl)-(6E)-6-hepten-3-ol exhibited stronger inhibitory effect [IC50=0.36 μM] without inducing cytotoxicity. The biological effect was much stronger than that of a reference compound, arbutin [IC50=174 μM]. We conclude that diarylheptanoid analogs are promising therapeutic agents for the treatment of skin disorders.