Antioxidant potential of hydrolyzed proteins from Thai rice varieties and docking studies of novel peptides with free radicals

Five native rice varieties from Thailand were used to extract seed storage proteins. The most prevalent proteins were glutelin, globulin, albumin, and prolamin. Significant scavenging activity of crude glutelin was seen in all samples, and this activity was further improved in hydrolysates made with pepsin. Using PeptideCutter (https://web.expasy.org/peptide_cutter/), 99 peptides were produced by simulating the gastrointestinal digestion of rice glutelin (Oryza sativa Indica Group; GenBank: AGT59178.1). AnOxPePred-1.0 (https://services.healthtech.dtu.dk/services/AnOxPePred-1.0/) was used to predict the antioxidant potential of many peptides. The top five peptides with high ABTS•+ and DPPH• scavenging activities were examined for molecular docking. The results indicate that, when compared to glutathione, the positive control, the octapeptide TNTPGVVY had the lowest binding affinity with DPPH• (-4.26 kcal/mol), and the 13-amino acid peptide, TQQQEQAQAQDQY, had the lowest binding affinity with ABTS•+ (-3.70 kcal/mol). The antioxidant properties of both synthetic peptides were confirmed by in vitro assays. Neither peptide exhibited cytotoxic effects on human cell lines. This research indicates the value of Thai red glutinous rice and its potential to be developed into health food products for those who love eating sticky rice

Ethnobotany and antimicrobial peptide from plants of Solanaceae family: An update and future prospect

The Solanaceae is an important plant family that has been playing an essential role in traditional medicine and human nutrition. Members of the Solanaceae are rich in bioactive metabolites and have been used by different tribes around the world for ages. Antimicrobial peptides (AMPs) from plants have drawn great interest in recent years and raised new hope for developing new antimicrobial agents for meeting the challenges of antibiotic resistance. This review aims to summarize the reported AMPs from plants of the Solanaceae with possible molecular mechanisms of action as well as to correlate their traditional uses with reported antimicrobial actions of the peptides. A systematic literature study was conducted using different databases until August 2019 based on the inclusion and exclusion criteria. According to literature, a variety of AMPs including defensins, protease inhibitor, lectins, thionin-like peptides, vicilin-like peptides, and snaking were isolated from plants of the Solanaceae and were involved in their defense mechanism. These peptides exhibited significant antibacterial, antifungal and antiviral activity against organisms for both plant and human host. Brugmansia, Capsicum, Datura, Nicotiana, Salpichora, Solanum, Petunia, and Withania are the most commonly studied genera for AMPs. Among these genera, Capsicum and the Solanum ranked top according to the total number of studies (35%–38% studies) for different AMPs. The mechanisms of action of the reported AMPs from Solanaceae was not any new rather similar to other reported AMPs including alteration of membrane potential and permeability, membrane pore formation, and cell aggregation. Whereas, induction of cell membrane permiabilization, inhibition of germination and alteration of hyphal growth were reported as mechanisms of antifungal activity. Plants of the Solanaceae have been used traditionally as antimicrobial, insecticidal, and antiinfectious agents, and as poisons. The reported AMPs from the Solanaceae are the products of chemical shields to protect plants from microorganisms and pests which unfold an obvious link with their traditional medicinal use. In summary, it is evident that AMPs from this family possess considerable antimicrobial activity against a wide range of bacterial and fungal pathogens and can be regarded as a potential source for lead molecules to develop new antimicrobial agents

Laccase isozymes of Pleurotus sajor-caju culture on husk and bran of black sticky rice and their potential on indigo carmine decolourisation

Extracellular laccases of Pleurotus sajor-caju grown on solid state medium consisted of husk and bran of black sticky rice, were partially purified by DEAE–cellulose chromatography. These laccases could be separated into three groups: unboundLac and bound fractions (pool1Lac and pool2Lac). The optimum pH of these laccases was studied using ABTS as substrate. It was found that the pH optimum for unboundLac fell in the range of 3–5 and 3–4 for pool1Lac and pool2Lac. The indigo carmine decolourisation capacity was compared between unboundLac and pool2Lac. It was found that the optimal pH for indigo carmine decolourisation were 5 and 3 for unboundLac and pool2Lac, respectively. In the range of various dye concentrations tested, it was found that indigo carmine at 10 ìM with the enzyme activity of 0.01 U, gave the best dye decolourisation with 40.47% within 120 min for unboundLac and with 18.61% within 150 min for pool2Lac. High amount of enzyme used of these laccases might improve decolourisation ability