The inhibition of viral protease is an important target in antiviral drug discovery and development. To date, protease inhibitor drugs, especially HIV-1 protease inhibitors, have been available for human clinical use in the treatment of coronaviruses. However, these drugs can have adverse side effects and they can become ineffective due to eventual drug resistance. Thus, the search for natural bioactive compounds that were obtained from bio-resources that exert inhibitory capabilities against HIV-1 protease activity is of great interest. Fungi are a source of natural bioactive compounds that offer therapeutic potential in the prevention of viral diseases and for the improvement of human immunomodulation. Here, we made a brief review of the current findings on fungi as producers of protease inhibitors and studies on the relevant candidate fungal bioactive compounds that can offer immunomodulatory activities as potential therapeutic agents of coronaviruses in the future.

In this study, we investigated the antioxidant and anti-inflammatory phytochemicals and paramagnetic species in dragon fruit using high-performance liquid chromatography (HPLC) and electron paramagnetic resonance (EPR). HPLC analysis demonstrated that dragon fruit is enriched with bioactive phytochemicals, with significant variations between each part of the fruit. Anthocyanins namely, cyanidin 3-glucoside, delphinidin 3-glucoside, and pelargonidin 3-glucoside were detected in the dragon fruit peel and fresh red pulp. Epicatechin gallate, epigallocatechin, caffeine, and gallic acid were found in the dragon fruit seed. Additionally, 25–100 mg × L⁻¹ of dragon fruit pulp and peel extracts containing enrichment of cyanidin 3-glucoside were found to inhibit the production of reactive oxygen species (ROS), reactive nitrogen species (RNS), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in cell-based studies without exerted cytotoxicity. EPR primarily detected two paramagnetic species in the red samples. These two different radical species were assigned as stable radicals and Mn²⁺ (paramagnetic species) based on the g-values and hyperfine components. In addition, the broad EPR line width of the white peel can be correlated to a unique moiety in dragon fruit. Our EPR and HPLC results provide new insight regarding the phytochemicals and related stable intermediates found in various parts of dragon fruit. Thus, we suggest here that there is the potential to use dragon fruit peel, which contains anthocyanins, as a natural active pharmaceutical ingredient.

Uvaria longipes (Craib) L.L.Zhou, Y.C.F.Su & R.M.K.Saunders, Artabotrys burmanicus A.DC, Marsypopetalum modestum (Pierre) B.Xue & R.M.K.Saunders and Dasymaschalon sp. have been used for traditional medicine to treat cancer-like symptoms in some ethnic groups of Thailand and Laos. We evaluated the anti-cancer activity of these Annonaceae plants against several human cancer cell lines. The apoptosis induction was detected by Annexin/propidium iodide (PI) staining. Phytochemical screening was tested by standard protocols and bioactive compounds were determined by HPLC. The crude extracts from leaves of U. longipes, Dasymaschalon sp., A. burmanicus, and M. modestum showed particular effects that were found to vary depending on the cancer cell line, suggesting that the effect was in a cell-type specific manner. Interestingly, the induction of apoptotic cell death was prominent by the leaves-derived crude extract of M. modestum. This crude was, therefore, subjected to cell cycle analysis by PI staining. Results showed that this crude extract arrested cell cycle and increased the percentage of cells in the SubG1 phase in some cancer cell lines. The phytochemical screening tests indicated that all crude extracts contained tannins and flavonoids. HPLC of flavonoids using standards identified rutin as an active compound in U. longipes and Dasymaschalon sp., whereas quercetin was found in U. longipes and M. modestum. These crude extracts provide a new source for rutin and quercetin, which might be capable of inducing cancer cell apoptotic death in a cell-type specific manner. This suggests, by analyzing the major bioactive compounds, the potential use of these crudes for chemotherapy in the future.

Five glutinous purple rice cultivars and non-glutinous purple rice cultivated in different altitudes in the north of Thailand were collected. The samples were extracted using ethanol and determined for anthocyanins using HPLC. The total phenolic content (TPC), total flavonoid content (TFC), and the antioxidant, anti-inflammatory, and antimicrobial activities against foodborne pathogens were investigated. The highland glutinous cultivar named Khao’ Gam Luem-Phua (KGLP) extract had significantly high levels of cyanidin 3-O-glucoside, peonidin 3-O-glucoside, delphinidin 3-O-glucoside, TPC, and TFC, as well as exerting a potent antioxidant activity through ABTS assay (524.26 ± 4.63 VCEAC, mg l-ascorbic-ascorbic/g extract), lipid peroxidation (IC₅₀ = 19.70 ± 0.31 µg/mL), superoxide anions (IC₅₀ = 11.20 ± 0.25 µg/mL), nitric oxide (IC₅₀ = 17.12 ± 0.56 µg/mL), a suppression effect on nitric oxide (IC₅₀ = 18.32 ± 0.82 µg/mL), and an inducible nitric oxide synthase production (IC₅₀ = 23.43 ± 1.21 µg/mL) in combined lipopolysaccharide-interferon-γ-activated RAW 264.7 murine macrophage cells. Additionally, KGLP also exhibited antimicrobial activity against foodborne pathogens, Staphylococcus aureus, Escherichia coli, Salmonella Enteritidis, and Vibrio parahaemolyticus. These results indicate that Thai glutinous purple rice cultivated on the highland could be a potent natural source of antioxidants, anti-inflammatories, and antimicrobial agents for use as a natural active pharmaceutical ingredient in functional food and nutraceutical products.

High performance liquid chromatography (HPLC) for catechins and related compounds in Miang (traditional Lanna fermented tea leaf) was developed to overcome the matrices during the fermentation process. We investigated a variety of columns and elution conditions to determine seven catechins, namely (+)-catechin, (−)-gallocatechin, (−)-epigallocatechin, (−)-epicatechin, (−)-epigallocatechin gallate, (−)-gallocatechin gallate, (−)-epicatechin gallate, as well as gallic acid and caffeine, resulting in the development of reproducible systems for analyses that overcome sample matrices. Among the three reversed-phase columns, column C (deactivated, with extra dense bonding, double endcapped monomeric C18, high-purity silica at 3.0 mm × 250 mm and a 5 µm particle size) significantly improved the separation between Miang catechins in the presence of acid in the mobile phase within a shorter analysis time. The validation method showed effective linearity, precision, accuracy, and limits of detection and quantitation. The validated system was adequate for the qualitative and quantitative measurement of seven active catechins, including gallic acid and caffeine in Miang, during the fermentation process and standardization of Miang extracts. The latter contain catechins and related compounds that are further developed into natural active pharmaceutical ingredients (natural APIs) for cosmeceutical and nutraceutical products.

The aim of this study is to determine antioxidant and anti-inflammatory activities relating to the antiosteoporosis effects of various perilla seed meal (PSM) fractions. The remaining waste of perilla seed obtained from cold oil compression was extracted with 70% ethanol and sequentially fractionated according to solvent polarity with hexane, dichloromethane, ethyl acetate, and water. The results indicated that the seed-meal ethyl acetate fraction (SMEF) exhibited the highest antioxidant and anti-inflammatory activities, and rosmarinic acid (RA) content. The signaling pathways induced by the receptor activator of the nuclear factor kappa B (NF-κB) ligand (RANKL) that trigger reactive oxygen species (ROS) and several transcription factors, leading to the induction of osteoclastogenesis, were also investigated. The SMEF clearly showed attenuated RANKL-induced tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts and TRAP activity. A Western blot analysis showed that the SMEF significantly downregulated RANKL-induced NF-κB, AP-1 activation, and the nuclear factor of activated T-cell 1 (NFATc1) expression. SMEF also suppressed RANKL-induced osteoclast-specific marker gene-like MMP-9 using zymography. Furthermore, the SMEF showed inhibition of RANKL-induced ROS production in RAW 264.7 cells. The results suggest that the SMEF, which contained high quantities of RA, could be developed as a natural active pharmaceutical ingredient for osteoclastogenic protection and health promotion.