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This review outlines the research that was carried out regarding the isolation of bioactive compounds from marine-derived bacteria and fungi by China-based research groups from 2009-2018, with 897 publications being surveyed. Endophytic organisms featured heavily, with endophytes from mangroves, marine invertebrates, and marine algae making up more than 60% of the microbial strains investigated. There was also a strong focus on fungi as a source of active compounds, with 80% of publications focusing on this area. The rapid increase in the number of publications in the field is perhaps most notable, which have increased more than sevenfold over the past decade, and suggests that China-based researchers will play a major role in marine microbial natural products drug discovery in years to come.

Antimicrobial peptides (AMPs) are highly associated with antipathogenic activity, without generating drug resistance in targeted bacteria. In this study, the existence of AMPs in the Tibetan swine, a China-native, cold-resistant and seldom-sick breed of pig, was investigated. A peptide secreted by a Tibetan swine intestinal tract-derived Bacillus strain was isolated using reversed-phase chromatography (RPC), ultrafiltration and reversed-phase high-performance liquid chromatography (RP-HPLC). The peptide was identified by mass spectrometry and was characterised for activity against Escherichia coli and Staphylococcus aureus. The 16-amino acid peptide (ASVVNKLTGGVAGLLK), named TP, had a molecular mass of 1568.919 Da and exhibited inhibitory activity against Gram-positive and Gram-negative bacteria [minimum inhibitory concentrations (MICs) of 2.5-5 µM and 10-20 µM for E. coli and S. aureus, respectively] as well as human MKN-45 and NB4 tumour cell lines [50% inhibitory concentration (IC 50 ) = 4.686 µM and 11.479 µM, respectively]. TP also exhibited weak haemolytic activity. Furthermore, TP enhanced cell membrane permeability and K + outflow, bound with E. coli genomic DNA in vitro and inhibited E. coli growth. Thus, TP represents a strong candidate as an antibacterial peptide., (Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)

Background: Corn gluten meal, containing approximately 600 g kg(-1) protein, is a main by-product of corn wet milling. The annual output of corn gluten meal in China is over 840 000 tons. However, it is difficult to utilise corn gluten meal in the food industry because of its low water solubility and amino acid imbalance. In the present study, corn gluten meal was hydrolysed by different proteases to produce hydrolysates with antioxidant activity in order to increase its value. The hydrolysis conditions were optimised by multiple linear regression and response surface methodology. Furthermore, the amino acid sequence of one corn peptide was determined., Results: The optimal conditions for alkaline protease hydrolysis were a pH of 9.5, an enzyme/substrate (E/S) ratio of 8 g per 100 g, a liquid/solid ratio of 25 mL g(-1) and a time of 75 min, while the optimal conditions for flavourzyme hydrolysis were a pH of 7, an E/S ratio of 4.2 g per 100 g and a time of 66 min. After gel filtration chromatography, fraction F2 exhibited the highest antioxidant activities. The amino acid sequence of a purified peptide in fraction F2 was determined as Gly-His-Lys-Pro-Ser (507.2 Da)., Conclusion: The results indicate that corn gluten meal hydrolysates and/or its isolated peptides are potent antioxidants., (© 2013 Society of Chemical Industry.)

Porcine reproductive and respiratory syndrome is an important infectious disease of pigs and has a significant harmful effect on the livestock industry, especially in China. PRRSV ORF1b gene encodes primary proteins which play a vital role during PRRSV replication. In this paper, various 12-amino-acid peptides were displayed. These peptides could bind to the polymerase and helicase of PRRSV ORF1b protein, respectively, in which p9 exerted the highest antiviral activity with an IC50 of 56 μM, and the minimum toxicity to cells. It was proved that p9 inhibited PRRSV replication in infected MARC-145 cells in a dose-dependent manner, and the amino acid sequence of HRILMRIR was important for antiviral activity of p9. Also, p9 could bind to the cell membrane and penetrated into cells. These result suggested that p9 might be a potential therapeutic drug for PRRSV infection., (Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.)

Chemical investigation of the EtOAc extract of the endophytic fungus Bionectria ochroleuca, isolated from the inner leaf tissues of the plant Sonneratia caseolaris (Sonneratiaceae) from Hainan island (China), yielded two new peptides, pullularins E and F (1 and 2) together with three known compounds (3-5). The structures of the new compounds were unambiguously determined on the basis of one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. The absolute configurations of amino acids were determined by HPLC analysis of acid hydrolysates using Marfey's method. The isolated compounds exhibited pronounced to moderate cytotoxic activity against the mouse lymphoma cells (L5178Y) with EC₅₀ values ranging between 0.1 and 6.7 µg/mL.

In this study, a new peptide named BmK AGP-SYPU1 with an analgesic effect was purified from the venom of Chinese scorpion Buthus martensi Karsch (BmK) through a four-step chromatographic process. The mouse twisting test was used to identify the target peptides in every separation step. The purified BmK AGP-SYPU1 was further qualified by RP-HPLC and HPCE. The molecular mass determined by the MALDI-4800-TOF/TOF MS for BmK AGP-SYPU1 was 7544 Da. Its primary structure of the N-terminal was obtained using Edman degradation. The gene sequence of BmK AGP-SYPU1 was cloned from the cDNA pool and genomic of scorpion glands, respectively, and then expressed in Escherichia coli. The sequence determination showed that BmK AGP-SYPU1 was composed of 66 amino acid residues with a new primary structure. The metal chelating affinity column and cation exchange chromatography were used to purify the recombinant BmK AGP-SYPU1. Consequently, the native and recombinant BmK AGP-SYPU1 showed similar analgesic effects on mice as assayed using a mouse twisting model. These results suggested that BmK AGP-SYPU1 is a new analgesic component found in the Chinese scorpion Buthus martensi Karsch., (Copyright © 2010 John Wiley & Sons, Ltd.)

Scorpion venom is a rich source of bioactive peptides. From the venom of Chinese scorpion Buthus martensi Karsch (BmK), a novel short chain peptide BmKX of 31-amino acid residues was purified, and its amino acid sequence and gene structure were determined. The gene of BmKX was composed of two exons interrupted by an 86-bp intron at the codon-7 upstream of the mature peptide. Although its gene structure is similar to those of other known scorpion toxins, its amino acid sequence, especially the cysteine framework, is different from those of all other known subfamilies of short-chain scorpion toxins. The solution structure of BmKX, determined with two-dimensional NMR spectroscopy, shows that BmKX also forms a typical cysteine-stabilized alpha/beta scaffold adopted by most short-chain scorpion toxins, consisting of a short 3(10)-helix and a two-stranded antiparallel beta-sheet, and the short N-terminal segment forms a pseudo-strand of the beta-sheet. However, the orientation between the helix and the beta-sheet is significantly different from the others, which might be the reason for its unique but still unclear physiological function.

Two groups of antimicrobial peptides have been isolated from skin secretions of Bombina maxima. Peptides in the first group, named maximins 1, 2, 3, 4 and 5, are structurally related to bombinin-like peptides (BLPs). Unlike BLPs, sequence variations in maximins occurred all through the molecules. In addition to the potent antimicrobial activity, cytotoxicity against tumor cells and spermicidal action of maximins, maximin 3 possessed a significant anti-HIV activity. Maximins 1 and 3 were toxic to mice with LD(50) values of 8.2 and 4.3 mg/kg, respectively. Peptides in the second group, termed maximins H1, H2, H3 and H4, are homologous with bombinin H peptides. cDNA sequences revealed that one maximin peptide plus one maximin H peptide derived from a common larger protein.

From a cDNA library made from venom glands of Chinese scorpions of Buthus martensii Karsch, full-length cDNAs encoding precursors of two venom peptides have been isolated using a cDNA probe synthesized by polymerase chain reaction. Sequence analysis of the cDNAs revealed that one encoded precursor was 85 amino acid residues long including a signal peptide of 19 residues and a mature peptide (named BmK T) of 66 residues, and another encoded precursor was 84 residues long containing the same length signal peptide and a mature peptide (BmK M4 isoform, named BmK M4') of 64 residues. The analysis of amino acid sequence similarity indicated that the BmK T was homologous with both mammalian and insect toxins from BmK scorpion or other scorpions, and the BmK M4' was highly homologous with the members of the mammalian neurotoxin family of BmK, having two point mutations in amino acid residue sequence compared to BmK M4, a natural toxin from BmK.

Three new variants of acidic proline-rich proteins (At, Au, Aw) were found in human parotid saliva by isoelectric focusing and basic gel electrophoresis. Electrophoretic comparison of the purified proteins and their tryptic peptides suggested minor charge and size differences from other acidic PRPs. Genetic and biochemical studies indicate that the At and Aw proteins are allelic products of the PRH1 locus. Gene frequencies of the At productive allele (PRH1(6)) in Japanese, Chinese, and Malays were 0.008, 0.012, and 0.004, respectively. The Au protein was also found in Japanese (2 in 746 samples), Chinese (1 in 215 samples), and Malays (1 in 220 samples), however, the Aw protein was found only in one Japanese (n = 746). These three proteins were not found in 106 Indian subjects.