Introduction

Saltwater algae (seaweeds) have considerable potential as a resource for next-generation biorefineries1. According to González Fernández et al.2, the distinctive algal extracts render it an increasingly promising alternative for diverse applications. Macroalgae could be classified into green, red, and brown categories3. Chlorophyta includes species that are called green algae4.

Some green algae species inhabit freshwater and saltwater ecosystems. Marine macroalgae from the Chlorophyta phylum mainly include the Ulvophyceae class5. Ulva lactuca, a species of green seaweed, constitutes a significant biomass. It is distinguished by a notably unique biological composition, particularly its elevated concentration of cell wall polysaccharides6. Sulfated polysaccharides (SPs) are negatively charged polysaccharides characterized by sulfate groups within their carbohydrate backbone, which may be naturally occurring or synthetically produced.

Ulvan (Ulv) is predominant in Ulva algae walls7, which constitutes 9–36% of Ulva dry weight8. Research indicated that Ulv primarily consists of different monosaccharides with different degrees of sulfation, exhibiting variability according to harvest season, species, growth environment, cultivation methods, and extraction techniques, and the interest in Ulv is due to its effective biological activity9,10.

Cancer, a significant health threat, primarily results from abnormalities in cell division. Disruptions may arise from genetic, chemical, and environmental factors11. Pancreatic cancer (PDAC) has become the third most lethal solid malignancy in the United States, following lung and colorectal cancer, and is projected to become the second-leading cause of cancer-related deaths in the United States by 203012. Exposure to chemical agents, including heavy metals, particularly at sufficiently high doses, can induce severe toxic effects such as cardiotoxicity, hepatotoxicity, neurotoxicity, nephrotoxicity, and potentially fatal hematopoietic toxicity, which may contribute to carcinogenic processes13. Therefore, novel antitumor compounds that exhibit minimal toxicity should be discovered14. Consequently, numerous researchers have concentrated on identifying novel anticarcinogenic compounds derived from algae and plants15.

Impairs the transmission and control of redox signals has the potential to cause molecular damage; this is known as oxidative stress. It has a role in the etiology of many diseases and the aging process16. Sulfated polysaccharides produced from algae, particularly ulvan, offer antioxidant and free-radical scavenging properties that may protect living things from oxidative harm17,18.

Viral infections are prevalent and impose considerable strain on healthcare systems globally. The availability of specific antiviral drugs for numerous viral infections is limited, resulting in symptomatic treatment and systemic supportive therapy being the main approaches14. There is an urgent requirement for innovative and efficient agents19. Investigations into natural antiviral agents exhibiting carbohydrate characteristics have underscored the significance of sulfated polysaccharides, such as ulvan, which exhibit notable antiviral properties20.

Herein, U. lactuca ulvan (ULU) was extracted, optimized, characterized, and assessed for its biological activities, such as anticancer effects against Panc-1 (pancreatic cancer), along with DPPH free radical scavenging assay, and potential of anti-Hepatitis A virus (HAV). Based on the findings, this study will be essential in exploring Ulvan’s potential utility as a natural molecule in cancer treatment, antioxidant therapy, and perhaps antiviral applications, laying the groundwork for future research and development in the biomedical and pharmaceutical industries.

Experimental section

Ulva lactuca sampling

Ulva lactuca was collected by Prof. Fekry Ashour Mourad, affiliated with the National Oceanography and Fisheries Institute in Egypt, during May 2022, specifically from the Gulf Suez coast of Egypt. Algal samples were collected from a non-protected public beach, where no permission or licence was required, and where no commercial use or genetic resource export was involved. Morphological and taxonomic identification were then conducted using the methods outlined by Aleem21,22, accompanied by a microscopic examination as described by Lipkin23, and subsequently verified through the Algae Base website24,25. After collection, samples underwent multiple H2O washes to exclude any associated biota or sand, etc. Following this, U. lactuca were rinsed again with fresh H2O to exclude salts, then 72 h in a shaded area before being oven-dried at 60 °C for 3 h using a Memmert oven from Germany; milling occurred via Brown Mill coffee grinder from Berlin, Germany, to obtain U. lactuca powder (ULp) that was stored for future experimental use. The voucher specimen (Ulva lactuca—Herb. Nasr-1Gr7-5–2022) has been deposited at the herbarium of late Professor Abdel-Halim Nasr at the Botany and Microbiology Department, Faculty of Science, Alexandria University, Egypt, with the help of Prof. Mohamed Saad Abdelkareem.

(ULU) extraction optimization

ULp de-pigmentation involved using 100 mL hexane for a day, accompanied by 3000 rpm shaking to eliminate non-polar impurities. The ULp was subsequently filtered. Then, it was submerged in 120 mL of 95% ethanol for another whole day, with moderate agitation, to eliminate soluble contaminants26. Following a three-hour exposure to a vacuum at 60 °C, the residue underwent drying.

In the subsequent phase of the experiment, 30 g of dried seaweed powder underwent a series of hot water extraction processes aimed at isolating ulvan (sulfated heteropolysaccharides) under a range of conditions, temperatures (40 °C, 60 °C, 80 °C, 100 °C, 120 °C, 140 °C, and 160 °C), seaweed-to-water ratios (1/10, 1/20, 1/30, 1/40, 1/50, and 1/60 w/v), a variety of pH levels (1.5, 3, 4.5, 6, and 7.5), and a range of extraction durations (20, 35, 50, 65, 80, 95, 110, and 125 min). Following filtration, the liquid portion underwent centrifugation at 6708× g for a quarter-hour, after which the supernatant was dialyzed for 2 days at 4 °C against H2O to eliminate minor contaminants. The obtained liquid portion volume was reduced via rotary evaporator and precipitated with four volumes of 100% ethanol at − 20 °C. Following 48 h, the precipitate was centrifuged and dried under vacuum at 60 °C.

Final ulvan extract yield (UY) measured as follows:

UY % = (ULU wt./ULp wt.) × 10027.

Chemical analysis of (ULU)

Sulfate content (SC)

According to Torres et al.28, sulfate content was estimated, which corroborates its consistency with traditional procedures29. Gelatin reagent (GR) and BaCl2 were initially made by mixing 75 mg gelatin in 25 mL H2O, then incubation occur at 80 °C for 10 min with vigorous mixing, then the addition of 250 mg barium chloride took place, finally kept at 4 °C. By using 96-well clear polystyrene microplate (WPM), 140 µL of 0.5 mol/L HCl were added in each well followed by the addition of 20 µL (non-hydrolyzed and hydrolyzed ULU) and 0.5 mol/L of the negative control HCl. After mixing with 40 µL GR in each well for 20 min, absorbance at 405 nm was determined via a Sunrise microplate reader device (TECAN, Woburn, Inc, USA, MA), subsequently SC was determined as follow:

SC = {(µH)− (µN) }± p σH² + σN².

Where σH and µH represent the standard deviation and mean of SC for hydrolyzed ULU, respectively and σN and µN represent those for non-hydrolyzed ULU, respectively.

Total Sugar Composition (TSC) and Total Protein Composition (TPC)

TSC and TPC were calculated in order to determine the Purity degree of ULU according to phenol–sulfuric acid method30 and the Lowry method31, respectively.

Moisture and ash content

Via oven heating ULU for 24 h at 103 °C, % dry weight was measured32. Ash content was calculated gravimetrically by drying 70 mg ULU at 550 °C for 14 h8.

Elemental analysis (EA)

C, N, H, and S in ULU were performed with a Vario Micro Cube(VMC), Germany Elementer (GE).

Uronic acid (UA)

UA was calculated via the meta-hydroxy diphenyl method33. In this procedure, 0.4 mL of 1 mg/mL ULU was applied to 2.4 mL of conc H2SO4, the mixture was heated for 30 min up to 100 °C with 120 mM sodium tetraborate, after cooling, 150 µL of m-hydroxydiphenyl reagent was applied with 15 min incubation, then ab was determined at a range (400 to 700 nm).

(ULU) characterization

HPLC

Monosaccharide composition of ULU was determined via HPLC (Agilent, USA, California) after a process of acid hydrolysis using different reference monosugars34.

FTIR

ULU active chemical groups were analyzed using an FTIR spectrometer (Bruker, Germany, ALPHA), which measured within the 4000–400 cm⁻¹ range, using a resolution of 4.0 cm⁻¹ and averaged over 128 scans35.

XRD

The crystallinity of Ulvan were detected using the Bruker D2 Phaser X-ray diffractometer, which is equipped with Cu Kα radiation (λ = 1.5412 Å) and operates at 30 mA and 40 kV over a 2θ range of 5° to 85°.

TGA

Thermogravimetric analysis (TGA) tests were conducted on a Netzsch (DSC) 204 through a stable flow of nitrogen. An amount of 1.71 mg ULU was progressively heated at 20 °C to 1000 °C per min., with recording the thermo-gram8.

(SEM & EDX) analysis

High Resolution Scan Electron Microscope {(HRSEM), Jeol, JSM-IT 200, Japan} using a 15 kV accelerating voltage was applied to study ULU surface morphology36,37. While ULU element composition was determine via the same device with an energy-dispersive X-ray spectrometer (EDX)38.

ULU cytotoxicity

Vero Cells (VCs) (derived from the kidney of an African green monkey) with the Panc-1 cell line supplied by the American Type Culture Collection (ATCC), Rockville, M, culturing in Dulbecco’s modified Eagle’s medium (DMEM) was done with a day of incubation in 37 °C at conc 5 × 10⁴ cells/well, ULU was then added to the 96-WP, with six wells containing media or 0.5% DMSO, used as controls and after a whole day, cell viability was measured and viability % was determine as follow39.

Viability%= {(ODs/ODc)} × 100%, where ODs and ODc represent the optical density of ULU and the control, respectively. Inhibitory conc (IC50), defined as the concentration inducing 50% toxicity in intact cells, was measured using the software GraphPad (CA, San Diego, USA).

DPPH free radical scavenging activity of (ULU)

Different concentrations of ULU were used at concentrations ranging from 2 to 1000 µg/mL, from each conc 4 µL was added to 3 mL of a DPPH solution prepared at 0.004% (w/v). Using the UV spec (Spectronic 1201, Milton Roy), absorbance was measured at 515 nm using ascorbic acid as reference, inhibition percentage % (IP) was measured as described below:

IP = {(AS - AC)/AS} x 100], where AS and AC represent the ab of test and control, respectively40.

Antiviral activity of (ULU) against Hepatitis A virus(HAV)

HAV (HM175) strain (ATCC, VR:1402) was cultured and tested in relation to vero cells (VCs) via MTT method41,42,43; after viral and VCs propagation with conc 2 × 105 cells/100 L, ULU was added for each well, OD at 590 nm was then measured with an ELISA reader (SunRise, TECAN, Inc., USA), to viral determine inhibition % (VI) with the evaluation of IC50 as follow39.

VI=(A − N)/(B − N) ˣ100%.

In which A, N, and B corresponded to the OD of ULU in virus-infected cells, the OD of the virus control and the OD of the cell control, respectively.

Statistical analysis

Statistical analysis was performed using SPSS software, version 9.4.1 (CA, San Diego, USA). Comparisons were made using one-way ANOVA, followed by Tukey’s post hoc test, with significance set at p < 0.05.

Results and discussion

Ulvans were produced using hot-water extraction followed by ethanol precipitation, as described by Binsuwaidan et al.44. Hot water extraction produced the maximum yield when compared to other studies45,46. The extraction conditions were optimized at 120 °C for 50 min, with a pH of 4.5 and a 1:30 ratio of algal powder to water (Figs. 1, 2, 3 and 4). This process yielded 23.33 ± 0.28% from 30 g of algal powder (Table 1). The yield was twice that reported by Binsuwaidan et al.44 (11.20 ± 0.32%) and exceeded those reported by Ponce et al.47 for Ulva ohnoi (14.84%), Chen et al.48 (17.8 ± 0.6%), and Klongklaewad et al.49 (15.2%). Table 1 summarizes the chemical composition and elemental analysis of the extracted ulvan (ULU), while Table 2 presents a comparison of Ulva species regarding extraction and purification methods, conditions, yield, and sulfate content44,45,46,47,48,49,50,51,52,53. Although advanced techniques such as microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) can achieve higher ulvan yields, they require specialized equipment, precise control of energy, and may cause partial degradation or alteration of sensitive compounds54,55. In contrast, our hot water extraction method offers a simpler, cost-effective, and reproducible approach suitable for large-scale production. The concentration of uronic acid was 5.19 µg/while the sulfate content was 35.35 ± 0.25%, considerably better than sulfate amounts reported by Ibrahim et al.56 (19.72%) and Binsuwaidan et al.44 (14.95%), which is responsible for the majority of the activities of ulvans57,58. Furthermore, TSC was 42.74 ± 0.32%, surpassing that of Ibrahim et al.56 (24.27%) and Binsuwaidan et al.44 (33.66%). The elevated sugar content (42.74 ± 0.32%) and reduced protein content (5.15 ± 0.05%) may be associated with heightened photosynthetic activity in May, which promotes growth and development59,60. The extract exhibited a moisture content of 56.4 ±0.35%, indicative of the hydrophilic and hygroscopic characteristics of ulvan polysaccharides61. In addition, the ash content was 39.001 ±0.26%, indicating a correlation between high ash content and raised sulfate levels, as shown by Costa et al.62, Olasehinde et al.63, and Ibrahim et al.56. The HPLC analysis (Fig. 5) delineated the monosaccharide composition of ULU, which includes rhamnose (14.10 µg/g dry weight), fucose (11.04 µg/g dry weight), fructose (10.35 µg/g dry weight), and galactose (7.41 µg/g dry weight), with rhamnose as the predominant sugar. Rhamnose is a significant indicator of ulvan64, with a small amount of galactose10.

Fig. 1
Fig. 1
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Effect of different temperature degrees on ulvan production from Ulva lactauca using a one factor at a time (OFAT) approach with (Time:30 min., pH:4, alga: water ratio,1:20 kept constant). Yield per 1 g of dry alga increased from 0.065 g at 40 ℃ to 0.212 g at 120 ℃. *The letters (a, b, and c) indicate a significance level of P < 0.05. *Values sharing the same letter are not significantly different. *Note: All experimental data representing the effect of optimized conditions were statistically analyzed using SPSS software (version 9.4.1, San Diego, CA, USA). One-way ANOVA followed by Tukey’s post hoc test was applied, and differences were considered significant at p < 0.05.

Fig. 2
Fig. 2
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Impact of varying extraction times on ulvan yield from Ulva lactauca using a one factor at a time (OFAT) approach with (Temperature 120 ℃, pH:4, alga: water ratio, 1:20 kept constant). Yield per 1 g of dry alga increased from 0.095 at 20 min to 0.243 at 50 min.

Fig. 3
Fig. 3
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Effect of varying pH levels on ulvan production in Ulva lactauca using a one factor at a time (OFAT) approach with (Temperature 120 ℃, Time:50 min, alga: water ratio, 1:20 kept constant). Yield per 1 g of dry alga increased from 0.091 at pH 1.5 to 0.221 at pH 4.5.

Fig. 4
Fig. 4
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Impact of varying water volumes on ulvan production in Ulva lactauca using a one factor at a time (OFAT) approach with (Temperature 120 ℃, Time:50 min, pH 4.5 kept constant).Yield per 1 g of dry alga increased from 0.099 at 1:10 to 0.228 at 1:30, the final optimized yield.

Table 1 Proximate chemical analysis and monosaccharide composition of Ulvan from Ulva lactauca.
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Table 2 Comparison of Ulva species: Extraction and purification methods, conditions, yield, and sulfate content in relation to the present study.
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Fig. 5
Fig. 5
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HPLC Chromograph of Ulvan from Ulva lactauca.

FTIR

The FTIR spectrum of ULU (Fig. 6) demonstrates multiple functional groups that signify its chemical structure, with purity similar to that of other Ulvamembers, according to Quemener et al.65; Tian et al.66; Mhatre et al.67; Olasehinde et al.63; Ibrahim et al.56; Binsuwaidan et al.44 and Maray et al.68.

Fig. 6
Fig. 6
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FT-IR spectra of ulvan extracted from Ulva lactauca.

The distinctive hydroxyl groups (OH) present in polysaccharides are responsible for the wide absorption band in the 3810.80–3629.79 cm⁻¹ area. That means the Ulvan structure does include sugar-based functional groups. A peak at 3184.79 cm⁻¹ indicates C-H vibrations, particularly from CH₂ groups. The observed peaks at 2918.24 and 2850.36 cm⁻¹ correspond to the C-H vibrations, which are characteristic of hydrocarbon chains (CH₂ and CH₃) found in the sugar backbone of polysaccharides, thereby reinforcing the organic composition of Ulvan69. Atmospheric interferences or CO₂ may be present in the region 2371.12–2340.69 cm⁻¹. It is a typical feature of FTIR spectra and has no impact on the analysis of Ulvan’s fundamental functional groups. The absorption at 1732.80 cm⁻¹ corresponds to C = O stretching vibrations, signifying carbonyl groups (C = O), often associated with uronic acids, a constituent of the Ulvan structure, hence corroborating the existence of polymeric characteristics in the sample70. The peaks at 1467.30–1342.50 cm⁻¹ indicate C-H bending and O-H deformation vibrations linked to aliphatic and hydroxyl groups within the polysaccharide66. The strong absorption in the range of 1280.88–1161.47 cm⁻¹ is due to S = O groups, indicating the presence of sulfate groups, a characteristic feature of Ulvan56, which contributes to its biological activities58. The range 1098.62–986.34 cm⁻¹ is related to C-O-C and C-OH restricting glycosidic bonds and hydroxyl groups in the polysaccharide sugar backbone66. The absorption within the range of 805.07–648.17 cm⁻¹ indicates C-O-S vibrations, hence substantiating the existence of sulfate esters, a crucial structural component in sulfated polysaccharides such as Ulvan. The peak at 455.76 cm⁻¹ is ascribed to low-frequency vibrations, presumably associated with the skeletal modes of the sugar backbone, offering more structural insights.

XRD

Figure 7shows that ULU has a semi-crystalline nature characterized by prominent peaks in accordance with Binsuwaidan et al.44.

Fig. 7
Fig. 7
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X-ray diffraction (XRD) analysis of ulvan extracted from Ulva lactauca.

The dominant peak at 2θ = 19.8° correlates to 021 plane, exhibiting a substantial level of structural order characteristic of semi-crystalline polysaccharides. Further peaks identified at 2θ values of 9.6° (010), 16.3° (004), 27.04° (115), 31.8° (310), and 49.1° (317) substantiate the ordered structure inside the ulvan matrix, enhancing its rigidity and stability. Although ulvan and similar polysaccharides are often considered amorphous71, this pattern demonstrates harmony between amorphous and semi-crystalline areas.

Olasehinde et al.63 proposed that repeated aldobiouronic units may explain its crystalline area, whereas Barakat et al.71 suggested that its amorphous region could be due to its heterogeneous chemical makeup. In biomaterials, the semi-crystalline areas improve thermal stability and structural integrity; in medicinal formulations, the amorphous parts improve bioavailability by increasing solubility and flexibility.

TGA

The thermal stability and decomposition characteristics of the ULU (Fig. 8) have been examined using thermogravimetric analysis (TGA). The findings are similar to those reported by Gruskiene et al.72. The TGA curve revealed the weight loss pattern over a temperature range from 40 °C to 1000 °C, emphasizing key stages of thermal breakdown. Weight loss started between 40.46 °C and 860.73 °C, with a notable beginning at 773.78 °C and ending at 864.86 °C. The midpoint of this phase was 814.59 °C, with a total weight decrease of 3.304 mg, equal to a 23.419% reduction. This phase likely indicates the removal of residual moisture and volatile organic compounds, suggesting that the original components of Ulvan stay stable up to about 770 °C, after which significant thermal disintegration begins. The main decomposition occurred between 860.73 °C and 994.93 °C, starting at 876.15 °C and ending at 919.10 °C, with a midpoint at 897.81 °C. During this phase, substantial weight loss was observed, with a reduction of 8.275 mg, or 58.656% of the total weight. This large weight loss suggests the breakdown of the core polysaccharide structure and its conversion into volatile products. The notable degradation at high temperatures highlights the durability of Ulvan’s molecular framework against decomposition, indicating the temperature at which its thermal stability is most tested. The results show that Ulvan maintains significant thermal stability up to about 770 °C, after which gradual decomposition occurs. The initiation of decomposition at higher temperatures indicates that Ulvan polysaccharides have inherent thermal resistance, likely due to their complex structure with sulfated polysaccharide chains.

Fig. 8
Fig. 8
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TGA of Ulvan from Ulva lactauca.

ULU SEM and EDX

According to Binsuwaidan et al.44, ULU has a semi-crystalline structure, is not smooth, and resembles Ulva lactauca in its irregular forms (Fig. 9 [A]). Further EDX examination (Fig. 9 [B]) revealed a variety of elements, with oxygen (O) accounting for 51.57%, carbon (C) for 12.08%, sulfur (S) for 14.78%, magnesium (Mg) for 2.71%, potassium (K) for 0.43%, calcium (Ca) for 0.48%, sodium (Na) for 16.08%, and chloride (Cl) for 1.86%.

Fig. 9
Fig. 9
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SEM micrographs (A), (scale bar 5 μm) and corresponding EDX elemental of ulvan (B) extracted from Ulva lactuca, showing various surface morphologies. The SEM images reveal semi-crystalline structures, which are closely correlated with the distribution of elements such as sulfur (S), sodium (Na), and magnesium (Mg) detected by EDX, suggesting that these elemental compositions may contribute to the observed crystalline-like features rather than originating solely from the polymeric chains of ulvan.

Cytotoxicity of ULU

The cytotoxicity illustrated in Fig. 10 reveals a dose-dependent inhibitory activity. At lower concentrations (2–62.5 µg/ml), the compound exhibited minimal or no significant cytotoxicity, with viability percentages surpassing 98%. However, at concentrations of 125 µg/ml and higher, a noticeable decrease in cell viability was observed, indicating a significant cytotoxic effect. The maximum inhibition (86.15%) occurred at 1000 µg/ml, resulting in a viability of 13.85%. The determined IC50value of 123.51 ± 10.95 µg/ml suggests that ULU has considerable cytotoxicity towards Panc-1 cells; this agrees with Maray et al.68, who reported nearly similar results of natural polysaccharides tested against lung cancer cells. The close alignment in IC50 values indicates that ULU shares comparable potency with previously studied polysaccharides in targeting cancer cells. Previous studies stated that the heteropolysaccharide ulvan extracted from Ulva showed significant antitumor growth activity73. As shown in Fig. 10, increasing concentrations of ulvan led to significant inhibition of cancer cell proliferation while exhibiting minimal effects on healthy cells. This suggests that ulvan possesses selective cytotoxicity towards cancer cells, highlighting its potential as a therapeutic agent.

Fig. 10
Fig. 10
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Cytotoxic effect of ulvan from Ulva lactauca on Panc-1 and Vero cell lines.

DPPH scavenging

Many studies demonstrate the antioxidant properties of ulvan48,74,75. Results in Table 3 suggest a concentration-dependent increase in scavenging activity, substantiating the compound’s antioxidant capability. At the lowest evaluated concentration (2 µg/mL), the scavenging activity was negligible (0.98% ±0.13). As the concentration increased, the activity markedly elevated, reaching 88.31% ±2.64 at the maximum concentration (1000 µg/mL). The IC50value, indicating the concentration necessary to scavenge 50% DPPH radicals, was established at 263.73 ± 9.41 µg/mL. Conversely, Maray et al.68 extracted ulvan from Ulva lactuca with similar techniques but indicated little antioxidant activity, with an IC50 value significantly above 263.73 µg/mL. This divergence underscores the heterogeneity in antioxidant activity, which may be associated with changes in algae species or the extraction methods utilized in contrast46. Antioxidant action relies on the sulfate content76. Although seasonal variation was not assessed in this study, recent research has demonstrated seasonal changes in the composition and antioxidant potential of Ulva lacinulata77. Such findings indicate that environmental and seasonal factors may influence ulvan’s antioxidant activity.

Table 3 DPPH scavenging activity of Ulvan from Ulva lactauca.
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The present work reveals that ULU has considerable antioxidant activity, with a notably lower IC50 value, signifying higher effectiveness than previously documented. While the current study did not explore chemical modifications or combinations with other bioactive compounds, such approaches could be investigated in future research to assess their potential impact on ulvan’s antioxidant capacity for broader medicinal and commercial applications.

ULU Virucidal

Koenighofer et al.78 indicate that ulvan significantly inhibits several virus strains. These chemicals inhibit viral entry by disrupting its binding with the target cell. ULU Virucidal effect could originate from ULU binding with viruses or receptors located on its surfaces79. Table 4 revealed moderate antiviral activity (40.25 ± 2.61%) at conc 50 µg/ml. EC₅₀ value for Ulvan was 60.95 ± 0.43 µg/ml, whereas the cytotoxic concentration (CC₅₀) was 230.53 ± 2.09 µg/ml, resulting in a Selectivity Index (SI) of 3.7.

Table 4 Antiviral activity of Ulvan from Ulva lactauca.
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The results indicate moderate antiviral activity of ulvan. Previous studies have shown that combining ulvan with other polysaccharides, such as fucoidan, can modulate antiviral effects, although synergistic activity is not guaranteed, and ulvan may antagonize certain effects80. Additionally, recent studies have highlighted that extraction conditions and algal morphology can significantly influence the chemical, thermal, and molecular properties of ulvan81,82,83, providing context for understanding the physicochemical profile of the polysaccharide observed in this study.

Conclusion

The Ulvan polysaccharide derived from Ulva lactuca (ULU) has significant anticancer activities, particularly at elevated amounts, highlighting its role as a promising viable treatment option; also, it may serve as a biosubstitute for chemical antioxidants. Nonetheless, its antiviral is also taken into consideration; recommended studies should focus on augmenting its virucidal effectiveness by optimizing its amounts, investigating synergizing medicines, or any other promising technique to boost its activities.