Cancer is the second leading cause of death worldwide. Conventional cancer therapies cause serious side effects and, at best, merely extend the patient's lifespan by a few years. Cancer control may therefore benefit from the potential that resides in alternative therapies. The demand to utilize alternative concepts or approaches to the treatment of cancer is therefore escalating. There is compelling evidence from epidemiological and experimental studies that highlight the importance of compounds derived from plants "phytochemicals" to reduce the risk of colon cancer and inhibit the development and spread of tumors in experimental animals. More than 25% of drugs used during the last 20 years are directly derived from plants, while the other 25% are chemically altered natural products. Still, only 5-15% of the approximately 250,000 higher plants have ever been investigated for bioactive compounds. The advantage of using such compounds for cancer treatment is their relatively non-toxic nature and availability in an ingestive form. An ideal phytochemical is one that possesses anti-tumor properties with minimal toxicity and has a defined mechanism of action. As compounds that target specific signaling pathways are identified, researchers can envisage novel therapeutic approaches as well as a better understanding of the pathways involved in disease progression. Here, we focus on 4 classes of natural anticancer drugs: methyltransferase inhibitors, DNA damaging/pro-oxidant drugs, HDAC inhibitors (HDACi), and mitotic disrupters, and we will focus on the mode of action for one promising example per group.

Overview of major classes of plant-derived anticancer drugs

Carissa carandas L. is traditionally used as antibacterial medicine and accumulates many antioxidant phytochemicals. Here, we expand this traditional usage with the green biosynthesis of silver nanoparticles (AgNPs) achieved using a Carissa carandas L. leaf extract as a reducing and capping agent. The green synthesis of AgNPs reaction was carried out using 1mM silver nitrate and leaf extract. The effect of temperature on the synthesis of AgNPs was examined using room temperature (25 °C) and 60 °C. The silver nanoparticles were formed in one hour by stirring at room temperature. In this case, a yellowish brown colour was developed. The successful formation of silver nanoparticles was confirmed by UV-Vis, Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) analysis. The characteristic peaks of the UV-vis spectrum and XRD confirmed the synthesis of AgNPs. The biosynthesised AgNPs showed potential antioxidant activity through DPPH assay. These AgNPs also exhibited potential antibacterial activity against human pathogenic bacteria. The results were compared with the antioxidant and antibacterial activities of the plant extract, and clearly suggest that the green biosynthesized AgNPs can constitute an effective antioxidant and antibacterial agent.

https://www.mdpi.com/2218-273X/11/2/299/pdf

Green Biosynthesis of Silver Nanoparticles Using Leaf Extract of Carissa carandas L. and Their Antioxidant and Antimicrobial Activity against Human Pathogenic Bacteria.

Nowadays, there are several approaches reported to accomplish the green synthesis of metal nanoparticles by using bacterial and fungi supernatants or by-products generated by these microorganisms. Therefore, agars as solely reductive regents have started to be used in order to obtain metal nanoparticles. This paper shows the results of the synthesis of gold and silver nanoparticles with different morphology, mainly triangular and truncated triangular, using Eosin Methylene Blue (EMB) agar as reducing agent. To control the reaction process, the necessary activation energy for the reducer was provided by three different techniques: microwave radiation, using a domestic microwave oven, ultraviolet radiation, and heating on a conventional plate. The evolution of the reduction process and stability of the samples was performed by ultraviolet visible spectroscopy. Morphology was carefully analyzed using high-resolution transmission electron microscopy (HRTEM) and Transmission electron microscopy (TEM). A one step synthesis for gold and silver nanoparticles was optimized with an eco-friendly and economic process.

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One-step synthesis of gold and silver non-spherical nanoparticles mediated by Eosin Methylene Blue agar.

Variability in essential oil composition and phenolic acid profile of Thymus daenensis Celak. populations from Iran

Citrus fruits are spread worldwide, grown across the globe and are wellappreciated for their refreshing juice and health benefits. This review aimed at investigating the applied health therapeutic uses of some citrus fruits exploited in the treatment of several health challenges as antitumor, anti-inflammatory, anticancer, antiviral, antimicrobial activities against cardiovascular diseases and macular degeneration. Citrus fruits abilities on the exploited benefits are not far from their rich bioactive compounds and phytochemical contents such as minerals, vitamins, flavonoids and carotenoids. These phytochemicals may act as antioxidants, boosting the action of protective enzymes in the liver, reverse lipid for oxidation of genetic material and improve immune system. We reviewed literature for the antioxidant compounds and health benefits of some citrus fruits (namely, oranges, lime, lemon and grapefruits) from electronic database search obtaining information from research studies and reports. We recommend more research into more varieties of citrus predominantly in the tropics.

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Antioxidant Compounds and Health Benefits of Citrus Fruits

Citrus limon (lemon) belongs to the Rutaceae family and has great therapeutic applications. The chemical ingredients of C. limon have been used in the formulation of several ethnic herbal medicines. The application of antibiotics has shown the development of drug resistance in antibacterial drugs. Due to the drug-resistant nature of microorganisms, there is an urgent need to develop a novel drug active against wildtype and MDR resistant strains of pathogens.

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Phytochemicals from Citrus Limon Juice as Potential Antibacterial Agents

Nanotechnology is an emerging field in the area of interdisciplinary research. Nanoparticle research is inevitable today due to its wide applications. So many chemical and physical methods have been used for nanoparticles synthesis. Many of these methods exert huge adverse environmental effects, need technical expertise, and high cost. Therefore, there is urgency to establish a trustworthy low-cost technology for nanoparticles synthesis. This method involving biological materials named plants, microorganisms, enzymes, etc. may be best eco-friendly alternatives. Synthesis of nanoparticles with plant extracts is additional beneficial over the other biological processes. The plant extracts are acting as reducing agent for nanoparticles synthesis. Moreover, plant-mediated nanoparticles synthesis is a single-step method for biosynthesis process. It is cost-effective, environmentally conducive, and safe for human therapeutic applications. Various plant materials such as extracts of fruits, leaves, roots, fruit peels, callus, etc. have been considered suitable agent for the synthesis of silver, gold, platinum, titanium, and other nanoparticles in different sizes and shapes. Biomedical applications of nanoparticles include antimicrobial, antifungal, immunomodulatory, and anticancer agents. More plant extracts or drugs can be loaded because of the lesser size and enormous surface area of nanoparticles, and hence it may act as appropriate vehicle for the drug delivery. The competence of absorption of drugs and upsurge in apoptosis of abnormal cells could be possible by using nanoparticles. Recently, some research reports have indicated the therapeutic efficacy of green synthesized nanoparticles against leishmaniasis and tuberculosis. In the future, nanoparticles practice may exposed a new vistas for healthcare and disease management.

Biomedical Applications of Green Synthesized Nanoparticles

Polyacetylenes (PA) are commonly present in nature but intense in specific taxa and are chemically and biologically active molecules. PA are more common in higher plants and ca. 2000 different polyacetylenes have been isolated from higher plants and fungi. PA are frequently recovered from the essential oils from plants. PA can be isolated and characterized by applying several analytical techniques such as ultraviolet (UV) spectroscopy, Raman mapping, high-performance liquid chromatography (HPLC), liquid chromatography coupled to mass spectrometry (LC-MS), one/two-dimensional nuclear magnetic resonance (1D/2D NMR). PA have shown numerous medicinal properties such as antibacterial, antifungal, antiinflammatory, platelet function inhibition, and serotogenic effects. PA also showed significant anticancer activity on different cancer cell lines, so they can inhibit tumor cell proliferation, promote cytotoxicity, and also induce twofold inhibitory action on acyl-CoA: diacylglycerol acyltransferase (DGAT) enzyme.

Analysis of polyacetylenes

Since the origination of human society, natural products and their derivatives especially obtained from medicinal plants have been used for the advantage of mankind due to their precious therapeutic potential. In Indian Ayurveda, different types of plant-based products have been used to cure several human diseases without any significant side effects, and that’s why an effective number of modern medicines has been isolated from natural sources involving medicinal plants. There are still some disease conditions where only synthetic drugs can be used for the treatment which quite often may lead to mild or severe side effects. It is, therefore, necessary to explore chemical compounds from Indian traditional medicinal plants as viable substitutes to the synthetic drugs in order to overcome their adverse effects and also the exorbitant cost. Glucocorticoids are widely used as potent anti-inflammatory and immunosuppressive agents for the treatment of various complications such as rheumatoid arthritis, joint pain, dermatitis, asthma, allergy, etc. Unfortunately, long-term use of corticosteroids even in low amount may cause severe adverse effects such as osteoporosis, reduction in bone mass, overweight, cataract–glaucoma, blurred vision, aggression, agitations, psychiatric and cognitive disturbance, cardiovascular disorders, hyperlipidemia, growth suppression, and many more. It has therefore been realized to explore plant-based principles as alternative and complementary therapeutics with almost no toxicity. The phyto-steroids such as solasodine, diosgenin, boswellic acid, glycyrrihizin, guggulsterones, withnolides, or sarsasapogenin are reported to have structural similarity with glucocorticoids or glycosides. In addition, the saponins, lactones, and some aliphatic compounds have been reported to possess efficiency to cure those diseases in which steroids are employed. However, extensive research is needed to detect other phytochemicals which may prove to act as potential substitutes of synthetic steroidal drugs. In this chapter, we have made an endeavor to present an updated account of those medicinal plants and corresponding phytochemicals with varied therapeutic properties as effective alternative steroids to be used against different chronic diseases.

Role of Natural Products as Alternative of Synthetic Steroidal Drugs

The identification and pharmacological validation of plant-based lead compounds for the cure of different diseases including cancer have always been globally strived. In addition to possessing numerous medicinal properties, many of the phytochemicals display antioxidant potential activities. Reactive oxygen species (ROS) causeoxidative stress leading to several severe diseases such as cancer. The antioxidants are substances that fight against ROS to protect the cells from their damaging effects. In the present study, the effects of methanol extract of Euglena tuba(ETME) have been evaluated for its antioxidant and antitumor potential against Dalton’s lymphoma (DL) introduced in BALB/cmice. After 24 h of intraperitoneal inoculation of DL cells in mice, ETME (300 mg kg−1 body weight) was administered intraperitoneally upto18 alternative days. On the 18th day, the mice were sacrificed; the blood and tissues (liver and brain) were collected to determine the tumor growth parameters including morphological, behavioural, haematological profile, and antioxidant indices. The results indicated that ETME exhibited significant antioxidative and antitumor properties when compared with the data from DL bearing mice. The results from the present study indicated that ETME contained remarkable antitumor efficacy, which was mediated through amelioration of oxidative stress. The data suggested that ETME could be used as a potential natural anticancer agent.

Priyanka Tiwari

Papers

Phytochemicals from Citrus Limon Juice as Potential Antibacterial Agents

Biomedical Applications of Green Synthesized Nanoparticles

Analysis of polyacetylenes

Role of Natural Products as Alternative of Synthetic Steroidal Drugs

Protective Effect of Methanolic Extract of Euglena tuba Against Dalton Lymphoma Induced Oxidative Stress in BALB/c Mice