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Objective: Cyanobacteria are novel sources of bioactive substances with important biological activities. In this study, the total phenolic content (TPC) and bioactive (antioxidant, antidiabetic, and antibacterial) properties of a freshwater cyanobacteria, Chroococcus minutus were investigated.Material and Method: Methanol extract of C. minutus were prepared and subjected to different biological assays to determine the TPC, antioxidant, and alpha-glucosidase inhibition properties. The antibacterial activity was done using microtiter plate dilution assay against various medically important bacterial pathogens.Result and Discussion: C. minutus has a TPC of 11.27 ± 0.14 mg GAE/g. Antioxidant efficiency of C. minutus are characterized by having potent DPPH scavenging activity with IC50 value of 255 μg/ml. Assessment of alpha-glucosidase inhibition property showed that C. minutus extract have potent inhibition activity with IC50 of 5.50 μg/ml as compared to acarbose (standard antidiabetic drug). In addition, C. minutus extract exhibited potent antibacterial activities against Bacillus cereus, Listeria monocytogenes, and Methicillin-resistant Staphylococcus aureus. The current investigation shows the potential of C. minutus as source of active metabolites with important use in pharmaceutical applications.

Seaweeds are known sources of marine bioactive substances with diverse biological activities important in the synthesis of medically important novel drugs. The proximate and elemental compositions as well as bioactive properties of a brown macroalga, Sargassum aquifolium (Turner) C. Agardh, were studied. Results showed that proximate composition of S. aquifolium contain high carbohydrate (32.29 ± 0.17%) and ash (30.19 ± 0.14%) content. Elemental composition of the seaweed exhibited a decreasing order of Na > Ca > K > Mg > Mn > Fe > Zn > Cu > Pb > Cr > Cd. The seaweed had a total phenolic content (TPC) of 5.74 ± 0.04 mg GAE/g. Antioxidant activities of S. aquifolium were characterized by having potent ABTS+ [2,2’-azino-bis (3-ethylbenzothiazoline- 6-sulfonic acid)] scavenging activity and high copper reduction capacity with IC50 value of 107 μg/mL and 21.01 μg/mL respectively. Evaluation of tyrosinase and elastase inhibition activities showed that S. aquifolium extract has potent inhibition activities with IC50 of 39.00 μg/mL and IC50 of 231.00 μg/mL, respectively – more effective than kojic acid and tocopherol. In addition, in vitro assessment of α-glucosidase and α-amylase inhibition property showed that S. aquifolium extract has potent inhibitory activity as compared to acarbose (standard anti-diabetic drug) with IC50 of 15.60 and 59.0 μg/mL, respectively. Also, the S. aquifolium extract exhibited effective antimicrobial activities against bacterial pathogens such as penicillin acylase-producing Bacillus cereus (MIC = 125 μg/mL), Staphylococcus saprophyticus (MIC = 250 μg/mL), methicillin-resistant Staphylococcus aureus (MRSA) (MIC = 250 μg/mL), Staphylococcus epidermidis (MIC = 250 μg/ mL), and Pseudomonas aeruginosa (MIC = 500 μg/mL). The current investigation is a pioneering study in the Philippines that shows the potential of S. aquifolium as novel source of bioactive compounds with important use for pharmaceutical applications.

Seaweeds are marine organisms capable of producing diverse kinds of chemical compounds with promising pharmacological use. The study evaluated the proximate and elemental composition and the potential antioxidant (using CUPRAC, ABTS+, and DPPH assays) and antibacterial activities (using microtiter plate dilution assay) of Ulva prolifera O. F. Müller. The seaweed has a total phenolic content of 829 ± 2.00 mg GAE/g. Antioxidant efficiency of U. prolifera exerted high ability of reducing copper ions, potent ABTS+ and DPPH scavenging activities in a concentration-dependent manner with IC50 value of 24.7 mg GAE/mL, 43.52 mg GAE/mL, and 54.1 mg GAE/mL, respectively, more effective than ascorbic acid. In vitro antibacterial activity assay showed that U. prolifera exhibited inhibitory activity against bacterial pathogens such as Methicillin-resistant Staphylococcus aureus (MIC = 125 mg/mL), S. epidermidis (MIC = 125 mg/mL), and Pseudomonas fluorescens (MIC = 500 mg/mL). This investigation is the first documented report regarding antibacterial activity of U. prolifera against P. fluorescens. In addition, results showed elemental composition to be in decreasing order of Ca K Mg Na Mn Fe Zn Cu Pb Cd Cr. Proximate composition of U. prolifera showed high carbohydrate and protein content with a percentage composition of 36.20 ± 0.27% and 23.72 ± 0.31% (dry weight), respectively. This study is the first report in the Philippines that shows the potential of U. prolifera as an excellent candidate organism as source of chemical compounds with relevant application to the pharmacological industry.

Phytotelmata are a unique habitat for the existence of new and rare species of microalgae. In the Philippines, no comprehensive study was documented regarding the diversity of microalgae on bromeliad phytotelmata. This study provides the first floristic survey that presents the taxonomy and species composition of phytotelm microalgae associated with bromeliad tanks of pineapple [Ananas comosus (L.) Merr] from Calauan, Laguna. A total of 15 algal taxa were taxonomically identified from the collected samples, of which six species (five genera) are classified as members of Cyanophyceae, four species (three genera) belong to Zygnematophyceae, three species (three genera) to Chlorophyceae, and one species (one genus) each for Euglenophyceae and Klebsormidiophyceae. The study reports an additional of nine species (Phacus monilatus, Monoraphidium lunare, Coelastrum proboscideum, Klebsormidium flaccidum, Cosmarium granatum, Cosmarium contractum var. rotundatum, Phormidium breve, Arthrospira jenneri, and Chroococcus subnudus) as new records in the global inventory list of phytotelm microalgae and 13 new taxa as additional records of microalgae in phytotelm microhabitat of Asia. Also, the occurrence of a rare photosynthetic euglenoid [Phacus monilatus (Stokes) Lemmerman] and a green microalga, [Monoraphidium lunare Nygaard, J. Komárek, J. Kristiansen, & O.M. Skulberg] are described for the first time in the Philippines. Diagnostic descriptions and keys are presented to distinguish the different species of phytotelm algae. The results of this study provide important knowledge regarding the species composition of microalgae in bromeliad phytotelmata found in the Philippines.

Objective: Green microalgae are fast growing organisms and are known to have diverse bioactive compounds and biomolecules. The chemical composition and antibacterial activities of a green microalga, A. dimorphus BIOTECH 4039 were studied. Material and Method: Dried algal biomass of A. dimorphus was subjected to proximate and elemental composition analysis. Methanolic extract of A. dimorphus was used to determine the total phenolic content and antibacterial activity of the microalga. The antibacterial activity against medically important bacterial pathogens was done using modified Kirby-Bauer inhibition assay. Results and Discussion: Acutodesmus dimorphus contained high amounts of protein, ash, and lipid with percent composition of 43.19 ± 0.13, 26.92 ± 0.01, and 14.17 ± 0.04, respectively. The elemental nutrient composition of the algal biomass was observed to be in a decreasing order of Ca > Mg > K > Mn > Na > Fe > Zn > Pb > Cu > Cd >Cr. In addition, A. dimorphus has a TPC of 5.34 ± 0.09 mg GAE/g. Potent antibacterial activities of A. dimorphus extract were observed against Methicillin-Resistant Staphylococcus aureus, S. epidermidis, penicillin acylase-producing Bacillus cereus with zones of inhibition of 15.1 ± 0.3 mm, 13.5 ± 0.1 mm, and 6.82 ± 0.7 mm, respectively. The study shows the use of A. dimorphus as good alternative source of important compounds and microelements that can be use in industrial and pharmaceutical application.

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