Mechanism of neem limonoids-induced cell death in cancer: Role of oxidative phosphorylation

"Comparative evaluation of cytotoxicity of three herbal endodontic irrigants at three intervals of time" - An in vitro study

Aim

The aim of the study was to evaluate and compare the cytotoxicity of 25% of neem leaf extract (Azadirachta indica), 20% of guava leaf extracts (Psidium guajava), and 20% of cinnamon extract (Cinnamomum zeylanicum) irrigants at three intervals of time.

Methodology

Four groups were formed (n = 15), Group 1 (control group) - normal saline solution, Group 2 - 25% of neem extract, Group 3 - 20% of guava extract, and Group 4 - 20% of cinnamon extract. Each group was further divided into three subgroups based on intervals (n = 5). Subgroup A - at 10 min, Subgroup B - at 20 min, and Subgroup C - at 30 min. One hundred microliters of each irrigant was added to 2 mL of the diluted red blood cells suspension obtained from a human volunteer. Hemoglobin (Hb) estimation was done with an automated hematology analyzer after incubating the test samples at 10, 20, and 30 min intervals.

Results

The reduction in the mean Hb values was not statistically significant in the normal saline, guava, and cinnamon groups. However, in the neem extract group, the mean Hb values reduced significantly at P < 0.001. Among the subgroups, Subgroup A (10 min) showed the least cytotoxicity.

Conclusion

In the present study, 20% guava extract had the lowest cytotoxicity and cytotoxicity increased with time. Hence, 20% guava extract can be used as an alternative to conventional irrigants as it has been shown to have the least cytotoxicity.

Mitochondria-Related Candidate Genes and Diagnostic Model to Predict Late-Onset Alzheimer's Disease and Mild Cognitive Impairment

Background

Late-onset Alzheimer's disease (LOAD) is the most common type of dementia, but its pathogenesis remains unclear, and there is a lack of simple and convenient early diagnostic markers to predict the occurrence.

Objective

Our study aimed to identify diagnostic candidate genes to predict LOAD by machine learning methods.

Methods

Three publicly available datasets from the Gene Expression Omnibus (GEO) database containing peripheral blood gene expression data for LOAD, mild cognitive impairment (MCI), and controls (CN) were downloaded. Differential expression analysis, the least absolute shrinkage and selection operator (LASSO), and support vector machine recursive feature elimination (SVM-RFE) were used to identify LOAD diagnostic candidate genes. These candidate genes were then validated in the validation group and clinical samples, and a LOAD prediction model was established.

Results

LASSO and SVM-RFE analyses identified 3 mitochondria-related genes (MRGs) as candidate genes, including NDUFA1, NDUFS5, and NDUFB3. In the verification of 3 MRGs, the AUC values showed that NDUFA1, NDUFS5 had better predictability. We also verified the candidate MRGs in MCI groups, the AUC values showed good performance. We then used NDUFA1, NDUFS5 and age to build a LOAD diagnostic model and AUC was 0.723. Results of qRT-PCR experiments with clinical blood samples showed that the three candidate genes were expressed significantly lower in the LOAD and MCI groups when compared to CN.

Conclusion

Two mitochondrial-related candidate genes, NDUFA1 and NDUFS5, were identified as diagnostic markers for LOAD and MCI. Combining these two candidate genes with age, a LOAD diagnostic prediction model was successfully constructed.

Assessing Oligomerization Status of Mitochondrial OXPHOS Complexes Via Blue Native Page

Mitochondrial metabolism plays key roles in pathologies such as cancer. The five complexes of the oxidative phosphorylation (OXPHOS) system are crucial for producing ATP and maintaining cellular functions and are particularly exploited in cancer cells. Understanding the oligomeric state of these OXPHOS complexes will help elucidate their function (or dysfunction) in cancer cells and can be used as a mechanistic tool for anticancer agents that target mitochondria. Here we describe a protocol to observe the oligomeric state of the five OXPHOS complexes by isolating mitochondrial-enriched fractions followed by assessing their oligomeric state by nondenaturing blue native page electrophoresis.

Exploring the role of Azadirachta indica (neem) and its active compounds in the regulation of biological pathways: an update on molecular approach

In ethnomedicine, plant parts and compounds are used traditionally to treat different diseases. Neem (Azadirachta indica A. Juss) is the most versatile and useful medicinal plant ever found. Its every part is rich in bioactive compounds, which have traditionally been used to treat different ailments including infectious diseases. Bioactive compounds such as nimbolide, azarirachtin, and gedunin of neem are reported to have a tremendous ability to regulate numerous biological processes in vitro and in vivo. The present review article aims to explore the importance of neem extracts and bioactive compounds in the regulation of different biological pathways. We have reviewed research articles up to March 2020 on the role of neem in antioxidant, anti-inflammatory, antiangiogenic, immunomodulatory, and apoptotic activities. Studies on the concerned fields demonstrate that the bioactive compounds and extracts of neem have a regulatory effect on several biological mechanisms. It has been unveiled that extensive research is carried out on limonoids such as nimbolide and azarirachtin. It is evidenced by different studies that neem extracts are the potential to scavenge free radicals and reduce ROS-mediated damage to cells. Neem can be used to normalize lipid peroxidation and minimize ROS-mediated cell death. Besides, neem extracts can significantly reduce the release of proinflammatory cytokines and elevate the count of CD4 + and CD8 + T-cells. This review indicates the pivotal roles of A. indica in the regulation of different biological pathways. However, future investigations on other bioactive compounds of neem may reveal different therapeutic potentials.

Bio-selective hormonal breast cancer cytotoxic and antioxidant potencies of Melia azedarach L. wild type leaves

•

1st report on physical qualities and phytochemical content of M. azedarach wild type leaves extract and fractions.

•

Ethyl acetate fraction was the most active against bio-selective hormonal breast cancer T47D cell cytotoxic and antioxidant activities.

•

The phytochemicals content of active fraction was steroids and triterpene saponin, limonoid (toosendanin, meliarachin, salannin, salannal, 12-hydroxyamoorastatin, meliacarpinin and its derivates), and flavonoids (quercetin glycoside).

•

Significant (p < 0.05) correlations were observed between TPC, IC₅₀DPPH, FRAP and IC₅₀T47D.

Melia azedarach L. is used widely in traditional medicine for local or systemic ailments. Although studies exist on phytochemicals and potencies of Chinese and Indian cultivars of Melia, the present study investigated in vitro antioxidant properties of Melia wild type and its cytotoxicity against T47D cell. The ethanolic extract of the Melia leaves was fractionated with n-hexane, ethyl acetate and water, and the secondary metabolites were obtained. The antioxidant properties were determined with IC₅₀ DPPH (2,2-diphenyl-1-pycrylhydrazyl) radical and FRAP (ferric reducing antioxidant power), while the cytotoxicity was determined with the MTT method. The total phenolic (TPC) and β-sitosterol (SC) contents were also measured. The results showed that the ethyl acetate fraction had higher antioxidant and cytotoxic activities (IC₅₀ 211.89 ± 10.86 and 147.90 ± 8.49 μg/mL, respectively) than others. Significant (p < 0.05) correlations were observed between TPC, IC₅₀DPPH, FRAP and IC₅₀T47D. LC-EI MS analysis of the ethyl acetate fraction revealed the steroid and triterpenoid saponins, limonoids and quercetin glycosides, which influenced the medicinal properties of the Melia leaves. Melia azedarach L. wild type leaf extracts are a promising natural resource for managing breast cancer.

Alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone inhibits cell proliferation, invasion, and migration in gastric cancer in part via autophagy

Gastric cancer is a leading cause of mortality worldwide. Alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone is a type of limonoid mainly isolated from Cedrela odorata (Meliaceae) that has been shown to suppress cell proliferation in several human carcinoma cell lines. In this study, we investigated the anti-cancer ability of alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone and its underlying mechanism in MKN45 cells. Alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone induced excess reactive oxygen species (ROS) accumulation. Transwell and wound healing assays demonstrated that alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone inhibited the invasion and migration ability of MKN45 cells. Moreover, autophagy-related proteins Beclin-1, Atg5, and Atg7 were up-regulated. Light chain 3 (LC3)-I protein was converted into LC3-II under alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone exposure. Transmission electron microscopy demonstrated that alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone treatment resulted in the formation of autophagosomes. Immunofluorescence assays suggested that alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone treatment elicited dot formation of green fluorescent protein (GFP)-LC3. 3-methyladenine (3-MA), an autophagy inhibitor, demonstrated that autophagy promoted death in MKN45 cells. Western blotting showed that ROS/mitogen activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathways play crucial roles in the intrinsic mechanism of alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone's activity. The combined use of N-acetyl-_L-cysteine (NAC) or U0126 validated the regulatory role of ROS/MEK/ERK signaling pathways. Alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone administration inhibited the growth of MKN45 xenograft tumors in nude mice and suppressed Ki67 expression. More importantly, a similar effect was achieved in a patient-derived xenograft (PDX) model, which is more relevant to clinical application. Taken together, alpha, 2'-dihydroxy-4,4'-dimethoxydihydrochalcone has the potential to be further developed into an anti-tumor agent for clinical treatment of gastric cancer.

Mitochondrial dysfunction-mediated apoptosis resistance associates with defective heat shock protein response in African-American men with prostate cancer

BACKGROUND

African-American (AA) patients with prostate cancer (PCa) respond poorly to current therapy compared with Caucasian American (CA) PCa patients. Although underlying mechanisms are not defined, mitochondrial dysfunction is a key reason for this disparity.

METHODS

Cell death, cell cycle, and mitochondrial function/stress were analysed by flow cytometry or by Seahorse XF24 analyzer. Expression of cellular proteins was determined using immunoblotting and real-time PCR analyses. Cell survival/motility was evaluated by clonogenic, cell migration, and gelatin zymography assays.

RESULTS

Glycolytic pathway inhibitor dichloroacetate (DCA) inhibited cell proliferation in both AA PCa cells (AA cells) and CA PCa cells (CA cells). AA cells possess reduced endogenous reactive oxygen species, mitochondrial membrane potential (mtMP), and mitochondrial mass compared with CA cells. DCA upregulated mtMP in both cell types, whereas mitochondrial mass was significantly increased in CA cells. DCA enhanced taxol-induced cell death in CA cells while sensitising AA cells to doxorubicin. Reduced expression of heat shock proteins (HSPs) was observed in AA cells, whereas DCA induced expression of CHOP, C/EBP, HSP60, and HSP90 in CA cells. AA cells are more aggressive and metastatic than CA cells.

CONCLUSIONS

Restoration of mitochondrial function may provide new option for reducing PCa health disparity among American men.