Antimicrobial, Antioxidant, Anticancer Activity and Phytochemical Analysis of the Red Alga, Laurencia papillosa

Enhanced biomass production and wastewater treatment in attached co-culture of Chlorella pyrenoidosa with nitrogen-fixing bacteria Azotobacter beijerinckii

Algae-bacteria symbiosis can promote the growth of microalgae and improve the efficiency of wastewater treatment. Attached culture is an efficient culture technique for microalgae, with benefits of high yield, low water consumption and easy harvesting. However, the promoting effects of bacteria on microalgae in attached culture are still unclear. In this study, different forms of a nitrogen-fixing bacteria, Azotobacter beijerinckii (including bacteria supernatant, live bacteria, and broken bacteria), were co-cultured with Chlorella pyrenoidosa in an attached culture system using wastewater as the culture medium. The results showed that the broken A. beijerinckii form had the best growth promotion effect on C. pyrenoidosa. Compared with the pure algae culture, the biomass of C. pyrenoidosa increased by 71.8% and the protein increased by 28.2%. The live bacteria form had the best effect on improving the efficiency of wastewater treatment by C. pyrenoidosa, with the COD, PO₄^3- and NH₄⁺-N removal rates increased by 20.8%, 18.5% and 8.9%, respectively, in comparison with the pure algae culture. The attached co-culture mode promoted the growth of C. pyrenodisa better than the suspended co-culture mode. This research offers a new way for improving microalgae biomass and wastewater treatment by attached algae-bacteria symbiont.

Enhancement of cytotoxic and antioxidant activities of Digenea simplex chloroform extract using the nanosuspension technique

Digenea simplex (D. simplex), an Egyptian marine red macroalga, contains a diverse group of phytochemicals with unique bioactivities. At the same time, the synthesis of nanosuspension (NS) has received increasing interest to optimize the technological aspects of drugs. Thence, the main objective of this work was to use the chloroform extract (ChlE) of D. simplex to prepare its nanosuspension (ChlE-NS) formulation to increase its aqueous solubility, thereby improving its bioactivity. By using FTIR, GC/MS analysis, and phytochemical screening assays, the chemical profiling of ChlE was assessed. NS was prepared by the antisolvent precipitation technique using 1.5% w/v polyvinyl alcohol (PVA). A light microscope, FTIR, particle size distribution, polydispersity index (PDI), and zeta potential (ZP) measurements was used to characterize the prepared NS. Four cancer cell lines were used in the MTT experiment to investigate the anticancer potential of ChlE and ChlE-NS. An apoptotic mechanism was established using acridine orange/ethidium bromide (AO/EB) dual staining, DNA fragmentation, and increased caspase activity. ChlE and ChlE-NS were also evaluated as antioxidants using DPPH and ABTS free radical assays. The results showed that, when compared to ChlE, ChlE-NS had greater cytotoxic activity against the four cancer cell lines. However, results of antioxidant activity showed that ChlE-NS had an IC₅₀ of 36.86 ± 0.09 and 63.5 ± 0.47%, while ChlE had values of 39.90 ± 0.08 and 86.5 ± 0.8% in DPPH and ABTS assays, respectively. Based on the results of this research, D. simplex ChlE-NS may be an effective strategy for enhancing ChlE's cytotoxic and antioxidant activities.

A novel nanoemulsion-based microalgal growth medium for enhanced biomass production

BACKGROUND

Microalgae are well-established feedstocks for applications ranging from biofuels to valuable pigments and therapeutic proteins. However, the low biomass productivity using commercially available growth mediums is a roadblock for its mass production. This work describes a strategy to boost algal biomass productivity by using an effective CO₂ supplement.

RESULTS

In the present study, a novel nanoemulsion-based media has been tested for the growth of freshwater microalgae strain Chlorella pyrenoidosa. Two different nanoemulsion-based media were developed using 1% silicone oil nanoemulsion (1% SE) and 1% paraffin oil nanoemulsion (1% PE) supplemented in Blue-green 11 media (BG11). After 12 days of cultivation, biomass yield was found highest in 1% PE followed by 1% SE and control, i.e., 3.20, 2.75, and 1.03 g L^-1, respectively. The chlorophyll-a synthesis was improved by 76% in 1% SE and 53% in 1% PE compared with control. The respective microalgal cell numbers for 1% PE, 1% SE and control measured using the cell counter were 3.00 × 10⁶, 2.40 × 10⁶, and 1.34 × 10⁶ cells mL^-1. The effective CO₂ absorption tendency of the emulsion was highlighted as the key mechanism for enhanced algal growth and biomass production. On the biochemical characterization of the produced biomass, it was found that the nanoemulsion-cultivated C. pyrenoidosa had increased lipid (1% PE = 26.80%, 1% SE = 23.60%) and carbohydrates (1% PE = 17.20%, 1% SE = 18.90%) content compared to the control (lipid = 18.05%, carbohydrates = 13.60%).

CONCLUSIONS

This study describes a novel nanoemulsion which potentially acts as an effective CO₂ supplement for microalgal growth media thereby increasing the growth of microalgal cells. Further, nanoemulsion-cultivated microalgal biomass depicts an increase in lipid and carbohydrate content. The approach provides high microalgal biomass productivity without altering morphological characteristics like cell shape and size as revealed by field emission scanning electron microscope (FESEM) images.

Medicinal Prospects of Antioxidants From Algal Sources in Cancer Therapy

Though cancer therapeutics can successfully eradicate cancerous cells, the effectiveness of these medications is mostly restricted to several deleterious side effects. Therefore, to alleviate these side effects, antioxidant supplementation is often warranted, reducing reactive species levels and mitigating persistent oxidative damage. Thus, it can impede the growth of cancer cells while protecting the normal cells simultaneously. Moreover, antioxidant supplementation alone or in combination with chemotherapeutics hinders further tumor development, prevents chemoresistance by improving the response to chemotherapy drugs, and enhances cancer patients' quality of life by alleviating side effects. Preclinical and clinical studies have been revealed the efficacy of using phytochemical and dietary antioxidants from different sources in treating chemo and radiation therapy-induced toxicities and enhancing treatment effectiveness. In this context, algae, both micro and macro, can be considered as alternative natural sources of antioxidants. Algae possess antioxidants from diverse groups, which can be exploited in the pharmaceutical industry. Despite having nutritional benefits, investigation and utilization of algal antioxidants are still in their infancy. This review article summarizes the prospective anticancer effect of twenty-three antioxidants from microalgae and their potential mechanism of action in cancer cells, as well as usage in cancer therapy. In addition, antioxidants from seaweeds, especially from edible species, are outlined, as well.

Antibacterial Use of Macroalgae Compounds against Foodborne Pathogens

The search for food resources is a constant in human history. Nowadays, the search for natural and safe food supplies is of foremost importance. Accordingly, there is a renewed interest in eco-friendly and natural products for substitution of synthetic additives. In addition, microbial contamination of food products during their obtaining and distribution processes is still a sanitary issue, and an important target for the food industry is to avoid food contamination and its related foodborne illnesses. These diseases are fundamentally caused by certain microorganisms listed in this review and classified according to their Gram negative or positive character. Algae have proven to possess high nutritional value and a wide variety of biological properties due to their content in active compounds. Among these capabilities, macroalgae are recognized for having antimicrobial properties. Thus, the present paper revises the actual knowledge of microbial contaminants in the food industry and proposes antimicrobial algal compounds against those pathogenic bacteria responsible for food contamination as valuable molecules for its growth inhibition. The capacity of algae extracts to inhibit some major food pathogen growth was assessed. Moreover, the main applications of these compounds in the food industry were discussed while considering their favorable effects in terms of food safety and quality control.

Antioxidant, Anticancer Activity and Phytochemical Analysis of Green Algae, Chaetomorpha Collected from the Arabian Gulf

Seaweeds are a group of marine multicellular algae; the presence of antioxidant phytochemical constituents in Seaweed Chaetomorpha sp. extracts has received attention for their role in the prevention of human diseases. This study explores the phytochemical constituents, antioxidant, and anticancer properties of the Cladophoraceae, Chaetomorpha sp. Energy dispersive x-ray spectroscopy (EDX), and Gas chromatography-mass spectrometry (GC/MS) were performed to study the chemical structure and chemical formula. Different concentrations of ethanol and aqueous extracts of Chaetomorpha were used to estimate antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and total flavonoid, phenolic, and tannins content assays. Anti-tumor activity against breast cancer cell lines (MCF-7 and MDA-MB-231) was assessed by 3-(4,5-Dimethylthiazol-2-cyl)-2,5-Diphenyltetrazolium Bromide (MTT) assay. The EDX analysis indicated the presence of oxygen, silicon, and calcium as dominant elements. Antioxidant assays indicated that the ethanol extracts of Chaetomorpha consisted of a total of 189.14 ± 0.99 mg QE/g flavonoid content, 21.92 ± 0.43 mg GAE/g phenolic content and 21.81 ± 0.04 mg GAE/g tannins content. The DPPH radical scavenging assay exhibited higher antioxidant activity IC₅₀ (9.41 ± 0.54 mg/mL) in the ethanol extract. Moreover, it showed high anticancer activity by growth inhibition in the MDA-MB-231 breast cancer cell line and low IC₅₀ (225.18 ± 0.61 µg/mL). GC/MS analysis revealed the presence of Dichloracetic acid (DCA) as the active antitumor constituent of Chaetomorpha sp.; other anticancer compounds identified were Oximes and L-α-Terpinol. The results revealed that the type of Chaetomorpha sp. studied here possesses very unique and novel constituents and active potent antitumor chemical constituents and it can act as a promising antioxidant and anticancer agent for future applications in pharmaceutical industries.

The Potential of Seaweeds as a Source of Functional Ingredients of Prebiotic and Antioxidant Value

Two thirds of the world is covered by oceans, whose upper layer is inhabited by algae. This means that there is a large extension to obtain these photoautotrophic organisms. Algae have undergone a boom in recent years, with consequent discoveries and advances in this field. Algae are not only of high ecological value but also of great economic importance. Possible applications of algae are very diverse and include anti-biofilm activity, production of biofuels, bioremediation, as fertilizer, as fish feed, as food or food ingredients, in pharmacology (since they show antioxidant or contraceptive activities), in cosmeceutical formulation, and in such other applications as filters or for obtaining minerals. In this context, algae as food can be of help to maintain or even improve human health, and there is a growing interest in new products called functional foods, which can promote such a healthy state. Therefore, in this search, one of the main areas of research is the extraction and characterization of new natural ingredients with biological activity (e.g., prebiotic and antioxidant) that can contribute to consumers' well-being. The present review shows the results of a bibliographic survey on the chemical composition of macroalgae, together with a critical discussion about their potential as natural sources of new functional ingredients.