Antifungal Role of Common Indian Spices & Herbs: A Narrative Review

Abstract:

A large variety of spices can be found in kitchens worldwide. The usage varies from region to region as per the cuisine. They hold nutritional values and are being exploited for their anticancer, antifungal, antibacterial, antiulcer, anti-inflammatory properties. This study highlights some of the commonly used Indian spices for their antifungal properties and summarizes their potential antifungal activity. Fungal diseases are deep-rooted and cause acute/chronic infections in humans, mainly Aspergillus and Candida species. As the tropical climate provides a breeding ground for fungal infections, such regions share a huge load of mycoses. Various spices have been shown to be effective against treating fungal diseases. The current study focuses on the potential anti-fungal role of the spices and reviews the current literature on the possible mechanism of action of the active compounds of these spices concerning the commonly used antifungal drugs. The spices consist of essential oils that work by inhibition mycotoxin biosynthesis, or disrupting and inhibiting cell wall formation and inhibiting efflux pumps and are comparable to the currently available antifungal drugs.

Characterization of an Arabidopsis Defensin-like Gene Conferring Resistance against Nematodes

Arabidopsis contains 317 genes for defensin-like (DEFL) peptides. DEFLs have been grouped into different families based mainly on cysteine motifs. The DEFL0770 group contains seven genes, of which four are strongly expressed in roots. We found that the expression of these genes is downregulated in syncytia induced by the beet cyst nematode Heterodera schachtii as revealed by RNAseq analysis. We have studied one gene of this group, At3g59930, in detail. A promoter::GUS line revealed that the gene is only expressed in roots but not in other plant organs. Infection of the GUS line with larvae of H. schachtii showed a strong downregulation of GUS expression in infection sites as early as 1 dpi, confirming the RNAseq data. The At3g59930 peptide had only weak antimicrobial activity against Botrytis cinerea. Overexpression lines had no enhanced resistance against this fungus but were more resistant to H. schachtii infection. Our data indicate that At3g59930 is involved in resistance to nematodes which is probably not due to direct nematicidal activity.

Evaluating Peptides of Picrorhiza kurroa and Their Inhibitory Potential against ACE, DPP-IV, and Oxidative Stress

Picrorhiza kurroa Royle ex Benth. is a high-altitude plant having great medicinal value. However, its medicinal value at the peptide level is still unknown, which limits its utility in the development of peptide-based therapeutics. Here, we identify 65 peptides fromP. kurroa hydrolysate. Sequence analysis suggests that one novel bioactive peptide, ASGLCPEEAVPRR (BP1), has antioxidant potential and shows angiotensin-converting enzyme (ACE) and dipeptidyl peptidase-IV (DPP-IV) inhibitory activities. The molecular docking study showed that BP1 has a lower binding energy and strong affinity toward active pockets of ACE and DPP-IV, which explains its higher ACE [IC₅₀ = 59.90 ± 9.52 μg/mL (43.40 μM)] and DPP-IV [IC₅₀ = 3.04 ± 0.26 μg/mL (2.2 μM)] inhibitory activities. BP1 protects HEK293 cells from H₂O₂-induced oxidative damage by inhibiting intracellular reactive oxygen species (ROS) and malondialdehyde accumulation and activating the intrinsic antioxidant defense system. Additionally, phase-contrast microscopy studies revealed that pre-treatment of BP1 to HEK293 cells before exposure to H₂O₂ retains the normal morphology and blocks apoptosis. Furthermore, it also suppresses ROS-induced mitochondrial apoptosis via restoring the mitochondrial membrane potential (ΔΨm) and inhibiting caspase 3/7 activity. Therefore, BP1 has antioxidant potential and ACE and DPP-IV inhibitory activities that could be used for peptide-based formulation(s) in pharmaceuticals to treat diabetes, cardiovascular diseases, and other diseases associated with ROS.

Plant Antimicrobial Peptides: State of the Art, In Silico Prediction and Perspectives in the Omics Era

Even before the perception or interaction with pathogens, plants rely on constitutively guardian molecules, often specific to tissue or stage, with further expression after contact with the pathogen. These guardians include small molecules as antimicrobial peptides (AMPs), generally cysteine-rich, functioning to prevent pathogen establishment. Some of these AMPs are shared among eukaryotes (eg, defensins and cyclotides), others are plant specific (eg, snakins), while some are specific to certain plant families (such as heveins). When compared with other organisms, plants tend to present a higher amount of AMP isoforms due to gene duplications or polyploidy, an occurrence possibly also associated with the sessile habit of plants, which prevents them from evading biotic and environmental stresses. Therefore, plants arise as a rich resource for new AMPs. As these molecules are difficult to retrieve from databases using simple sequence alignments, a description of their characteristics and in silico (bioinformatics) approaches used to retrieve them is provided, considering resources and databases available. The possibilities and applications based on tools versus database approaches are considerable and have been so far underestimated.

Purification of an Antifungal Peptide from Seeds of Brassica oleracea var. gongylodes and Investigation of Its Antifungal Activity and Mechanism of Action

In this study, a 8.5-kDa antifungal peptide designated as BGAP was purified from the crude extract of the seeds of Brassica oleracea var. gongylodes by employing a protocol that comprised cation exchange chromatography on SP-Sepharose, cation exchange chromatography on Mono S and gel filtration chromatography on Superdex peptide. BGAP showed the highest amino acid sequence similarity to defensin peptides by mass spectrometric analysis. BGAP showed a broad spectrum of antifungal activity with a half maximal inhibitory concentration at 17.33 μg/mL, 12.37 μg/mL, 16.81 μg/mL, and 5.60 μg/mL toward Colletotrichum higginsianum, Exserohilum turcicum, Magnaporthe oryzae and Mycosphaerella arachidicola, respectively. The antifungal activity of BGAP remained stable (i) after heat treatment at 40–100 °C for 15 min; (ii) after exposure to solutions of pH 1–3 and 11–13 for 15 min; (iii) after incubation with solutions containing K⁺, Ca²⁺, Mg²⁺, Mn²⁺ or Fe³⁺ ions at the concentrations of 20–150 mmol/L for 2 h; and (iv) following treatment with 10% methyl alcohol, 10% ethanol, 10% isopropanol or 10% chloroform for 2 h. Fluorescence staining experiments showed that BGAP brought about an increase in cell membrane permeability, a rise in reactive oxygen species production, a decrease in mitochondrial membrane potential, and an accumulation of chitin at the hyphal tips of Mycosphaerella arachidicola.

Amebicidal effects of fenugreek (Trigonella foenum-graecum) against Acanthamoeba cysts

Trigonella foenum-graecum L. (TF) is known to the public as a chest emollient, mucous expectorant, laxative and is used to prevent maturation of boils and diabetes since ancient times. In this study, we aimed to determine the amebicidal effects against Acanthamoeba cysts. Plant extracts were prepared at concentrations of 1, 2, 4, 8, 16, and 32 mg/ml and were placed in a hemocytometer with cell counts 22 × 106 cell/ml. The fatty acid profiles of TF seeds were determined. Standard Acanthamoeba cysts were added and incubated at 25°C. The viability of the parasite was checked and recorded at hours 3, 24, 48, 72, 96, and 102. The values of lethal concentration doses (LD50 and LD90) were calculated using probit analysis. This study revealed that T. foenum-graecum prevented proliferation of the parasite at certain times. However, further for in vivo and controlled experimental studies are needed in order to find out how to use this plant as medication.