Plant-derived natural products are significant resources for drug discovery and development including appreciable potentials in preventing and managing oxidative stress, making them promising candidates in cancer and other disease therapeutics. Their effects have been linked to phytochemicals such as phenolic compounds and their antioxidant activities. The abundance and complexity of these bio-constituents highlight the need for well-defined in vitro characterization and quantification of the plant extracts/preparations that can translate to in vivo effects and hopefully to clinical use. This review article seeks to provide relevant information about the applicability of cell-based assays in assessing anti-cytotoxicity of phytochemicals considering several traditional and current methods.

Phenolic compounds and other phytochemicals are significant resources for drug discovery and development. Plant‐derived natural products have contributed in preventing and managing oxidative stress, and in cancer therapeutics. Recent reports indicate that 83% of new anti‐cancer agents are of natural product origin. The aim of this study was to assess the content and properties of bioactive phytochemicals in water, ethanol, methanol, acetone, and dichloromethane extracts of Prunus africana, Pausinystalia yohimbe, Moringa oleifera, Momordica charantia and Orthero spp, and test their therapeutic effect on a wide range of diseases. In the first part of the study, the content of total polyphenols (TPC), flavonoids (TFC), carotenoid, anthocyanin, and antioxidant properties of the extracts of the different plant parts of these five plants were measured using the Folin‐Ciocalteu, 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity (DPPH), ferric reducing antioxidant power (FRAP), and 2,2′‐Azino‐bis(3‐ ethylbenzthiazoline‐6‐sulfonic acid) radical scavenging (ABTS) assays. For most samples, extraction yields were highest when either ethanol or methanol were used as extraction solvent. The FRAP values were in the range of 6.04 – 112.00 μM Fe2+/g, while the highest TPC and TFC were seen in the methanol extract of P. africana bark from Cameroon (1397.33 mg GAE/g) and acetone extract of M. charantia leaf (217.33 mg RU/g), respectively. The concentration required to obtain a 50% antioxidant effect (EC50) for the acetone and methanol extracts of P. africana bark (Cameroon), methanol and ethanol extracts of P. yohimbe leaf and the methanol extract of P. yohimbe root were comparable to that of ascorbic acid. Seven phenolic acids were identified in the extracts of P. africana and P. yohimbe using high performance liquid chromatography (HPLC). The most abundant phenolic acids were; vanillic acid (116.41 mg/g dry extract in P. yohimbe leaf methanol extract) and trans‐sinapic acid (102.22 mg/g dry extract in P. africana bark water extract). This study shows that these plants parts are valuable sources of natural polyphenols and antioxidants and their individual and/ synergistic effect may modulate cellular and signaling events involved in growth and invasion of cancer cells.Support or Funding InformationUSDA‐NIFADelaware State UniversityThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Glioblastoma is the most malignant and fatal of all primary brain tumors. Each year in the United States, about 22,000 cases of glioma are diagnosed and about 70% of these patients die. The current treatment modality options available for glioma patients are limited to temozolomide, radiation, and surgery. The poor outcome with these treatment options has necessitated the search for a better chemotherapeutic strategy to improve patient outcomes. In a previous study, a genome-scale clustered regularly interspaced short palindromic repeats (CRISPR) screen in glioblastoma was performed under human type II topoisomerase (TOP2) poison selection and found that various aminoacyl tRNA synthetases (AARS) were the most enriched in our screen. This high expression of AARS was validated by western blot and the gliomas were treated with sub-nanomolar doses of AARS inhibitors. Our results showed that AARS inhibitor treatment effectively killed 75 to 90% of the tumors within 72 h and that this killing is independent of DNA damage repair machinery. Taken together, the findings suggest that application of AARS inhibitors might be curative for glioma, but more experimental in-vivo tests will be needed to validate this.

This review article seeks to provide relevant information about the applicability of cell-based assays in assessing cytotoxicity of phytochemicals in light of several traditional methods available. Phenolic compounds and other phytochemicals are significant resources for drug discovery and development, thus underlining the enormous potentials of plant-derived natural products for the prevention and management of oxidative stress associated with cancer and other diseases. These effects have been linked to the content of phytochemicals such as phenolic compounds and their antioxidant properties. The abundance and complexity of these bio-constituents highlight the need for well-defined methods for the in vitro characterization and quantification of extracts and/or preparations that can translate to in vivo effects. Cell culture systems provide a useful model for basic research and a wide range of clinical in vitro studies and physiological processes as well as assessing the toxicity and therapeutic potential of compounds including plant extracts with potential medicinal benefits. Their use in cancer research provide a useful insight into possible therapeutic properties of phytochemicals at the cellular level. This approach has been instrumental in the initial stages of developing chemotherapeutic agents where human cancer cell lines are used as experimental models. These models have continued to contribute to elucidating specific requirements for certain biochemical events associated with proliferation, metabolism, loss of cell viability/apoptosis. Cell culture systems remain a promising tool in natural product development.

Hexane (HEX) and dichloromethane (DCM) have been used to extract oils from various sources due to their expansive solubility and low volatility that ease removal at low temperatures. However, environmental and health concerns make them undesirable solvents. The aim of this study was to evaluate the extraction efficiency and physicochemical characteristics of palm kernel oil (PKO) extracted with the addition of acetone in HEX‐acetone (1:1, vol/vol) and DCM‐acetone (1:1, vol/vol) mixtures as an alternative to DCM and HEX alone. PKO extracted with co‐solvent systems had better quality characteristics compared with single solvent extracts. The oil recovered, free fatty acid content, peroxide value and other quality characteristics, and thermal properties were within the range for PKO, and similar oils as stipulated in standards. Monounsaturated fatty acid content in PKO was up to 70% of which lauric acid was the most abundant (48%–52%). A total of 50 volatile compounds were identified by GC–MS in all the extracts including amide (1), alcohol (1), aldehydes (2), ketones (3), acids (6), esters (6) and hydrocarbons (31) with higher numbers of volatiles in the HEX extracts compared to the DCM extracts. Dodecanoic acid, hexanal, and 2‐undecanone were the most abundant acid, aldehyde, and ketone, respectively. Principal component analysis (PCA) differentiated the volatiles identified on the polar and non‐polar columns with 88.2% and 8.8%, and 67.3% and 19.6% of the variation accounted for by PC1 and PC2, respectively, with several common volatile components forming a cluster from all the solvents used.