Australis Extract Research Articles

Cytotoxic Potential of Berunok Sea Cucumber (Paracaudina australis) Against Breast Cancer Cells (T47D)

Background Sea cucumbers can be explored as alternative raw materials by the pharmaceutical and fishery industries as anticancer agents because they contain potential bioactive compounds. Methods This study aimed to determine the anticancer activity of Paracaudina australis extract against breast cancer cells (T47D) using an MTT assay. The secondary metabolites found in P.australis are steroids, terpenoids, saponins, and phenolics. The Thin-Layer Chromatography test results are indicated by Rf values, and steroid compounds in the ethyl acetate fraction are included in the standard Rf values. The isolates obtained were identified by Gas Chromatography-Mass Spectrometry, Fourier-Transform Infrared Spectroscopy, High-performance liquid chromatography, and UV-Visual spectrophotometry. Results The isolated compounds were Dihydrocholesterol and Cholestan-3-ol, with a molecular formula (C27H48O). The ion weight and molecular mass of the compound were m/z 388,7. Conclusions This compound may be responsible for the anticancer activity of P.australis. The IC50 of Isolate F4 was 25,3 μg/ml, and IC50 of Isolate F7,8 was 13,76 μg/ml.

Celtis australis Exhibits Cytotoxic Effects by Inducing DNA Damage in Human Ovarian Cancer Cells

Native to the Mediterranean and southwest Asia, Celtis australis is used in folk medicine to treatment of many diseases such as peptic ulcer, diarrhea, dysentery, pain, and colic. However, there are very few studies on the effects of this species on cancer. We report for the first time the cytotoxic and genotoxic properties of C. australis on the human ovarian cancer cell line A2780.
 In the study, C. australis extract prepared in ethanol/phosphate buffer was applied to A2780 cells. The change in viability level in A2780 cells after treatment was determined by MTT assay and DNA damage was determined by single-cell gel electrophoresis (Comet) analysis.
 Our results showed that plant extract application at doses above 200 µg/ml significantly decreased A2780 cell viability (p

Lipid Composition, Cytotoxic and Acetylcholinesterase Inhibition Effects of Two Brown Algae Species Lobophora tsengii and Lobophora australis.

In this paper, the lipid classes, compositions of the neutral lipids, phospholipids and fatty acids, acetylcholinesterase inhibition and cytotoxic activity of two brown algae Lobophora tsengii D. Tien & Z. Sun and Lobophora australis Z. Sun, F. C. Gurgel & H. Kawai have been investigated. The polar lipid class had the highest content in total lipid (TL) (43.47% in L. tsengii and 48.95% in L. australis). Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were the main components in the phospholipids of two studied brown algae with contents varied from 32.27% to 52.33%. Total lipids were rich in PUFA (42.54% of total fatty acids for L. australis and 32.98% for L. tsengii), with EPA (11.46%, 14.30%) and AA (8.0%, 11.96%). L. tsengii methanol extract inhibited acetylcholinesterase (AChE) in in vitro assay with an IC50 value of 25.45 µg/mL. Both Lobophora methanol extracts display cytotoxic effects against four human cancer cell lines (KB, MCF7, HepG2 and A549) with IC50 in the range of 21.11-83.61 µg/mL. Especially, L. australis extract showed a strong cytotoxicity against KB cell lines with IC50 value of 21.11±0.39 µg/mL.

Exploring the antioxidant and antibacterial capacities of Padina australis extracts, and their utilization in starch-based coatings for preserving rainbow trout (Oncorhynchus mykiss) fillets

This study aimed to investigate different extraction methods for obtaining phenolic compounds from Padina australis and evaluate their total phenolic content, antioxidative, and antibacterial activities. The extracts were further incorporated into a starch solution to create active coatings for rainbow trout (Oncorhynchus mykiss) fillets during cold storage. Results showed that microwave-ultrasound-assisted extraction yielded the highest phenolic content and extraction yield. Microwave, microwave-assisted, and microwave-ultrasound extraction methods exhibited the highest ABTS, DPPH scavenging activity, and FRAP, respectively. Additionally, microwave-ultrasound, microwave, microwave-ultrasound, and microwave-assisted extraction methods demonstrated the highest inhibition zone against various bacteria. Fish fillets treated with coatings containing extracts from microwave-ultrasound-assisted extraction exhibited the lowest peroxide values, free fatty acid content, total volatile basic nitrogen, and bacterial counts. These findings suggest that phenolic compounds from P. australis could be utilized in the development of active packaging with antimicrobial and antioxidant properties.

Green and ligand-free gold nanoparticles in Padina australis extract for colorimetric detection of Cu2+ in water

The green and ligand-free gold nanoparticles (P-AuNPs) from Padina australis extract were easily and quickly prepared. A colorimetric probe based on P-AuNPs was designed for easy and visual detection of Cu2+ in domestic water with excellent sensitivity. The –OH and –NH2 in polysaccharides and proteins of Padina australis had played a reduced and protected role for AuNPs and also been easy to complex Cu2+ because of chelation. The complexed Cu2+ dragged P-AuNPs closely to aggregation, causing the red sol to turn blue. Also, the UV–vis spectrum was red-shifted, and a new peak developed. The limits of UV–vis detection are as low as 0.43 μM. The absorbance ratio (A630/A520) showed an excellent linear relationship with Cu2+ concentration (R2 = 0.9926) with a range of 20–60 μM by UV–vis.

Brown Seaweed (Padina australis) Extract can Promote Performance, Innate Immune Responses, Digestive Enzyme Activities, Intestinal Gene Expression and Resistance against Aeromonas hydrophila in Common Carp (Cyprinus carpio).

Eight-week oral administration of Padina australis ethyl acetate extract at 100, 200, and 400 mg/kg diets was assessed on the growth performance, tight junction proteins, intestinal immunity, and disease resistance to Aeromonas hydrophila in common carp (Cyprinus carpio). A total of 300 healthy common carp weighing around 14.8 ± 0.03 g were randomly assigned into four equal groups within 12 glass aquariums, each in three replicates (25 fish/tank), for the feeding trial experiment. The first group served as the control group and was fed an un-supplemented diet, whilst the other three groups were offered diets containing graded amounts of Padina australis ethyl acetate extract at 100, 200, and 400 mg/kg, respectively. The growth indices, including final weight, length, weight gain rate, specific growth rate, and feed conversion ratio, were meaningfully improved in fish fed with the algae at 200 and 400 mg/kg compared to the control fish (p < 0.05). Similarly, digestive enzyme activities and serum immune parameters were significantly higher in all treatments, especially 200 and 400 mg/kg fed groups, compared to the control (p < 0.05). In parallel, significant upregulation of genes related to integrity and the immune system was shown in the intestine of these treatment groups compared to control fish (p < 0.05). When fish were challenged with A. hydrophila, the cumulative survival percentages were 53.3% (p = 0.215), 70.0 % (p = 0.009), and 76.7% (p = 0.002) in fish fed 100, 200, and 400 mg/kg diets, respectively, compared to 36.7% survival in control fish (p = 0.134). These data show that the eight-week dietary administration of P. australis extract to common carp can enhance growth performance, digestive enzyme activity, immune response, and disease resistance to A. hydrophila infection.

Can allelopathy of Phragmites australis extracts aggravate the effects of salt stress on the seed germination of Suaeda salsa?

Phragmites australis is highly adaptable with high competitive ability and is widely distributed in the coastal wetland of the Yellow River Delta. However, allelopathic effects of P. australis on the growth of neighboring plants, such as Suaeda salsa, are poorly understood. In this study, germination responses of S. salsa seeds collected from two different habitats (intertidal zone and inland brackish wetland) to the extracts from different part of P. australis were compared. Potential allelopathic effects on germination percentage, germination rate, radicle length, and seedling biomass were analyzed. The germination of S. salsa was effectively inhibited by P. australis extract. Extract organ, extract concentration, and salt concentration showed different effects, the inhibitory rates were highest with belowground extract of P. australis between the four different parts. Germination percentage and germination rate were significantly decreased by the interactive effect of salt stress and extract concentration in S. salsa from a brackish wetland but not in S. salsa from the intertidal zone. The impact of different extracts of P. australis on radicle length and seedling biomass of S. salsa showed significant but inconsistent variation. The response index results showed that the higher concentration of extract solution (50 g·L−1) of P. australis had stronger inhibitory effect on the seed germination and seedling growth of S. salsa while the belowground extract had the strongest negative effect. Our results indicated that allelopathy is an important ecological adaptation mechanism for P. australis to maintain a high interspecific competitive advantage in the species’ natural habitat.

Application of Box-Behnken Design for the Extraction of Padina australis

Optimization extraction of the brown algae Padina australis using the Box-Behnken design has been carried out. Box-Behnken design in relation to Response Surface Methodology analysis was conducted with four experimental factors (i.e., solvent concentration, temperature, extraction time, and sample to solvents ratio) towards the responses of yield antioxidant, anti-tyrosinase, anti-glycation, total phenolic content, and fucoxanthin content, completing with 29 running experiments. P. australis extraction's optimum condition was acquired at 79.99% solvent concentration, 18.48 hours extraction time, 44.50ºC temperature, and 1:9 ratio powders and solvents. The optimum condition provided a 7.30% extraction yield, 43.94% antioxidant activity, 86.83% anti-tyrosinase, 98.06% anti-glycation, 9.53 mg GAE/g total phenolic content, and 347.55 µg/g fucoxanthin content. Respond Surface Methodology analysis with the Box-Behnken design succeeded in making the appropriate model for producing the optimum P. australis extract.

Phytochemical and Safety Evaluations of Finger Lime, Mountain Pepper, and Tamarind in Zebrafish Embryos.

Plants play a pivotal role in drug discovery, constituting 50% of modern pharmacopeia. Many human diseases, including age-related degenerative diseases, converge onto common cellular oxidative stress pathways. This provides an opportunity to develop broad treatments to treat a wide range of diseases in the ageing population. Here, we characterize and assess the toxicological effects of finger lime (Citrus australasica), mountain pepper (Tasmannia lanceolata), and small-leaved tamarind (Diploglottis australis) extracts. The characterization demonstrates that these Australian native plants have antioxidant potential and, importantly, they have high concentrations of distinct combinations of different antioxidant classes. Using zebrafish larvae as a high-throughput pre-clinical in vivo toxicology screening model, our experiment effectively discriminates which of these extracts (and at what exposure levels) are suitable for development towards future therapies. The LC50-96h for finger lime and tamarind were >480 mg/L, and 1.70 mg/L for mountain pepper. Critically, this work shows that adverse effects are not correlated to the properties of these antioxidants, thus highlighting the need for combining characterization and in vivo screening to identify the most promising plant extracts for further development. Thus, we present a high-throughput pre-clinical screening that robustly tests natural plant products to utilize the diversity of antioxidant compounds for drug development.

Evaluation of Phytochemical, Antioxidant and Antibacterial Activities of Selected Medicinal Plants

Medicinal plants are important reservoirs of bioactive compounds that need to be explored systematically. Because of their chemical diversity, natural products provide limitless possibilities for new drug discovery. This study aimed to investigate the biochemical properties of crude extracts from fifteen Nepalese medicinal plants. The total phenolic contents (TPC), total flavonoid contents (TFC), and antioxidant activity were evaluated through a colorimetric approach while the antibacterial activities were studied through the measurement of the zone of inhibition (ZoI) by agar well diffusion method along with minimum inhibitory concentrations (MIC) by broth dilution method. The methanolic extracts of Acacia catechu and Eupoterium adenophorum showed the highest TPC (55.21 ± 11.09 mg GAE/gm) and TFC (10.23 ± 1.07 mg QE/gm) among the studied plant extracts. Acacia catechu showed effective antioxidant properties with an IC50 value of 1.3 μg/mL, followed by extracts of Myrica esculenta, Syzygium cumini, and Mangifera indica. Morus australis exhibited antibacterial activity against Klebsiella pneumoniae (ZoI: 25mm, MIC: 0.012 mg/mL), Staphylococcus aureus ATCC 25923 (ZoI: 22 mm, MIC: 0.012 mg/mL), Pseudomonas aeruginosa (ZoI; 20 mm, MIC: 0.05 mg/mL), and methicillin-resistant Staphylococcus aureus (MRSA) (ZoI: 19 mm, MIC: 0.19 mg/mL). Morus australis extract showed a broad-spectrum antibacterial activity, followed by Eclipta prostrata, and Hypericum cordifolium. Future study is recommended to explore secondary metabolites of those medicinal plants to uncover further clinical efficacy.

Cytotoxic Effects of Trifolium pratense, Baptisia australis, and Rubus idaeus Extracts on CHO-K1 Cells

The cytotoxic effects of red clover, blue false indigo, and red raspberry plant extracts were evaluated on CHO-K1 cells. The hormone-dependent CHO-K1 cells are ovarian cells derived from Chinese hamsters. Trifolium pratense (red clover) extracts were obtained from the blossoms and leaves of the red clover plant. Baptisia australis (blue false indigo) extracts were obtained from the roots, stems, and leaves of the blue false indigo plant. Rubus idaeus (red raspberry) extracts were prepared from the fruits of the red raspberry plant. Two methods, soxhlet and microwave assisted extractions, were utilized and evaluated for their effectiveness in producing phyto extracts. Methanol was the solvent used in both methods. In all experiments, the CHO-K1 cell line was exposed to the different extracts for a period of 48 hours. An MTS assay was performed to evaluate the effectiveness of the cytotoxic capabilities of each extract at different concentrations on the CHO-K1 cell line. After the collection of all the data, the 1:1 combination of red clover and red raspberry extracts, obtained via soxhlet extraction, yielded the most potent cytotoxic effects on the CHO-K1 cell line.

UJI AKTIVITAS EKSTRAK Padina australis SEBAGAI ANTIBAKTERI Propionibacterium acnes PENYEBAB JERAWAT

The apperance of acne is a problem for many suffers because can lower confidience and shame. Many people have attempted to treat or eliminate acne, that is by antibiotic. However of antibiotic clearly has side effects, and the ultilization of natural material is the solution. One of them is Padina australis which contains flavonoid, tanin dan saponin potentially as an antibacterial. The purpose of this research is to derermne the concentration of Padina australis extract with methanol 98% which has optimal activity in improving the growth of Propionibacterium acnes based on inhibition zone test and minimum inhibitory concetration (MIC). Qualitative phytochemical test were carried out on alkoloids, flavonoids, saponins, tannin and steroids. Testing these bacteria using disc dffusion methods. MIC of Padina australis extrct used dilution method with concentrtaion of 3.75%, 7.5%, 15% and 30%. Inhibition zone test used disc diffusion method with concentrtaion of 60%, 80% and 100%. The result of phytochemical screening testing Padina australis extrct test showed that there are secondary metabolite compounds alkoloids, flavonoids, saponins, tannin and steroids. MIC test of Padina australis extrct against Propionibacterium acnes occured at a concentration of 30% and the inhibition zone test was found at concentration of 100% which was the most optimal in inhibiting with an average of the inhibition zone width 6.20 mm.

Optimization of ultrasound‐assisted extraction conditions for phenolics, antioxidant, and tyrosinase inhibitory activities of Vietnamese brown seaweed (Padina australis)

This study aimed to determine the optimum ultrasound-assisted extraction (UAE) conditions for obtaining the highest yields of phenolics and antioxidants from Padina australis. The effects of extraction variables including temperature (40–60°C), extraction time (50–80 min), ethanol concentration (0%–60%) and sample-to-solvent ratio (1–5 g/100 mL) on the total phenolic content (TPC), DPPH radical scavenging activity (DRSA) and ferric reducing antioxidant power (FRAP) were determined and optimized using Box-Behnken design in conjunction with response surface methodology (RSM). The extraction temperature, ethanol concentration and sample-to-solvent ratio significantly affected TPC and DRSA, while extraction time had no impact on TPC and antioxidant activity of P. australis within the tested ranges. The optimal UAE conditions were determined to be ultrasonic temperature of 60°C, ultrasonic time of 60 min, solvent concentration of 60% (v/v) aqueous ethanol and sample-to-solvent ratio of 1 g/100 mL. The developed mathematical models were found to be reliable predictors for TPC, DRSA and FRAP, and the predicted values fit well with the experimental data (R2 = 0.86–0.96). The extract was then fractionated to generate n-hexane, ethyl acetate and aqueous fractions. Of these fractions, ethyl acetate fraction was found to possess the highest values of TPC (807.20 mg GAE/g), DPPH (1,417.01 mg TE/g), FRAP (615.07 mg TE/g dry fraction) and the strongest tyrosinase inhibitory activity (29.90 mg AAE/g). Practical applications The study employed ultrasound-assisted extraction technique, an advanced extraction method, and RSM method for maximizing the yields of phenolics and antioxidants from P. australis. In addition, the tyrosinase inhibitory activity of P. australis extract and its fractions, for the first time, was also investigated. The results suggested the optimal UAE conditions to recover phenolics and bioactive compounds with high antioxidant and tyrosinase inhibitory properties from P. australis. Moreover, this study establishes that the ethyl acetate fraction derived from P. australis was a rich source of phenolics and antioxidants; thus, it could be further isolated and purified to obtain individual bioactive compounds for the utilization in the food and cosmeceutical industries.

Phytochemical composition and in -vitro pharmacological evaluation of Emex australis Steinh: A natural source of enzyme inhibitors

The current research investigated the chemical profiling and biological activities of Emex australis Steinh. aerial and fruit parts (methanol and dichloromethane-DCM extracts). Chemical composition was established by determining the amounts of phenolic and flavonoid contents, HPLC-PDA polyphenolic quantification, and UHPLC-MS secondary metabolites profiling to understand the observed biological activities. Antioxidant evaluation was performed utilizing six different assays (DPPH, ABTS, FRAP, CUPRAC, phosphomolybdenum, and metal chelation). Moreover, enzyme inhibition abilities against cholinesterases, α-amylase, α-glucosidase, and tyrosinase were also determined. The fruit methanol extract contained the highest phenolic (157.96 mg GAE/ g extract) and flavonoid contents (41.43 mg QE/g extract), which could justify the observed significant antioxidant (except metal chelating), α-amylase, α-glucosidase, and tyrosinase inhibitory potentials. The other extracts were active against cholinesterases and tyrosinase. The HPLC-PDA polyphenolic analysis quantified a number of 11 phenolic secondary metabolites. The fruit-MeOH extract was found to quantify the maximum phenolics with catechin (4.27 μg/g extract) and gallic acid (4.84 μg/g extract) in higher amounts. Similarly, rutin present in maximum quantity in the aerial-MeOH extract (2.93 μg/g extract). Furthermore, the UHPLC-MS study of aerial and fruit methanol extracts reveals the existence of 22 secondary metabolites, most of which were flavonoid derivatives. Besides that, Pearson coefficient analysis (PCA) was also carried to determine a possible correlation between bioactive contents and observed biological assays. Thus, it is concluded that E. australis extracts contain important classes of secondary metabolites and also exhibited considerable antioxidant and inhibition potential against clinically relevant enzymes.

Antibacterial activity of Padina australis extract tablet against Escherichia coli

Antibacterial activity of Padina australis extract tablet against Escherichia coli

Eco-friendly reduction of graphene oxide via agricultural byproducts or aquatic macrophytes

Commercial and chemically synthesized graphite oxides were subjected to reduction processes using two plant extracts. Ficus carica (agricultural byproduct) and Phragmites australis (aquatic macrophyte) extracts were used as alternative reducing agents to conventional chemicals to prepare reduced graphene oxide (rGO). The raw and prepared materials were characterized through UV–Vis spectroscopy, SEM-EDX, particle size distribution, elemental analysis, thermal analysis, Raman spectroscopy, FT-IR, and X-ray diffraction. Results showed the reduction capability of these plant extracts for the oxygen functional groups on the surface of graphite oxides. UV–Vis spectroscopy results are similar to that observed when chemical reducing agents are used. The X-ray diffraction peaks for the chemically synthesized and commercial graphite oxides were detected at 2θ = 10.8° and 11°, respectively. Subsequent to the reduction process, the peaks of rGO were observed at 24.50° and 43°, indicating the successful reduction of graphite oxide. The synthesized rGO samples comprised 5–7 layers.

Synergistic effects of Iranian seaweed compounds for anticandidal properties and optimization by Response Surface Methodology

An optimization procedure was applied to the anticandicidal property investigation of four different Iranian seaweed extract composition. Response surface methodology (RSM) by the four levels- three factor Box–Behnken design, including Gracilaria arquata concentration (X1), Nizimudidnia zanardini concentration (X2), Cystoceria indica concentration (X3) and Padina australis concentration (X4), has been used to antiCandidal property screening. Results showed the coefficient determination (R2) was appropriate for the second-order model using multiple regression analysis. Concerning the anticandicidal property, the seaweeds extract composition of 10mg/ml Gracilaria arquata extract, 5mg/ml Nizimudinia zanardini extract, 4.5mg/ml Cystoceria indica extract and 2mg/ml Padina australis extract was found to be optimal. Under the optimized composition, the Candida albicans growth inhibition zone was 26.23 mm. The experimental yield was well matched with the predicted yield.

Effectiveness of Brown Algae (Padina australis) Extract as Antioxidant Agent

The pattern of disease development has shifted from infectious diseases to degenerative diseases that are triggered by a free radical. The body needs an antioxidant that able to ward off free radicals. One of the potential natural resources is brown algae that contain bioactive compounds and widely used in medicine and the pharmaceutical industry. This research aims to identify the effectiveness of brown algae (Padina australis) extract as a natural antioxidant agent. This research was carried out in several steps, including algae extraction by sonicator method, phytochemical test to identify secondary metabolites in extract and antioxidant test by using DPPH method. The results showed that the extract of brown algae (Padina australis) contained flavonoids, alkaloids, saponin, and steroids. It also has antioxidant activity with an IC50 value of 102,590 µg/mL.

Antioxidant capacity of the extracts from flowers of Erica australis L.: Comparison between microwave hydrodiffusion and gravity (MHG) and distillation extraction techniques - Formulation of sunscreen creams

Microwave hydrodiffusion and gravity (MHG) extraction of Erica australis flowers was optimized evaluating different microwave irradiation powers (25−200 W). Collected extracts were compared with the liquid phase obtained by conventional distillation. Their total phenolic content, antioxidant capacity and color features were evaluated. Microscopical properties of the flower tissues allowed assessing the distinct effects of the extraction processes. The cosmetic application of the collected bioactive extracts in the formulation of sunscreen creams with waters from three different thermal spring waters and the corresponding characterization (e.g. chemical, bioactive and rheological features) and sensory analysis were also made. For cosmetic comparative purposes, extracts from Ulex europaeus flowers obtained by MHG procedure was also analyzed. The stability of these oil-in-water model emulsions was tested during accelerated oxidation conditions. Results indicated that MHG at 50 W for 130 min was the most adequate work conditions for the extraction of antioxidant compounds from these wild flowers (around 0.27 mg Trolox eq/g flower dry weight and 0.01 mg ascorbic acid/g flower dry weight or 0.04 mg FeSO4 * 7H2O/g flower dry weight). This procedure also led a drop of energy consumption environmental impact (about 8 times less) in comparison with distillation method. Small total color differences were detected between the gathered extracts. The incorporation of flower extracts produced similar effects when compared with added commercial antioxidants except for viscous behavior. Sensorially, E. australis extract incorporated with thermal waters displayed a positive effect on the skin cream application of the formulated cosmetic, mainly with thermal water 3.

Antibacterial Potential of Aqueous Extracts and Compounds from Selected Brown Seaweeds

Background: The incident of antibacterial resistance is increasing rapidly. Seaweeds, the marine macroalgae that are rich in bioactive compounds have the potential to be applied as an antimicrobial agent.Objective: The objective was to assess the potential of brown seaweed aqueous extracts (Sargassum polycystum and Padina australis) and commercial pure compounds (alginic acid and fucoidan) as antimicrobial agent toward Gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa as well as Gram-positive bacteria, Staphylococcus aureus.Methods: Powdered brown seaweeds were macerated with distilled water and followed by filtration. The aqueous extracts were recovered by ethanol precipitation, oven-dried, and stored at 4°C. Aqueous extracts were examined for their qualitative phytochemical content and antibacterial susceptibility test using Kirby–Bauer method.Results: S. polycystum was reported for higher extraction yield (7.00%) than P. australis (1.40%). The presence of steroid, phytosterols, and phenols was observed in S. polycystum extract while steroid and phytosterols were observed in P. australis extract. In antibacterial susceptibility test, there was no inhibition shown by both seaweed extracts against the four bacteria tested. Fucoidan (0.50 mol/L) and alginic acid (0.50 mol/L) were observed to have antibacterial property against S. aureus (with inhibition zone of 7.43±0.17 mm and 7.45±0.14 mm, respectively).Conclusion: The aqueous extracts of S. polycystum and P. australis have shown low antibacterial activity, as compared to fucoidan and alginic acid. Further studies on the mode of antibacterial activity possessed by fucoidan and alginic acid will be carried out.