Plant serine protease inhibitor (SPI): A potent player with bactericidal, fungicidal, nematicidal and antiviral properties

Abstract

This review describes plant originated serine protease inhibitors (SPIs) that target or inhibit different families of serine proteases (SPs), protein-digesting enzymes of various pathogens. SPs play a crucial task in many biological events by catalyzing proteolysis that serves as mediators of signal initiation, transmission and termination of the cellular events leading to regulation of an organism's life cycle. The activity of proteases has to be closely regulated by proteinase inhibitors (PIs) to avoid the damage that proteases might cause in vivo, in the host organism. Based on the selectivity and inhibitory activity PIs are categorized into four mechanistic class viz. aspartic PI (pepstatins), serine PI (serpins), cysteine PI (cystatins) and metallocarboxy PI. Among these SPI family is the largest. Many organisms including bacteria, fungus, viruses, protists, insects and vertebrates derive their nutritional requirement from various life forms by finding a suitable host. Proteases constitute 1-5% of genomes of these infectious organisms among which SPs regulate protein synthesis, turnover and physiological functions viz. fertilization, growth and development, digestion, cell signaling or migration, immune defense, wound healing and disease propagation. SPs mediate the process of pathogenesis and/or host tissue penetration for a number of diseases in the host organisms. SPs are generally found either as constitutive components in plant storage tissues like seeds and tubers or expressed in response to pest and pathogen attack besides acting as a defense system against a wide variety of pathogens. These expressed or endogenously present SPIs can attenuate SPs with cross-protection against a wide array of protease families of pathogens like bacteria, fungus, nematodes and viruses.

A Trypsin Inhibitor from Moringa oleifera Flowers Modulates the Immune Response In Vitro of Trypanosoma cruzi-Infected Human Cells

“…The deregulation of proteases is a triggering factor for the onset of various pathologies and recent research has pointed out protease inhibitors as promising pharmacological agents [ 13 , 14 ]. Antioxidant, anti-inflammatory, immunomodulatory, antiviral, antimicrobial and antiparasitic activities of these molecules have been demonstrated [ 15 , 16 , 17 , 18 ]. Sangenito et al [ 19 ] reported that inhibitors of HIV aspartyl peptidase affected the integrity of cellular structures of T. cruzi trypomastigotes, leading to metabolic disorders.…”

Potential roles of medicinal plants for the treatment of viral diseases focusing on COVID‐19: A review

“…(f) Natural compounds isolated from medicinal plants for antiviral activity: (E)-1-(2-Hydroxy-4-methoxyphenyl)-3-[3-[(E)-3-(2-hydroxy-4-methoxyphenyl)-3-oxoprop-1-enyl]phenyl]prop-2-en-1-one (74), beta,beta 0 -(4-Methoxy-1,3-phenylene)bis(2 0 -hydroxy-4 0 ,6 0 -dimethoxyacrylophenone (75), Isoscutellarein (76), 5,7-Dimethoxyflavone (77), Tetramethyllueteonin (78), Tri methyl apigenin (79),5-Hydroxy-7-methoxyflavone (80), Ginkgetin (81), Quercetin 3-rhamnoside (82), Celastrol (83), Pristimerin (84), Tingenone (85). (g) Natural compounds isolated from medicinal plants for antiviral activity: Dieckol (86), Eckol (87), Triphloretol A (88), Dioxinodehydroeckol (89), 2-Phloroeckol (90), 7-Phloroeckol (91), Phlorofucofuroeckol A (92), Fucodiphloroethol G (93)3.2 | Inhibition of viral proteaseProtease inhibitors alter or deactivate the configuration of protease involved in the proteolytic activity (events) associated with diseases like AIDS, cancer, thrombosis, hepatitis, and cirrhosis(Mishra, Reddy & Prasad, 2020). Fisetin (60) and rutin (61)(Figure 2e) act as a 3C protease (3Cpro) inhibitors against enterovirus A71 with IC 50 of 85 and 110 μM, respectively (Y.-J Lin et al, 2012)…”