Guaiazulene and related compounds: A review of current perspective on biomedical applications.

BACKGROUND: Thousands of people worldwide pass away yearly due to neurological disorders, cardiovascular illnesses, cancer, metabolic disorders, and microbial infections. Additionally, a sizable population has also been impacted by hepatotoxicity, ulcers, gastroesophageal reflux disease, and breast fissure. These ailments are likewise steadily increasing along with the increase in life expectancy. Finding innovative therapies to cure and consequently lessen the impact of these ailments is, therefore, a global concern. METHODS AND MATERIALS: All provided literature on Guaiazulene (GA) and its related compounds were searched using various electronic databases such as PubMed, Google Scholar, Web of Science, Elsevier, Springer, ACS, CNKI, and books via the keywords Guaiazulene, Matricaria chamomilla, GA-related compounds, and Guaiazulene analogous. RESULTS: The FDA has approved the bicyclic sesquiterpene GA, commonly referred to as azulon or 1,4-dimethyl-7-isopropylazulene, as a component in cosmetic colorants. The pleiotropic health advantages of GA and related substances, especially their antioxidant and anti-inflammatory effects, attracted a lot of research. Numerous studies have found that GA can help to manage various conditions, including bacterial infections, tumors, immunomodulation, expectorants, diuretics, diaphoresis, ulcers, dermatitis, proliferation, and gastritis. These conditions all involve lipid peroxidation and inflammatory response. In this review, we have covered the biomedical applications of GA. Moreover, we also emphasize the therapeutic potential of guaiazulene derivatives in pre-clinical and clinical settings, along with their underlying mechanism(s). CONCLUSION: GA and its related compounds exhibit therapeutic potential in several diseases. Still, it is necessary to investigate their potential in animal models for various other ailments and establish their safety profile. They might be a good candidate to advance to clinical trials.

Integrated computational and experimental approach for novel anti-leishmanial molecules by targeting Dephospho-coenzyme A kinase.

Coenzyme A acts as a necessary cofactor for many enzymes and is a part of many biochemical processes. One of the critical enzymes involved in Coenzyme A synthesis is Dephospho-coenzyme A-kinase (DPCK). In this study, we have used integrated computational and experimental approaches for promising inhibitors of DPCK using the natural products available in the ZINC database for anti-leishmanial drug development. The top hit compounds chosen after molecular docking were Veratramine, Azulene, Hupehenine, and Hederagenin. The free binding energy of Veratramine, Azulene, Hupehenine, and Hederagenin was estimated. Besides the favourable binding point, the ligands also showed good hydrogen bonding and other interactions with key residues of the enzyme's active site. The natural compounds were also experimentally investigated for their effect on the L. donovani promastigotes and murine macrophage (J774A.1). A good antileishmanial activity by the compounds on the promastigotes was observed as estimated by the MTT assay. The in-vitro experiments revealed that Hupehenine (IC50 = 7.34 ± 0.37 µM) and Veratramine (IC50 = 12.46 ± 2.28 µM) exhibited better inhibition than Hederagenin (IC50 = 23.36 ± 0.54 µM) and Azulene (IC50 = 24.42 ± 3.28 µM). This work has identified novel anti-leishmanial molecules possibly acting through the inhibition of DPCK.

Design, Synthesis, and Biological Activity of Guaiazulene Derivatives.

Guaiazulene and related derivatives were famous for diverse biological activities. In an effort to discover new highly efficient candidate drugs derived from guaiazulene, four series of guaiazulene derivatives were designed, synthesized, and evaluated for antiproliferation, antiviral, anti-inflammatory and peroxisome proliferators-activated receptor γ (PPARγ) signalling pathway agonist activities. Among them, two guaiazulene condensation derivatives showed selective cytotoxic activities towards K562 cell with IC50 values 5.21 µM and 5.14 µM, respectively, accompanied by slight effects on normal cell viability. For the first time, one guaiazulene derivative from series I exhibited potent antiviral activity towards influenza A virus with IC50 of 17.5 µM. A guaiazulene-based chalcone showed higher anti-inflammatory activity than positive drug indomethacin with an inhibitory rate of 34.29 % in zebrafish model in vivo. One guaiazulene-based flavonoid could strongly agitate PPARγ pathway at 20 µM, indicating the potential of guaiazulene derivatives to reduce obesity development and ameliorate hepatic steatosis. Preliminary in silico ADME studies predicted the excellent drug-likeness properties of bioactive guaiazulene derivatives.

Photodynamic anti-inflammatory activity of azulene derivatives on mammalian macrophages and their intracellular mechanism of action.

Azulene derivatives have been studied previously as photodynamic therapy agents. They have anti-cancer, anti-microbial and anti-inflammatory activities. Together with their photodynamic activity they enable more control on their activation which aims to decrease possible side effects that have been encountered with their constitutively active drug counterparts. In our current study we focused on photodynamic anti-inflammatory activities of two azulene derivatives whose synthesis methods were described before. We found that when mammalian macrophages J774.2 cells were incubated with these two derivatives in the presence of LPS in dark conditions, these molecules had anti-inflammatory activity at their highest concentrations based on ELISA results on the pro-inflammatory cytokine levels. After light application, both derivatives exerted strong anti-inflammatory activities by substantially decreasing the TNF, IL6, GMCSF and IL12p40 cytokine production levels. When the intracellular mechanism of action for both derivatives was tested, only one of them acted through p38 and PI3K pathways whereas the other derivative did not affect either of these pathways. Our results suggest that these two azulene derivatives can be utilized as photodynamic anti-inflammatory drug candidates.

Azulene-Containing Squaraines for Photoacoustic Imaging and Photothermal Therapy.

Photoacoustic imaging (PAI) guided photothermal therapy (PTT) can realize real-time diagnosis and in situ treatment of cancer at the same time. Absorption in the near-infrared (NIR) region with large molar extinction coefficient (ε) and high value of photothermal conversion efficiency (PCE) are key prerequisites for photothermal agents (PTAs) to realize dual PAI and PTT treatments. Squaraines have stable quinoid structures with strong planarity and rigidity, in favor of the NIR absorption and high ε values. On the other hand, azulene derivatives mostly have very faint fluorescence emission, which is beneficial for photothermal transformation. Herein, two azulene-containing squaraines Az-SQ-1 and Az-SQ-2 are synthesized as high-performance PTAs. In comparison with Az-SQ-1, Az-SQ-2 possesses larger εmax of 3 × 105 M-1 cm-1 at 780 nm in organic solution and higher PCE of 53.2% in the form of nanoparticles under 808 nm laser irradiation. Accordingly, Az-SQ-2 NPs present stronger photoacoustic signals (about 15.1-times the background signal) and more efficient suppression of tumor growth. Our research indicates that the introduction of azulene unit to traditional NIR dyes is a simple but effective approach to obtain outstanding PTAs in the aspect of phototheranostics.

The azulene scaffold from a medicinal chemist's perspective: Physicochemical and in vitro parameters relevant for drug discovery.

Azulene is a bicyclic scaffold rarely applied in medicinal chemistry. Here we report physicochemical and in vitro parameters relevant for drug discovery for a series of diversely substituted azulenes. We synthesized and characterized several scaffold hopping series of analogously substituted azulenes, indoles and naphthalenes. This enabled a comparison of azulene with the more common scaffolds indole and naphthalene. Our data indicates that undesirably low photostability of azulenes is restricted to certain substitution patterns. Generally, we conclude that azulene is an underused lipophilic bicycle and should be considered as a valuable complement to the collection of medicinal chemistry scaffolds.

Challenging Approach to the Development of Novel Estrogen Receptor Modulators Based on the Chemical Properties of Guaiazulene.

Tamoxifen, a therapeutic agent for breast cancer, has been associated with genetic polymorphisms in the metabolism of N,N-dialkylaminoethyl substituent, which plays an important role in the expression of selective estrogen receptor modulator (SERM) activity. To solve this problem, we developed a novel estrogen receptor (ER) modulator, Az-01, on the basis of the aromaticity, dipole moment, and isopropyl group of guaiazulene. Az-01 showed four-fold lower binding affinity for ER than E2 but had similar ER-binding affinity to that of 4-hydroxytamoxifen (4-HOtam). Unlike tamoxifen, Az-01 acted as a partial agonist with very weak estrogenic activity at high concentrations when used alone, and it showed potent anti-estrogenic activity in the presence of E2. The cell proliferation and inhibition activities of Az-01 were specific to ER-expressing MCF-7 cells, and no effect of Az-01 on other cell proliferation signals was observed. These findings are important for the development of new types of SERMs without the N,N-dialkylaminoethyl substituent as a privileged functional group for SERMs.

Photoswitchable inhibitors of human ß-glucocerebrosidase.

Light-switchable inhibitors of the enzyme ß-glucocerebrosidase (GCase) have been developed by anchoring a specific azasugar to a dihydroazulene or an azobenzene responsive moiety. Their inhibitory effect towards human GCase, before and after irradiation are reported, and the effect on thermal denaturation of recombinant GCase and cytotoxicity were studied on selected candidates.

Guaiazulene derivative 1,2,3,4-tetrahydroazuleno[1,2-b] tropone reduces the production of ATP by inhibiting electron transfer complex II.

Molecularly targeted therapy has been used for treatment of various types of cancer. However, cancer cells often acquire resistance to molecularly targeted drugs that inhibit specific molecular abnormalities, such as constitutive activation of kinases. Even in cancer cells that have acquired resistance, enhanced anabolism, including the synthesis of nucleotides, amino acids and lipids, is common to normal cancer cells. Therefore, there is a renewed interest in effectively eliminating cancer cells by specifically targeting their abnormal energy metabolism. Multiple strategies are currently being developed for mitochondrial-targeted cancer therapy, with agents targeting oxidative phosphorylation, glycolysis, the tricarboxylic acid cycle and apoptosis. In this study, we found that one of the guaiazulene derivatives, namely, 1,2,3,4-tetrahydroazuleno[1,2-b] tropone (TAT), inhibited the proliferation of cancer cell lines stronger than that of normal cells. In addition, we showed that TAT inhibited energy production in cancer cell lines, resulting in apoptosis. Analyses done in cancer cell lines and in the animal model Caenorhabditis elegans suggested that TAT acts on the mitochondrial electron transfer complex II and suppresses cellular energy production by inhibiting oxidative phosphorylation across species. These results suggest that TAT could represent a novel anticancer agent that selectively targets mitochondria.

Sesquiterpene lactones; Damsin and neoambrosin suppress cytokine-mediated inflammation in complete Freund's adjuvant rat model via shutting Akt/ERK1/2/STAT3 signaling.

ETHNOPHARMACOLOGIAL RELEVANCE: Although Damsissa (Ambrosia maritima) is traditionally used as anti-inflammatory and diuretic, the biological activity and mechanism of action of its major constituents are to be elucidated. AIM: to decipher the anti-arthritic potential of damsin (DMS) and neoambrosin (NMS) and to unfold their molecular signaling in complete Freund's adjuvant (CFA)-induced arthritis model. MATERIALS AND METHODS: the right hind paw was inoculated with CFA (0.1 ml) at day 0 and 7 while treatments were started from the 14th day and continued for 2 weeks. Rats were randomly assigned into 4 groups; normal group (NRML), CFA-induced arthritis group, CFA-induced arthritis treated with DMS and NMS (10 mg/kg/day) as 3rd and 4th group; respectively. RESULTS: Throughout experimental period, treatments ameliorated the increase of paw volume, knee joint diameter and nociception tests as reflected in open field arena. Also, DSM and NMS suppressed phosphorylation of Akt, STAT-3, ERK1/2 which was further mirrored by inactivation of GSK3ß and downregulation of MCP-1 together with CCN1 and NF-kß in hind paw tissue. Concomitantly, inflammation markers; TNF-α, IL-6, -12 were lowered as confirmed microscopically during examination of hind paw tissue. CONCLUSION: DSM and NMS-induced suppression of NF-kß subdues clinical features of RA most probably through repression of Akt/ERK1/2/STAT3 pathway. Therefore, DMS and NMS can serve as safe and effective treatment for rheumatoid arthritis, one of the most disabling chronic, inflammatory and painful autoimmune disease.

Antitumor Effects and Tumor-specificity of Guaiazulene-3-Carboxylate Derivatives Against Oral Squamous Cell Carcinoma In Vitro.

AIM: The aim of this study was to investigate the antitumor potential of guaiazulene-3-carboxylate derivatives against oral malignant cells. MATERIALS AND METHODS: Twelve guaiazulene-3-carboxylate derivatives were synthesized by introduction of either with alkyl group [1-5], alkoxy group [6, 7], hydroxyl group [8, 9] or primary amine [10-12] at the end of sidechains. Tumor-specificity (TS) was calculated by the ratio of mean 50% cytotoxic concentration (CC50) against 3 human oral mesenchymal cell lines to that against 4 human oral squamous cell carcinoma (OSCC) cell lines. Potency-selectivity expression (PSE) was calculated by dividing TS value by CC50value against OSCC cell lines. Cell cycle analysis was performed by cell sorter. RESULTS: [6, 7] showed the highest TS and PSE values, and induced the accumulation of both subG1 and G2/M cell populations in HSC-2 OSCC cells. Quantitative structure-activity relationship analysis demonstrated that their tumor-specificity was correlated with chemical descriptors that explain the 3D shape, electric state and ionization potential. CONCLUSION: Alkoxyl guaiazulene-3-carboxylates [6, 7] can be potential candidates of lead compound for developing novel anticancer drugs.

PARP-1 inhibitor-AG14361 suppresses acute allograft rejection via stabilizing CD4+FoxP3+ regulatory T cells.

Acute allograft rejection is the most common complication in organ transplantation leading to organ loss. Treg cells play an important role in preventing acute rejection, but they are unstable and easily lose function. Poly(ADP-ribose) polymerase 1(PARP-1) is involved in the differentiation stabilization of Treg cells, it has been suggested that PARP-1 inhibition could prevent acute rejection and prolong allograft survival. This study investigated AG14361 effects on acute allograft rejection. We used a fully MHC-mismatched murine heart transplantation model to compare the effect of PARP-1 inhibitor-AG14361 on alloimmunity to the control. Mice treated with PARP-1 inhibitors showed a longer median survival time of allografts (MS14 compared with the control group, MST was 8 days, and AG14361 was 6 days, P = 0.019). The combination of sirolimus and AG14361 significantly delayed allograft MST (AG14361 + sirolimus for 30 days, sirolimus for 16 days, P = 0.002). AG14361 markedly augmented the number of the CD25+FoxP3+ Treg cells in the graft and periphery. In addition, it could enhance the suppressive function of Treg cells by upregulating the level of CTLA-4, PD-1 and ICOS. In vivo, the Treg/Th17 ratio increased significantly in the AG14351 group compared to the control. In the combination with sirolimus treatment, AG14361 promoted the long-term allograft survival. Our results highlight novel effects of a PARP-1 inhibitor. PARP-1 inhibitor AG14361 may be a promising agent to attenuate acute allograft rejection as it can maintain the number and function of Treg cells in allografts.

Anti-Cancer and Anti-Inflammatory Activities of Bromo- and Cyano-Substituted Azulene Derivatives.

Natural products and their synthetic derivatives gathered attention due to their pharmaceutical capacities. They have been in use against different types of diseases ranging from cancer to inflammatory disorders. In order to increase their efficacy and prevent the possible side effects, these natural compounds are manipulated at the laboratory conditions and modified according to our needs. Azulene is one of these compounds whose anti-inflammatory potential have been shown by the previous studies, but a detailed analysis of its effect at the cellular level in terms of pro-inflammatory cytokine production has not been studied yet. Moreover, its derivative potential has not been characterized extensively. In our study, we examined the cytotoxic, immunomodulatory and immunostimulatory potential of bromo- and cyano-substituted azulenes on the mammalian macrophages. These unique compounds had differential effects on the production of pro-inflammatory cytokines and they were anti-inflammatory immunomodulators. Furthermore, they exerted anti-proliferative effect on breast and prostate cancer cells which supports their anti-cancer potential as well.

Sodium azulene sulfonate reverses multidrug resistance in K562/A02 cells.

Overexpression of p-glycoprotein (p-gp) is the main cause of multidrug resistance and chemotherapy failure in leukemia. Sodium azulene sulfonate (SAS) was used to reverse the multidrug resistance of human leukemia adriamycin-resistant strain K562/A02, and the underlying mechanism was investigated. Human leukemia cell line K562 and drug-resistant cell line K562/A02 in logarithmic phase were used in this study. After 48 hours of treatment of K562/A02 cells with SAS, the intrinsic cytotoxicity of chlorogenic acid and its sensitivity to adriamycin (ADM) were determined with MTT assay. The degree of reversal was calculated. Using ADM accumulation and rhodamine 123 efflux experiments, the average fluorescence intensity of ADM and rhodamine 123 (Rh123) in chlorogenic acid-treated K562/A02 cells was determined flow cytometrically. The expressions of p-gp, t-Akt and p-Akt in K562/A02 cells were assayed using Western blotting. SAS had almost no cytotoxic effect, and the degree of inhibition was only about 20% at the highest concentration of 100 mu-M. The EC50 of MDR reversal by SAS was in the nano range (539±37nM), and it had a high selectivity index for normal cells (>185). The accumulation of ADM in drug-resistant cells was increased significantly after treatment with 1 and 5 mu-M SAS, while the efflux of Rh123 was significantly inhibited, suggesting that SAS reversed MDR by inhibiting p-gp function. Western blotting experiments showed that SAS downregulated the expression of p-gp by inhibiting PI3K/Akt signaling pathway. This contributed to the reversal of drug resistance.SAS effectively reverses multidrug resistance in vitro by inhibiting the function of p-gp in K562/A02 cells, through a mechanism involving downregulation of the P13K/Akt signaling pathway. Therefore, SAS may be a potential candidate drug for reversal of MDR.

Antibacterial and antiproliferative activities of the fresh leaf essential oil of Psidium guajava L. (Myrtaceae) / Atividades antibacteriana e antiproliferativa do óleo essencial das folhas frescas de Psidium guajava L. (Myrtaceae)

Abstract This study evaluated the antibacterial and antiproliferative activities of the essential oil of Psidium guajava leaves (PG-EO), traditionally used in folk medicine. The essential oil was obtained from fresh leaves by hydrodistillation, using a modified Clevenger apparatus. The major PG-EO chemical constituents were identified by GC-MS and GC-FID as being β-caryophyllene (16.1%), α-humulene (11.9%), aromadendrene oxide (14.7%), δ-selinene (13.6%), and selin-11-en-4α-ol (12.5%). The antibacterial activity of the essential oil of P. guajava leaves was determined in terms of its minimum inhibitory concentrations (MIC) using the broth microdilution method in 96-well microplates. PG-EO had moderate activity against Streptococcus mutans (MIC = 200 µg/mL), S. mitis (MIC = 200 µg/mL), S. sanguinis (MIC = 400 µg/mL), S. sobrinus (MIC = 100 µg/mL), and S. salivarius (MIC = 200 µg/mL). The antiproliferative activity was evaluated against different tumor cell lines: breast adenocarcinoma (MCF-7), human cervical adenocarcinoma (HeLa), and human gliobastoma (M059J). A normal human cell line (GM07492A, lung fibroblasts) was included. The antiproliferative activity was evaluated using the XTT assay and the results were expressed as IC50. The essential oil showed significantly lower IC50 values against MCF-7 and M059J lines than that obtained for the normal line, showing selectivity. Our results suggest that the essential oil of Psidium guajava L. has promising biological activities and can be considered a new source of bioactive compounds.

Resumo Este estudo avaliou as atividades antibacteriana e antiproliferativa do óleo essencial das folhas frescas de Psidium guajava (PG-OE), tradicionalmente utilizadas na medicina popular. O óleo essencial foi obtido por hidrodestilação das folhas frescas, utilizando aparelho do tipo Clevenger. Os principais constituintes químicos de PG-OE identificados por CG-EM e CG-DIC foram: β-cariofileno (16,1%), α-humuleno (11,9%), óxido de aromadendreno (14,7%), δ-selineno (13,6%) e selin-11-en-4α-ol (12,5%). A atividade antibacteriana do óleo essencial das folhas de P. guajava foi determinada em termo de sua concentração inibitória mínima (CIM) utilizando o método de microdiluição de caldo em microplacas de 96 poços. PG-OE apresentou moderada atividade contra Streptococcus mutans (CIM = 200 μg/mL), S. mitis (CIM = 200 μg/mL), S. sanguinis (CIM = 400 μg/mL), S. sobrinus (CIM = 100 μg/mL) e S. salivarius (CIM = 200 μg/mL). A atividade antiproliferativa foi avaliada frente a diferentes linhagens de células tumorais como: adenocarcinoma de mama (MCF-7), adenocarcinoma cervical humano (HeLa) e gliobastoma humano (M059J). Foi incluída uma linhagem celular humana normal (GM07492A, fibroblastos pulmonares). A atividade antiproliferativa foi avaliada utilizando o ensaio XTT e os resultados foram expressos como CI50. As linhagens MCF-7 e M059J mostraram valores significativamente mais baixos de CI50 do que os obtidos para a linhagem normal, mostrando seletividade. Nossos resultados sugerem que o óleo essencial das folhas frescas de Psidium guajava L. possui atividades biológicas promissoras e pode ser considerado como uma nova fonte de compostos bioativos.

Quantitative Structure-Cytotoxicity Relationship of Azulene Amide Derivatives.

BACKGROUND/AIM: Very few studies of anticancer activity of azulene amides led us to investigate the cytotoxicity of 21 N-alkylazulene-1-carboxamides introduced either with 3-methyl [1-7], 7-isopropyl-3-methyl [8-14] or 2-methoxy group [15-21] Materials and Methods: Tumor-specificity (TS) was calculated by the ratio of mean 50% cytotoxic concentration (CC50) against three normal human oral mesenchymal cells to that against four human oral squamous cell carcinoma (OSCC) cell lines. Potency-selectivity expression (PSE) was calculated by dividing TS value by CC50 value against OSCC cell lines. Apoptosis-inducing activity was evaluated by caspase-3 activation and appearance of subG1 cell population. RESULTS: [8-14] showed higher TS and PSE values, than [1-7] and [15-21] The most active compound [8-14] induced apoptosis in C9-22 OSCC cells at 4-times higher CC50 Quantitative structure-activity relationship analysis of [1-14] demonstrated that their tumor-specificity was correlated with chemical descriptors that explain the molecular shape and hydrophobicity. CONCLUSION: 7-Isopropyl-3-methyl-N-propylazulene-1-carboxamide [8] can be a potential candidate of lead compound for manufacturing new anticancer drug.

Diverse compounds from pleuromutilin lead to a thioredoxin inhibitor and inducer of ferroptosis.

The chemical diversification of natural products provides a robust and general method for the creation of stereochemically rich and structurally diverse small molecules. The resulting compounds have physicochemical traits different from those in most screening collections, and as such are an excellent source for biological discovery. Herein, we subject the diterpene natural product pleuromutilin to reaction sequences focused on creating ring system diversity in few synthetic steps. This effort resulted in a collection of compounds with previously unreported ring systems, providing a novel set of structurally diverse and highly complex compounds suitable for screening in a variety of different settings. Biological evaluation identified the novel compound ferroptocide, a small molecule that rapidly and robustly induces ferroptotic death of cancer cells. Target identification efforts and CRISPR knockout studies reveal that ferroptocide is an inhibitor of thioredoxin, a key component of the antioxidant system in the cell. Ferroptocide positively modulates the immune system in a murine model of breast cancer and will be a useful tool to study the utility of pro-ferroptotic agents for treatment of cancer.

Structure-Activity Relationships of 1-Benzoylazulenes at the OX1 and OX2 Orexin Receptors.

We previously demonstrated the potential of di- or trisubstituted azulenes as ligands (potentiators, weak agonists, and antagonists) of the orexin receptors. In this study we investigated 27 1-benzoylazulene derivatives, uncovering seven potentiators of the orexin response on OX1 and two weak dual orexin receptor agonists. For potentiators, replacement of the azulene scaffold by indole retained the activity of four out of six compounds. The structure-activity relationships for agonism and potentiation can be summarized into a bicyclic aromatic ring system substituted with two hydrogen-bond acceptors (1-position, benzoyl; 6-position, carboxyl/ester) within 7-8 Šof each other; a third acceptor at the 3-position is also well tolerated. The same pharmacophoric signature is found in the preferred conformations of the orexin receptor agonist Nag26 from molecular dynamics simulations. Subtle changes switch the activity between weak agonism and potentiation, suggesting overlapping binding sites.

Antibacterial and antiproliferative activities of the fresh leaf essential oil of Psidium guajava L. (Myrtaceae).

This study evaluated the antibacterial and antiproliferative activities of the essential oil of Psidium guajava leaves (PG-EO), traditionally used in folk medicine. The essential oil was obtained from fresh leaves by hydrodistillation, using a modified Clevenger apparatus. The major PG-EO chemical constituents were identified by GC-MS and GC-FID as being ß-caryophyllene (16.1%), α-humulene (11.9%), aromadendrene oxide (14.7%), δ-selinene (13.6%), and selin-11-en-4α-ol (12.5%). The antibacterial activity of the essential oil of P. guajava leaves was determined in terms of its minimum inhibitory concentrations (MIC) using the broth microdilution method in 96-well microplates. PG-EO had moderate activity against Streptococcus mutans (MIC = 200 µg/mL), S. mitis (MIC = 200 µg/mL), S. sanguinis (MIC = 400 µg/mL), S. sobrinus (MIC = 100 µg/mL), and S. salivarius (MIC = 200 µg/mL). The antiproliferative activity was evaluated against different tumor cell lines: breast adenocarcinoma (MCF-7), human cervical adenocarcinoma (HeLa), and human gliobastoma (M059J). A normal human cell line (GM07492A, lung fibroblasts) was included. The antiproliferative activity was evaluated using the XTT assay and the results were expressed as IC50. The essential oil showed significantly lower IC50 values against MCF-7 and M059J lines than that obtained for the normal line, showing selectivity. Our results suggest that the essential oil of Psidium guajava L. has promising biological activities and can be considered a new source of bioactive compounds.

Structural modification on rupestonic acid leads to highly potent inhibitors against influenza virus.

Influenza viruses are responsible for seasonal epidemics and occasional pandemics, which cause significant morbidity and mortality. Although several drugs (adamantanes and neuraminidase inhibitors) are available in the market, the worldwide spread of drug-resistant influenza strains poses an urgent need for novel antiviral drugs. Artemisia rupestris L. is a folk medicine used to treat cold. In this paper, we structurally modified rupestonic acid, a bioactive component of A. rupestris, to synthesize a series of 2-substituted rupestonic acid methyl esters (3a-3o). Their structures were fully characterized by 1H NMR, 13C NMR, HRMS spectra. Among them, compounds 3b and 3c exhibited potent activities against influenza H1N1 with micromolar IC50 values and might serve as new lead compounds for the treatment of influenza.