Discovery and development of natural product-derived chemotherapeutic agents based on a medicinal chemistry approach

Combating anoikis resistance: bioactive compounds transforming prostate cancer therapy

The study aims to discuss the challenges associated with treating prostate cancer (PCa), which is known for its complexity and drug resistance. It attempts to find differentially expressed genes (DEGs), such as those linked to anoikis resistance and circulating tumor cells, in PCa samples. This study involves analyzing the functional roles of these DEGs using gene enrichment analysis, and then screening of 102 bioactive compounds to identify a combination that can control the expression of the identified DEGs. In this study, 53 DEGs were identified from PCa samples including anoikis-resistant PCa cells and circulating tumor cells in PCa. Gene enrichment analysis with regards to functional enrichment of DEGs was performed. An inclusive screening process was carried out among 102 bioactive compounds to identify a combination capable of affecting and regulating the expression of selected DEGs. Eventually, gastrodin, nitidine chloride, chenodeoxycholic acid, and bilobalide were selected, as their combination demonstrated ability to modulate expression of 50 out of the 53 genes targeted. The subsequent analysis focused on investigating the biological pathways and processes influenced by this combination. The findings revealed a multifaceted and multidimensional approach to tumor regression. The combination of bioactive compounds exhibited effects on various genes including those related to production of inflammatory cytokines, cell proliferation, autophagy, apoptosis, angiogenesis, and metastasis. The current study has made a valuable contribution to the development of a combination of bioactive natural compounds that can significantly impede the development of treatment resistance in prostate tumor while countering the tumors' evasion of the immune system. The implications of this study are highly significant as it suggests the creation of an enhanced immunotherapeutic, natural therapeutic concoction with combinatorial potential.

Computational and experimental approaches manifest the leishmanicidal potential of α-mangostin resourced from Garcinia cowa

Owing to the persistent number of parasitic deaths, Visceral leishmaniasis continues to haunt several economically weaker sections of India. The disease causes over 30,000 deaths and threatens millions annually on a global scale. The standard pentavalent antimonials, on the other hand, are associated with health adversities and disease relapse. The current study is focused on the search for the most potential natural bioactive phytocompound from the bark extract of the Northeastern Indian plant, Garcinia cowa, that shows potent anti-leishmanial properties. The High Resonance Liquid Chromatography followed by Mass Spectrometry (HR-LCMS) study followed by an in silico molecular docking using computational tools revealed that α-mangostin might potentially possess antiparasitic activity. To validate the anti-leishmanial efficacy of the compound, a cell viability assay was performed, which demonstrated the parasite-specific inhibitory activity of α-mangostin; with IC50 values ranging from 4.95 - 7.37 µM against the different forms of Leishmania donovani parasite. The flow cytometric analysis of the phytocompound treated parasites indicated an oxidative and nitrosative stress-mediated apoptotic cell death in the parasites, by the suggestive surge in nuclear fragmentation and mitochondrial dysfunction. Simultaneously, a cytokine profiling study suggested approximate two-to-three-fold upregulated levels of pro-inflammatory cytokines post-compound treatment, which is predicted to actively contribute to parasite-killing. α-mangostin was also found to reduce the chances of parasite survival by inhibiting arginase enzyme activity, which in favorable conditions facilitates its sustenance. This study thereby substantiates that α-mangostin significantly possesses anti-leishmanial potentiality that can be developed into a cure for this infectious disease.

The role of current synthetic and possible plant and marine phytochemical compounds in the treatment of acne

Acne is a long-standing skin condition characterized by plugged hair follicles due to the accumulation of dead skin cells, sebum, and Propionibacterium acnes (P. acnes) bacteria, causing inflammation, and the formation of pimples or lesions. Acne was recognized in the ancient times by the ancient Egyptians, Greeks, and Romans. Since ancient times, folk medicine from different cultures have comprised herbal and natural products for the treatment of acne. Current acne medications include antibiotics, keratolytics, corticosteroids, in addition to hormonal therapy for women. However, these conventional drugs can cause some serious side effects. And therefore, seeking new safe treatment options from natural sources is essential. Plants can be a potential source of medicinal phytochemicals which can be pharmacologically active as antibacterial, antioxidant, anti-inflammatory, keratolytic and sebum-reducing. Organic acids, obtained from natural sources, are commonly used as keratolytics in dermatology and cosmetology. Most of the promising phytochemicals in acne treatment belong to terpenes, terpenoids, flavonoids, alkaloids, phenolic compounds, saponins, tannins, and essential oils. These can be extracted from leaves, bark, roots, rhizomes, seeds, and fruits of plants and may be incorporated in different dosage forms to facilitate their penetration through the skin. Additionally, medicinal compounds from marine sources can also contribute to acne treatment. This review will discuss the pathogenesis, types and consequences of acne, side effects of conventional treatment, current possible treatment options from natural sources obtained from research and folk medicine and possible applied dosage forms.

Discovery, biosynthesis, organic synthesis, and bioactivities of meroterpenoids from Rhododendron species

Meroterpenoids discovered in Rhododendrons species possess unique chemical structures and biological activities and are expected to become new drug targets for Alzheimer's disease, metabolic disorders, and chronic kidney disease, and these compounds have attracted increasing attention in recent years. In this study, Rhododendron meroterpenoids and their structures, classifications, racemate distribution, biosynthetic pathways, chemical synthesis, and bioactivities are reviewed prior to 2023.

Inhibiting the Aggregation of Aβ by Natural Product Molecules

The abnormal aggregation of Aβ has been considered one of the primary causative factors for Alzheimer's disease. Diverse molecular entities have been developed to mitigate the formation of toxic Aβ aggregates within the brain by inhibiting Aβ aggregation. Recognizing that many FDA-approved drugs are derived from natural products, we present a summary of recent discoveries involving natural product molecules with inhibitory effects on Aβ aggregation. By consolidating these findings, our review offers researchers a concise overview of the latest advancements in natural product-based interventions for Alzheimer's disease.

Phytochemical profiling, antioxidant, cytotoxic, and anti-inflammatory activities of Plectranthus rugosus extract and fractions: in vitro, in vivo, and in silico approaches

BACKGROUND

Inflammation is a key biological reaction that comprises a complex network of signals that both initiate and stop the inflammation process.

PURPOSE

This study targets to evaluate the anti-inflammatory potential of the leaves of the Plectranthus rugosus (P. rugosus) plant involving both in vitro and in vivo measures. The current available drugs exhibit serious side effects. Traditional medicines impart an essential role in drug development. P. rugosus is a plant used in traditional medicine of Tropical Africa, China, and Australia to treat various diseases.

METHODS

Lipopolysaccharide (LPS), an endotoxin, kindles macrophages to discharge huge quantities of pro-inflammatory cytokines like TNF-α and IL-6. So, clampdown of macrophage stimulation may have a beneficial potential to treat various inflammatory disorders. The leaves of the P. rugosus are used for swelling purpose by local population; however, its use as an anti-inflammatory agent and associated disorders has no scientific evidence.

RESULTS

The extracts of the plant Plectranthus rugosus ethanolic extract (PREE), Plectranthus rugosus ethyl acetate extract (PREAF), and the compound isolated (oleanolic acid) suppress the pro-inflammatory cytokines (IL-6 and TNF-α) and nitric oxide (NO), confirming its importance in traditional medicine.

CONCLUSION

The pro-inflammatory cytokines are inhibited by P. rugosus extracts, as well as an isolated compound oleanolic acid without compromising cell viability.

Rheological and Biological Properties of Adhesive Skin Secretions from Eupsophus vertebralis (Anura: Alsodidae)

Skin secretions from Patagonian ground frogs, Eupsophus vertebralis, have previously been reported as a potent proteinaceous adhesive with potential biomedical applications. Here, we conducted a rheological analysis indicating the mechanical robustness of these secretions, with a storage modulus ranging from 1 to 10 Pa. In addition, antimicrobial and cytotoxicity assays were performed, revealing no antimicrobial activity against both the Gram-positive and Gram-negative bacteria. The cytotoxicity results were intriguing, as three samples showed no harm, and one exhibited a severe cytotoxic effect on the human cell line MG63. These properties, as indicated by these preliminary results, reinforce their potential for practical applications in the industrial and medical sectors.

Antiviral potency of lupane and oleanane alkynyl-derivatives against human cytomegalovirus and papillomavirus

A library of 18 structurally diverse semisynthetic lupane, oleanane, and ursane types triterpenoids, including C19- or C28-(1,2,3-triazolyl)- and aminomethylated derivatives obtained by the «click» reaction with various aromatic and sugar azides or by Mannich reaction with secondary amines, were tested for antiviral activity against HCMV, HSV-1, and HPV-11 types. C28-Triazolyl-derivative with a benzyl substituent of 2,3-indolo-oleanolic acid was the most active against the HCMV virus with EC50 < 0.05 (SI > 81). Lupane 3,28-diacetoxy-triazolyl derivatives with phenyl- and fluorophenyl-fragments possess the highest activity among all screened compounds toward HPV-11 type virus with EC50 values of 2.97 µM and 1.20 μM, SI90 values of 28 and >125, respectively. One can see that modification of triterpenic alkynes to Mannich bases was more efficient in increasing an activity against HSV-1 than their conversion to triazoles.

Molecular docking analysis of triterpenoids from Cassia fistula with breast cancer targets

Breast cancer is a well-known complex disease. The availability of different screening approaches and booming phytochemical drug synthesis can contribute towards breast cancer treatment. Hence, we document the molecular docking analysis of triterpenoids from Cassia fistula with breast cancer targets.

Selected Plant Triterpenoids and Their Derivatives as Antiviral Agents

The results of the most recent investigation of triterpenoid-based antiviral agents namely in the HIV-1 and HSV-1 treatment were reviewed and summarized. Several key historical achievements are included to stress consequences and continuity in this research. Most of the agents studied belong to a series of compounds derived from betulin or betulinic acid, and their synthetic derivative is called bevirimat. A termination of clinical trials of bevirimat in Phase IIb initiated a search for more successful compounds partly derived from bevirimat or designed independently of bevirimat structure. Surprisingly, a majority of bevirimat mimics are derivatives of betulinic acid, while other plant triterpenoids, such as ursolic acid, oleanolic acid, glycyrrhetinic acid, or other miscellaneous triterpenoids, are relatively rarely involved in a search for a novel antiviral agent. Therefore, this review article is divided into three parts based on the leading triterpenoid core structure.

Discovering the anti-cancer phytochemical rutin against breast cancer through the methodical platform based on traditional medicinal knowledge

A number of therapeutic drugs have been developed from functional chemicals found in plants. Knowledge of plants used for medicinal purposes has historically been transmitted by word of mouth or through literature. The aim of the present study is to provide a systemic platform for the development of lead compounds against breast cancer based on a traditional medical text. To verify our systematic approach, integrating processes consisted of text mining of traditional medical texts, 3-D virtual docking screening, and in vitro and in vivo experimental validations were demonstrated. Our text analysis system identified rutin as a specific phytochemical traditionally used for cancer treatment. 3-D virtual screening predicted that rutin could block EGFR signaling. Thus, we validated significant anticancer effects of rutin against breast cancer cells through blockade of EGFR signaling pathway in vitro. We also demonstrated in vivo anti-cancer effects of rutin using the breast cancer recurrence in vivo models. In summary, our innovative approach might be proper for discovering new phytochemical lead compounds designing for blockade of malignant neoplasm including breast cancer. [BMB Reports 2023; 56(11): 594-599].

Artemisia brevifolia Wall. Ex DC Enhances Cefixime Susceptibility by Reforming Antimicrobial Resistance

(1) Background: A possible solution to antimicrobial resistance (AMR) is synergism with plants like Artemisia brevifolia Wall. ex DC. (2) Methods: Phytochemical quantification of extracts (n-hexane (NH), ethyl acetate (EA), methanol (M), and aqueous (Aq)) was performed using RP-HPLC and chromogenic assays. Extracts were screened against resistant clinical isolates via disc diffusion, broth dilution, the checkerboard method, time-kill, and protein quantification assays. (3) Results: M extract had the maximum phenolic (15.98 ± 0.1 μg GAE/mgE) and flavonoid contents (9.93 ± 0.5 μg QE/mgE). RP-HPLC displayed the maximum polyphenols in the M extract. Secondary metabolite determination showed M extract to have the highest glycosides, alkaloids, and tannins. Preliminary resistance profiling indicated that selected isolates were resistant to cefixime (MIC 20-40 µg/mL). Extracts showed moderate antibacterial activity (MIC 60-100 µg/mL). The checkerboard method revealed a total synergy between EA extract and cefixime with 10-fold reductions in cefixime dose against resistant P. aeruginosa and MRSA. Moreover, A. brevifolia extracts potentiated the antibacterial effect of cefixime after 6 and 9 h. The synergistic combination was non- to slightly hemolytic and could inhibit bacterial protein in addition to cefixime disrupting the cell wall, thus making it difficult for bacteria to survive. (4) Conclusion: A. brevifolia in combination with cefixime has the potential to inhibit AMR.

Investigation of the Membrane Localization and Interaction of Selected Flavonoids by NMR and FTIR Spectroscopy

In this report, we discuss the effects of undescribed flavone derivatives, HZ4 and SP9, newly isolated from the aerial parts of Hottonia palustris L. and Scleranthus perennis L. on membranes. Interaction of flavonoids with lipid bilayers is important for medicinal applications. The experiments were performed with FTIR and NMR techniques on liposomes prepared from DPPC (dipalmitoylphosphatidylcholine) and EYPC (egg yolk phosphatidylcholine). The data showed that the examined polyphenols incorporate into the polar head group region of DPPC phospholipids at both 25 °C and 45 °C. At the lower temperature, a slight effect in the spectral region of the ester carbonyl group is observed. In contrast, at 45 °C, both compounds bring about the changes in the spectral regions attributed to antisymmetric and symmetric stretching vibrations of CH2 and CH3 moieties. Similarly, as in DPPC lipids, the tested compounds interact with the fingerprint region of the polar head groups of the EYPC lipids and cause its reorganization. The outcomes obtained by NMR analyses confirmed the localization of both flavonoids in the polar heads zone. Unraveled effects of HZ4 and SP9 in respect to lipid bilayers can partly determine their biological activities and are crucial for their usability in medicine as disease-preventing phytochemicals.

New Natural Eugenol Derivatives as Antiproliferative Agents: Synthesis, Biological Evaluation, and Computational Studies

Semisynthetic modifications of natural products have bestowed us with many anticancer drugs. In the present work, a natural product, eugenol, has been modified synthetically to generate new anticancer agents. The final compounds were structurally confirmed by NMR, IR, and mass techniques. From the cytotoxicity results, compound 17 bearing morpholine was found to be the most active cytotoxic agent with IC₅₀ 1.71 (MCF-7), 1.84 (SKOV3), and 1.1 μM (PC-3) and a thymidylate synthase (TS) inhibitor with an IC₅₀ of 0.81 μM. Further cellular studies showed that compound 17 could induce apoptosis and arrest the cell cycle at the S phase in PC-3 carcinoma. The docking study strongly favors compound 17 to be a TS inhibitor as it displayed a similar interaction to 5-fluorouracil. The in silico pharmacokinetics and DFT computational studies support the results obtained from docking and biological evaluation and displayed favorable pharmacokinetic profile for a drug to be orally available. Compound 17 was found to be a promising TS inhibitor which could suppress DNA synthesis and consequently DNA damage in prostate cancer cells.

Synthesis and Cytotoxicity Evaluation of Betulin Cycloolefin Derivatives by Ruthenium-Catalyzed Ring-Closing Metathesis

The combination of ring-closing metathesis with betulin enables the design and synthesis of novel biomolecules representing a library of triterpenoid derivatives for potential pharmacological research. In this work, cyclic olefin betulin derivatives were attempted to be prepared by the combination of ring-closing metathesis with betulin. Dicyclohexyl carbodiimide coupling reaction allowed the transformation of betulin into two types of linear olefin derivatives that have different methylene spacer lengths between the olefin and ester groups. Subsequently, betulin-based cycloolefins were synthesized by ring-closing metathesis using Grubbs first-generation catalyst. The influence of different parameters including solvents, temperature, catalysts, and catalyst loading on ring-closing metathesis was investigated. Cytotoxicity results indicated that these betulin-based olefin derivatives, derived from renewable bioresources, have potential applications in the biomedical field.

Design, synthesis and biological evaluation of new eugenol derivatives containing 1,3,4-oxadiazole as novel inhibitors of thymidylate synthase

We report the preparation and cytotoxicity of two new eugenol derivatives that contain 1,3,4-oxadiazole, as novel inhibitors of thymidylate synthase; these derivatives are shown to be promising chemotherapeutic agents.

Design, Synthesis, and Antiproliferative Activity of Novel Neocryptolepine-Rhodanine Hybrids

A series of novel neocryptolepine-rhodanine hybrids (9a,b, 11a-d, 14, and 16a,b) have been synthesized by combining neocryptolepine core 5 modified at the C-11 position with rhodanine condensed with the appropriate aryl/hetero aryl aldehydes. Based on these findings, the structures of the hybrids were confirmed by spectral analyses. By employing the MTT assay, all hybrids were tested for their in vitro antiproliferative activity against two cancer cell lines, including MDA-MB-231 (human breast) and HepG-2 (hepatocellular carcinoma). Interestingly, the IC50 values of all hybrids except 9b and 11c showed activity comparable to the standard anticancer drug, 5-fluorouracil, against HepG-2 cancer cells. Furthermore, the cytotoxicity of all the synthesized hybrids was investigated on a normal skin human cell line (BJ-1), and the results showed that these compounds had no significant cytotoxicity toward these healthy cells at the highest concentration used in this study. This study also indicated that the active hybrids exert their cytotoxic activity via the induction of apoptosis. A molecular docking study was used to shed light on the molecular mechanism of their anticancer activity. The docking results revealed that the hybrids exert their mode of action through DNA intercalation. Furthermore, in silico assessment for pharmacokinetic properties was performed on the most potent compounds, which revealed candidates with good bioavailability, high tolerability with cell membranes, and positive drug-likeness values.

Synthesis and Biological Evaluation of Steviol Derivatives with Improved Cytotoxic Activity and Selectivity

Steviol is an ent-kaurene diterpenoid with interesting pharmacological activity. Several steviol derivatives with an exo-methylene cyclopentanone unit were discovered as potent antitumor agents. However, their poor selectivity for tumor cells relative to normal cells reduces their prospects as potential anticancer drugs. In this study, based on previous work, 32 steviol derivatives, including 28 new analogues, were synthesized. Their cytotoxicity against tumor cells and normal cells was evaluated. Several new derivatives, such as 7a, 7h, and 8f, with improved cytotoxic selectivity and antiproliferative activity were obtained, and the structure-activity relationship correlations were investigated. The new compound 8f displayed potent antiproliferative activity against Huh7 cells (IC₅₀ = 2.6 μM) and very weak cytotoxicity against the corresponding normal cells HHL5 (IC₅₀ = 97.0 μM). Further investigation showed that 8f arrested the cell cycle at the G0/G1 phase and caused reactive oxygen species overproduction, decreased mitochondrial membrane potential, and induced apoptosis of Huh7 cells through inhibition of the PI3K/Akt/mTOR and NF-κB pathway as well as upregulation of Bax/Bcl-2 ratio. The present study suggested that 8f is a promising lead compound for new cancer therapies, and the results presented herein may encourage the further modification of steviol for additional derivatives with enhanced efficacy and selectivity.

Synthesis of ring-A serjanic acid derivatives and their cytotoxic evaluation through the brine shrimp lethality assay (BSLA)

Sixteen serjanic acid derivatives were synthesized by modification of the A-ring of the triterpenoid skeleta. Fischer indolization of intermediate 2 with the requisite aromatic hydrazines afforded the indolo-triterpenes 8–13. Also, reaction of 2 with hydroxylamine hydrochloride in pyridine provided the desired C-3 oxime 14, while pyrazine 15 was obtained by condensation of 2 in the presence of ethylenediamine and sulphur in morpholine. Finally, the Claisen-Schmidt condensation of intermediate 2 with corresponding substituted benzaldehydes 16–23, afforded benzylidine ketones 24–31. All compounds were elucidated on the basis of NMR and HR-MS spectroscopic data and evaluated for their in-vitro cytotoxicity to the Brine Shrimp Lethality Assay (BSLA). As a result, the compounds exhibited medium to good cytotoxic potential and this activity was as high as eight times that of serjanic acid (1) on the tested zoophytes.

Combined de novo transcriptomic and physiological analyses reveal RyALS3-mediated aluminum tolerance in Rhododendron yunnanense Franch

Rhododendron (Ericaceae) not only has ornamental value, but also has great medicinal and edible values. Many Rhododendron species are native to acid soils where aluminum (Al) toxicity limits plant productivity and species distribution. However, it remains unknown how Rhododendron adapts to acid soils. Here, we investigated the physiological and molecular mechanisms of Al tolerance in Rhododendron yunnanense Franch. We found that the shoots of R. yunnanense Franch did not accumulate Al after exposure of seedlings to 50 μM Al for 7 days but predominantly accumulated in roots, suggesting that root Al immobilization contributes to its high Al tolerance. Whole-genome de novo transcriptome analysis was carried out for R. yunnanense Franch root apex in response to 6 h of 50 μM Al stress. A total of 443,639 unigenes were identified, among which 1,354 and 3,413 were up- and down-regulated, respectively, by 6 h of 50 μM Al treatment. Both Gene Ontology (GO) enrichment and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses revealed that genes involved in "ribosome" and "cytoskeleton" are overrepresented. Additionally, we identified Al-tolerance homologous genes including a tonoplast-localized ABC transporter RyALS3; 1. Overexpression of RyALS3; 1 in tobacco plants confers transgenic plants higher Al tolerance. However, root Al content was not different between wild-type plants and transgenic plants, suggesting that RyALS3; 1 is responsible for Al compartmentalization within vacuoles. Taken together, integrative transcriptome, physiological, and molecular analyses revealed that high Al tolerance in R. yunnanense Franch is associated with ALS3; 1-mediated Al immobilization in roots.

Synthesis of 6-Halo-Substituted Pericosine A and an Evaluation of Their Antitumor and Antiglycosidase Activities

The enantiomers of 6-fluoro-, 6-bromo-, and 6-iodopericosine A were synthesized. An efficient synthesis of both enantiomers of pericoxide via 6-bromopericosine A was also developed. These 6-halo-substituted pericosine A derivatives were evaluated in terms of their antitumor activity against three types of tumor cells (p388, L1210, and HL-60) and glycosidase inhibitory activity. The bromo- and iodo-congeners exhibited moderate antitumor activity similar to pericosine A against the three types of tumor cell lines studied. The fluorinated compound was less active than the others, including pericosine A. In the antitumor assay, no significant difference in potency between the enantiomers was observed for any of the halogenated compounds. Meanwhile, the (−)-6-fluoro- and (−)-6-bromo-congeners inhibited α-glucosidase to a greater extent than those of their corresponding (+)-enantiomers, whereas (+)-iodopericosine A showed increased activity when compared to its (−)-enantiomer.

An Insight into Anticancer Effect of Propolis and Its Constituents: A Review of Molecular Mechanisms

Propolis is a natural compound collected by honeybees from different parts of plants. Honeybees produce a sticky component besides honey by mixing the tree resin and other botanical sources with saliva called propolis or bee glue. Propolis was traditionally used as a wound healing substance, cosmetic, medicine, and many other conditions. Till now, there is no definite curable treatment for most cancers and chemotherapeutic drugs and drugs used for targeted therapies have serious side effects. According to a recent research, natural products are becoming increasingly essential in cancer prevention. Natural products are a great source of potential therapeutic agents, especially in the treatment of cancer. Previous studies have reported that the presence of caffeic acid phenethyl ester (CAPE), artepillin C, and chrysin is responsible for the anticancer potential of propolis. Most of the previous studies suggested that propolis and its active compounds inhibit cancer progression by targeting multiple signaling pathways including phosphoinositide 3-kinases (PI3K)/Akt and mitogen-activated protein kinase (MAPK) signaling molecules, and induce cell cycle arrest. Induction of apoptosis by propolis is mediated through extrinsic and intrinsic apoptotic pathways. The aim of this review is to highlight and summarize the molecular targets and anticancer potential of propolis and its active compounds on cell survival, proliferation, metastasis, and apoptosis in cancer cells.

Anticancer Activity of Natural and Semi-Synthetic Drimane and Coloratane Sesquiterpenoids

Drimane and coloratane sesquiterpenoids are present in several plants, microorganisms, and marine life. Because of their cytotoxic activity, these sesquiterpenoids have received increasing attention as a source for new anticancer drugs and pharmacophores. Natural drimanes and coloratanes, as well as their semi-synthetic derivatives, showed promising results against cancer cell lines with in vitro activities in the low micro- and nanomolar range. Despite their high potential as novel anticancer agents, the mode of action and structure–activity relationships of drimanes and coloratanes have not been completely enlightened nor systematically reviewed. Our review aims to give an overview of known structures and derivatizations of this class of sesquiterpenoids, as well as their activity against cancer cells and potential modes-of-action. The cytotoxic activities of about 40 natural and 25 semi-synthetic drimanes and coloratanes are discussed. In addition to that, we give a summary about the clinical significance of drimane and coloratane sesquiterpenoids.

Design, synthesis, anticancer activity and mechanism studies of novel 2-amino-4-aryl-pyrimidine derivatives of ursolic acid

A series of novel 2-amino-4-aryl-pyrimidine derivatives of ursolic acid were designed, synthesized, and evaluated for their anticancer activities against four cancer cell lines (MCF-7, HeLa, HepG2, and A549) and a human hepatocyte cell line (LO2) via MTT assay.

Preservation of HIV-1 Gag Helical Bundle Symmetry by Bevirimat Is Central to Maturation Inhibition

The assembly and maturation of human immunodeficiency virus type 1 (HIV-1) require proteolytic cleavage of the Gag polyprotein. The rate-limiting step resides at the junction between the capsid protein CA and spacer peptide 1, which assembles as a six-helix bundle (6HB). Bevirimat (BVM), the first-in-class maturation inhibitor drug, targets the 6HB and impedes proteolytic cleavage, yet the molecular mechanisms of its activity, and relatedly, the escape mechanisms of mutant viruses, remain unclear. Here, we employed extensive molecular dynamics (MD) simulations and free energy calculations to quantitatively investigate molecular structure-activity relationships, comparing wild-type and mutant viruses in the presence and absence of BVM and inositol hexakisphosphate (IP6), an assembly cofactor. Our analysis shows that the efficacy of BVM is directly correlated with preservation of 6-fold symmetry in the 6HB, which exists as an ensemble of structural states. We identified two primary escape mechanisms, and both lead to loss of symmetry, thereby facilitating helix uncoiling to aid access of protease. Our findings also highlight specific interactions that can be targeted for improved inhibitor activity and support the use of MD simulations for future inhibitor design.

Therapeutic indications, chemical composition and biological activity of native Brazilian species from Psidium genus (Myrtaceae): A review

ETHNOPHARMACOLOGICAL IMPORTANCE

Brazilian medicinal species of the Psidium genus are rich in secondary metabolites such as terpenes and phenolic compounds and present biological activities for several human diseases. For the native Psidium species, there are no specific research reports for any member of the genus about ethnobotanical research, hindering the joint analysis of its therapeutic indications together with the scientific evidence already investigated.

STUDY OBJECTIVE

Analyze the therapeutic indications, the main chemical constituents, and the biological activities of native species of the Psidium to Brazil.

MATERIALS AND METHODS

Systematic research was carried out in the Scopus, ScienceDirect, PubMed, and Web of Science databases over a period of ten years. Articles in English, Portuguese and Spanish were used. The research was divided into three phases, seeking information on ethnobotany, chemical composition and biological activities. The words were combined to structure the descriptors used in the search.

RESULTS

A total of 13 native species belonging to the Psidium genus were identified in this analysis, Psidium acutangulum DC., Psidium brownianum Mart. ex DC., Psidium cattleyanum Sabine, Psidium densicomum Mart. ex DC., Psidium grandifolium Mart. ex DC., Psidium guineense Sw., Psidium laruotteanum Cambess., Psidium myrsinites DC, Psidium myrtoides O. Berg, Psidium salutare (Kunth) O. Berg, Psidium schenckianum Kiaersk., Psidium sobralianum Proença & Landrum, Psidium striatulum Mart. ex DC. Of these, six were indicated in folk medicine, digestive system disorders being their main therapeutic indication. Most species presented an investigation of chemical composition and biological activity. They are rich in phenolic compounds, flavonoids, and terpenes and have antimicrobial, antioxidant, antiproliferative, and repellent activities.

CONCLUSIONS

Native species of the Psidium genus are important sources of active ingredients in combating adversities that affect the human health, especially regarding the digestive system. They have a rich chemical composition, responsible for the biological activities demonstrated for the species.

Total saponins from Tupistra chinensis baker inhibits growth of human gastric cancer cells in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Tupistra chinensis Baker (syn. Rohdea chinensis), an antitumor folk herb mainly distributed in China, its rhizome has been historically used to treat gastric cancer. Studies showed that the steroidal saponins were the main bioactive components in the rhizome of T. chinensis. Our previous studies have confirmed that the steroidal saponins have a variety of anti-tumor activities. However, the underlying anti-tumor mechanism of the total steroidal saponins of T. chinensis (TCS) remains to be revealed.

AIM OF THE STUDY

In the present study, we studied the potential anti-proliferative activity and anti-tumor mechanism of TCS on gastric cancer in vitro and in vivo.

METHODS

In vitro, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to detect the proliferation ability of TCS on SGC-7901 cells and AGS cells. Flow cytometry were performed to analyze cell apoptosis, cell cycle, mitochondrial membrane potential and reactive oxygen species expression level. Western blotting was performed to validate the expression of proteins in related pathways. In vivo, a xenograft model was established by injecting SGC-7901 cells into nude mice.

RESULTS

In vitro, TCS inhibited the proliferation of gastric cancer cells. TCS effectively induced apoptosis by PI3K/Akt/mTOR signaling pathway in SGC-7901 cells, and promoted apoptosis via p53-mediated pathway in AGS cells. TCS also exhibited inhibitory activity in blocking the migration of gastric cancer cells. In vivo, TCS significantly inhibited the growth of xenograft tumor.

CONCLUSION

These results indicated that TCS exhibited significant anti-gastric cancer effects in vitro and in vivo.

Glycyrrhetinic acid: a promising scaffold for the discovery of anticancer agents

INTRODUCTION

Oleanane-type pentacyclic triterpenes named glycyrrhetinic acids (GAs) featuring a C-30 carboxylic acid group, are extracted from the licorice (Glycyrrhiza uralensis). Numerous biological properties of GA have been reported and have attracted researchers from all over the world in recent years due to the peculiar GA scaffold-based semisynthetic cytotoxic effects.

AREAS COVERED

This review represents the applications of semisynthetic derivatives of GA for the development of future cancer treatments. Included in the review are important structural features of the semisynthetic GAs crucial for cytotoxic effects.

EXPERT OPINION

Numerous semisynthetic GA derivatives illustrated excellent cytotoxic effects toward various cancer cells. Notably the C-₃(OH) at ring A along with C_30-CO₂H at ring E as vital structural features, make GA very appealing as a lead scaffold for medicinal chemistry, since these two groups permit the creation of further chemical diversity geared toward improved cytotoxic effects. Furthermore, numerous GA derivatives have been synthesized and indicate that compounds featuring cyanoenone moieties in ring A, or compounds having the amino group or nitrogen comprising heterocycles and hybrids thereof, illustrate more potent cytotoxicity. Furthermore, GA has a great capability to be conjugated with other anticancer molecules to synergistically enhance their combined cytotoxicity.

Discovery of 8,9-seco-ent-Kaurane Diterpenoids as Potential Leads for the Treatment of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a lethal malignancy without safe and effective therapeutic drugs. In this study, the anti-TNBC bioassay-guided isolation of the medicinal plant Croton kongensis followed by the structural modification led to the construction of a small ent-kaurane diterpenoid library (1-25). With subsequent biological screening, 20 highly potent compounds (IC₅₀s < 3 μM) were identified. Among them, 8,9-seco-ent-kaurane 6 displayed comparable activity (IC₅₀s ∼ 80 nM) to doxorubicin but with better selectivity. The analysis of structure-activity relationships suggested that the cleavage of the C8-C9 bond and the presence of α,β-unsaturated ketone moiety were essential for the activity. The mechanistic study revealed that 6 induced apoptosis, autophagy, and metastasis suppression in TNBC cells via inhibition of Akt. In vivo, 6 significantly suppressed the TNBC tumor growth without causing side effects. All these results suggested that 6 may serve as a promising lead for the development of novel anti-TNBC agents in the future.

Synthesis and Evaluation of the Tetracyclic Ring-System of Isocryptolepine and Regioiso-Mers for Antimalarial, Antiproliferative and Antimicrobial Activities

A series of novel quinoline-based tetracyclic ring-systems were synthesized and evaluated in vitro for their antiplasmodial, antiproliferative and antimicrobial activities. The novel hydroiodide salts 10 and 21 showed the most promising antiplasmodial inhibition, with compound 10 displaying higher selectivity than the employed standards. The antiproliferative assay revealed novel pyridophenanthridine 4b to be significantly more active against human prostate cancer (IC₅₀ = 24 nM) than Puromycin (IC₅₀ = 270 nM) and Doxorubicin (IC₅₀ = 830 nM), which are used for clinical treatment. Pyridocarbazoles 9 was also moderately effective against all the employed cancer cell lines and moreover showed excellent biofilm inhibition (9a: MBIC = 100 µM; 9b: MBIC = 100 µM).

Design, synthesis, and structure activity relationship analysis of new betulinic acid derivatives as potent HIV inhibitors

Prior modification of betulinic acid (1), a natural product lead with promising anti-HIV activity, produced 3-O-(3',3'-dimethylsuccinyl)betulinic acid (bevirimat, 3), the first-in-class HIV maturation inhibitor. After 3-resistant variants were found during Phase I and IIa clinical trials, further modification of 3 produced 4 with improved activity against wild-type and 3-resistant HIV-1. In continued efforts to optimize 1, 63 final products have now been designed, synthesized, and evaluated for anti-HIV-1 replication activity against HIV-1_NL4-3 infected MT-4 cell lines. Five known and 21 new derivatives were as or more potent than 3 (EC₅₀ 0.065 μM), while eight new derivatives were as or more potent than 4 (EC₅₀ 0.019 μM). These derivatives feature expanded structural diversity and chemical space that may improve the antiviral activity and address the growing resistance crisis. Structure-Activity Relationship (SAR) correlations were thoroughly analyzed, and a 3D Quantitative SAR model with high predictability was constructed to facilitate further rational design and development of new potent derivatives.

Antiparasitic Effects of Selected Isoflavones on Flatworms

Medicinal plants have been successfully used in the ethno medicine for a wide range of diseases since ancient times. The research on natural products has allowed the discovery of biologically relevant compounds inspired by plant secondary metabolites, what contributed to the development of many chemotherapeutic drugs. Flavonoids represent a group of therapeutically very effective plant secondary metabolites and selected molecules were shown to exert also antiparasitic activity. This work summarizes the recent knowledge generated within past three decades about potential parasitocidal activities of several flavonoids with different chemical structures, particularly on medically important flatworms such as Schistosoma spp., Fasciola spp., Echinococcus spp., Raillietina spp., and model cestode Mesocestoides vogae. Here we focus on curcumin, genistein, quercetin and silymarin complex of flavonolignans. All of them possess a whole spectrum of biological activities on eukaryotic cells which have multi-therapeutic effects in various diseases. In vitro they can induce profound alterations in the tegumental architecture and its functions as well as their activity can significantly modulate or damage worm´s metabolism directly by interaction with enzymes or signaling molecules in dose-dependent manner. Moreover, they seem to differentially regulate the RNA activity in numbers of worm´s genes. This review suggests that examined flavonoids and their derivates are promising molecules for antiparasitic drug research. Due to lack of toxicity, isoflavons could be used directly for therapy, or as adjuvant therapy for diseases caused by medically important cestodes and trematodes.

Design, Synthesis, Molecular Modelling, and Biological Evaluation of Oleanolic Acid-Arylidene Derivatives as Potential Anti-Inflammatory Agents

INTRODUCTION

Oleanolic acid, a pentacyclic triterpenic acid, is widely distributed in medicinal plants and is the most commonly studied triterpene for various biological activities, including anti-allergic, anti-cancer, and anti-inflammatory.

METHODS

The present study was carried out to synthesize arylidene derivatives of oleanolic acid at the C-2 position by Claisen Schmidt condensation to develop more effective anti-inflammatory agents. The derivatives were screened for anti-inflammatory activity by scrutinizing NO production inhibition in RAW 264.7 cells induced by LPS and their cytotoxicity. The potential candidates were further screened for inhibition of LPS-induced interleukin (IL-6) and tumour necrosis factor-alpha (TNF-α) production in RAW 264.7 cells.

RESULTS

The results of in vitro studies revealed that derivatives 3d, 3e, 3L, and 3o are comparable to that of the oleanolic acid on the inhibition of TNF-α and IL-6 release. However, derivative 3L was identified as the most potent inhibitor of IL-6 (77.2%) and TNF-α (75.4%) when compared to parent compound, and compounds 3a (77.18%), 3d (71.5%), and 3e (68.8%) showed potent inhibition of NO than oleanolic acid (65.22%) at 10µM. Besides, from docking score and Cyscore analysis analogs (3e, 3L, 3n) showed greater affinity towards TNF-α and IL-1β than dexamethasone.

CONCLUSION

Herein, we report a series of 15 new arylidene derivatives of oleanolic acid by Claisen Schmidt condensation reaction. All the compounds synthesized were screened for their anti-inflammatory activity against NO, TNF-α and IL-6. From the data, it was evident that most of the compounds exhibited better anti-inflammatory activity.

Molecular genomic features associated with in vitro response of the NCI-60 cancer cell line panel to natural products

Natural products remain a significant source of anticancer chemotherapeutics. The search for targeted drugs for cancer treatment includes consideration of natural products, which may provide new opportunities for antitumor cytotoxicity as single agents or in combination therapy. We examined the association of molecular genomic features in the well-characterized NCI-60 cancer cell line panel with in vitro response to treatment with 1302 small molecules which included natural products, semisynthetic natural product derivatives, and synthetic compounds based on a natural product pharmacophore from the Developmental Therapeutics Program of the US National Cancer Institute's database. These compounds were obtained from a variety of plant, marine, and microbial species. Molecular information utilized for the analysis included expression measures for 23059 annotated transcripts, lncRNAs, and miRNAs, and data on protein-changing single nucleotide variants in 211 cancer-related genes. We found associations of expression of multiple genes including SLFN11, CYP2J2, EPHX1, GPC1, ELF3, and MGMT involved in DNA damage repair, NOTCH family members, ABC and SLC transporters, and both mutations in tyrosine kinases and BRAF V600E with NCI-60 responses to specific categories of natural products. Hierarchical clustering identified groups of natural products, which correlated with a specific mechanism of action. Specifically, several natural product clusters were associated with SLFN11 gene expression, suggesting that potential action of these compounds may involve DNA damage. The associations between gene expression or genome alterations of functionally relevant genes with the response of cancer cells to natural products provide new information about potential mechanisms of action of these identified clusters of compounds with potentially similar biological effects. This information will assist in future drug discovery and in design of new targeted cancer chemotherapy agents.

Evaluation of A-azepano-triterpenoids and related derivatives as antimicrobial and antiviral agents

A series of semisynthetic triterpenoids with A-ring azepano- and A-seco-fragments as well as hydrazido/hydrazono-substituents at C3 and C28 has been synthesized and evaluated for antimicrobial activity against key ESKAPE pathogens and DNA viruses (HSV-1, HCMV, HPV-11). It was found that azepanouvaol 8, 3-amino-3,4-seco-4(23)-en derivatives of uvaol 21 and glycyrrhetol-dien 22 as well as azepano-glycyrrhetol-tosylate 32 showed strong antimicrobial activities against MRSA with MIC ≤ 0.15 μM that exceeds the effect of antibiotic vancomycin. Azepanobetulinic acid cyclohexyl amide 4 exhibited significant bacteriostatic effect against MRSA (MIC ≤ 0.15 μM) with low cytotoxicity to HEK-293 even at a maximum tested concentration of >20 μM (selectivity index SI 133) and may be considered a noncytotoxic anti-MRSA agent. Azepanobetulin 1, azepanouvaol 8, and azepano-glycyrrhetol 15 showed high potency towards HCMV (EC₅₀ 0.15; 0.11; 0.11 µM) with selectivity indexes SI₅₀ 115; 136; 172, respectively. The docking studies suggest the possible interactions of the leading compounds with the molecular targets.

Enzymology and biosynthesis of the orsellinic acid derived medicinal meroterpenoids

The advent of synthetic biology has yielded fruitful studies on orsellinic acid-derived meroterpenoids, which reportedly possess important biological activities. Genomics and transcriptomics have significantly accelerated the discovery of the biosynthetic genes for orsellinic acid-derived fungal and plant meroterpenoids. Subsequently, a well-developed heterologous host provides a convenient platform to generate a supply of useful natural products. Furthermore, in vitro reconstitution and genome editing tools have been increasingly employed as efficient means to fully understand the enzyme reaction mechanisms. With the knowledge of the biosynthetic machinery, combinatorial and engineered biosyntheses have yielded novel molecules with improved bioactivities. These studies will lay the foundation for the production of meroterpenoids with novel medicinal properties.

11, 13-Dehydro Lactone Moiety in Gynecologic Cancer Cells

Background:

To study the anti-cancer effect of isoalantolactone, a sesquiterpene lactoneisolated from the roots of Inula heleniumon human gynecologic cancer cells.

Methods:

A structure-activity relationship experiment was designed to identify the functional moiety of isoalantolactone for its significant anti-cancer activity. Five gynecologic cancer cell lines were treated with isoalantolactone. Cell proliferation was determined by MTT assay in vitro and cell apoptosis by flow cytometry.

Results:

We found isoalantolactone strongly inhibited the cell proliferationofHEC-1, HAC-2, HOC-21, and HeLa cells. Its inhibitory effect was comparable to that of well-known chemotherapeutic agents, cisplatin and taxol. Furthermore, isoalantolactone induced apoptosis in HeLa cells via caspase. On the contrary, its 11, 13-dihydro derivatives had much weaker anti-proliferative activities than the parent compound.

Conclusion:

Isoalantolactone exhibited strong anti-proliferative activities and apoptosis-inducing effects on gynecologic cancer cells. The 11, 13-dehydro lactone moiety was critical for its anti-proliferative activity.

Synthesis and biological evaluation of ethacrynic acid derivatives bearing sulfonamides as potent anti-cancer agents

A series of ethacrynic acid (2-[2,3-dichloro-4-(2-methylidenebutanoyl)phenoxy]acetic acid) (EA, Edecrin) containing sulfonamides linked via three types of linkers namely 1,2-ethylenediamine, piperazine and 4-aminopiperidine was synthesized and subsequently evaluated in vitro against HL60 and HCT116 cancer cell lines. All the EA analogs, excluding 6a and 6c, showed anti-proliferative activity with IC_50s in the micromolar range (less than 4 uM). Three derivatives 6b, 7b and 7e were selected for their interesting dual activity on HL60 cell line in order to be further evaluated against a panel of cancer cell lines (HCT116, A549, MCF7, PC3, U87-MG and SKOV3) as well as on MRC5 as a normal cell line. These compounds displayed IC₅₀ values in nanomolar range against A549, MCF7, PC3 and HCT116 cell lines, deducing the discovery that piperazine or 4-aminopiperidine is the linker's best choice to develop EA analogs with highly potent anti-proliferative activities own up to 24 nM. Besides, in terms of selectivity, those linkers are more suitable offering safety ratios of up to 63.8.

Phytocannabinoids: Origins and Biosynthesis

Phytocannabinoids are bioactive natural products found in some flowering plants, liverworts, and fungi that can be beneficial for the treatment of human ailments such as pain, anxiety, and cachexia. Targeted biosynthesis of cannabinoids with desirable properties requires identification of the underlying genes and their expression in a suitable heterologous host. We provide an overview of the structural classification of phytocannabinoids based on their decorated resorcinol core and the bioactivities of naturally occurring cannabinoids, and we review current knowledge of phytocannabinoid biosynthesis in Cannabis, Rhododendron, and Radula species. We also highlight the potential in planta roles of phytocannabinoids and the opportunity for synthetic biology approaches based on combinatorial biochemistry and protein engineering to produce cannabinoid derivatives with improved properties.

A novel time-dimension and circadian rhythm-dependent strategy for pharmacodynamic evaluation of Uncaria in the regulation of neurotransmitter circadian metabolic homeostasis in spontaneously hypertensive rats

In the present study, we aimed to use metabolomics platforms to examine circadian-regulated neurotransmitters across a 24-h day and the effects of Uncaria administration on daily rhythmicity in order to establish a strategy for evaluating the spatiotemporal efficacy evaluation strategy of Uncaria. By using targeted ultrahigh performance liquid chromatography-mass spectrometry metabolomics, we quantified 32 neurotransmitter metabolites every 4 h over 24 h. To assess 24-h metabolite rhythmicity, we performed cosinor analysis. The expression of hypothalamic rhythm genes was detected by reverse transcription polymerase chain reaction (RT-PCR). Data revealed circadian loss of many neurotransmitters during the entire circadian cycle in the serum of group M, indicating that hypertension causes circadian rhythm disorders. Cosinor analysis of the rhythmic oscillations of the levels of 32 neurotransmitters in the three groups showed that the metabolite rhythms peaked at approximately the same time of day (ZT4 and ZT16). Moreover, the amplitudes of the metabolite rhythms were altered. After treatment with Uncaria, the amplitudes of 13 neurotransmitters reverted to normal. The change trends in the hypothalamic rhythm genes confirmed the rhythm changes in neurotransmitters. Collectively, a novel pharmacodynamic evaluation strategy was established to dynamically observe the holistic effects of Uncaria on 32 circulating neurotransmitters within 24 h from the perspective of time dimension.

Daurichromenic Acid from the Chinese Traditional Medicinal Plant Rhododendron dauricum Inhibits Sphingomyelin Synthase and Aβ Aggregation

Species of the genus Rhododendron have been used in traditional Chinese medicine, with the medicinal herb "Manshanfong" used as an expectorant and for the treatment of acute bronchitis. Daurichromenic acid (DCA), a constituent of Rhododendron dauricum, is a meroterpenoid with antibacterial, anti-HIV, and anti-inflammatory activities. However, the mechanisms underlying these pharmacologic activities are poorly understood. To develop new drugs based on DCA, more information is required regarding its interactions with biomolecules. The present study showed that DCA inhibits the activity of the enzyme sphingomyelin synthase, with an IC₅₀ of 4 µM. The structure-activity relationships between DCA and sphingomyelin synthase were evaluated using derivatives and cyclized hongoquercin A. In addition, DCA was found to inhibit amyloid β aggregation. These results may help in the design of effective drugs based on DCA.

Recent advances in natural anti-HIV triterpenoids and analogs

The human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic is one of the world's most serious health challenges. Although combination antiretroviral therapy provides effective viral suppression, current medicines used against HIV cannot completely eradicate the infectious disease and often have associated toxicities and severe side effects in addition to causing drug resistance. Therefore, the continued development of new antiviral agents with diverse structures and novel mechanisms of action remains a vital need for the management of HIV/AIDS. Natural products are an important source of drug discovery, and certain triterpenes and their analogs have demonstrated potential as pharmaceutical precursors for the treatment of HIV. Over the past decade, natural triterpenoids and analogs have been extensively studied to find new anti-HIV drugs. This review discusses the anti-HIV triterpenoids and analogs reported during the period of 2009-2019. The article includes not only a comprehensive review of the recent anti-HIV agent development from the perspective of medicinal chemistry, but also discusses structure-activity relationship analyses of the described triterpenoids.

An Aqueous Extract of a Bifidobacterium Species Induces Apoptosis and Inhibits Invasiveness of Non-Small Cell Lung Cancer Cells

Chemotherapy regimens for non?small cell lung cancer (NSCLC) have various adverse effects on the human body. For this reason, probiotics have received attention regarding their potential value as a safe and natural complementary strategy for cancer prevention. This study analyzed the anticancer effects of aqueous extracts of probiotic bacteria Bifidobacterium bifidum (BB), Bifidobacterium longum (BL), Bifidobacterium lactis (BLA), Bifidobacterium infantis 1 (BI1), and Bifidobacterium infantis 2 (BI2) on NSCLC cell lines. When the aqueous extracts of probiotic Bifidobacterium species were applied to the NSCLC cell lines A549, H1299, and HCC827, cell death increased considerably; in particular, the aqueous extracts from BB and BLA markedly reduced cell proliferation. p38 phosphorylation induced by BB aqueous extract increased the expression of cleaved caspase 3 and cleaved poly (ADP-ribose) polymerase (PARP), consequently inducing the apoptosis of A549 and H1299 cells. When the p38 inhibitor SB203580 was applied, phosphorylation of p38 decreased, and the expression of cleaved caspase 3 and cleaved PARP was also inhibited, resulting in a reduction of cell death. In addition, BB aqueous extracts reduced the secretion of MMP-9, leading to inhibition of cancer cell invasion. By contrast, after transfection of short hairpin RNA shMMP-9 (for a knockdown of MMP-9) int°Cancer cells, BB aqueous extracts treatment failed to suppress the cancer cell invasiveness. According to our results about their anticancer effects on NSCLC, probiotics consisting of Bifidobacterium species may be useful as adjunctive anticancer treatment in the future.

Palladium-Catalyzed C-2 and C-3 Dual C-H Functionalization of Indoles: Synthesis of Fluorinated Isocryptolepine Analogues

Here we report a protocol to synthesize diversiform fluorinated isocryptolepine analogues with potential biological activities in one step via directed C-2 and C-3 dual C-H functionalization of indoles. We also attempted to take into account fluorinated imidoyl chlorides as a novel kind of synthons in the directed C-H functionalization reactions. As a result, a variety of fluorinated isocryptolepine analogues were obtained in up to 96% yield. Moreover, we conducted control experiments to disclose the reaction mechanism.

Natural Products Containing Olefinic Bond: Important Substrates for Semi-synthetic Modification Towards Value Addition

:

Semi-synthesis, the way of preparing novel bioactive molecules via modification of compounds isolated from natural sources is very much useful nowadays in the drug discovery process. The modification is based on the reaction of functional group(s) present in a natural compound. Among the examples of functional group transformation, double bond modification is also common in the literature. Several reactions like hydrogenation, cyclopropanation, epoxidation, addition reaction (halogenations, hydroxylation), Michael addition, Heck reaction, cycloaddition, dipolar cycloaddition, etc. are employed for this purpose. In this review, we have tried to gather the reactions performed with several double bond containing classes of natural products like diterpenes, xanthones, sesquiterpene exomethylene lactones, diaryl heptanoids, steroidal lactones, triterpenoids, limonoids, and alkamides. Where available, the effects of transformations on the biological activities of the molecules are also mentioned.

Limonoid compounds from Xylocarpus granatum and their anticancer activity against esophageal cancer cells

Background

To investigate the anticancer effects of limonoid compounds that were isolated and purified from Xylocarpus granatum fruits on human esophageal cancer (EC) cells. A structure‐activity relationship experiment was designed to identify the functional moiety of limonoid compounds identified as being critical for its anticancer activity.

Methods

Eca109 cells were cultured in RPMI1640 medium and treated with limonoid compounds. Cell proliferation was determined by the MTT assay in vitro. Eca109 cells apoptosis was analyzed by by flow cytometry after being treated with xylogranatin C. The expression of p53, Bax, bcl‐2, caspase‐3 and GRP78 in Eca109 cells after xylogranatin C treatment was examined by western blot assay.

Results

Four linonoid compounds strongly inhibited the cellular proliferation of Eca109 cells. Xylogranatin C was the strongest inhibitor, whose inhibitory effect was comparable to that of the well‐known chemotherapeutic agent, cisplatin. Furthermore, xylogranatin C might induce Eca109 cell apoptosis through joint effects on multiple pathways, including the death receptor and endoplasmic reticulum pathways. Additionally, xylogranatin C suppressed tumor cell proliferation by upregulating miR‐203a expression in Eca109 cells.

Conclusions

Xylogranatin C induced Eca109 cellular apoptosis and exerted antitumor activity. Xylogranatin C suppressed tumor cell proliferation by upregulating miR‐203a expression in Eca109 cells.

Correlation between Antibacterial Activity and Free-Radical Scavenging: In-Vitro Evaluation of Polar/Non-Polar Extracts from 25 Plants

Objectives: The current study aimed to measure the antioxidant and antibacterial activities of 25 wild Palestinian edible plants, which were subjected to extraction by polar and non-polar solvents. Correlations between free radical scavenging activity and antibacterial activity of the extracts were assessed for both polar and non-polar fractions. Materials: Twenty-five wild edible plant species that are frequently consumed by people in Palestine (mainly in a rural area) were examined. Among them, 10 plant species were among those with the highest mean cultural importance values, according to an ethnobotanical survey that was conducted in the West Bank, Palestine, a few years ago. Method: The protocol of the DPPH assay for testing free-radical scavenging was utilized for determining EC50 values, while microdilution tests were conducted to determine the 50% inhibitory concentration (IC50) of the extracts for the microorganism Staphylococcus mutans. Results and Discussion: Eight extracts (non-polar fractions) were found to possess an antibacterial IC50 of less than 20 ppm, such as Foeniculum vulgare, Salvia palaestinafruticose, Micromeria fruticose, Trigonella foenum-graecum, Cichorium pumilum jacq, Salvia hierosolymitana boiss, Ruta chalepensis, and Chrysanthemum coronarium. The polar fractions possess higher antioxidant activity, while non-polar fraction possess higher antibacterial activity. Looking at all the results together can deceive and lead to the conclusion that there is no correlation between antibacterial activity against S. mutans and free radical scavenging (R2 equals 0.0538). However, in-depth analysis revealed that non-polar plant extracts with an EC50 of free radical scavenging ≤100 ppm have a four-fold order of enrichment toward more activity against S. mutans. These findings are of high importance for screening projects. A four-fold order of enrichment could save plenty of time and many in screening projects. The antibacterial active extracts marked by low-medium free radical scavenging might act through a mechanism of action other than that of highly active, free radical scavenging extracts. Conclusion: The screening of antioxidant and antimicrobial activity performed on 25 selected wild plant extracts revealed a satisfactory free radical scavenging and antimicrobial potential that could be of value in the management of oxidative stress. Further studies are recommended to explore novel and highly active natural antibacterial products.

Recent Advances in Developing K-Ras Plasma Membrane Localization Inhibitors

The Ras proteins play an important role in cell growth, differentiation, proliferation and survival by regulating diverse signaling pathways. Oncogenic mutant K-Ras is the most frequently mutated class of Ras superfamily that is highly prevalent in many human cancers. Despite intensive efforts to combat various K-Ras-mutant-driven cancers, no effective K-Ras-specific inhibitors have yet been approved for clinical use to date. Since K-Ras proteins must be associated to the plasma membrane for their function, targeting K-Ras plasma membrane localization represents a logical and potentially tractable therapeutic approach. Here, we summarize the recent advances in the development of K-Ras plasma membrane localization inhibitors including natural product-based inhibitors achieved from high throughput screening, fragment-based drug design, virtual screening, and drug repurposing as well as hit-to-lead optimizations.

Discovery of an Oleanolic Acid/Hederagenin-Nitric Oxide Donor Hybrid as an EGFR Tyrosine Kinase Inhibitor for Non-Small-Cell Lung Cancer

Natural triterpenoids, such as oleanolic acid (OA) and hederagenin, display anti-lung cancer effects, and nitric oxide (NO) is associated with some oncogenic signaling pathways. Accordingly, 17 OA/hederagenin-NO donor hybrids were designed, synthesized, and evaluated against tumor cells. The most potent compound, 13, significantly inhibited the proliferation of five tumor cell lines (IC₅₀ 4.6-5.2 μM), while hederagenin inhibited the growth of only A549 tumor cells (IC₅₀ > 10 μM). Furthermore, compound 13 showed stronger inhibitory effects on EGFR-LTC kinase activity (IC₅₀ 0.01 μM) than hederagenin (IC₅₀ > 20 μM) and inhibited the proliferation of gefitinib-resistant H1975 (IC₅₀ 8.1 μM) and osimertinib-resistant H1975-LTC (IC₅₀ 7.6 μM) non-small-cell lung cancer (NSCLC) cells. Moreover, compound 13 produced the most NO in H1975 tumor cells, which indicated that NO may play a synergistic role. Collectively, compound 13, a novel hederagenin-NO donor hybrid with a different chemical structure from those of the current FDA-approved EGFR-targeted anti-NSCLC drugs, may be a promising lead compound for the treatment of NSCLC expressing gefitinib-resistant EGFR with a T790 M mutation or osimertinib-resistant EGFR-LTC with an L858R/T790M/C797S mutation. This work should shed light on the discovery of new anti-NSCLC drugs targeting EGFR from natural products.