The effect of Aspalathus linearis (Burm.f.) R.Dahlgren and its compounds on tyrosinase and melanogenesis

Pigmentation, a process controlled by melanogenesis, plays a vital role in protecting the skin against harmful ultraviolet rays. The level of protection is compromised in case of hypopigmentation. This study aimed to evaluate an Aspalathus linearis extract, fractions and phytoconstituents, for their efficacy on melanogenesis stimulation. Fifteen compounds were kinetically assessed against tyrosinase; the rate-limiting enzyme of melanogenesis. Aspalathin and catechin significantly (p value < 0.001) increased the enzymatic rate, showing 50% stimulatory effects at 119.70 ± 2.06 μg/ mL and 143.30 ± 2.74 μg/mL, respectively, by acting as subversive substrates. Five compounds inhibited the enzyme’s activity, of which four exhibited competitive inhibition. To investigate the molecular interactions between the compounds and the active site, molecular docking was done, using tyrosinase (PBD: 2Y9X) and tyrosinase related protein 1 (PBD: 5M8P). All the compounds docked successfully with acceptable docking scores. Further quantitative structure–activity relationship analysis identified potential functional groups, linked to the specific activity. The crude extract, its fractions, and compounds exhibited low antiproliferative activity with 50% cell viability at concentrations higher than 100 μg/mL. Finally, both aspalathin and catechin exhibited a significant increase (4.5%) in melanin production at 119.82 μg/mL and 76.92 μg/mL, respectively. This is the first report of A. linearis’ compounds on skin re-pigmentation.The National Research Foundation.https://www.nature.com/srepam2022Plant Production and Soil Scienc

Antibiotic-potentiation, antioxidant, cytotoxic, anti-inflammatory and anti-acetylcholinesterase potential of Antidesma madagascariense Lam. (Euphorbiaceae)

Antidesma madagascariense Lam. (AM) is used in the treatment and management of a panoply of human diseases. Leaf decoction, acetone extracts and fractions of AM were evaluated for antimicrobial, antioxidant, anti-inflammatory, cytotoxicity and acetylcholinesterase (AChE) inhibitory activity. The antibiotic potentiating activity of crude acetone extract (AE) was assessed against ATCC bacterial strains of Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923 using standard antibiotics. Decoction extract showed significant inhibitory activity against Acinetobacter spp. (MIC: 0.25 mg/mL) which had higher inhibitory effect compared to the positive control Streptomycin (MIC: 1.00 mg/mL). Acetone and decoction extracts inhibited the growth of Candida albicans (MIC: 4.00 mg/mL). All fractions of AE showed broad spectrum activity against ATCC and clinical strains (MIC 0.03–4.00 mg/mL). The results of the combination pro- files of the AE with Ciprofloxacin, Chloramphenicol and Streptomycin revealed synergistic interactions (FICI ≤ 0.50) against P. aeruginosa. Crude decoction, acetone extract and fractions were found to be potent reducing agent as well DPPH radical scavenger and ABTS cation scavenger. A significant correlation between DPPH, ABTS and total phenolic content (p b 0.05, r=−0.75 and −0.82 respectively) was recorded. Three fractions namely DCM:MeOH (85:15) (F5), DCM:MeOH (95:05) (F3) and DCM (F2) [IC50 0.02–0.09 mg/mL] demonstrated significant anti-inflammatory activity as compared to the positive control, diclofenac sodium [IC50 0.18 (0.10–0.31) mg/mL]. AE and its fractions showed AChE inhibitory activities at an IC50 of 35.92–492.6 μg/mL. Cytotoxicity study against Vero cells revealed that AE and hexane fraction were non-cytotoxic while decoction showed cytotoxic effect. Further studies are required to explore the potential of AM crude extracts and fractions as natural source of antimicrobial, antioxidant, anti-inflammatory agents as well as AChE inhibitors.http://www.elsevier.com/locate/sajb2018-07-31hb2017Plant Production and Soil Scienc

Isolation of flavonoids and flavonoid glycosides from Myrsine africana and their inhibitory activities against mushroom tyrosinase

Bioassay-guided fractionation of the methanol extract of the shoots of Myrsine africana led to the isolation of the new compound myricetin 3-O-(2″,4″-di-O-acetyl)-α-l-rhamnopyranoside (9) and 11 known compounds. The known compounds quercetin 3-O-(3″,4″-di-O-acetyl)-α-l-rhamnopyranoside (8), rutin (10), quercetin 3-O-α-l-rhamnopyranoside (11), and myricetin 3-O-α-l-rhamnopyranoside (12) are reported for the first time from the methanol extract of the shoots of M. africana. Compounds 10 and 12 showed significant inhibition of tyrosinase with 50% inhibition (IC50 values) of the enzyme at 0.13 ± 0.003 and 0.12 ± 0.002 mM, respectively, which was supported by the docking fitness scores obtained through molecular docking analysis. In addition, compounds 1–12 displayed significant antioxidant activity with IC50 values ranging 1.90 to 3.90 μM.The University of Pretoria and the National Research Foundation.https://pubs.acs.org/journal/jnprdfhj2019Plant Production and Soil Scienc

Pluripharmacological potential of Mascarene endemic plant leaf extracts

DATA AVAILABILITY : Data will be made available on request.Please read abstract in the article.The Mauritius Research Innovation Council under the National Research and Innovation Chair Program studentship and the Royal Society and Royal Society of Chemistry international exchange award.https://www.elsevier.com/locate/babhj2024Plant Production and Soil ScienceSDG-15:Life on lan

Assessing anti-inflammatory activities and compounds in switchgrass (Panicum virgatum)

SUPPLEMENTARY MATERIAL : TABLE S1: Putative identification of the secondary metabolites with known anti-inflammatory activities in switchgrass through untargeted metabolomics analyses.; TABLE S2: In vitro biological activities of the extracts derived from the four switchgrass cultivars. Antibacterial and antimycobacterial activities were evaluated against 2 bacterial strains Cutibacterium acnes and Mycobacterium smegmatis, respectively. Anticancer activity was investigated using human colorectal adenocarcinoma (HT-29) and human malignant melanoma (UCT-MEL-1) cell lines.Switchgrass is a bioenergy feedstock that potentially possesses multiple health benefits. However, the biological properties and associated bioactive compounds of switchgrass have not been adequately investigated. In the current study, we assessed the anti-inflammatory properties of switchgrass. Results from in vitro bioassays indicated that the methanolic extracts of switchgrass contained compounds exerting inhibitory effects on the expression of inflammatory mediators (TNF- , IL-6, IL-8, and IL-10) induced in the U-937 model system. The extracts derived from four switchgrass cultivars (Alamo, Kanlow, Liberty, and Show Me) inhibited the secretion of all inflammatory mediators examined, with the only exception of the Liberty extract, which showed no significant effect on IL-10 expression. The degree of cytokine inhibition was variable, depending on the particular cultivar, the concentrations tested, and the cytokines examined. A global metabolomics approach was utilized to putatively identify possible molecules with known anti-inflammatory capacities in different switchgrass cultivars using ultra-high performance liquid chromatography with high-resolution mass spectrometry (UHPLC-HRMS). The content of multiple bioactive antiinflammatory compounds in switchgrass was determined by liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) analyses. Our results suggest that switchgrass, particularly the Alamo and Kanlow cultivars, may represent a promising natural anti-inflammatory source for the cosmetic, nutraceutical, and pharmaceutical industries.This work was supported by the USDA/ARS Dale Bumpers Small Farm Research Center, Agreement number 58-6020-6-001 from the USDA Agricultural Research Service, Center for Agroforestry at University of Missouri, University of Pretoria, and Missouri Department of Agriculture Specialty Crop Block Grant Program (SCBGP) #16SCBGPMO0003. The Sumner lab and the MU Metabolomics Center have been graciously supported by several entities over the years for the development of natural products profiling and plant metabolomics. These specifically include support from the University of Missouri, The Samuel Roberts Noble Foundation, Bruker Daltonics Gmbh, Agilent Technologies, US National Science Foundation (NSF)-JST Metabolomics for a Low Carbon Society #1139489, NSF MRI DBI #1126719, NSF RCN #1340058, and NSF MCB #1024976.https://www.mdpi.com/journal/agricultuream2023Plant Production and Soil Scienc

Antibiotic-potentiating activity, phytochemical profile, and cytotoxicity of Acalypha integrifolia Willd. (Euphorbiaceae)

Acalypha integrifolia Willd. (Euphorbiaceae) (AI), an indigenous medicinal plant of the Mascarene Islands is traditionally used to manage infectious diseases. The authors aimed to evaluate the antimicrobial, antibiotic-potentiating activity and cytotoxicity of AI. Decoction as traditionally used and organic extracts (hexane, dichloromethane, ethyl acetate, and methanol) of AI leaves were screened for their antimicrobial activity against nine ATCC strains and 10 clinical isolates. A fractional inhibitory concentration index (FICI) was determined to establish any synergistic interaction between the extracts and antibiotics using the variable ratio analysis method. The phytochemical profile was established using chemical and thin-layer chromatography methods. The decoction and methanolic extracts inhibited the growth of all tested bacteria (minimum inhibitory concentration (MIC) ranged between 0.06–2.00 mg/ml). The methanolic extract showed potent antibacterial activity against Escherichia coli (EC) (MIC: 0.06 mg/ml), Pseudomonas aeruginosa (MIC: 0.50 mg/ml), and Staphyloccocus aureus (SA) (MIC: 0.06 mg/ml). The highest antibacterial activity was observed against clinical isolates of Enterococcus faecalis, S. aureus, and Methicillin-Resistant S. aureus (MRSA) (MIC: 0.50 mg/ml). Moderate antifungal activity was observed against Candida albicans. Combination profiles of the extract with Ciprofloxacin, Chloramphenicol, and Streptomycin showed synergistic action (FICI ≤ 0.50) against ATCC strains of EC and SA. Decoction and methanolic extracts showed low cytotoxicity against normal adult African green monkey kidney cells. Data obtained tends to corroborate with the reported traditional usage of the plant. Since the leaf decoction is traditionally used against skin infections as well as consumed for its astringent and purgative properties, the reported data tend to correlate with the low cytotoxicity as well as its anti-infective property. There may also be the potential towards the discovery of novel antimicrobial compounds.https://www.elsevier.com/locate/hermed2019-03-01hj2018Plant Production and Soil Scienc

Antimicrobial, antioxidant and cytotoxic evaluation of two underutilised food plants : Averrhoa bilimbi L. (Oxalidaceae) and Phyllanthus acidus L. Skeels (Phyllanthaceae)

Averrhoa bilimbi (P1) and Phyllantus acidus (P2) are traditionally used in the management of various diseases in several cultures. Leaf (L) and fruit (F) extracts (decoction, hexane, dichloromethane, ethyl acetate- EtOAc and methanol) were prepared and investigated for their antimicrobial, antioxidant and cytotoxic properties in vitro. P1 and P2 extracts showed broad spectrum activity against ATCC bacterial strains and clinical isolates. P1L and P2F EtOAc extracts inhibited the growth of ATCC strains of S. aureus and V. parahaemolytius (MIC = 250 μg/ml). P1F EtOAc extract was found active against ATCC strains of E. coli and S. aureus (MIC = 250 μg/ml). P1F was active against all tested clinical isolate strains with maximum inhibition against S. aureus ((MIC = 130 μg/ml). Hexane and EtOAc extracts of P2F showed activity against clinical isolate strains of S. aureus ((MIC = 130 and 250 μg/ml, respectively). P2F hexane extract displayed antimicrobial activity against MRSA at MIC value similar to that of streptomycin (250 μg/ml). Furthermore, the antioxidant activity of the different extracts was assessed using DPPH, ABTS and the FRAP assay. The cytotoxicity of the decoction and methanol extracts were also determined using normal adult African green monkey kidney cells (Vero cells). Leaf decoction of P1 showed DPPH radical scavenging activity at an IC50 of 5.30 μg/ml, which was comparable to the positive control, ascorbic acid (IC50: 5.89 μg/ml). Leaf extracts of P1 were better hydrogen donors compared to leaf and fruit extracts of P2. The methanol and decoction extracts of P1L showed low activity against the ABTS cation at an IC50 value of 39.26 and 31.68 μg/ml, respectively. The P2L and P2F extracts were unable to scavenge ABTS cation radicals. The FRAP values for P2L and P2F extracts were in the range of 59.83–120.89 and 23.98–90.71 TE μM, respectively. Decoction and methanol extracts showed no toxicity at the highest concentration tested. In conclusion, data amassed from the present investigation could open new avenues for research and may serve as the basis for the development of novel drugs.https://www.elsevier.com/locate/bab2020-03-01hj2019Plant Production and Soil Scienc

Selected essential oils inhibit key physiological enzymes and possess intracellular and extracellular antimelanogenic properties in vitro

Essential oils (EOs) extracted from six medicinal herbs and food plants [Cinnamomum zeylanicum (CZ), Psiadia arguta (PA), Psiadia terebinthina (PT), Citrus grandis (CGp), Citrus hystrix (CH), and Citrus reticulata (CR)] were studied for any inhibitory potential against key physiological enzymes involved in diabetes (α-glucosidase), skin aging (collagenase and elastase), and neurodegenerative disorders (acetylcholinesterase). Kinetic studies of the active EOs on the aforementioned enzymes were determined using Lineweaver–Burk plots. The intracellular and extracellular antimelanogenic potential of the EOs were evaluated on B16F10 mouse melanocytes. CH and CR were found to significantly inhibit (2.476 ± 0.13 μg/mL and 3.636 ± 0.10 μg/mL, respectively) acetylcholinesterase, compared with galantamine (3.989 ± 0.16 μg/mL). CH inhibited collagenase (50% inhibitory concentration 28.71 ± 0.16 μg/mL) compared with the control (24.45 ± 0.19 μg/mL). The percentage inhibition in the elastase assay of CH was 63.21% compared to the positive control (75.09%). In addition, CH, CR, CGp, CZ, and PT were found to significantly inhibit α-glucosidase (276.70 ± 0.73 μg/mL, 169.90 ± 0.58 μg/mL, 240.60 ± 6.50 μg/mL, 64.52 ± 0.69 μg/mL, and 313.0 ± 5.0 μg/mL, respectively), compared to acarbose (448.80 ± 0.81 μg/mL). Active EOs showed both uncompetitive and competitive types of inhibition. The EOs also inhibited intracellular (50% inhibitory concentration 15.92 ± 1.06 μg/mL, 23.75 ± 4.47 μg/mL, and 28.99 ± 5.70 μg/mL for CH, CR, and CGp, respectively) and extracellular (< 15.625 μg/mL for CH, CR, CGp, and PT) melanin production when tested against B16F10 mouse melanocytes. Results from the present study tend to show that EOs extracted from these medicinal plants can inhibit key enzymes and may be potential candidates for cosmetic and pharmaceutical industries

Synthesis and characterization of gold nanoparticles biosynthesised from Aspalathus linearis (Burm.f.) R.Dahlgren For progressive macular hypomelanosis

Please read abstract in the article.The National Research Foundationhttps://www.elsevier.com/locate/hermed2022-07-22hj2022Plant Production and Soil Scienc