Extracts Of Indian Medicinal Plants Research Articles

Exploring bioactive compounds and antioxidant properties of twenty-six Indian medicinal plant extracts: A correlative analysis for potential therapeutic insights

The aim of the present study was to analyse the bioactive constituents and antioxidant potential of twenty-six medicinal plant extracts and their correlation for potential therapeutic insights. The total phenolic contents (TPC) and total flavonoid (TF) of plant extracts were determined by Folin–Ciocalteau reagent and aluminum chloride calorimetric assay, respectively. The extract was used to determine the antioxidant potential using different assay including total antioxidant activity, DPPH, and FRAP. The methanolic Terminalia chebula, Aloe vera, and Curcuma longa extracts showed the highest (p < 0.05) values of total phenolic content being 39.11, 38.80 and 38.14 mgGAE/g dw, respectively. The Ocimum tenuiflorum and Aloe vera extract had the highest (8.12 mg/g) total antioxidant capacity (p < 0.05) as compared to other extracts. The higher FRAP value (mMFe+2/g) was observed in methanolic extracts of Cinnamomum cassia, Moringa oleifera, and Withania somnifera and lowest was in water extract of Zizyphus zuzube. Correlation study indicated that TPC was found correlated with antioxidant capacity of plant extracts (TAC, r = 0.670, p < 0.01; FRAP, r = 0.501, p < 0.01; DPPH-IC50, r = −0.664, p < 0.01). The methanolic extracts from most of the plants had much higher TPC and antioxidant activities. The phenolic compounds are a primary contributor to the antioxidant efficacy among the medicinal plant species under investigation for potential therapeutic application. Overall, the current investigation demonstrated that the selected plants are potential sources for producing bioactive principles capable of scavenging free radicals.

Anti-malarial Activity of Indian Medicinal Plant Extracts by Haemazoin Inhibition Assay

Anti-malarial Activity of Indian Medicinal Plant Extracts by Haemazoin Inhibition Assay

Nephroprotective effects of Hydroalcoholic Extracts of Four selected Indian Medicinal Plants in Gentamicin-induced Nephrotoxic Wistar Rats

All the selected Indian medicinal plants, Ficus religiosa; Tinospora cordifolia; Moringa oleifera; Boerhaevia diffusa have profound pharmacological uses which have been proved by the study of Ayurvedic literature. An Aminoglycoside like Gentamicin is a broad-spectrum antibiotic in combination with beta-lactams for the treatment of systemic infection. The major risk associated with Gentamicin is nephrotoxicity and ototoxicity The present study was done to evaluate the comparative Nephroprotective effects of four selected Indian medicinal plant extracts in albino Wistar rats in Gentamicin-induced nephrotoxicity. Hydroalcoholic extracts of stem bark of Ficus religiosa, stem of Tinospora cordifolia, leaves of Moringa oleifera and roots of Boerhaevia diffusa were used at two doses levels of 200, and 400mg/kg respectively to evaluate Nephroprotective activity in albino Wistar rats by interfering Body weight, Blood urea nitrogen (BUN), Serum creatinine (Serum Creatinine), Serum total proteins, Urine volume, Urine creatinine, Creatinine clearance with Histopathology of Kidney. To observe the effect of various treatments on animals the rats were divided into Eleven groups, Six in each group. Urine creatinine, serum urea, and blood urea nitrogen were found to be significantly (P &lt; 0.001) increased in rats treated with only gentamicin; whereas treatment with the Hydroalcoholic extract of stem of Tinospora cordifolia and root of Boerhaevia diffusa reversed the effect of gentamicin indicating nephroprotective activity in compared to other plant extract treated animals. The Hydroalcoholic extract of Tinospora cordifolia and Boerhaevia diffusa at a dose level of 400mg/kg was found to be rich in flavonoids, polyphenolics, and other phytoconstituents which are responsible for good nephroprotective action in Gentamicin-induced nephrotoxicity in rats.

The factors affecting optimisation of phytosynthesis of silver nanoparticles using Indian medicinal plant species and their biological applications: A review

Recently, silver nanoparticles (AgNPs) hold a centre stage in the vast arena of research in nanomedicine. Biological methods of synthesis of nanoparticles are being adopted to avoid the use of chemicals that are toxic and hazardous and used in chemical synthetic methods. The choice of the plant extracts used for the synthesis of AgNPs is based on their phytochemicals and pharmaceutical properties. Another importance of the phytosynthesis method is that it is simple, easy, fast, reliable and cost effective. The phytochemical components of the herbal extracts not only cause reduction of Ag+1 to Ag0, but also increase the biological activities of the nanoparticles. This article briefly describes the research on green synthesis of AgNPs using Indian medicinal plant extracts. We aim to provide a systemic depth of information regarding the effect of various reaction factors during the synthesis of AgNPs such as the concentration of silver salt and phytoextract, light intensity, time, temperature, pH of the reaction mixture. The characterizations of nanoparticles are done by X-ray diffraction, ultraviolet- visible spectroscopy, Fourier-transform infrared spectra, transmission electron microscopy, dynamic light scattering and zeta potential analysis. The phytochemicals and pharmaceutical activities present in the plant extracts are also reported here. The articles from 2011 to 2022 were selected and studied in detail to get in-depth knowledge about the phytosynthesis of AgNPs and their biological activities.

In vitro anti-HIV activity of some Indian medicinal plant extracts

BackgroundHuman Immunodeficiency Virus (HIV) persists to be a significant public health issue worldwide. The current strategy for the treatment of HIV infection, Highly Active Antiretroviral Therapy (HAART), has reduced deaths from AIDS related disease, but it can be an expensive regime for the underdeveloped and developing countries where the supply of drugs is scarce and often not well tolerated, especially in persons undergoing long term treatment. The present therapy also has limitations of development of multidrug resistance, thus there is a need for the discovery of novel anti-HIV compounds from plants as a potential alternative in combating HIV disease.MethodsTen Indian medicinal plants were tested for entry and replication inhibition against laboratory adapted strains HIV-1IIIB, HIV-1Ada5 and primary isolates HIV-1UG070, HIV-1VB59 in TZM-bl cell lines and primary isolates HIV-1UG070, HIV-1VB59 in PM1 cell lines. The plant extracts were further evaluated for toxicity in HEC-1A epithelial cell lines by transwell epithelial model.ResultsThe methanolic extracts of Achyranthes aspera, Rosa centifolia and aqueous extract of Ficus benghalensis inhibited laboratory adapted HIV-1 strains (IC80 3.6–118 μg/ml) and primary isolates (IC80 4.8–156 μg/ml) in TZM-bl cells. Methanolic extract of Strychnos potatorum, aqueous extract of Ficus infectoria and hydroalcoholic extract of Annona squamosa inhibited laboratory adapted HIV-1 strains (IC80 4.24–125 μg/ml) and primary isolates (IC80 18–156 μg/ml) in TZM-bl cells. Methanolic extracts of Achyranthes aspera and Rosa centifolia, (IC801-9 μg/ml) further significantly inhibited HIV-1 primary isolates in PM1cells. Methanolic extracts of Tridax procumbens, Mallotus philippinensis, Annona reticulate, aqueous extract of Ficus benghalensis and hydroalcoholic extract of Albizzia lebbeck did not exhibit anti-HIV activity in all the tested strains. Methanolic extract of Rosa centifolia also demonstrated to be non-toxic to HEC-1A epithelial cells and maintained epithelial integrity (at 500 μg/ml) when tested in transwell dual-chamber.ConclusionThese active methanolic extracts of Achyranthes aspera and Rosa centifolia, could be further subjected to chemical analysis to investigate the active moiety responsible for the anti-HIV activity. Methanolic extract of Rosa centifolia was found to be well tolerated maintaining the epithelial integrity of HEC-1A cells in vitro and thus has potential for investigating it further as candidate microbicide.

Indian medicinal plant extracts to control multidrug-resistant S. aureus, including in biofilms

The objective of this study is to evaluate the in vitro antibacterial effectiveness of select Indian medicinal plants against multidrug-resistant (MDR) and biofilm-forming Staphylococcus. Twenty Indian medicinal plants used traditionally were preselected for testing against 17 different clinical strains (originating from animal or hospital patients), resistant to five classes of antibiotics, and one biofilm-forming Staphylococcus. The minimum inhibitory concentration (MIC50) and biofilm inhibitory concentration (BIC50) were determined. Plants with anti-staphylococcal activity not reported before include Cinnamomum glaucescens, Smilax zeylanica, Syzygium praecox, Trema orientalis, Bischofia javanica, Elaeocarpus serratus, Acacia pennata, Holigarna caustica, Murraya paniculata, and Pterygota alata. They can be used to control the formation of S. aureus biofilms, or to discover active molecules that may lead to novel drugs. In addition to the aforementioned plants, Beilschmiedia roxburghiana and Mikania micrantha also deserve further study regarding their mechanism of action, as they inhibit the growth of S. aureus resistant to all five groups of antibiotics tested. The active compounds from the aforementioned plants have potential in the fight against multidrug-resistant Staphylococcus infections.

Prospective bacterial quorum sensing inhibitors from Indian medicinal plant extracts.

A novel alternative prospect to prevent bacterial infections without inhibiting the growth is to apply chemicals that inhibit quorum sensing mechanism of the pathogens. Antiquorum property of 61 medicinal plants was evaluated by the ability of their leaf extract(s) to inhibit production of pigment (violacein in Chromobacterium violaceum MTCC 2656, pyocyanin in Pseudomonas aeruginosa MTCC 2297) or swarming in P.aeruginosa MTCC 2297. The most prospective plants (for the development of quorum sensing inhibitor), showing inhibition of violacein production without affecting bacterial growth, were Astilbe rivularis, Fragaria nubicola and Osbeckia nepalensis.

Broad Spectrum Anti-Quorum Sensing Activity of Tannin-Rich Crude Extracts of Indian Medicinal Plants.

Quorum sensing (QS) mechanisms have been demonstrated to have significance in expression of pathogenicity in infectious bacteria. In Gram negative bacteria the autoinducer molecules that mediate QS are acyl homoserine lactones (AHL) and in Gram positive bacteria they are peptides called autoinducing peptides (AIP). A screening of tannin-rich medicinal plants was attempted to identify extracts that could interrupt the QS mechanisms in both Gram positive and Gram negative bacteria over a wide range of concentrations and therefore potentially be potent agents that could act as broad spectrum QS inhibitors. Six out of the twelve Indian medicinal plant extracts that were analyzed exhibited anti-QS activity in Chromobacterium violaceum 12472 and in S. aureus strain with agr:blaZ fusion over a broad range of subinhibitory concentrations, indicating that the extracts contain high concentration of molecules that can interfere with the QS mechanisms mediated by AHL as well as AIP.

Biosynthesis of nanosilver using Indian medicinal plants and evaluation of their antibacterial activity

Phytosynthesised silver nanoparticles (AgNPs) were developed from silver nitrate (AgNO3) through a simple and eco-friendly route using the aqueous extracts of Indian medicinal plants Acacia nilotica, Solanum trilobatum and Punica granatum. The AgNP formation were characterised by using UV-Visible spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and energy dispersive X-ray spectroscopy (EDAX). The average particle size of the AgNPs synthesised from A. nilotica, S. trilobatum and P. granatum was determined to be 50, 110 and 60 nm, respectively. Anti-bacterial activity studies revealed that AgNPs synthesised from P. granatum exerted maximum effect against the few pathogenic and non-pathogenic bacterial strains. Phytochemical screening of the crude extracts of the three chosen plants identified tannins to be the active component responsible for the reduction of silver ions to nanoparticles. This study also revealed that green procedure would be preferred for large-scale operation with high biocompatibility.

Mosquitocidal activity of indigenenous plants of Western Ghats, Achras sapota Linn. (Sapotaceae) and Cassia auriculata L. (Fabaceae) against a common malarial vector, Anopheles stephensi Liston (Culicidae: Diptera)

Objective: To evaluate the mosquito larvicidal, ovicidal, pupicidal and repellent activities of hexane, diethyl ether, dichloromethane, acetone and methanol extracts of Indian medicinal plants, Achras sapota (A. sapota) and Cassia auriculata (C. auriculata) at different concentrations against Anopheles stephensi (An. stephensi), a malarial vector. Methods: Twenty five early third instar larvae of An. stephensi were exposed to various concentrations (30-210 mg/L) of plants extracts and were assayed in the laboratory by using the protocol of WHO 2005; then after 24 h LC50 values of the A. sapota and C. auriculata leaf extract was determined by probit analysis. The ovicidal activity was tested with the extracts ranging from 50350 mg/L. The pupicidal activity was recorded after 24 h of exposure to the extract. The repellent efficacy was determined against mosquito species at two different concentrations 1.5 and 3.0 mg/ cm 2 under laboratory conditions. Results: Among the five different extracts tested against the An. stephensi, methanol extract of A. sapota proved to be an more effective solvent extract in almost all the parameters studied than C. auriculata. Conclusions: It is inferred that the leaf extract of A. sapota and C. auriculata could be used in vector control programme.

In Vitro and In Vivo Inhibitory Activities of Four Indian Medicinal Plant Extracts and their Major Components on Rat Aldose Reductase and Generation of Advanced Glycation Endproducts

The polyol enzyme aldose reductase (AR) and advanced glycation endproducts (AGEs) play an important role in diabetic complications such as cataracts. The purpose of this study was to investigate four standardized plant extracts used for the treatment of diabetes and related diseases, and their principal components for AR inhibitory activity and to find out their influence in diabetic complications. Thus, Boswellia serrata Triana & Planch. (Burseraceae), Lagerstroemia speciosa (L.) Pers. (Lythraceae), Ocimum gratissimum (L.) (Lamiaceae) and Syzygium cumin (L.) Skeels. (Myrthaceae) and their respective major constituents, boswellic acid, corosolic acid, ursolic acid and ellagic acid, were studied for their inhibitory activity against rat lens AR, rat kidney AR, human recombinant AR and generation of AGEs. In addition, in vivo inhibition of lens galactitol accumulation by the major constituents of the plants in galactose-fed rat has been studied. The results revealed that all the tested extracts and their active ingredients possess significant AR inhibitory actions in both in vitro and in vivo assays with urosolic acid showing the most potent effect. Furthermore, the study indicates the potential of the studied plants and their major constituents as possible protective agents against long-term diabetic complications.

Inhibition of Propionibacterium acnes lipase by extracts of Indian medicinal plants

Lipases play an important role in pathogenesis of acne by hydrolysing sebum triglycerides and releasing irritating free fatty acids in the pilosebaceous follicles. Lipase is a strong chemotactic and proinflammatory antigen. Therefore, lipase has generated a high interest as a pharmacological target for antiacne drugs. The aim of this study was to identify inhibitory effects of plant extracts on the lipase activity of Propionibacterium acnes. Colorimetric microassay was used to determine lipase activity. Extracts from Terminalia chebula and Embelia ribes showed lower IC(50) value (1 μg mL(-1) ) for lipase inhibition as compared to Vitex negundo and Picrorhiza kurroa (19 and 47 μg mL(-1) , respectively). The active component responsible for lipase inhibition was isolated. This study reports for the first time the novel antilipase activity of chebulagic acid (IC(50) : 60 μmol L(-1) ) with minimum inhibitory concentration value of 12.5 μg mL(-1) against P. acnes. The inhibitory potential of plant extracts was further confirmed by plate assay. The organism was grown in the presence of subinhibitory concentrations of extracts from P. kurroa, V. negundo, T. chebula, E. ribes and antibiotics such as clindamycin and tetracycline. Extract from T. chebula showed significant inhibition of lipase activity and number of P. acnes.

Hydroalcoholic extracts of Indian medicinal plants can help in amelioration from oxidative stress through antioxidant properties

The in vitro study of the antioxidant properties of the hydroalcoholic extracts of various Indian medicinal plants can logically help to develop a better and safer way of amelioration from oxidative stress. As aimed, the present study has been done to estimate and thereby conclude regarding the antioxidant activities of a few Indian medicinal plants, viz., Terminalia chebula, Terminalia belerica, Emblica officinalis, Caesalpinia crista, Cajanus cajan, and Tinospora cordifolia. The extracts of the plants have been subjected to the evaluation of antioxidant properties through scavenging assays for reactive oxygen species like superoxide, nitric oxide, peroxynitrite, hypochlorous acid, singlet oxygen, etc. and measurement of TEAC values and other phytochemical parameters. The phenolic and flavonoid contents of each plant have been found to be correlated to their individual antioxidant activity. The results showed the hydroalcoholic extracts of the plants were efficient indicators of their antioxidant capacity thus concreting their basis to be used as natural antioxidant.

Antimicrobial and free radical scavenging activity of extracts of some Indian medicinal plants

Antimicrobial and antioxidant potency of aqueous and organic solvent extracts of five Indian medicinal plants (Prosopis cineraria, Capparis decidua, Tinospora cordifolia, Carissa carandas and Cordia dichotoma) was investigated. The acetone and ethanol extracts exhibited highest antimicrobial activity (60 to 80% and 40 to 60%, respectively) againstStaphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Aspergillus niger andCandida albicans. Acetone extracts showed inhibitory zones ranging from 11.2 - 19.8 mm whereas no inhibitory effect was observed for aqueous extracts. During NBT assay of acetone and ethanol extracts of all the plants, maximum antioxidant activity was noticed in C. carandas (63.5 and 61.0% for acetone and ethanol extracts, respectively). The inhibitory potential when compared with known antioxidant (L-ascorbic acid), it was observed that IC50values of acetone extracts of C. carandas and T. cordifolia (93 and 97 µg/ml) were very close to L-ascorbic acid (81 µg/ml). The results suggest that C. carandas has promising antimicrobial and antioxidant activities. Key words: Antimicrobial activity, antioxidant activity, microbial susceptibility index, NBT, medicinal plants.

Antimicrobial activity of leaf extracts of Indian medicinal plants against clinical and phytopathogenic bacteria

The ethnobotanical efficacy of Indian medicinal plants; Achyranthes aspera, Artemisia parviflora, Azadirachta indica, Calotropis gigantean, Lawsonia inermis, Mimosa pudica, Ixora coccinea, Parthenium hysterophorus and Chromolaena odorata were examined using agar disc diffusion method against clinical bacteria (Escherichia coli and Staphylococcus aureus) and phytopathogenic bacteria (Xanthomonas vesicatoria and Ralstonia solanacearum). Leaves were extracted using different solvents such as methanol, ethanol, ethyl acetate and chloroform. Among treatments, maximum in vitro inhibition was scored in methanol extracts of C. odorata which offered inhibition zone of 10, 9, 12 and 12 mm against E. coli, S. aureus, X. vesicatoria and R. solanaccearum, respectively, followed by chloroform extract of the same plant leaf with inhibition zone of 8, 4, 4 and 4 mm, respectively. A significant inhibition of E. coli was found in aqueous and in all tested solvent extracts of A. indica. In case of S. aureus, maximum inhibition of 8 mm was obtained in aqueous extracts of A. indica and 6 mm from methanol extract of L. inermis. The minimum inhibitory concentration (MIC) value for the clinical bacteria ranged between 0.35 to 4.0 mg/ml and 0.25 to 4.0 mg/ml for phytopathogenic bacteria when tested with all four solvents extracts of C. odorata. Whereas, extracts of A. aspera, A. parviflora, C. gigantean, L. inermis, M. pudica and I. coccinea were found to be ineffective or showed poor inhibition on tested human and phytopathogenic bacteria.

Antimicrobial activity of leaf extracts of Indian medicinal plants against clinical and phytopathogenic bacteria

The ethnobotanical efficacy of Indian medicinal plants; Achyranthes aspera, Artemisia parviflora, Azadirachta indica, Calotropis gigantean, Lawsonia inermis, Mimosa pudica, Ixora coccinea, Parthenium hysterophorus and Chromolaena odorata were examined using agar disc diffusion method against clinical bacteria (Escherichia coli and Staphylococcus aureus) and phytopathogenic bacteria (Xanthomonas vesicatoria and Ralstonia solanacearum). Leaves were extracted using different solvents such as methanol, ethanol, ethyl acetate and chloroform. Among treatments, maximum in vitro inhibition was scored in methanol extracts of C. odorata which offered inhibition zone of 10, 9, 12 and 12 mm against E. coli, S. aureus, X. vesicatoria and R. solanaccearum, respectively, followed by chloroform extract of the same plant leaf with inhibition zone of 8, 4, 4 and 4 mm, respectively. A significant inhibition of E. coli was found in aqueous and in all tested solvent extracts of A. indica. In case of S. aureus, maximum inhibition of 8 mm was obtained in aqueous extracts of A. indica and 6 mm from methanol extract of L. inermis. The minimum inhibitory concentration (MIC) value for the clinical bacteria ranged between 0.35 to 4.0 mg/ml and 0.25 to 4.0 mg/ml for phytopathogenic bacteria when tested with all four solvents extracts of C. odorata. Whereas, extracts of A. aspera, A. parviflora, C. gigantean, L. inermis, M. pudica and I. coccinea were found to be ineffective or showed poor inhibition on tested human and phytopathogenic bacteria.

Antioxidant activities and phenolic contents of the aqueous extracts of some Indian medicinal plants

Antioxidants protect the body against oxidative stress by neutralizing free radicals. Plants contain rich amount of polyphenols which are very potent natural antioxidants. The present study was designed to evaluate the relative contribution of different polyphenols such as total phenolics, flavonoids and flavonol contents and their antioxidants activities. For this purpose the total phenolics, flavonoids and flavonol contents of some medicinal plants were determined in the aqueous extracts of leaves of Trichosenthes dioica, fruits ofMoringa olifera and Ficus bengalensis as well as seeds of Emblica officinalis. Total antioxidant activity of these extracts was monitored by Free Radical Absorbing Power (FRAP) assay. In this paper, those parts of the plants are used for the analysis of aforesaid parameters which are normally overlooked. The total phenolic content of T. dioica leaves was about two times more than that obtained from the fruits and seeds of M. olifera and E. officinalis, respectively.However, the aerial roots of F. bengalensis registered presence of least phenolic content. The aqueous preparation from E. officinalis exhibited total flavonoid content twice as high as that of the other three plants. The extract from seeds ofE. officinalis was found to contain highest antioxidant activity as compared to the preparations from other plants. The high antioxidant activity and flavonoids contents in E. officinalis seeds indicated that it could be exploited as an ingredient in developing a potential antioxidant supplement. Key words: Antioxidant, flavonoids, flavonols, phenolics, FRAP assay, Ficus bengalensis, Trichosanthes dioica, Emblica officinalis, Moringa oleifera.

Effect of alcoholic extracts of Indian medicinal plants on the altered enzymatic activities of diabetic rats

In present study, the effect of alcoholic extract of Momordica charantia, Aegle marmelos and Eugenia jambolana was studied on serum glutamic oxaloacetate transminase and serum glutamic pyruvate transminase activities and on serum urea, total protein and albumin concentrations of streptozotocin diabetic rats. Diabetes in rats was induced by single dose of streptozotocin (30 mg/kg i. p.). On confirming the diabetes after 48 h of injection, alcoholic extracts of three plants were administered orally in doses of 250 mg and 500 mg/kg/d for 30 d. Glibenclamide (300 μg/kg/d) was used as a reference drug for comparison. Streptozotocin diabetic rats showed a significant increase in serum glutamic oxaloacetate transminase and serum glutamic pyruvate transminase activities and serum urea concentration but a significant decrease in serum total protein and albumin concentrations and albumin/globulin ratio. Oral administration of alcoholic extract of Momordica charantia, Aegle marmelos and Eugenia jambolana in daily doses of 250 mg and 500 mg/kg for a period of 1 mo produced dose- and duration-dependent decrease in serum glutamic oxaloacetate transminase and serum glutamic pyruvate transminase activities as well as decrease in serum urea concentration and restored the serum total protein and albumin concentration and albumin/globulin ratio to a great extent in streptozotocin diabetic rats. The beneficial effects of these plants in 500 mg/kg dose in streptozotocin diabetic rats were comparable to that of glibenclamide (300 μg/kg), a standard oral hypoglycaemic drug used in clinical practice.

Comparative inhibitory properties of some Indian medicinal plant extracts against photosensitization-induced lipid damage

The protective activities of Emblica officinalis, Terminalia bellerica and Terminalia chebula ethanol extracts against photosensitization-induced oxidation of rat liver mitochondrial lipid were assessed. All the extracts could effectively prevent lipid peroxidation, as assessed by measuring thiobarbituric acid-reactive substrates, lipid hydroperoxide, conjugated diene and 4-hydroxynonenal. The E. officinalis extract was the most potent, revealing its superior ability to scavenge 1O 2. The extracts also afforded excellent protection against iron-mediated lipid peroxidation that might also be useful in reducing photo-induced iron toxicity. The activities of the extracts were primarily due to their constituent phenolics.