Valorization of Rejected Macroalgae Kappaphycopsis cottonii for Bio-Oil and Bio-Char Production via Slow Pyrolysis.

Kappaphycopsis cottonii, a prominent macroalgae species cultivated in an Indonesian marine culture, yields significant biomass, a portion of which is often rejected by industry. This study explores the potential valorization of rejected K. cottonii biomass through slow pyrolysis for bio-oil and biochar production, presenting an alternative and sustainable utilization pathway. The study utilizes a batch reactor setup for the thermal decomposition of K. cottonii, conducted at temperatures between 400 and 600 °C and varying time intervals between 10 and 50 min. The study elucidates the temperature-dependent behavior of K. cottonii during slow pyrolysis, emphasizing its impact on product distributions. The results suggest that there is a rise in bio-oil production when the pyrolysis temperature is raised from 400 to 500 °C. This uptick is believed to be due to improved dehydration and greater thermal breakdown of the algal biomass. Conversely, at 600 °C, bio-oil yield diminishes, indicating secondary cracking of liquid products and the generation of noncondensable gases. Chemical analysis of bio-oils reveals substantial quantities of furan derivatives, aliphatic hydrocarbons, and carboxylic acids. Biochar exhibits calorific values within the range of 17.52-19.46 MJ kg-1, and slow pyrolysis enhances its specific surface area, accompanied by the observation of carbon nanostructures. The study not only investigates product yields but also deduces plausible reaction routes for the generation of certain substances throughout the process of slow pyrolysis. Overall, the slow pyrolysis of rejected K. cottonii presents an opportunity to obtain valuable chemicals and biochar. These products hold promise for applications such as biofuels and diverse uses in wastewater treatment, catalysis, and adsorption, contributing to both environmental mitigation and the circular economy.

An In Vitro Examination of Whether Kratom Extracts Enhance the Cytotoxicity of Low-Dose Doxorubicin against A549 Human Lung Cancer Cells.

Doxorubicin is an effective chemotherapeutic agent in the treatment of solid hematological and non-hematological carcinoma. However, its long-term usage could result in side effects, such as cardiomyopathy, chronic heart failure, neurotoxicity and cancer cell resistance. In this study, we reported the sensitivity enhancement of A549 human lung cancer cells on doxorubicin at a low dose (0.1 ppm) in combination with 10-60 ppm of crude and alkaloid extracts derived from the leaves of Kratom (Mitragyna speciosa (Korth.) Havil. Rubiaceae). A549 cancer cell lines were insensitive to the crude extract containing low mitragynine (MG) (4-5%), while these cells were moderately inhibited by the alkaloid extract containing 40-45% MG (IC50 of 48-55 ppm). The alkaloid extract was found to inhibit A549 cancer cells via apoptosis as suggested by the higher relative fluorescence intensity with Annexin compared to that in propidium iodide (PI), i.e., a positive Annexin and a negative PI. The combination of crude extract and doxorubicin sensitized A549 cancer cells to doxorubicin by 1.3 to 2.4 times, while the combination with the alkaloid induced a 2.6- to 3.4-fold increase in sensitivity. The calculated combination index (CI) for doxorubicin with the crude and alkaloid extracts was 0.6 and 0.3, respectively, showing potential synergistic combinations to reduce the level of dosage of doxorubicin used in chemotherapy. In addition, the synergistic enhancement effect of crude extract on the cytotoxic activity of doxorubicin provides insights into the plausibility of non-alkaloids to influence the biological activities of Kratom.

Evaluations of Andrographolide-Rich Fractions of Andrographis paniculata with Enhanced Potential Antioxidant, Anticancer, Antihypertensive, and Anti-Inflammatory Activities.

Andrographis paniculata is widely used as a traditional medicine in Asian countries. It has been classified as a safe and non-toxic medicine by traditional Chinese medicine. The investigation of the biological activities of A. paniculata is still focused on the crude extract and isolation of its main active compound, andrographolide, and its derivatives. However, the use of andrographolide alone has been shown to exacerbate unwanted effects. This highlights the importance of developing a fraction of A. paniculata with enhanced efficacy as an herbal-based medicine. In this study, the extraction and fractionation of A. paniculata, followed by quantitative analysis using high-performance liquid chromatography coupled with a DAD detector, were established to quantify the andrographolide and its derivative in each fraction. Biological activities, such as antioxidant, anticancer, antihypertensive, and anti-inflammatory activities, were evaluated to study their correlations with the quantification of active substances of A. paniculata extract and its fractions. The 50% methanolic fraction of A. paniculata exhibited the best cytotoxic activities against CACO-2 cells, as well as the best anti-inflammatory and antihypertensive activities compared to other extracts. The 50% methanolic fraction also displayed the highest quantification of its main active compound, andrographolide, and its derivatives, 14-deoxy-11,12-didehydroandrographolide, neoandrographolide, and andrograpanin, among others.

Cutting Edge Aquatic-Based Collagens in Tissue Engineering.

Aquatic-based collagens have attracted much interest due to their great potential application for biomedical sectors, including the tissue engineering sector, as a major component of the extracellular matrix in humans. Their physical and biochemical characteristics offer advantages over mammalian-based collagen; for example, they have excellent biocompatibility and biodegradability, are easy to extract, and pose a relatively low immunological risk to mammalian products. The utilization of aquatic-based collagen also has fewer religious restrictions and lower production costs. Aquatic-based collagen also creates high-added value and good environmental sustainability by aquatic waste utilization. Thus, this study aims to overview aquatic collagen's characteristics, extraction, and fabrication. It also highlights its potential application for tissue engineering and the regeneration of bone, cartilage, dental, skin, and vascular tissue. Moreover, this review highlights the recent research in aquatic collagen, future prospects, and challenges for it as an alternative biomaterial for tissue engineering and regenerative medicines.

Secondary Metabolites from Marine-Derived Bacteria with Antibiotic and Antibiofilm Activities against Drug-Resistant Pathogens.

The search for new antibiotics against drug-resistant microbes has been expanded to marine bacteria. Marine bacteria have been proven to be a prolific source of a myriad of novel compounds with potential biological activities. Therefore, this review highlights novel and bioactive compounds from marine bacteria reported during the period of January 2016 to December 2021. Published articles containing novel marine bacterial secondary metabolites that are active against drug-resistant pathogens were collected. Previously described compounds (prior to January 2016) are not included in this review. Unreported compounds during this period that exhibited activity against pathogenic microbes were discussed and compared in order to find the cue of the structure-bioactivity relationship. The results showed that Streptomyces are the most studied bacteria with undescribed bioactive compounds, followed by other genera in the Actinobacteria. We have categorized the structures of the compounds in the present review into four groups, based on their biosynthetic origins, as polyketide derivatives, amino acid derivatives, terpenoids, as well as compounds with mixed origin. These compounds were active against one or more drug-resistant pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE), vancomycin-resistant Enterococci (VRE), multidrug-resistant Mycobacterium tuberculosis (MDR-TB), and amphotericin B-resistant Candida albicans. In addition, some of the compounds also showed activity against biofilm formation of the test bacteria. Some previously undescribed compounds, isolated from marine-derived bacteria during this period, could have a good potential as lead compounds for the development of drug candidates to overcome multidrug-resistant pathogens.

In-depth study of bio-oil and biochar production from macroalgae Sargassum sp. via slow pyrolysis.

Sargassum is undoubtedly one of the most predominant brown macroalgae, posing a significant disposal problem for coastal areas worldwide. The effective valorization of Sargassum sp. would be beneficial not only for environmental mitigation but also for producing high-value chemicals. However, the valorization of Sargassum sp. for bio-oil and biochar production via slow pyrolysis has not been well studied yet. Hence, this study aimed to conduct a comprehensive investigation into bio-oil and biochar production from Sargassum sp. via slow pyrolysis to provide valuable data for further valorization. A batch reactor was employed, and the pyrolysis of Sargassum sp. was conducted in a temperature range of 400-600 °C and with retention times of 10-50 min. The results showed significant compounds could be identified in bio-oil from Sargassum sp., including carboxylic acids, furan derivatives, aliphatic hydrocarbons, and N-aromatic compounds. Based on the ultimate analysis, the H/C and O/C atomic ratios of biochar were lower than the feedstock, reflecting the occurrence of dehydration and decarboxylation reactions throughout the pyrolysis. Biochar exhibited calorific values in the range of 23.12-25.89 MJ kg-1, indicating it has more potential to be used as a solid fuel than low-ranked coals. Surface morphological analysis was performed by scanning electron microscopy (SEM) and showed a larger surface area in biochar than in the algal feedstock. Furthermore, a reaction model was deduced, and it was confirmed that the pyrolysis reaction obeyed the Arrhenius behaviour. Overall, the slow pyrolysis of Sargassum sp. provides an opportunity to obtain value-added chemicals and biochars, which could be further utilized for other applications.

Antiviral Activities of Algal-Based Sulfated Polysaccharides.

An antiviral agent is urgently needed based on the high probability of the emergence and re-emergence of future viral disease, highlighted by the recent global COVID-19 pandemic. The emergence may be seen in the discovery of the Alpha, Beta, Gamma, Delta, and recently discovered Omicron variants of SARS-CoV-2. The need for strategies besides testing and isolation, social distancing, and vaccine development is clear. One of the strategies includes searching for an antiviral agent that provides effective results without toxicity, which is well-presented by significant results for carrageenan nasal spray in providing efficacy against human coronavirus-infected patients. As the primary producer of sulfated polysaccharides, marine plants, including macro- and microalgae, offer versatility in culture, production, and post-isolation development in obtaining the needed antiviral agent. Therefore, this review will describe an attempt to highlight the search for practical and safe antiviral agents from algal-based sulfated polysaccharides and to unveil their features for future development.

Secondary Metabolites from Marine-Derived Fungi and Actinobacteria as Potential Sources of Novel Colorectal Cancer Drugs.

Colorectal cancer is one of the most common cancers diagnosed in the world. Chemotheraphy is one of the most common methods used for the pharmacological treatment of this cancer patients. Nevertheless, the adverse effect of chemotherapy is not optimized for improving the quality of life of people who are older, who are the most vulnerable subpopulation. This review presents recent updates regarding secondary metabolites derived from marine fungi and actinobacteria as novel alternatives for cytotoxic agents against colorectal cancer cell lines HCT116, HT29, HCT15, RKO, Caco-2, and SW480. The observed marine-derived fungi were from the species Aspergillus sp., Penicillium sp., Neosartorya sp., Dichotomomyces sp., Paradendryphiella sp., and Westerdykella sp. Additionally, Streptomyces sp. and Nocardiopsis sp. are actinobacteria discussed in this study. Seventy one compounds reviewed in this study were grouped on the basis of their chemical structures. Indole alkaloids and diketopiperazines made up most compounds with higher potencies when compared with other groups. The potency of indole alkaloids and diketopiperazines was most probably due to halogen-based functional groups and sulfide groups, respectively.

Antioxidant and antibacterial activities in 21 species of Indonesian sea cucumbers.

Sea cucumbers are marine organisms with uses in food, cosmetics, and medicine. This study aimed to identify Indonesian sea cucumbers with high antioxidant and antibacterial activities. Twenty-one sea cucumber species were used for this study. Antioxidant capacity was evaluated using the 2,2-diphenyl-ß-picrylhydrazine assay. Antibacterial activity was assessed using the disk diffusion assay, whereas the resazurin-based assay was employed to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Volatile compounds possibly related to the biological activity of sea cucumbers were analyzed via gas chromatography-mass spectrometry (GC-MS). Holothuria atra had the strongest antioxidant capacity (IC50 = 14.22 ± 0.87 µg µL-1). Stichopus vastus displayed the best antibacterial activity against Staphylococcus aureus, whereas Stichopus ocellatus extract was most potent against Vibrio cholerae. Holothuria albiventer, which controlled Bacillus subtilis most effectively while also being active against S. aureus and V. cholerae, was the optimal antimicrobial species. H. albiventer and Actinopyga echinites inhibited B. subtilis growth at 12.5 µg µL-1. The MBC tests indicated that the antibacterial activities of sea cucumbers at the MIC were bacteriostatic, rather than bactericidal, in nature. GC-MS analysis uncovered long-chain fatty acids that might be associated with the antibacterial activities of sea cucumbers.

Structure-Activity Relationship of Cytotoxic Natural Products from Indonesian Marine Sponges.

Indonesian marine natural products have been one of the most promising sources in the race to obtain potential drugs for cancer treatment. One of the primary producers of cytotoxic compounds is sponges. However, there are still limited sources of comprehensive reviews related to the relationship between the structure of isolated compounds and their cytotoxic activity. This review remarks the attempt to provide a preliminary guidance from the perspective of structure-activity relationship and its participation on marine natural products research. This guidance is segregated by the compound's classes and their cytotoxic targets to obtain and organized a reliable summary of inter-study of the isolated compounds and their cytotoxicity. Structure-activity relationship is well-known for its ability to tune the bioactivity of a specific compound, especially on synthetic organic chemistry and in silico study but rarely used on natural product chemistry. The present review is intended to narrow down the endless possibilities of cytotoxicity by giving a predictable structure-activity relationship for active compounds. In addition, bioactive framework leads were selected by uncovering a noticeable structure-activity relationship with the intervention of cytotoxic agents from natural sources, especially Indonesian marine sponge.

Antiviral Activities of Andrographolide and Its Derivatives: Mechanism of Action and Delivery System.

Andrographispaniculata (Burm.f.) Nees has been used as a traditional medicine in Asian countries, especially China, India, Vietnam, Malaysia, and Indonesia. This herbaceous plant extract contains active compounds with multiple biological activities against various diseases, including the flu, colds, fever, diabetes, hypertension, and cancer. Several isolated compounds from A. paniculata, such as andrographolide and its analogs, have attracted much interest for their potential treatment against several virus infections, including SARS-CoV-2. The mechanisms of action in inhibiting viral infections can be categorized into several types, including regulating the viral entry stage, gene replication, and the formation of mature functional proteins. The efficacy of andrographolide as an antiviral candidate was further investigated since the phytoconstituents of A. paniculata exhibit various physicochemical characteristics, including low solubility and low bioavailability. A discussion on the delivery systems of these active compounds could accelerate their development for commercial applications as antiviral drugs. This study critically reviewed the current antiviral development based on andrographolide and its derivative compounds, especially on their mechanism of action as antiviral drugs and drug delivery systems.

Cembranoids of Soft Corals: Recent Updates and Their Biological Activities.

Soft corals are well-known as excellent sources of marine-derived natural products. Among them, members of the genera Sarcophyton, Sinularia, and Lobophytum are especially attractive targets for marine natural product research. In this review, we reported the marine-derived natural products called cembranoids isolated from soft corals, including the genera Sarcophyton, Sinularia, and Lobophytum. Here, we reviewed 72 reports published between 2016 and 2020, comprising 360 compounds, of which 260 are new compounds and 100 are previously known compounds with newly recognized activities. The novelty of the organic molecules and their relevant biological activities, delivered by the year of publication, are presented. Among the genera presented in this report, Sarcophyton spp. produce the most cembranoid diterpenes; thus, they are considered as the most important soft corals for marine natural product research. Cembranoids display diverse biological activities, including anti-cancer, anti-bacterial, and anti-inflammatory. As cembranoids have been credited with a broad range of biological activities, they present a huge potential for the development of various drugs with potential health and ecological benefits.

Chemical Diversity and Biological Activity of Secondary Metabolites Isolated from Indonesian Marine Invertebrates.

Marine invertebrates have been reported to be an excellent resource of many novel bioactive compounds. Studies reported that Indonesia has remarkable yet underexplored marine natural products, with a high chemical diversity and a broad spectrum of biological activities. This review discusses recent updates on the exploration of marine natural products from Indonesian marine invertebrates (i.e., sponges, tunicates, and soft corals) throughout 2007-2020. This paper summarizes the structural diversity and biological function of the bioactive compounds isolated from Indonesian marine invertebrates as antimicrobial, antifungal, anticancer, and antiviral, while also presenting the opportunity for further investigation of novel compounds derived from Indonesian marine invertebrates.

Marine-Derived Indole Alkaloids and Their Biological and Pharmacological Activities.

Novel secondary metabolites from marine macroorganisms and marine-derived microorganisms have been intensively investigated in the last few decades. Several classes of compounds, especially indole alkaloids, have been a target for evaluating biological and pharmacological activities. As one of the most promising classes of compounds, indole alkaloids possess not only intriguing structural features but also a wide range of biological/pharmacological activities including antimicrobial, anti-inflammatory, anticancer, antidiabetic, and antiparasitic activities. This review reports the indole alkaloids isolated during the period of 2016-2021 and their relevant biological/pharmacological activities. The marine-derived indole alkaloids reported from 2016 to 2021 were collected from various scientific databases. A total of 186 indole alkaloids from various marine organisms including fungi, bacteria, sponges, bryozoans, mangroves, and algae, are described. Despite the described bioactivities, further evaluation including their mechanisms of action and biological targets is needed to determine which of these indole alkaloids are worth studying to obtain lead compounds for the development of new drugs.

Unique Polyhalogenated Peptides from the Marine Sponge Ircinia sp.

Two new bromopyrrole peptides, haloirciniamide A (1) and seribunamide A (2), have been isolated from an Indonesian marine sponge of the genus Ircinia collected in the Thousand Islands (Indonesia). The planar structure of both compounds was assigned on the basis of extensive 1D and 2D NMR spectroscopy and mass spectrometry. The absolute configuration of the amino acid residues in 1 and 2 was determined by the application of Marfey's method. Compound 1 is the first dibromopyrrole cyclopeptide having a chlorohistidine ring, while compound 2 is a rare peptide possessing a tribromopyrrole ring. Both compounds failed to show significant cytotoxicity against four human tumor cell lines, and neither compound was able to inhibit the enzyme topoisomerase I or impair the interaction between programmed cell death protein PD1 and its ligand, PDL1.

An Effective Heterogeneous Catalyst of [BMIM]3 PMo12 O40 for Selective Sugar Epimerization.

The development of heterogeneous catalysts for the epimerization of sugars has received much less attention than that for the isomerization of sugars. To date, molybdates are the most effective catalysts for the epimerization of sugars, although they lack stability toward hydrolysis of their active sites in water. To solve the issue of the formation of a highly water-soluble heteropolyblue (PMored ) for phosphomolybdates (PMos) in aqueous reaction systems, herein, a 1-butyl-3-methylimidazolium phosphomolybdate ([BMIM]3 PMo12 O40 ) was synthesized through an ion-exchange method. This catalyst was effective and selective for the C2-epimerization of sugars under mild reaction conditions (<100 °C; 1-2 h) with good water-tolerant properties. The reaction was confirmed to occur in a heterogeneous manner and no leaching of PMored was detected by means of UV/Vis spectroscopy. Moreover, the catalyst can be simply separated by filtration and reused for at least eight cycles without a drop in catalytic activity. XRD, FTIR, and X-ray photoelectron spectroscopy measurements indicate that the catalyst is stable under the reaction conditions. In a comparison of the catalytic activity and surface wettability with those of other PMo salts, that is, 1-ethyl-3-methylimidazolium phosphomolybdate ([EMIM]3 PMo12 O40 ), 1-hexyl-3-methylimidazolium ([HexMIM]3 PMo12 O40 ), [choline]3 PMo12 O40 , and cetyltrimethylammonium phosphomolybdate ([CTA]3 PMo12 O40 ), it is found that [BMIM]3 PMo12 O40 has more appropriate hydrophobic-hydrophilic balance, which should be responsible for better catalytic activity and stability.