An overview on chemical aspects and potential health benefits of limonoids and their derivatives

Haizao Yuhu decoction ameliorates silica-induced lung injury by inhibiting transforming growth factor-beta1/Smad pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Haizao Yuhu Decoction (HYD) is a traditional Chinese herbal formula known for regulating Qi and dispersing stasis.

AIM OF THE STUDY

This study investigates the effects of HYD on silica-induced lung injury and the underlying mechanisms.

MATERIALS AND METHODS

The main constituents of HYD were identified using ultra-performance liquid chromatography Q-Exactive mass spectrometry (UPLC-QE-MS). Network pharmacology was employed to predict the targets and pathways through which HYD ameliorates silicosis, which were validated in a silica-induced lung injury mouse model and a TGF-β1-induced alveolar epithelial cell model. Pathological evaluation was conducted using hematoxylin-eosin (H&E) and Masson staining, while inflammatory cytokines and fibrosis were assessed via enzyme-linked immunosorbent assay (ELISA) and hydroxyproline quantification. Western blotting (WB) was performed to analyse protein expression levels of targeted markers. Proliferation and migration capabilities of MLE12 cells treated with HYD and its bioactive constituents (glycitein, diosmetin, and limonin) were assessed using cell counting kit-8 (CCK-8) and wound healing assays.

RESULTS

HYD significantly alleviated silica-induced lung injury, reducing inflammatory response and collagen deposition. A total of 176 constituents were identified in HYD, with 111 being pharmacologically active and linked to 1397 potential therapeutic targets, 107 associated with silicosis. Enrichment analyses highlighted the TGF-β1/Smad pathway and epithelial-mesenchymal transition (EMT) in HYD's anti-silicosis effects, which was validated by the restoration of TGF-β1, p-Smad2/Smad2, p-Smad3/Smad3, E-cadherin, and Vimentin following HYD treatment. Additionally, glycitein, diosmetin, and limonin inhibited the proliferation and migration of TGF-β1-induced MLE12 cells and suppressed the activation of TGF-β1/Smad pathway and EMT.

CONCLUSIONS

HYD effectively alleviates silica-induced lung injury by specifically inhibiting the TGF-β1/Smad pathway and EMT process.

Plants Utilize a Protection/Deprotection Strategy in Limonoid Biosynthesis: A "Missing Link" Carboxylesterase Boosts Yields and Provides Insights into Furan Formation

The furan ring is a defining feature of limonoids, a class of highly rearranged and bioactive plant tetranortriterpenoids. We recently reported an apparent complete biosynthetic pathway to these important natural furanoids. Herein, we disclose the subsequent discovery of a yield-boosting "missing link" carboxylesterase that selectively deprotects a late-stage intermediate, so triggering more efficient furan biosynthesis. This has allowed, for the first time, the isolation and structural elucidation of unknown intermediates, refining our understanding of furan formation in limonoid biosynthesis.

Phytoconstituents from Turraea obtusifolia and their antiplasmodial activity

Three new steroids, turranin M, N and O (1-3), together with four known limonoids, nymania 1 (4), rubralin B (5), aphapolynin C (6) and Trichillia substance Tr B (7), were isolated from the leaves of Turraea obtusifolia. Their chemical structures were elucidated using NMR and MS. Rubralin B (5) displayed good activity against the asexual parasites from the drug sensitive Plasmodium falciparum NF54 strain with an IC50 value of 3.47 µg/mL (4.57 µM), nymania 1 (4) showed a weak activity (IC50 13.36 µg/mL (19.40 µM)) and the rest of compounds had IC50 > 20 µg/mL.

Limonin (LM) and its derivatives: Unveiling the neuroprotective and anti-inflammatory potential of LM and V-A-4 in the management of Alzheimer's disease and Parkinson's disease

Neuroinflammation and neuronal apoptosis are central pathogenic consequences associated with Alzheimer's Disease (AD) and Parkinson's Disease (PD). Limonin (LM), a tetracyclic triterpenoid available in citrus fruits, has anti-tumor, antioxidant, anti-inflammatory, hepatoprotective, and neuroprotective actions. LM derivative, V-A-4 emerged as a potential neuroprotective drug due to their ability to target multiple molecular pathways intertwined with neuroinflammation and neuronal apoptosis. To date, the treatment of AD and PD is not successful even though the understanding of the mechanism of neuroinflammation and neuronal apoptosis is vast in the literature. Thus, there is an urgent need to identify novel neuroprotective drugs that could target the multiple molecular pathways associated with neuroinflammation and neuronal apoptosis. The various online databases (Google scholar, Pubmed, Scopus) were searched via keywords: limonin, limonin derivatives and neuroprotection. This review highlights the multifunctional nature of LM and derivatives in combating neuroinflammation and neuronal apoptosis by stimulating PI3K/AKT and downregulating TLR4/NF-κB critical pathways. By intervening in the secretion of NO and TNF-α from glial cells, V-A-4 attenuates the damaging cascade of neuroinflammation by suppressing IKK-α and IKK-β. Furthermore, V-A-4 demonstrates its versatility by suppressing the manifestation of miR-146a and miR-155, both intimately linked to neuroinflammation, this review summarized the activities of LM and its derivatives against AD and PD, with a special focus on V-A-4 as an effective neuroprotective drug. V-A-4's ability to stimulate PI3K/AKT signaling further underscores its neuroprotective effect in combating AD and PD. More in-vitro cell line studies are needed to develop V-A-4 as an upcoming neuroprotective compound.

Assessment of the in vitro anti-diabetic activity with molecular dynamic simulations of limonoids isolated from Adalia lemon peels

Limonoids are important constituents of citrus that have a significant impact on promoting human health. Therefore, the primary focus of this research was to assess the overall limonoid content and isolate limonoids from Adalia lemon (Citrus limon L.) peels for their potential use as antioxidants and anti-diabetic agents. The levels of limonoid aglycones in the C. limon peel extract were quantified through a colorimetric assay, revealing a concentration of 16.53 ± 0.93 mg/L limonin equivalent. Furthermore, the total concentration of limonoid glucosides was determined to be 54.38 ± 1.02 mg/L. The study successfully identified five isolated limonoids, namely limonin, deacetylnomilin, nomilin, obacunone 17-O-β-D-glucopyranoside, and limonin 17-O-β-D-glucopyranoside, along with their respective yields. The efficacy of the limonoids-rich extract and the five isolated compounds was evaluated at three different concentrations (50, 100, and 200 µg/mL). It was found that both obacunone 17-O-β-D-glucopyranoside and limonin 17-O-β-D-glucopyranoside possessed the highest antioxidant, free radical scavenging, and anti-diabetic activities, followed by deacetylnomilin, and then the limonoids-rich extract. The molecular dynamic simulations were conducted to predict the behavior of the isolated compounds upon binding to the protein's active site, as well as their interaction and stability. The results revealed that limonin 17-O-β-D-glucopyranoside bound to the protein complex system exhibited a relatively more stable conformation than the Apo system. The analysis of Solvent Accessible Surface Area (SASA), in conjunction with the data obtained from Root-Mean-Square Deviation (RMSD), Root-Mean-Square Fluctuation (RMSF), and Radius of Gyration (ROG) computations, provided further evidence that the limonin 17-O-β-D-glucopyranoside complex system remained stable within the catalytic domain binding site of the human pancreatic alpha-amylase (HPA)-receptor. The research findings suggest that the limonoids found in Adalia lemon peels have the potential to be used as effective natural substances in creating innovative therapeutic treatments for conditions related to oxidative stress and disorders in carbohydrate metabolism.

Limonoids from the fruits of Chisocheton erythrocarpus and their mosquito larvicidal activities

Phytochemical study of the fruits of Chisocheton erythrocarpus (Hiern) allowed the identification of eight undescribed limonoids, namely erythrocarpines O - V (1-6, 7a and 7b), along with seven known compounds. The structures of these compounds were elucidated based on spectroscopic and HRMS data, along with electronic circular dichroism to configure the absolute configuration. Erythrocarpines O and P are γ-hydroxybutenolide analogs of mexicanolide-type limonoids while erythrocarpine Q - V are phragmalin-type limonoids possessing a 1,29-oxymethylene bridge with either benzoyl or cinnamoyl moiety in their structures. Mosquito larvicidal activity revealed that crude DCM extract of C. erythrocarpus possessed a good larvicidal effect against Aedes aegypti larvae in 48 h (LC50 = 153.0 ppm). Subsequent larvicidal activity of isolated compounds indicated that erythrocarpine G (10) and 14-deoxyxyloccensin K (11) were responsible for the enhanced larvicidal effect of the extract, reporting LC50 values of 18.55 ppm and 41.16 ppm, respectively. Moreover, residual activity testing of the crude DCM extract revealed that the duration of its larvicidal effects is up to 14 days, where it maintained a 98 % larval mortality throughout the test period, under laboratory conditions.

Limonin inhibits the stemness of cancer stem-like cells derived from colorectal carcinoma cells potentially via blocking STAT3 signaling

BACKGROUND

Limonin is one of the most abundant active ingredients of Tetradium ruticarpum. It exerts antitumor effects on several kinds of cancer cells. However, whether limonin exerts antitumor effects on colorectal cancer (CRC) cells and cancer stem-like cells (CSCs), a subpopulation responsible for a poor prognosis, is unclear.

AIM

To evaluate the effects of limonin on CSCs derived from CRC cells.

METHODS

CSCs were collected by culturing CRC cells in serum-free medium. The cytotoxicity of limonin against CSCs and parental cells (PCs) was determined by cholecystokinin octapeptide-8 assay. The effects of limonin on stemness were detected by measuring stemness hallmarks and sphere formation ability.

RESULTS

As expected, limonin exerted inhibitory effects on CRC cell behaviors, including cell proliferation, migration, invasion, colony formation and tumor formation in soft agar. A relatively low concentration of limonin decreased the expression stemness hallmarks, including Nanog and β-catenin, the proportion of aldehyde dehydrogenase 1-positive CSCs, and the sphere formation rate, indicating that limonin inhibits stemness without presenting cytotoxicity. Additionally, limonin treatment inhibited invasion and tumor formation in soft agar and in nude mice. Moreover, limonin treatment significantly inhibited the phosphorylation of STAT3 at Y705 but not S727 and did not affect total STAT3 expression. Inhibition of Nanog and β-catenin expression and sphere formation by limonin was obviously reversed by pretreatment with 2 μmol/L colievlin.

CONCLUSION

Taken together, these results indicate that limonin is a promising compound that targets CSCs and could be used to combat CRC recurrence and metastasis.

Widespread occurrence of in-source fragmentation in the analysis of natural compounds by liquid chromatography-electrospray ionization mass spectrometry

RATIONALE

The in-source fragmentation (ISF) of analyte or co-eluting substances produces unintentional fragment ions, which hampers identification and quantification by liquid chromatography-mass spectrometry (LC/MS). Natural compounds derived from plants also contain fragile moieties that may undergo ISF. However, the characteristics of ISF of natural compounds in LC/MS are still unclear.

METHODS

The ISF behavior of 214 natural compounds was assayed in LC with Q/orbitrap MS in electrospray ionization (ESI) mode and the extent of ISF was evaluated.

RESULTS

Up to 82% of tested compounds underwent ISF and half of the tested natural compounds that contain more than one fragile moiety underwent successive and severe ISF to generate serial structurally related ISF products. The major ISF-altering moieties for natural compounds were hydroxyl, lactone, glycosyl and ether, resulting in neutral loss of H₂ O or CO, deglycosylation or cleavage of ether bond, respectively. Some compounds such as terpenoids underwent severe ISF and less than 1% parent form can be observed. For natural compounds, ISF products with similar structures are more likely to cause interference in analysis because the ISF products may share identical mass-to-charge ratio and similar MS² fragmentation patterns with precursor ions of the homologs in plants. Furthermore, severe ISF may cause a false negative in the identification of the parent form.

CONCLUSIONS

In summary, ISF was a highly frequent phenomenon for analysis of natural compounds by LC/ESI-MS, and extensive and successive ISF of natural products may cause misannotation and misidentification with homologs in plants. The study should raise awareness of ISF interference during the analysis of natural compounds.

Pregnane X receptor agonist nomilin extends lifespan and healthspan in preclinical models through detoxification functions

Citrus fruit has long been considered a healthy food, but its role and detailed mechanism in lifespan extension are not clear. Here, by using the nematode C. elegans, we identified that nomilin, a bitter-taste limoloid that is enriched in citrus, significantly extended the animals' lifespan, healthspan, and toxin resistance. Further analyses indicate that this ageing inhibiting activity depended on the insulin-like pathway DAF-2/DAF-16 and nuclear hormone receptors NHR-8/DAF-12. Moreover, the human pregnane X receptor (hPXR) was identified as the mammalian counterpart of NHR-8/DAF-12 and X-ray crystallography showed that nomilin directly binds with hPXR. The hPXR mutations that prevented nomilin binding blocked the activity of nomilin both in mammalian cells and in C. elegans. Finally, dietary nomilin supplementation improved healthspan and lifespan in D-galactose- and doxorubicin-induced senescent mice as well as in male senescence accelerated mice prone 8 (SAMP8) mice, and induced a longevity gene signature similar to that of most longevity interventions in the liver of bile-duct-ligation male mice. Taken together, we identified that nomilin may extend lifespan and healthspan in animals via the activation of PXR mediated detoxification functions.

Meliaceae genomes provide insights into wood development and limonoids biosynthesis

Meliaceae is a useful plant family owing to its high-quality timber and its many limonoids that have pharmacological and biological activities. Although some genomes of Meliaceae species have been reported, many questions regarding their unique family features, namely wood quality and natural products, have not been answered. In this study, we provide the whole-genome sequence of Melia azedarach comprising 237.16 Mb with a contig N50 of 8.07 Mb, and an improved genome sequence of Azadirachta indica comprising 223.66 Mb with a contig N50 of 8.91 Mb. Moreover, genome skimming data, transcriptomes and other published genomes were comprehensively analysed to determine the genes and proteins that produce superior wood and valuable limonoids. Phylogenetic analysis of chloroplast genomes, single-copy gene families and single-nucleotide polymorphisms revealed that Meliaceae should be classified into two subfamilies: Cedreloideae and Melioideae. Although the Meliaceae species did not undergo additional whole-genome duplication events, the secondary wall biosynthetic genes of the woody Cedreloideae species, Toona sinensis, expanded significantly compared to those of A. indica and M. azedarach, especially in downstream transcription factors and cellulose/hemicellulose biosynthesis-related genes. Moreover, expanded special oxidosqualene cyclase catalogues can help diversify Sapindales skeletons, and the clustered genes that regulate terpene chain elongation, cyclization and modification would support their roles in limonoid biosynthesis. The expanded clans of terpene synthase, O-methyltransferase and cytochrome P450, which are mainly derived from tandem duplication, are responsible for the different limonoid classes among the species. These results are beneficial for further investigations of wood development and limonoid biosynthesis.

Comparative Untargeted Metabolic Profiling of Different Parts of Citrus sinensis Fruits via Liquid Chromatography-Mass Spectrometry Coupled with Multivariate Data Analyses to Unravel Authenticity

Differences between seven authentic samples of Citrus sinensis var. Valencia peel (albedo and flavedo) and juices from Spain and Uruguay, in addition to a concentrate obtained from Brazil, were investigated by untargeted metabolic profiling. Sixty-six metabolites were detected by nano-liquid chromatography coupled to a high-resolution electrospray-ionization quadrupole time-of-flight mass spectrometer (nLC-ESI-qTOF-MS) belonging to phenolic acids, coumarins, flavonoid glycosides, limonoids, terpenes, and fatty acids. Eleven metabolites were detected for the first time in Citrus sinensis and identified as citroside A, sinapic acid pentoside, apigenin-C-hexosyl-O-pentoside, chrysoeriol-C-hexoside, di-hexosyl-diosmetin, perilloside A, gingerol, ionone epoxide hydroxy-sphingenine, xanthomicrol, and coumaryl alcohol-O-hexoside. Some flavonoids were completely absent from the juice, while present most prominently in the Citrus peel, conveying more industrial and economic prospects to the latter. Multivariate data analyses clarified that the differences among orange parts overweighed the geographical source. PCA analysis of ESI-(-)-mode data revealed for hydroxylinoleic acid abundance in flavedo peel from Uruguay the most distant cluster from all others. The PCA analysis of ESI-(+)-mode data provided a clear segregation of the different Citrus sinensis parts primarily due to the large diversity of flavonoids and coumarins among the studied samples.

Comprehensive studies of biological characteristics, phytochemical profiling, and antioxidant activities of two local citrus varieties in China

Citrus is widely grown all over the world, and citrus fruits have long been recognized for their nutritional and medical value for human health. However, some local citrus varieties with potentially important value are still elusive. In the current study, we elucidated the biological characteristics, phylogenetic and phytochemical profiling, antioxidants and antioxidant activities of the two local citrus varieties, namely Zangju and Tuju. The physiological and phylogenetic analysis showed that Zangju fruit has the characteristics of wrinkled skin, higher acidity, and phylogenetically closest to sour mandarin Citrus sunki, whereas, Tuju is a kind of red orange with vermilion peel, small fruit and high sugar content, and closely clustered with Citrus erythrosa. The phytochemical analysis showed that many nutrition and antioxidant related differentially accumulated metabolites (DAMs) were detected in the peel and pulp of Zangju and Tuju fruits. Furthermore, it was found that the relative abundance of some key flavonoids and phenolic acids, such as tangeritin, sinensetin, diosmetin, nobiletin, and sinapic acid in the peel and pulp of Zangju and Tuju were higher than that in sour range Daidai and satsuma mandarin. Additionally, Zangju pulp and Tuju peel showed the strongest ferric reducing/antioxidant power (FRAP) activity, whereas, Tuju peel and pulp showed the strongest DPPH and ABTS free radical scavenging activities, respectively. Moreover, both the antioxidant activities of peel and pulp were significantly correlated with the contents of total phenols, total flavonoids or ascorbic acid. These results indicate that the two local citrus varieties have certain nutritional and medicinal value and potential beneficial effects on human health. Our findings will also provide an important theoretical basis for further conservation, development and medicinal utilization of Zangju and Tuju.

Limonoids from the fruits of Chisocheton lasiocarpus (Meliaceae)

Two new azadirone-type limonoids, namely lasiocarpine A (1) and lasiocarpine B (2) were isolated from the fruit of Chisocheton lasiocarpus along with three known limonoids (3-5). UV, IR, one- and two- dimensional NMR, and mass spectrometry were used to determine the chemical structure of the isolated compounds. Furthermore, their cytotoxic activity against breast cancer cell line MCF-7 was evaluated using PrestoBlue reagent. From these compounds, lasiocarpine A (1) showed the strongest activity with an IC₅₀ value of 43.38 μM.

Status of research on natural protein tyrosine phosphatase 1B inhibitors as potential antidiabetic agents: Update

Protein tyrosine phosphatase 1B (PTP1B) is a crucial therapeutic target for multiple human diseases comprising type 2 diabetes (T2DM) and obesity because it is a seminal part of a negative regulator in both insulin and leptin signaling pathways. PTP1B inhibitors increase insulin receptor sensitivity and have the ability to cure insulin resistance-related diseases. However, the few PTP1B inhibitors that entered the clinic (Ertiprotafib, ISIS-113715, Trodusquemine, and JTT-551) were discontinued due to side effects or low selectivity. Molecules with broad chemical diversity extracted from natural products have been reported to be potent PTP1B inhibitors with few side effects. This article summarizes the recent PTP1B inhibitors extracted from natural products, clarifying the current research progress, and providing new options for designing new and effective PTP1B inhibitors.

Nomilin and Its Analogues in Citrus Fruits: A Review of Its Health Promotion Effects and Potential Application in Medicine

Nomilin is one of the major limonoids, which are plant secondary metabolites also known as tetranortriterpenoids. Nomilin is found mostly in common edible citrus fruits including lemons, limes, oranges, grapefruits, mandarins, along with traditional Chinese medicines derived from citrus fruits, such as tangerine seed, tangerine peel, fructus aurantii immaturus, etc. A number of studies have demonstrated that nomilin and its analogues exhibit a variety of biological and pharmacological activities. These include anti-cancer, immune-modulatory, anti-inflammatory, anti-obesity, anti-viral, anti-osteoclastogenic, anti-oxidant, and neuro-protective effects. Thus, nomilin and its analogues have emerged as a potential therapy for human diseases. The purpose of this review is to chronicle the evolution of nomilin research from examining its history, structure, occurrence, to its pharmacological and disease-preventing properties as well as its potential utilization in medicine and food science.

Limonoids with anti-inflammatory activity: A review

The natural limonoids distributed mainly in the Meliaceae and Rutaceae plants are known for their unique and complex structure with high degree oxidation and cyclic rearrangement. However, these compounds exhibit a broad range of biological activities such as insecticidal, antibacterial, antifungal, antimalarial, antioxidant, anticancer, antiviral, and anti-inflammatory. There is still limited report about the biological activity of the anti-inflammatory effect of limonoids isolated from plants. Therefore, this study aimed to examine the effect of intact, deformed and rearranged limonoids as anti-inflammatory agents. The majority of anti-inflammatory investigations were evaluated by in vitro and in vivo assays of the isolated pure compounds and their derivatives. For the in vitro study, intact and C-ring seco limonoids showed a potent inhibitory effect against NO production. The in vivo analysis of Intact, C-seco, and AD-seco limonoids showed a potent effect based on the inhibition of pro-inflammatory cytokines expression, indicating their potency as anti-inflammatory agents.

Anti-inflammatory and anti-oxidant properties of Melianodiol on DSS-induced ulcerative colitis in mice

Background

Ulcerative colitis is a unique inflammatory bowel disease with ulcerative lesions of the colonic mucosa. Melianodiol (MN), a triterpenoid, isolated from the fruits of the Chinese medicinal plant Melia azedarach, possesses significant anti-inflammatory properties.

Objective

The present study investigated the protective effects of MN on lipopolysaccharide (LPS)-induced macrophages and DSS-mediated ulcerative colitis in mice.

Methods

In the study, mice were given MN (50, 100, and 200 mg/kg) and 5-ASA (500 mg/kg) daily for 9 days after induction by DSS for 1 week. The progress of the disease was monitored daily by observation of changes in clinical signs and body weight.

Results

The results showed that MN effectively improved the overproduction of inflammatory factors (IL-6, NO, and TNF-α) and suppressed the activation of the NF-κB signalling cascade in LPS-mediated RAW264.7 cells. For DSS-mediated colitis in mice, MN can reduce weight loss and the disease activity index (DAI) score in UC mice, suppress colon shortening, and alleviate pathological colon injury. Moreover, MN treatment notably up regulated the levels of IL-10 and down regulated those of IL-1β and TNF-α, and inhibited the protein expression of p-JAK2, p-STAT3, iNOS, NF-κB P65, p-P65, p-IKKα/β, and p-IκBα in the colon. After MN treatment, the levels of MDA and NO in colonic tissue were remarkably decreased, whereas the levels of GSH, SOD, Nrf-2, Keap-1, HO-1, IκBα, and eNOS protein expression levels were significantly increased.

Conclusion

These results indicate that MN can activate the Nrf-2 signalling pathway and inhibit the JAK/STAT, iNOS/eNOS, and NF-κB signalling cascades, enhance intestinal barrier function, and effectively reduce the LPS-mediated inflammatory response in mouse macrophages and DSS-induced intestinal injury in UC.

Chemical constituents of Entandrophragma angolense and their anti-inflammatory activity

From the stem bark of Entandrophragma angolense, six undescribed compounds were isolated, including seco-tirucallane type triterpenoids, limonoids, and a catechin glucoside, along with nineteen known structures. All structures were determined by interpretation of spectroscopic and HRMS data, and absolute configuration was confirmed with the aid of electronic circular dichroism. The isolated compounds were tested for LPS-induced NO inhibition in RAW 264.7 macrophages and EC₅₀ values for moluccensin O and (-)-catechin were 81 μM and 137 μM, respectively.

The Antimicrobial Potential of the Neem Tree Azadirachta indica

Azadirachta indica (A. Juss), also known as the neem tree, has been used for millennia as a traditional remedy for a multitude of human ailments. Also recognized around the world as a broad-spectrum pesticide and fertilizer, neem has applications in agriculture and beyond. Currently, the extensive antimicrobial activities of A. indica are being explored through research in the fields of dentistry, food safety, bacteriology, mycology, virology, and parasitology. Herein, some of the most recent studies that demonstrate the potential of neem as a previously untapped source of novel therapeutics are summarized as they relate to the aforementioned research topics. Additionally, the capacity of neem extracts and compounds to act against drug-resistant and biofilm-forming organisms, both of which represent large groups of pathogens for which there are limited treatment options, are highlighted. Updated information on the phytochemistry and safety of neem-derived products are discussed as well. Although there is a growing body of exciting evidence that supports the use of A. indica as an antimicrobial, additional studies are clearly needed to determine the specific mechanisms of action, clinical efficacy, and in vivo safety of neem as a treatment for human pathogens of interest. Moreover, the various ongoing studies and the diverse properties of neem discussed herein may serve as a guide for the discovery of new antimicrobials that may exist in other herbal panaceas across the globe.

Fruit Juice Industry Wastes as a Source of Bioactives

Food processing sustainability, as well as waste minimization, are key concerns for the modern food industry. A significant amount of waste is generated by the fruit juice industry each year. In addition to the economic losses caused by the removal of these wastes, its impact on the environment is undeniable. Therefore, researchers have focused on recovering the bioactive components from fruit juice processing, in which a great number of phytochemicals still exist in the agro-industrial wastes, to help minimize the waste burden as well as provide new sources of bioactive compounds, which are believed to be protective agents against certain diseases such as cardiovascular diseases, cancer, and diabetes. Although these wastes contain non-negligible amounts of bioactive compounds, information on the utilization of these byproducts in functional ingredient/food production and their impact on the sensory quality of food products is still scarce. In this regard, this review summarizes the most recent literature on bioactive compounds present in the wastes of apple, citrus fruits, berries, stoned fruits, melons, and tropical fruit juices, together with their extraction techniques and valorization approaches. Besides, on the one hand, examples of different current food applications with the use of these wastes are provided. On the other hand, the challenges with respect to economic, sensory, and safety issues are also discussed.

Metabolic Activation and Hepatotoxicity of Furan-Containing Compounds

Furan-containing compounds are abundant in nature, and many, but not all, have been found to be hepatotoxic and carcinogenic. The furan ring present in the chemical structures may be one of the domineering factors to bring about the toxic response resulting from the generation of reactive epoxide or cis-enedial intermediates, which have the potential to react with biomacromolecules. This review sets out to explore the relationship between the metabolic activation and hepatotoxicity of furan-containing compounds on the strength of scientific reports on several typical alkylated furans, synthetic pharmaceuticals, and components extracted from herbal medicines. The pharmacological activities as well as concrete evidence of their liver injuries are described, and the potential toxic mechanisms were discussed partly based on our previous work. Efforts were made to understand the development of liver injury and seek solutions to prevent adverse effects. SIGNIFICANCE STATEMENT: This review mainly elucidates the vital role of metabolic activation in the hepatotoxicity of furan-containing compounds through several typical chemicals studied. The possible mechanisms involved in the toxicities are discussed based on collective literatures as well as our work. Additionally, the structural features responsible for toxicities are elaborated to predict toxicity potentials of furan-containing compounds. This article may assist to seek solutions for the occurring problems and prevent the toxic effects of compounds with furan(s) in clinical practice.

Limonin Alleviates Non-alcoholic Fatty Liver Disease by Reducing Lipid Accumulation, Suppressing Inflammation and Oxidative Stress

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and continues to rise in the worldwide. Limonin is a triterpenoid compound widely found in the fruits of citrus plants with a wide range of pharmacological effects, including anti-cancer, anti-inflammation, anti-viral, anti-oxidation and liver protection properties. However, the potential molecular mechanism of limonin on NAFLD in zebrafish remains unknown. In this study, zebrafish larvae were exposed to thioacetamide to establish an NAFLD model and the larvae were treated with limonin for 72 h simultaneously. The human liver cell line was stimulated with lipid mixture and meanwhile incubated with limonin for 24 h. The results showed that Limonin significantly reduced the accumulation of lipid droplets in the liver and down-regulated the levels of lipogenic transcription factors FASN and SREBP1 in NAFLD. Limonin suppressed macrophages infiltration and the down-regulated the relative expression levels of the pro-inflammatory factors IL-6, IL-1β and TNF-α secreted by macrophages. Besides, limonin could reversed the reduction of glutathione and the accumulation of reactive oxygen species through up-regulating NRF2/HO-1 signaling pathway in the liver. In conclusion, this study revealed that limonin has a protective effect on NAFLD due to its resistance to lipid deposition as well as antioxidant and anti-inflammatory actions.

Limonin Inhibits IL-1β-Induced Inflammation and Catabolism in Chondrocytes and Ameliorates Osteoarthritis by Activating Nrf2

Osteoarthritis (OA), a degenerative disorder, is considered to be one of the most common forms of arthritis. Limonin (Lim) is extracted from lemons and other citrus fruits. Limonin has been reported to have anti-inflammatory effects, while inflammation is a major cause of OA; thus, we propose that limonin may have a therapeutic effect on OA. In this study, the therapeutic effect of limonin on OA was assessed in chondrocytes in vitro in IL-1β induced OA and in the destabilization of the medial meniscus (DMM) mice in vivo. The Nrf2/HO-1/NF-κB signaling pathway was evaluated to illustrate the working mechanism of limonin on OA in chondrocytes. In this study, it was found that limonin can reduce the level of IL-1β induced proinflammatory cytokines such as INOS, COX-2, PGE2, NO, TNF-α, and IL-6. Limonin can also diminish the biosynthesis of IL-1β-stimulated chondrogenic catabolic enzymes such as MMP13 and ADAMTS5 in chondrocytes. The research on the mechanism study demonstrated that limonin exerts its protective effect on OA through the Nrf2/HO-1/NF-κB signaling pathway. Taken together, the present study shows that limonin may activate the Nrf2/HO-1/NF-κB pathway to alleviate OA, making it a candidate therapeutic agent for OA.

Comparative Metabolomics Analysis of Citrus Varieties

Many citrus varieties are hybridized to improve their quality and to overcome the effects of climate change. However, there is limited information on the effect of the chemical profiles of hybrid varieties on their quality. In this study, we analyzed 10 citrus varieties and evaluated the correlation with their general characteristics and antioxidant activities. Chemical profiles, including the contents of sugars, organic acid compounds, flavonoids, limonoids, and carotenoids, which are related to taste, color, and health benefits, were significantly different depending on the citrus varieties, leading to different antioxidant capacities and general quality parameters. Based on these data, the correlations were investigated, and 10 citrus varieties were clustered into four groups-Changshou kumquat and Jeramon (cluster I); Setoka (cluster II-1); Natsumi, Satsuma mandarin, and Navel orange (cluster II-2); Kanpei, Tamnaneunbong, Saybyeolbong, and Shiranui (cluster II-3). Moreover, a metabolomic pathway was proposed. Although citrus peels were not analyzed and the sensory and functional qualities of the citrus varieties were not investigated in this study, our results are useful to better understand the relationship between citrus quality and metabolite profiles, which can provide basic information for the development and improvement of new citrus varieties.

Nutrients and bioactives in citrus fruits: Different citrus varieties, fruit parts, and growth stages

Citrus fruits are consumed in large quantities worldwide due to their attractive aromas and taste, as well as their high nutritional values and various health-promoting effects, which are due to their abundance of nutrients and bioactives. In addition to water, carbohydrates, vitamins, minerals, and dietary fibers are important nutrients in citrus, providing them with high nutritional values. Citrus fruits are also rich in various bioactives such as flavonoids, essential oils, carotenoids, limonoids, and synephrines, which protect from various ailments, including cancer and inflammatory, digestive, and cardiovascular diseases. The composition and content of nutrients and bioactives differ significantly among citrus varieties, fruit parts, and growth stages. To better understand the nutrient and bioactive profiles of citrus fruits and provide guidance for the utilization of high-value citrus resources, this review systematically summarizes the nutrients and bioactives in citrus fruit, including their contents, structural characteristics, and potential health benefits. We also explore the composition variation in different citrus varieties, fruits parts, and growth stages, as well as their health-promoting effects and applications.

Ethnomedicinal Use, Phytochemistry, and Pharmacology of Xylocarpus granatum J. Koenig

The mangrove plants are the potential sources of foods and remedies for people living in the forests and nearby communities. Xylocarpus granatum J. Koenig is traditionally used to treat various diseases including diarrhea, cholera, dysentery, fever, malaria, and viral infections, among others. To summarize critically the taxonomy, ethnomedicinal, phytochemistry, and pharmacological activities of X. granatum, information was collected from different databases. An up-to-date search (till June 2020) was carried out with the help of various scientific web resources from databases such as PubMed, Science Direct, Google Scholar, and various patent offices (e.g., WIPO, CIPO, and USPTO) using the keywords “Xylocarpus granatum” and then paired with ethnomedicinal use and phytochemical, phytochemistry, and pharmacological activity (in vitro, ex vivo, and in vivo studies). Findings revealed that seeds, fruits, stem bark, leaf, and twigs of X. granatum exhibited a wide range of key phytochemicals including limonoids, phragmalin, limonoid-based alkaloids, mexicanolides, protolimonoids, flavonols, and lactones. The plant possessed potent antioxidant, anticancer, antidiabetic, antimicrobial, antimalarial, antifeedant, and neuroprotective activities. No clinical studies have been reported in the databases. Ethnomedicinal assessment indicated the application of X. granatum in various fields of medical science specially to treat various human ailments, and this was attributed to the presence of enormous alkaloids as confirmed by pharmacological studies. However, to understand the mechanism of action in-depth studies are required. In view of these findings, more research is necessary to explore and characterize the chemical compounds and toxicological aspects of this medicinal mangrove plant. Overall, it can be stated that X. granatum may be one of the hopeful medicinal herbs for the treatment of various diseases in human beings.

Khayalactone- and phragmalin-type limonoids with PTP1B inhibitory activity from Trichilia sinensis Bentv

An investigation on the extract from the plant Trichilia sinensis Bentv. led to the isolation of 13 new limonoids (1-13), in which two were of khayalactone skeleton and 11 were phragmalin-type limonoids, and eight known phragmalin-type limonoids (14-21). Their structures were elucidated by using spectroscopic techniques and HRESIMS experiment. Compounds 6 and 17 displayed potent protein tyrosine phosphatase 1B inhibitory activity with IC₅₀ values of 1.2 ± 0.1 and 8.1 ± 0.5 μM, respectively.

Multifunctional inhibitors of SARS-CoV-2 by MM/PBSA, essential dynamics, and molecular dynamic investigations

The ongoing COVID-19 pandemic demands a novel approach to combat and identify potential therapeutic targets. The SARS-CoV-2 infection causes a hyperimmune response followed by a spectrum of diseases. Limonoids are a class of triterpenoids known to prevent the release of IL-6, IL-15, IL-1α, IL-1β via TNF and are also known to modulate PI3K/Akt/GSK-3β, JNK1/2, MAPKp38, ERK1/2, and PI3K/Akt/mTOR signaling pathways and could help to avoid viral infection, persistence, and pathogenesis. The present study employs a computational approach of virtual screening and molecular dynamic (MD) simulations of such compounds against RNA-dependent RNA polymerase (RdRp), Main protease (Mpro), and Papain-like protease (PLpro) of SARS-CoV-2. MD simulation, Molecular Mechanics Poisson-Boltzmann Surface Area (MM/PBSA), and Essential dynamics revealed that the macromolecule-ligand complexes are stable with very low free energy of binding. Such compounds that could modulate both host responses and inhibit viral machinery could be beneficial in effectively controlling the global pandemic.

Epigenetics of Triple-negative breast cancer via natural compounds

Triple-negative breast cancer (TNBC) is a highly resistant, lethal, and metastatic sub-division of breast carcinoma, characterized by the deficiency of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). In women, TNBC shows a higher aggressive behavior with poor patient prognosis and a higher recurrence rate during reproductive age. TNBC is defined by the presence of epithelial-to-mesenchymal-transition (EMT), which shows a significant role in cancer progression. At the epigenetic level, TNBC is characterized by epigenetic signatures, such as DNA methylation, histone remodeling, and a host of miRNA, MiR-193, LncRNA, HIF-2α, eEF2K, LIN9/NEK2, IMP3, LISCH7/TGF-β1, GD3s and KLK12 mediated regulation. These modifications either are silenced or activate the necessary genes that are prevalent in TNBC. The review is based on epigenetic mediated mechanistic changes in TNBC. Furthermore, Thymoquinone (TQ), Regorafenib, Fangjihuangqi decoction, Saikosaponin A, and Huaier, etc., are potent antitumor natural compounds extensively reported in the literature. Further, the review emphasizes the role of these natural compounds in TNBC and their possible epigenetic targets, which can be utilized as a potential therapeutic strategy in treatment of TNBC.

Metabolomic profiling and biological properties of six Limonium species: novel perspectives for nutraceutical purposes

The genus Limonium includes important halophyte plants containing a variety of bioactive compounds of therapeutic interest. In the present work, the untargeted phytochemical profiles of both aerial part and root extracts from six Limonium species namely, L. bellidifolium, L. globuliferum, L. gmelinii, L. lilacinum, L. sinuatum and L. iconicum from Turkey were determined. Furthermore, several biological activities (in vitro antioxidant and enzyme inhibitory effects) were investigated. Overall, significant amounts of total phenolics (43.64-238.18 mg g-1) and flavonoids (1.61-129.69 mg g-1) were recorded. Particularly, the root extracts of L. gmelinii, L. iconicum and L. globuliferum showed the highest total phenolic content (204.13-238.18 mg g-1), whilst the highest total flavonoid content was recorded in the root extracts of L. gmelinii (129.69 mg g-1). Overall, the tested extracts demonstrated potent radical scavenging activities in both DPPH (2,2- diphenyl-1-picrylhydrazyl) and ABTS (3-ethylbenzothiazoline-6-sulphonic acid) (90.10-507.94 mg g-1 and 163.39-1175.34 mg g-1, respectively). However, the highest scavenging potential (p < 0.05) was displayed by the root extracts of L. iconicum. Conversely, the metal chelating ability assay revealed that L. lilacinum root extract showed the highest activity (21.03 mg g-1). Interestingly, all the extracts were found to be active inhibitors of cholinesterases (AChE (acetylcholinesterase): 4.20-5.11 mg GALAE (galantamine equivalent) per g; BChE (butyrylcholinesterase): 3.89-10.75 mg GALAE per g), amylase (0.52-1.09 mmol ACAE (acarbose equivalent) per g) and tyrosinase (119.41-155.67 mg KAE (kojic acid equivalent) per g), unlike for glucosidase (2.31-2.41 mmol ACAE per g). Taken together, these findings demonstrated a diverse chemical profiles and biological of the extracts, to be potentially considered as phytotherapeutic or functional ingredients due to their antioxidant properties and inhibition of key enzymes involved in several diseases.

LC-MS/MS Profiles and In Vitro Biological Activities of Extracts of an Endemic Species from Turkey: Stachys cretica ssp. anatolica

Background: Genus Stachys is one of the largest of the Lamiaceae family, having around 300 different plant species inhabiting areas with temperate and warm climates. The Stachys species in Turkey are represented with 81 taxa; 51 of them being endemic. Plants of the Stachys genus have been known for their biological activity and their use in ethnomedicine. Methods: The dominant components of S. cretica ssp. anatolica aqueous and methanol extracts were studied with the LC-MS/MS technique. Results: Chlorogenic acid, apigenin-7-glucoside and verbascoside present as the dominant polyphenols found in studied extracts. The prominent biological activity of the studied S. cretica ssp. anatolica methanol and aqueous extracts showed strong antioxidant activity and inhibition of enzymes tyrosinase and α-amylase, involved in skin disorders and diabetes mellitus type II. Conclusions: This study has proven that the aqueous and methanol extracts of S. cretica ssp. anatolica have prominent antioxidant activity, due to a high abundance of polyphenols. The strong antioxidant properties of S. cretica ssp. anatolica extracts show promising application for the pharmaceutical, food, and cosmetics industries.

Limonin Enhances the Antifungal Activity of Eugenol Nanoemulsion against Penicillium Italicum In Vitro and In Vivo Tests

Penicillium italicum, the cause of citrus blue mold, is a pathogenic fungus that seriously affects the postharvest quality of citrus fruit and causes serious economic loss. In this study, a eugenol nanoemulsion containing limonin, an antimicrobial component from citrus seeds, was prepared using a high-pressure microfluidizer and the antifungal activity of the nanoemulsions against P. italicum was evaluated based on the conidial germination rate, mycelial growth, and scanning electron microscopy analysis. The results showed that the minimum inhibitory concentration and the inhibition rate of limonin-loaded eugenol nanoemulsion was 160 μg/mL and 59.21%, respectively, which was more potent than that of the limonin-free eugenol emulsion. After treatment with the nanoemulsions, the integrity of the P. italicum cell membrane was disrupted, the cell morphology was abnormal, and the leakage of nucleic acid and protein was observed. In addition, the challenge test on citrus fruits revealed that the limonin-loaded eugenol emulsion inhibited citrus infection for longer periods, with an infection rate of 29.2% after 5 days. The current research shows that nanoemulsions containing limonin and eugenol have effective antifungal activity against P. italicum, and may be used as a substitute for inhibiting blue mold in citrus fruits.

Limonoid biosynthesis 3: Functional characterization of crucial genes involved in neem limonoid biosynthesis

Neem (Azadirachta indica L.) is well known for its medicinal, agricultural, and pesticidal applications since ages. The secondary metabolites, limonoids, confer these biological properties, wherein over 150 different limonoids have been reported from neem. To understand limonoid biosynthesis, we analyzed tissue-specific (kernel, pericarp, leaves, and flower) transcriptome that resulted in the identification of one farnesyl diphosphate synthase (AiFDS), one squalene synthase (AiSQS), three squalene epoxidases (AiSQE1, AiSQE2, and AiSQE3), two triterpene synthases (AiTTS1 and AiTTS2), cycloartenol synthase (AiCAS), two cytochrome P450 reductases, and ten cytochrome P450 systems. Comparative tissue-expression analysis indicated that AiFDS, AiSQS, AiSQE3, and AiTTS1 are expressed higher in the kernel than in the other tissues. Heterologously expressed recombinant AiTTS1 produced tirucalla-7,24-dien-3β-ol as the sole product. Expression profile data, phylogeny with triterpene synthases from Meliaceae and Rutaceae families, real-time PCR of different tissues, and transient transformation revealed the involvement of tirucalla-7,24-dien-3β-ol synthase (AiTTS1) in limonoid biosynthesis. Further, mutagenesis studies of AiTTS1 indicated that Y125 and F260 are probably involved in stabilization of dammarenyl cation. A 2.6-fold increase in production of tirucalla-7,24-dien-3β-ol was observed when AiSQE1 was co-expressed with mutant AiTTS1 in a yeast system. Furthermore, we functionally characterized the highly expressed cytochrome P450 reductases and cycloartenol synthase. This study helps in further analysis and identification of genes involved in limonoid biosynthesis in Meliaceae/Rutaceae and their production in a metabolically tractable heterologous system.

Biological activities of limonoids in the Genus Khaya (Meliaceae): a review

Background

Limonoids are a class of highly oxygenated modified triterpenoids with a diverse range of biological activities. Although with restricted occurrence in the plant kingdom, these compounds are found extensively in the Meliaceae and Rutaceae families. Limonoids are of great interest in science given that the small number of plant families where they occur exhibit a broad range of medicinal properties that promote health and prevent disease.

Main text

The Meliaceae family includes the genus Khaya and comprises tree species that have been used in traditional medicine to treat several ailments. In recent years, the genus Khaya has attracted much research interest owing to the presence of limonoids in different plant parts of a few species that can serve as therapeutic molecules in the pharmaceutical industry. In this study, a literature search over the past two decades (2000–2020) was conducted on the biological activities of limonoids in the genus Khaya using different databases such as Google Scholar, PubMed, Scopus and ISI Web of Science. The taxonomy, geographical distribution and the various traditional uses of the genus are presented in detail. This study reveals that the currently documented biological activities of limonoids both in vivo and in vitro are limited to four species (K. anthotheca, K. grandifoliola, K. ivorensis and K. senegalensis) in the genus Khaya, and include anticancer, antimalarial, hepatoprotection, anti-inflammatory, neuroprotection, antimicrobial, antifungal and antifeedant. The most well-researched species, K. senegalensis, has the most notable biological activities and traditional uses in the genus Khaya.

Conclusion

The present detailed and up-to-date review of recent literature on the biological activities in the genus Khaya reveals the potentials of limonoids for drug development in managing several ailments.

Valorization and extraction optimization of Citrus seeds for food and functional food applications

Valorization of food byproducts has attracted recently considerable attention. Citrus fruits provide considerable non-edible residues reach 80% in juice production. They are considered agri-wastes to comprise peel, pulp and seeds. Previous investigations have focused on peel and pulp to recover value-added products. The review presents for the first-time phytochemical composition of Citrus seeds' products, i.e., oil and extracts. Fatty acids, phytosterols and tocopherols amounted as the major bioactives in Citrus seeds, in addition to limonoids, dietary fibers and flavonoids. Besides their nutritional values, these chemicals have promising applications including production of biodiesel, food enhancers and antioxidants, especially from mandarin and grapefruit seeds. Optimum conditions of the different Citrus seeds' valorization are discussed to improve extraction yield and lessen environmental hazards of solvent extraction. This review presents the best utilization practices for one of the largest cultivated fruit seeds worldwide and its different applications.

Limonoids and other triterpenoids from Entandrophragma angolense

Four new compounds (1-4) were isolated from the stem bark of Entandrophragma angolense along with eleven known structures (5-15). The chemical structures were elucidated on the basis of spectroscopic and HRMS data, and the absolute configuration was established with the aid of electronic circular dichroism. Compound 5 displayed moderate cytotoxicity against MDA-MB-231, OVCAR3, MDA-MB-435, and HT29 cell lines, with IC₅₀ values ranging from 2.0-5.9 μM.

Development of Potential Antitumor Agents from the Scaffolds of Plant-Derived Terpenoid Lactones

Naturally occurring terpenoid lactones and their synthetic derivatives have attracted increasing interest for their promising antitumor activity and potential utilization in the discovery and design of new antitumor agents. In the present perspective article, selected plant-derived five-membered γ-lactones and six-membered δ-lactones that occur with terpenoid scaffolds are reviewed, with their structures, cancer cell line cytotoxicity and in vivo antitumor activity, structure-activity relationships, mechanism of action, and the potential for developing cancer chemotherapeutic agents discussed in each case. The compounds presented include artemisinin (ART, 1), parthenolide (PTL, 2), thapsigargin (TPG, 3), andrographolide (AGL, 4), ginkgolide B (GKL B, 5), jolkinolide B (JKL B, 6), nagilactone E (NGL E, 7), triptolide (TPL, 8), bruceantin (BRC, 9), dichapetalin A (DCT A, 10), and limonin (LMN, 11), and their naturally occurring analogues and synthetic derivatives. It is hoped that this contribution will be supportive of the future development of additional efficacious anticancer agents derived from natural products.

Sudachinoid- and Ichangensin-Type Limonoids from Citrus junos Downregulate Pro-Inflammatory Cytokines

Limonoids, a dominant group of phytochemicals in the Rutaceae family, are known to exhibit several pharmacological activities. To identify natural products having efficacy against inflammatory bowel disease (IBD), we isolated 13 limonoids including a new compound, methyl sudachinoid A, from the seeds of Citrus junos and investigated their anti-inflammatory effects by assessing the expression of pro-inflammatory cytokines in lipopolysaccharide-stimulated RAW 264.7 mouse macrophages and HT-29 human colon epithelial cells. Our findings revealed that limonoids significantly downregulated the pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-α, and nuclear transcription factor κB. In particular, sudachinoid-type compounds, methyl sudachinoid A and sudachinoid B, and ichangensin-type compound, 1-O-methyichangensin downregulated the expression of pro-inflammatory cytokines more potently than other limonoids, nomilin and limonin, which have been previously reported to exhibit anti-inflammatory activities in other cells; nomilin and limonin were therefore employed as positive controls in this study. Herein, we reveal that the anti-inflammatory activities of limonoids including a new compound methyl sudachinoid A from C. junos were mediated via the downregulation of pro-inflammatory cytokines and these limonoids can be employed as potential therapeutic phytochemicals for IBD.

Impact of kinnow peel and nano-limonin on the performance and meat quality of commercial broilers

This study was taken up with the objective to assess the effect of limonin on the performance of commercial broilers and quality of meat. Day old chicks (200) were divided into 8 groups, each group contained 4 replicates of 6 chicks each in equal sex ratio. The iso-nitrogenous and iso-caloric diets were fed for 35 days, i.e. starter, grower and finisher phase. Kinnow peel powder (KPP) and solid lipid nanoparticles (SLN) of kinnow peel powder containing 7.47 mg limonin/g was added in the required quantity of feed to supply 0, 0.5, 1.0 and 1.5 mg limonin/bird/day. The data was analyzed using 2×4 factorial design. The data revealed that the birds fed diet supplemented with SLN consumed more feed in comparison to those fed diet supplemented with KPP, resulting in higher gain in weight, but without affecting feed conversion ratio (FCR). The digestibility of CP was lower and that of CF was higher when diet was supplemented with SLN in comparison to the one supplemented with KPP. As compared to control diet, limonin up to 1% level did not have any adverse effect on the digestibility of nutrients, but it was depressed beyond 1% level of limonin supplementation. The limonin beyond 1% depressed the dressing percentage. It was concluded that nano-formulations @ 1.0 mg/bird/d is an effective carrier of limonins, leading to improved growth, health characteristics in broilers and meat enriched with limonin.

Anti-androgenic, anti-oxidant and anti-apoptotic effects of the aqueous and methanol extracts of Pterorhachis zenkeri (Meliaceae): Evidence from in vivo and in vitro studies

The aim of this study was to evaluate the effects of Pterorhachis zenkeri (Meliaceae) on sex organ growth in immature male rats and, oxidative stress and apoptosis markers in CCL-97 (R2C) Leydig cells. For the in vivo studies, 70 immature male Wistar rats (n = 10/group) were treated for 2 or 4 weeks with: distilled water (10 ml/kg, per os) plus soya oil (1 ml/kg, sc), bicalutamide (10 mg/kg, per os), aqueous or methanol extract of P. zenkeri (10 mg/kg or 62 mg/kg, per os) or testosterone propionate (3 mg/kg, sc). After each treatment period, body and sexual organ weights, plasmatic testosterone, total proteins and total cholesterol levels were measured. In the in vitro test, the effects of the methanol extract of P. zenkeri on cell viability, apoptosis, reactive oxygen species (ROS) production, intracellular calcium release and caspases 3/9 were assessed using CCL-97 Leydig cells. Pterorhachis zenkeri extracts decreased sex organ weights, plasmatic testosterone and protein levels in rats. In the in vitro studies, P. zenkeri inhibited apoptosis, ROS production, calcium release and caspase 3/9 activities. These results suggest that P. zenkeri has anti-androgenic, anti-oxidant and anti-apoptotic activities with methanol extract being the most active and could be an effective alternative for the management of androgen-related diseases.

Fraxinellone: From pesticidal control to cancer treatment

Fraxinellone (FRA) is a degraded limonoid isolated from the root bark of Dictamnus plants. The potent insecticidal activity of FRA has led to the synthesis of numerous derivatives (presented here with the structure-activity relationships) active against the oriental armyworm Mythimna separata Walker. In addition to its pesticidal activity, the natural product displays potent anti-inflammatory and immuno-modulatory effects at the origin of hepatoprotective and anticancer properties. This mini-review provides an update of the mechanism of action of FRA to highlight the recently discovered capacity of the compound to deactivate cancer-associated fibroblasts and thus to limit the immunosuppressive tumor microenvironment. The anticancer mode of action of FRA raises new ideas to better understand its primary insecticidal activity. The relationship between drug-induced cancer cell death and insect cell death is discussed. A drug interaction with the insect cytokine growth-blocking peptide (GBP), a member of the large EGF family, is proposed, supported by preliminary molecular modeling data. Altogether, the review shed light on the pharmacological properties of fraxinellone as an antitumor agent and a natural insecticide.

Synthesis of Degraded Limonoid Analogs as New Antibacterial Scaffolds against Staphylococcus aureus

Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) have become serious infections in humans and ruminants. S. aureus strains are showing rapid changes to develop resistance in traditional antibiotic-containing systems. In the continuous fierce fight against the emergent multi-drug resistant bacterial strains, straightforward and scalable synthetic procedures to produce new active molecules are in demand. Analysis of molecular properties points to degraded limonoids as promising candidates. In this article, we report a simple synthetic approach to obtain degraded limonoid analogs as scaffolds for new antibacterial molecules. The minimum inhibitory concentrations against S. aureus were evaluated for the stereoisomer mixtures by the broth microdilution method. Analysis of results showed that the acetylated derivatives were the most active of them all.

A practical synthesis of amino limonin/deoxylimonin derivatives as effective mitigators against inflammation and nociception

A practical synthetic route, consisting of 5 steps, has been developed and applied successfully for converting limonin/deoxylimonin into the corresponding amino derivatives I- 5a-I- 5e and II- 5a-II- 5e. Deoxylimonin analogs II- 5a and II- 5b bearing an open A ring structure underwent ring closure reaction by employing the Mitsunobu procedure to afford II- 6a and II- 6b. All of the 12 newly synthesized compounds were subjected to preliminary screening for evaluating their inflammation and nociception inhibition efficacy. The most promising compounds, I- 5b and II- 5d, were selected for further investigation by a carrageenan-induced mouse paw edema model, both of which displayed a dose-response dependent manner and demonstrated superior anti inflammation capacity to that of indomethacin in the first 2 hours.

In-vivo biotransformation of citrus functional components and their effects on health

Citrus, one of the most popular fruits worldwide, contains various functional components, including flavonoids, dietary fibers (DFs), essential oils (EOs), synephrines, limonoids, and carotenoids. The functional components of citrus attract special attention due to their health-promoting effects. Food components undergo complex biotransformation by host itself and the gut microbiota after oral intake, which alters their bioaccessibility, bioavailability, and bioactivity in the host body. To better understand the health effects of citrus fruits, it is important to understand the in-vivo biotransformation of citrus functional components. We reviewed the biotransformation of citrus functional components (flavonoids, DFs, EOs, synephrines, limonoids, and carotenoids) in the body from their intake to excretion. In addition, we described the importance of biotransformation in terms of health effects. This review would facilitate mechanistic understanding of the health-promoting effect of citrus and its functional components, and also provide guidance for the development of health-promoting foods based on citrus and its functional components.

Synthesis of Limonin Derivatives with Improved Anti-inflammatory and Analgesic Properties

Background:

Limonoids represent an important class of natural products which possess a broad range of biological activities. Albeit their enormous potentials as therapeutic candidates, they usually suffer from low bioavailability, poor aqueous solubility and relatively weak biological activities which result in significant challenges in the clinic applications. Therefore, the exploration and development of novel limonin derivatives with improved drug-like properties through the structural modifications recently have attracted great attention in the biological and medicinal chemistry field.

Methods:

Based on the structural modifications of C17-furan ring in limonin, a series of limonin derivatives was designed, synthesized and screened for their anti-inflammatory and analgesic activities in vivo.

Results and Conclusion:

Preliminary pharmacological studies revealed that most tested compounds exhibited more potent anti-inflammatory and analgesic efficacies than lead molecule limonin. Especially, for compound 3f, it exhibited a stronger anti-inflammatory effect than that of naproxen and comparable analgesic potency with aspirin. In the formalin test, 3f showed an obviously attenuated phase-II pain response which indicated that it may produce an anti-inflammatory effect in the periphery. Furthermore, the significantly low hERG inhibition (IC50 >100 μM) and high LD50 value of target molecule 3f further demonstrated it as a promising analgesic/anti-inflammatory candidate with excellent drug-like profiles.

Processing and Polyherbal Formulation of Tetradium ruticarpum (A. Juss.) Hartley: Phytochemistry, Pharmacokinetics, and Toxicity

Herbal medicine is a major part of traditional Chinese medicine (TCM), which is evolved as a system of medical practice from ancient China. The use of herbal medicine is mainly based on practice and theories and concepts rooted in ancient philosophy. In the era of evidence-based medicine, it is essential to accurately evaluate herbal remedy with standard/modern medical practice approaches. Tetradium ruticarpum (A. Juss.) Hartley (TR), a medicinal plant with diversify bioactive components, has been broadly used to treat pain and gastrointestinal disorders in TCM. However, TR has also been reported to have potential toxicity by long-term use or excessive doses, though the associated compounds are yet to be identified. TR is usually processed, and/or combined with other herbs in TCM formulas in order to achieve a synergistic effect or reduce its toxicity. Since processing or polyherbal formulation of TR may lead to changes in its chemical composition and contents, quality, efficacy and toxicity, comparison of TR samples before and after processing, as well as its combination with other medicines, would provide useful knowledge of bioactive compounds, efficacy and toxicity of this valuable medicinal plant. Here we reviewed the recent studies about the phytochemistry, pharmacokinetic behaviors and toxicity of TR under various processing or polyherbal formulation conditions, which would expand our understanding of mechanisms of TR's efficacy and toxicity and be valuable for quality control in industrial manufacturing, future medicinal research, and safety and rational use of TR in TCM.