Aspergillus flavus as a Model System to Test the Biological Activity of Botanicals: An Example on Citrullus colocynthis L. Schrad. Organic Extracts

The Antifungal and Antibacterial Effect of Citrullus Colocynthis: In Vitro Study

Introduction: Bacteria almost exclusively cause caries and other oral and dental diseases. This study evaluated the inhibitory effect of the alcoholic extract of Citrullus colocynthis on bacteria and fungi common in oral bacteria diseases. Method and materials: The ethanol extract and essential oil of Citrullus colocynthis were obtained via water distillation. After conducting phytochemical tests, including determination of total phenolic and flavonoid compounds of the extracts, GC-MASS test and microbial tests of the extracts were conducted on S. mutans, E. coli, S. salivarius, L. acidophilus, C. albicans, and S. aureus. The cytotoxicity test was assessed by MTT assay. Results: MIC and MBC values for S. mutans, S. salivalius, and L. acidophilus were 1.56 mg/ml and 3.12 mg/ml, respectively. Moreover, Citrullus colocynthis also has an inhibitory effect on bacteria and C. albicans at these concentrations, according to the DAD test. The survival rate of cells at concentrations of 5 mg/ml and 10 mg/ml was less than 50%, and at concentrations of 2.5 mg/ml and 1.25 mg/ml was less than 70% after 24 hours and 48 hours. Conclusion: According to the cytotoxicity results of this plant at concentrations of 1.56 mg/ml and 3.125 mg/ml, the ethanolic extract of C. colocynthis has inhibitory and lethal effects against pathogenic bacteria and fungi.

In Vitro Sprouted Plantlets of Citrullus colocynthis (L.) Schrad Shown to Possess Interesting Levels of Cucurbitacins and Other Bioactives against Pathogenic Fungi

Cucurbitacins, structurally different triterpenes mainly found in the members of Cucurbitaceae, possess a vast pharmacological potential. Genus Cucurbita, Cucumis, and Citrullus are affluent in these bioactive compounds, and, amongst them, Citrullus colocynthis (L.) Schrad. is widely exploited in folk medicine, since a huge number of diseases are successfully treated with organic and aqueous extracts obtained from different organs and tissues of the plant. The well-known pharmacological activities of such species have been attributed to its peculiar composition, which includes cucurbitacins and other bioactive molecules; thus, owing to its high importance as a valuable natural resource for pharmaceuticals and nutraceuticals, C. colocynthis propagation and multiplication protocols are considered significant, but the exploitation of its phytochemical potential is limited by the restricted cultivation conditions and the low rate of seed germination in the natural environment; in fact, the assessment of accumulation rate of specific phytochemicals under controlled conditions is still missing. Axenically sprouted plantlets obtained without the use of culture media or the addition of hormones have been evaluated here for the production of bioactive compounds and relevant bioactive features. Our results proved that derived organic extracts contain cucurbitacins and other bioactives, show antioxidant potential, and exert activity against some pathogenic fungi (Candida krusei, C. albicans, C. parapsilosis, C. glabrata, and Aspergillus flavus), supporting the feasibility of a methodology intended to scale-up cultivation of this species as a source of pharmaceutically interesting compounds, achievable from plantlets cultivated under laboratory conditions.

Investigation of Seeds and Peels of Citrullus colocynthis as Efficient Natural Adsorbent for Methylene Blue Dye

Natural adsorbents as low-cost materials have been proved efficient for water remediation and have significant capacity for the removal of certain chemicals from wastewater. The present investigation aimed to use Citrullus colocynthis seeds (CCSs) and peels (CCPs) as an efficient natural adsorbent for methylene blue (MB) dye in an aqueous solution. The examined biosorbents were characterized using surface area analyzer (BET), scanning electron microscope (SEM), thermogravimetric analyzer (TGA) and Fourier transform infra-red (FT-IR) spectroscopy. Batch adsorption experiments were conducted to optimize the main factors influencing the biosorption process. The equilibrium data for the adsorption of MB by CCSs were best described by the Langmuir isotherm followed by the Freundlich adsorption isotherms, while the equilibrium data for MB adsorption by CCPs were well fitted by the Langmuir isotherm followed by the Temkin isotherm. Under optimum conditions, the maximum biosorption capacity and removal efficiency were 18.832 mg g−1 and 98.00% for MB-CCSs and 4.480 mg g−1 and 91.43% for MB-CCPs. Kinetic studies revealed that MB adsorption onto CCSs obeys pseudo-first order kinetic model (K1 = 0.0274 min−1), while MB adsorption onto CCPs follows the pseudo-second order kinetic model (K2 = 0.0177 g mg−1 min−1). Thermodynamic studies revealed that the MB biosorption by CCSs was endothermic and a spontaneous process in nature associated with a rise in randomness, but the MB adsorption by CCPs was exothermic and a spontaneous process only at room temperature with a decline in disorder. Based on the obtained results, CCSs and CCPSs can be utilized as efficient, natural biosorbents, and CCSs is promising since it showed the highest removal percentage and adsorption capacity of MB dye.

Potential of Citrullus colocynthis L. Schrad. Immature Seed Extracts as Food Preservative against a Fungal Mycotoxigenic Contaminant

The world of plant extracts and natural compounds have long been regarded as a promise land for the individuation of healthy alternatives to chemical preservatives, against microbial contamination, in food and feed commodities. A plethora of aromatic and medicinal plant species have been studied from decades to explore their antimicrobial and antioxidant properties, in order to both validate their ethnobotanical use for healing microbial illnesses and assess their suitability as food preservation agents. In fact, after terrestrialization and during the following evolutionary pathway, plants had to develop chemical compounds—constitutive and/or induced—for defence against specific pathogens, therefore becoming a potential source of new natural products usable with antimicrobial purposes. Aside from the most common contaminants that could occur in foodstuff, mycotoxigenic fungal species represent a big concern, mainly in cereals and derived products: aflatoxins in particular are the most dreaded among such toxic and cancerogenic secondary metabolites, and the control of the main producer Aspergillus flavus is currently one of the most pursued goals in the field of food safety. As aromatic and medicinal plants have a long history of use in the Mediterranean basin for both food preservation and pest control in crops, the exploitation of native species for the control of mycotoxigenic phytopathogens is almost rationale. The present work provides novel insights into the possible use of C. colocynthis seed organic extracts as antimycotoxigenic additives, demonstrating, for some of them, a feasible application as crop and food protectants with specific regard to aflatoxin contamination. Additionally, the evaluation of their cytotoxic potential and nitric oxide production on human cell lines has been reported for the first time.

Oligosaccharides Derived from Tramesan: Their Structure and Activity on Mycotoxin Inhibition in Aspergillus flavus and Aspergillus carbonarius

Food and feed safety are of paramount relevance in everyday life. The awareness that different chemicals, e.g., those largely used in agriculture, could present both environmental problems and health hazards, has led to a large limitation of their use. Chemicals were also the main tool in a control of fungal pathogens and their secondary metabolites, mycotoxins. There is a drive to develop more environmentally friendly, “green”, approaches to control mycotoxin contamination of foodstuffs. Different mushroom metabolites showed the potential to act as control agents against mycotoxin production. The use of a polysaccharide, Tramesan, extracted from the basidiomycete Trametes versicolor, for controlling biosynthesis of aflatoxin B1 and ochratoxin A, has been previously discussed. In this study, oligosaccharides obtained from Tramesan were evaluated. The purified exopolysaccharide of T. versicolor was partially hydrolyzed and separated by chromatography into fractions from disaccharides to heptasaccharides. Each fraction was individually tested for mycotoxin inhibition in A. flavus and A. carbonarius. Fragments smaller than seven units showed no significant effect on mycotoxin inhibition; heptasaccharides showed inhibitory activity of up to 90% in both fungi. These results indicated that these oligosaccharides could be used as natural alternatives to crop protection chemicals for controlling these two mycotoxins.

Vegetables from the Cucurbitaceae family and their products: Positive effect on human health

The Cucurbitaceae family is a large group of crops with more than 800 species known worldwide. Vegetables from this family have been used for centuries, not only for consumption, but also for their medicinal value. The most characteristic cucurbits are pumpkin and cucumber, which are cultivated and consumed in many parts of the world. Seeds from cucurbits have many health benefits and are a popular snack. Cucurbit plants are rich in carotenoids, terpenoids, saponins, and phytochemicals. Vegetables from the Cucurbitaceae family have a positive influence on human health, and various studies have clearly indicated that cucurbit vegetables have antioxidant, antidiabetic, antiinflammatory, and purgative properties. This mini review evaluates the current literature about vegetables from the Cucurbitaceae family and their products, in addition to their positive effect on human health.