Non-alkaloidal Compounds Research Articles

Non-Alkaloidal Compounds from Tubers of Gloriosa superba and their In vitro and In silico Antibacterial and Antioxidant Activities

Background: The tubers of Gloriosa superba L. (Colchicaceae) are previously well known for their alkaloidal constituents. The present work aimed to investigate the non-alkaloidal constituents and evaluate their in vitro and in silico antibacterial and antioxidant activities from the tuber. Methods: The chloroform: methanol (1:1) tuber extract was fractionated over silica gel column chromatography, and isolated compounds were characterized by NMR spectroscopy. Various extracts and isolated compounds were evaluated for their antibacterial and antioxidant activities against certain pathogenic strains and oxidants. The in silico drug-likeness properties of isolated compounds were also studied against 6F86 antibacterial and 1HD2 antioxidant protein models. Results: Three non-alkaloidal compounds, β-sitosterol (1), 3-(cyclopenta-2,4-dienyloxy) β- sitosterol (2) and 1,2-n-dipropyl phthalate (3), were reported herein. The n-hexane and chloroform extracts displayed better antibacterial activity against E. coli (9.83 ± 0.28 mm) and P. aeruginosa (10.65 ± 0.79 mm), and S. aureus (10.33 ± 0.3 mm), respectively, at 100,000 μg/mL concentration. Compound 3 established a better activity against all bacterial strains (9.78 ± 0.63-11.07 ± 0.09 mm) at 1000 μg/mL (IC50 values of 1.5-3.2 μg/mL). All the extracts exhibited a DPPH free radical scavenging activity comparable to ascorbic acid (IC50 value of 1.2 μg/mL), whereas isolated compounds were found with negligible DPPH scavenging activity and weak ferric ion reduction power up to 500 μg/mL dose. The docking study revealed that all the compounds fulfilled Lipinski’s rule of five by contravening no more than one rule with strong binding affinity shown by compound 1 (-8.2 kcal/mol) and compound 3 (-4.5 kcal/mol) to the 6F86 bacterial and 1HD2 antioxidant protein models, respectively, which are comparable to the ciprofloxacin (-7.2 kcal/mol) and ascorbic acid (- 4.5 kcal/mol) drugs. All the compounds also did not show any cytotoxicity properties. Whereas compound 1 showed an immunotoxicity and mutagenicity properties; and compounds 2 and 3 were found as immunotoxic and carcinogenic isolates, respectively. Conclusion: The promising antioxidant activity result of the various tubers extracts may highlight the potential use of Gloriosa superba as a source of foods by conducting further phytochemical investigation and additional bioassay evaluation, including the cytotoxicity effect of the whole part of the plant.

Application of effect-directed analysis using TLC-bioautography for rapid isolation and identification of antidiabetic compounds from the leaves of Annona cherimola Mill.

Type 2 diabetes mellitus is a globally prevalent chronic disease characterised by hyperglycaemia and oxidative stress. The search for new natural bioactive compounds that contribute to controlling this condition and the application of analytical methodologies that facilitate rapid detection and identification are important challenges for science. Annona cherimola Mill. is an important source of aporphine alkaloids with many bioactivities. The aim of this study is to isolate and identify antidiabetic compounds from alkaloid extracts with α-glucosidase and α-amylase inhibitory activity from A. cherimola Mill. leaves using an effect-directed analysis by thin-layer chromatography (TLC)-bioautography. Guided fractionation for α-glucosidase and α-amylase inhibitors in leaf extracts was done using TLC-bioassays. The micro-preparative TLC was used to isolate the active compounds, and the identification was performed by mass spectrometry associated with web-based molecular networks. Additionally, in vitro estimation of the inhibitory activity and antioxidant capacity was performed in the isolated compounds. Five alkaloids (liriodenine, dicentrinone, N-methylnuciferine, anonaine, and moupinamide) and two non-alkaloid compounds (3-methoxybenzenepropanoic acid and methylferulate) with inhibitory activity were isolated and identified using a combination of simple methodologies. Anonaine, moupinamide, and methylferulate showed promising results with an outstanding inhibitory activity against both enzymes and antioxidant capacity that could contribute to controlling redox imbalance. These high-throughput methodologies enabled a rapid isolation and identification of seven compounds with potential antidiabetic activity. To our knowledge, the estimated inhibitory activity of dicentrinone, N-methylnuciferine, and anonaine against α-glucosidase and α-amylase is reported here for the first time.

Lignans and some other non-alkaloid compounds from the stem bark of Zanthoxylum rhetsa and their biological activities

Four lignans, asarinin (1), horsfieldin (2), 5-(4-(3,4,5-trimethoxyphenyl)hexahydrofuro[3,4-c]furan-1-yl)benzo[d][1,3]dioxole (3), 5-(4-(3,5-dimethoxyphenyl)hexahydrofuro[3,4-c]furan-1-yl)benzo[d][1,3]dioxole (4), and four non-alkaloid compounds, piperonylic acid (5), hesperidin (6), syringin (7), and β-sitosterol (8) were isolated from the stem bark of Zanthoxylum rhetsa grown in Vietnam. Their chemical structures were elucidated by spectroscopic analysis and compared with the references. Except for compound 6, all the remaining compounds (1–5, 7, and 8) were isolated for the first time from Z. rhetsa. The isolated compounds were tested for their cytotoxic activity against three human cancer cell lines, LU-1, Hep-G2, and KB. Compound 5 showed moderate cytotoxic activity against all three cell lines with IC50 values ranging from 48.13 to 49.06 µg mL−1. Notably, compound 6 demonstrated selective cytotoxicity against LU-1, Hep-G2, and KB cancer cell lines (IC50 66.48–67.41 µg mL−1) while non-toxic toward normal Vero cell. Compound 6 also exhibited its ability to inhibit main protease (Mpro) enzyme in vitro with an IC50 value of 55.49 µg mL−1 and in silico with the binding affinity toward targeted protein of −14.36 kcal mol−1.

A review on efforts for improvement in medicinally important chemical constituents inAconitum through biotechnological interventions.

The genus Aconitum belongs to the family Ranunculaceae, is endowed with more than 350 species on the earth. Medicinally important aconitine type of diterpenoid alkaloids are the characteristic compounds in most of the Aconitum species. The present review endeavored the major research carried out in the field of genetic resource characterization, pharmacological properties, phytochemistry, major factors influencing quantity, biosynthetic pathways and processing methods for recovery of active ingredients, variety improvement, propagation methods, and important metabolite production through cell/organ culture of various Aconitum species. More than 450 derivatives of aconitine-type C19 and C20-diterpenoid alkaloids along with a few other non-alkaloidal compounds, such as phenylpropanoids, flavonoids, terpenoids, and fatty acids, have been identified in the genus. A few Aconitum species and theircommon diterpenoid alkaloid compounds are also well characterized for analgesic, inflammatory and cytotoxic properties. However, the different isolated compound needs to be validated for supporting other traditional therapeutical uses of the plant species. Aconitine alkaloids shared common biosynthesis pathway, but their diversification mechanism remains unexplored in the genus. Furthermore, the process needs to be developed on secondary metabolite recovery, mass-scale propagation methods, and agro-technologies for maintaining the quality of products. Many species are losing their existence in nature due to over-exploitation or anthropogenic factors; thus, temporal monitoring of the population status in its habitat, and suitable management programs for ascertaining conservation needs to be developed.

A comprehensive review of non-alkaloidal metabolites from the subfamily Amaryllidoideae (Amaryllidaceae)

Abstract Amaryllidoideae is a subfamily belonging to the Amaryllidaceae and is widely distributed in the southern hemisphere. The subfamily is well known for its content of pharmacologically active alkaloids and represents an important epicenter of Amaryllidaceae-alkaloid diversity. Other metabolites from Amaryllidoideae such as phenolics including flavonoids, lignans, chromones, and acetophenones, in addition to terpenoids and ceramides, have been reported and received less attention compared to alkaloids. Currently, 224 non-alkaloidal compounds have been isolated and identified from ∼7% of the subfamily members. Many of the isolated compounds showed interesting biological activities. Isolation of certain compounds such as flavans and phytosterols from Amaryllidoideae has significant taxonomical value among the Amaryllidaceae subfamilies. This article represents an extensive review of the non-alkaloidal chemical constituents of Amaryllidoideae and their biological activities including a brief discussion of their chemotaxonomical importance.

Alkaloids with cholinesterase inhibitory activities from the bulbs of Crinum × amabile Donn ex Ker Gawl

Seven previously undescribed alkaloids, crinamabilines A–G, two non-alkaloidal compounds, crinamabidiene and 6-phenylpiperonyl alcohol, two first naturally occurring alkaloids, 3-epibuphanisine and (+)-1β,2β-epoxy-epicrinine, together with nineteen known alkaloids, were isolated from the bulbs of Crinum × amabile Donn ex Ker Gawl. Their structures and absolute configurations were elucidated by NMR, MS and ECD spectroscopic techniques. Ungeremine displayed the most potent inhibitory activity against acetylcholinesterase (IC50 0.21 μM), which was about 6-fold more active than the reference drug, galanthamine (IC50 1.23 μM). Ungeremine also exhibited the strongest inhibitory activity against butyrylcholinesterase (IC50 3.57 μM), which was comparable to galanthamine (IC50 3.11 μM). The molecular docking studies were performed and were well in agreement with the experimental results.

In silico screening of some compounds derived from the desert medicinal plant Rhazya stricta for the potential treatment of COVID-19

The latest coronavirus pandemic (SARS-CoV-2) poses an exceptional threat to human health and society worldwide. The coronavirus (SARS-CoV-2) spike (S) protein, which is required for viral–host cell penetration, might be considered a promising and suitable target for treatment. In this study, we utilized the nonalkaloid fraction of the medicinal plant Rhazya stricta to computationally investigate its antiviral activity against SARS-CoV-2. Molecular docking and molecular dynamics simulations were the main tools used to examine the binding interactions of the compounds isolated by HPLC analysis. Ceftazidime was utilized as a reference control, which showed high potency against the SARS-CoV-2 receptor binding domain (RBD) in an in vitro study. The five compounds (CID:1, CID:2, CID:3, CID:4, and CID:5) exhibited remarkable binding affinities (CID:1, − 8.9; CID:2, − 8.7; and CID:3, 4, and 5, − 8.5 kcal/mol) compared to the control compound (− 6.2 kcal/mol). MD simulations over a period of 200 ns further corroborated that certain interactions occurred with the five compounds and the nonalkaloidal compounds retained their positions within the RBD active site. CID:2, CID:4, and CID:5 demonstrated high stability and less variance, while CID:1 and CID:3 were less stable than ceftazidime. The average number of hydrogen bonds formed per timeframe by CID:1, CID:2, CID:3, and CID:5 (0.914, 0.451, 1.566, and 1.755, respectively) were greater than that formed by ceftazidime (0.317). The total binding free energy calculations revealed that the five compounds interacted more strongly within RBD residues (CID:1 = − 68.8, CID:2 = − 71.6, CID:3 = − 74.9, CID:4 = − 75.4, CID:5 = − 60.9 kJ/mol) than ceftazidime (− 34.5 kJ/mol). The drug-like properties of the selected compounds were relatively similar to those of ceftazidime, and the toxicity predictions categorized these compounds into less toxic classes. Structural similarity and functional group analyses suggested that the presence of more H-acceptor atoms, electronegative atoms, acidic oxygen groups, and nitrogen atoms in amide or aromatic groups were common among the compounds with the lowest binding affinities. In conclusion, this in silico work predicts for the first time the potential of using five R. stricta nonalkaloid compounds as a treatment strategy to control SARS-CoV-2 viral entry.

LC-MS/MS-based metabolomics approach revealed novel phytocompounds from sugarcane rind with promising pharmacological value.

Sugarcane provides many secondary metabolites for the pharmacological and cosmetic industries. Secondary metabolites, such as phenolic compounds, flavonoids, and anthocyanins, have been studied, but few reports focus on the identification of alkaloid and non-alkaloid phytocompounds in sugarcane. In this study, we identified 40 compounds in total from the rinds of cultivated sugarcane varieties (including eight alkaloids, 24 non-alkaloids, and eight others) by using the liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach. Among these compounds, 31 were novel and are reported for the first time in sugarcane. Some alkaloids such as 3-indoleacrylic acid, N,N-dimethyl-5-methoxytryptamine, tryptamine, 6-hydroxynicotinic acid, and 6-deoxyfagomine are identified the first time in sugarcane rind. Four alkaloids such as trigonelline, piperidine, 3-indoleacrylic acid, and 6-deoxyfagomine are found abundantly in sugarcane rind and these compounds have promising pharmaceutical value. Some phytocompounds such as choline and acetylcholine (non-alkaloid compounds) were most common in the rind of ROC22 and Yuetang93/159 (YT93/159). Hierarchical cluster analysis and principal component analysis revealed that the ROC22, Taitang172 (F172), and Yuetang71/210 (YT71/210) varieties were quite similar in alkaloid composition when compared with other sugarcane varieties. We have also characterized the biosynthesis pathway of sugarcane alkaloids. The rind of F172, ROC22, and YT71/210 showed the highest total alkaloid content, whereas the rind of ROC16 revealed a minimum level. Interestingly, the rind extract from YT71/210 and F172 showed maximum antioxidant activity, followed by ROC22. Our results showed the diversity of alkaloid and non-alkaloid compounds in the rind of six cultivated sugarcanes and highlighted the promising phytocompounds that can be extracted, isolated, and utilized by the pharmacological industry. © 2022 Society of Chemical Industry.

Non-alkaloid constituents of Hymenocallis littoralis

Perennial herb Hymenocallis littoralis(Amaryllidaceae) boasts anti-tumor, anti-virus, and anti-inflammatory activities. As the representative constituents, alkaloids have attracted much attention, whereas the non-alkaloid constituents have been rarely reported. Therefore, this study investigated the non-alkaloid constituents of H. littoralis and their contribution to the various pharmacological activities of the herb. Thirteen non-alkaloid compounds were isolated from the 95% ethanol extract of dried whole plant of H. littoralis after a series of chromatographic separation steps and spectral analysis, and they were identified as 5,7-dihydroxy-6,8-dimethoxy-2-hydroxymethyl-4H-chromoen-4-one(1), undulatoside A(2),(2S)-7,4'-dihydroxyflavane(3), naringenin(4), 4',7-hydroxy-8-methylflavanone(5), 8-methylnaringenin(6), 8-demethylfarrerol(7), 6-methyl-aromadendrin(8), 4',5,7-trihydroxy-8-methylflavanone(9), syzalterin(10), 6-methylapigenin(11), isoliquiritigenin(12), and undatuside C(13) based on the spectroscopic data analysis. Among them, compound 1 was a new chromone derivative, and compounds 2 and 4-13 were isolated form this plant for the first time.

Hemijski sastav alkaloidnog ekstrakta izolovanog iz nadzemnog dela biljke Hylotelephium spectabile (Boreau) H. Ohba x telephium (L.) H. Ohba

There are many motives to study alkaloids within Crassulaceae family, such as chemotaxonomic consideration of alkaloid distribution and evaluation of their biological potential. Data on alkaloids from Sedum telephium (syn. H. telephium) aroused interest for further alkaloid investigation within the genus Hylotelephium H. Ohba. Thus, the aim of this study was to investigate and characterize other plant sources of alkaloids from the same genus. An alkaloid extract (AE-HS) was isolated from fresh aerial parts of a cultivated hybrid H. spectabile x telephium. The chemical composition of AE-HS was determined by GC-MS (gas chromatography - mass spectrometry) method. Eight components were identified, which made up 91.8% of the sample. The most present component of AE-HS was g-crotonolactone (78.6%) followed by 3-methyl-2-butenal (8.6%) and (E)-coniferyl alcohol (2.8%). Nicotine was identified as the only alkaloid in the AE-HS (0.4%). Along with many non-alkaloid compounds, a previous study found six alkaloids in AE of S. telephium (~7%), suggesting differences from our results. Additionally, alkaloid distribution is limited within other genera of the family and belonging to the same genus does not mean a uniform qualitative composition. Further analyzes of AEs of Hylotelephium taxa would certainly shed light on the pattern of alkaloid distribution.

Non-Alkaloidal Compounds from Khat (Catha edulis) Leaves

Khat belongs to the family Celastraceae, genus Catha, and species edulis. More than 200 compounds have previously been identified in Khat leaves, including: 40 alkaloids, terpenoids and sterol, flavonoids, glycosides, tannins, amino acids, vitamins and minerals. Researchers have spent their effort and time merely on study of the alkaloidal components (mainly the stimulant agents, cathinone and cathine) of Khat both qualitatively and quantitatively. The two principal Khat stimulant compounds, cathinone and cathine, by now are well established. But, on the contrary, previous studies on the non-alkaloidal constituents of the plant were limited. The objective of this work was therefore to isolate and characterize compounds from non-alkaloidal fractions of the plant’s leaves. In this work, two non-alkaloidal compounds (KNA-1 and KNA-2) were isolated and characterized from the acid-EtOAc extract of fresh and oven-dried leaves of Khat (Catha edulis). From the present study, it is possible to conclude that investing more effort and time on searching additional non-alkaloidal principles from the leaves of Khat is so necessary. And further works could be done in the future to isolate extra non-alkaloidal compounds from the leaves and other parts of Khat and evaluate their biological activity.

First isolation of acetovanillone and piceol from Crinum buphanoides and Crinum graminicola (I. Verd.) Amaryllidaceae

Screening of three native South African Amaryllidaceae bulbs, aimed at finding new metabolites for their promising biological activities, lead to the initial discovery of two interesting non-alkaloid compounds viz., acetovanillone 1 (also known as apocynin) and 4-hydroxyacetophenone 2 (also named piceol) isolated from Crinum buphonoides, while only the former was isolated from Crinum graminicola. This is the first time that acetovanillone 1 and piceol 2 were isolated from C. graminicola and C. buphanoides, respectively. Acetovanillone 1 was recently reported as a metabolite of Boophane disticha (L.f.), another South Africa Amaryllidacea species.

Anti-Candida and anti-Cryptococcus evaluation of 15 non-alkaloidal compounds from Pterogyne nitens

ObjectiveTo evaluate anti-Candida and anti-Cryptococcus activities of 15 non-alkaloidal compounds from Pterogyne nitens Tulasne (Leguminosae), a South American medicinal plant. MethodsCompounds were submitted to antifungal assays, using microdilution method described by Clinical and Laboratory Standards Institute document, with minor modifications. Five species of Candida and two species of Cryptococcus, including clinical isolates were screened. Antifungal activity was expressed by minimum inhibitory concentration (MIC). Amphotericin B and fluconazole were used as standard antifungal drugs. ResultsAmong tested compounds, six substances presented fungal growth inhibition (MIC < 31.2 μg/mL) [three flavone derivatives (1–3), a glycosylated flavonol derivative (5) and two phenolic acids (10 and 12)]. Sorbifolin (1), exhibited potent antifungal activity, demonstrating MIC value of 3.90 μg/mL against Candida glabrata ATCC 90030, Cryptococcus gattii 118 and fluconazole-resistant clinical isolate of Cryptococcus neoformans var. grubii. Pedalin (2) and nitensoside B (3), two glycosylated flavone derivatives, were active against Cryptococcus neoformans ATCC 90012 (MIC = 7.80 μg/mL). ConclusionsFlavone derivatives from Pterogyne nitens can serve as prototypes for the design and development of innovative anti-Candida and anti-Cryptococcus hits.

Non-alkaloid constituents of Vinca major

The present study was designed to investigate the non-alkaloid compounds from the leaves and stems of Vinca major cultivated in Yunnan Province, China. The compounds were isolated using chromatographic techniques. The structures were elucidated by 1D- and 2D-NMR spectroscopic methods in combination with UV, IR, and MS analyses. The 1, 1-diphenyl-2-picrylhydrazyl (DPPH)-scavenging activity of Compounds 1–7 were evaluated. One new iridoid glycoside (compound 1), together with 11 known compounds, were isolated from Vinca major. Compounds 1, 5, and 6 showed moderate DPPH-scavenging activity, with IC50 values being 70.6, 32.8, and 62.2 μmol·L−1, respectively. In conclusion, compound 1 is a newly identified iridoid glycoside with moderate antioxidant activity.

Non-alkaloidal compounds from the bulbs of the Egyptian plant Pancratium maritimum.

Phytochemical investigation of the cytotoxic fractions of fresh bulbs of Pancratium maritimum L. led to the isolation and structure identification of two new compounds, pancricin (1) and pancrichromone (4), together with four known compounds, including 2,4-dihydroxy-6-methoxy-3-methyl acetophenone (2), 5-formylfurfuryl acetate (3), 7-beta-D-glucosyloxy-5-hydroxy-2-methylchromone (5), and ethyl-beta-D-glucopyranoside (6). Their structures were established on the basis of 1D and 2D NMR spectroscopy (1H, 13C, COSY, HSQC, and HMBC), as well as HR mass spectral analyses. The compounds were evaluated for their antimigratory and antiproliferative activities against the highly metastatic human prostate cancer cell line (PC-3M). Compound 5 was the most active compound displaying good activity in the proliferation assay comparable to that of the positive control 4-hydroxyphenylmethylene hydantoin, while it displayed only weak antimigratory activity compared to the positive control 4-ethylmercaptophenylmethylene hydantoin.

Novel sesquiterpene and copyrine alkaloids from Anaxagorea javanica Blume

A novel sesquiterpene, nordine (or 2,2,9-trimethyl-5-methylene-12-oxa-bicyclo[6.3.1]dodecane-4,9-diol) (1) and two new copyrine alkaloids of eupolauridine skeleton, viz., 4,11-dimethoxyeupolauridine (2) and 2-methoxy-3-hydroxyeupolauridine (3), along with five alkaloidal (4–8) and nine non-alkaloidal compounds (9–17), have been isolated from the bark and roots of Anaxagorea javanica Blume. The structures of the new constituents were deduced by NMR spectral data. Compounds 6 and 7 displayed moderate inhibition of NO production with IC50 values of 18.2 and 32.3μg/ml respectively.

A review of phytochemistry, bioactivities and ethno medicinal uses of Rhazya stricta Decsne (Apocynaceae)

Rhazya stricta Decne is an important medicinal plant belonging to family Apocynaceae. Its chemical constituents, biological and pharmacological activities, and ethno medicinal uses have been reviewed in the present study. The reported phytochemical studies conducted on various parts of R. stricta plant revealed presence of over 100 alkaloids and few non-alkaloidal compounds. Most of the activities of the plant reside in its alkaloidal fractions. The compounds have been reported to exhibit ambulatory, antifungal, antimicrobial, antioxidant, endogenous monoamine oxidase (MAO) A and B inhibitory and herbicidal activities. They also showed effects on arachidonic acid (AA) metabolism, blood pressure, central nervous system (CNS), immunity, smooth muscles and glucose homeostasis. Different parts of the plant have been reported to be used in traditional medicine against various ailments such as diabetes, foot burning, skin diseases, stomach pain etc. But more work needs to be done regarding its medicinal importance (recording and exploring recipes) for the benei¬t of improving human health. As the plant of R. strictahas immense potential as an anti-microbial due to its richness of phytochemicals it possesses, therefore, such studies are recommended in various parts of the countries of Arabian Peninsula and the Indian subcontinent where it grows. Key words: Photochemistry, bioactivities, Rhazya stricta, apocynaceae.

A non-aqueous solid phase extraction method for alkaloid enrichment and its application in the determination of hyoscyamine and scopolamine

A non-aqueous solid phase extraction (SPE) method utilizing silica based strong cation exchange (SCX) was developed and optimized for the enrichment of alkaloids. In this method, silica based SCX SPE columns were used for the elimination of non-alkaloid compounds and the preconcentration of alkaloids from the extracts. Mass spectrometry was employed to analyze the alkaloid-enriched fraction, and results showed that the SPE method developed in this study was effective for the removal of non-alkaloids. Then, this pretreatment method was combined with high performance liquid chromatography for the quantification of scopolamine and hyoscyamine from Scopolia tangutica Maxim. The recoveries of scopolamine and (-)-hyoscyamine were 98.51% and 91.12%, respectively. Relative standard deviation values were 1.4% for scopolamine and 1.6% for (-)-hyoscyamine. The linearity was good in the 0.01-0.8 mg mL(-1) range for hyoscyamine and 0.01-0.4 mg mL(-1) range for scopolamine.

Non-alkaloid components from Uncaria sinensis (Oliv.) Havil. and their chemotaxonomic significance

Ten non-alkaloid compounds (1-10) including one aromatic compound, one anthraquinone, two triterpenoids and five i¬‚avonoids were isolated from Uncaria sinensis (oliv.) Havil. for the first time, except compounds 3 and 9. The chemotaxonomic signii¬cance of these compounds was summarized. Key words: Uncaria sinensis (oliv.) Havil., Rubiaceae, natural products, chemotaxonomic studies.

Antibacterial Pterocarpans from Erythrina subumbrans

Seven pterocarpans, erybraedin B ( 1), erybraedin A ( 2), phaseollin ( 3), erythrabyssin II ( 4), erystagallin A ( 5), erythrabissin-1 ( 6) and erycristagallin ( 7), two flavanones, 5-hydroxysophoranone ( 8) and glabrol ( 9), and one isoflavone, erysubin F ( 10), were isolated from the stems of Erythrina subumbrans (Leguminosae). Their structures were identified by means of spectroscopy. This is the first report of the isolation of the non-alkaloidal compounds from Erythrina subumbrans and the observed dehydration of 6a-hydroxypterocarpans 5 and 6 in CDCl 3 to the corresponding pterocarpenes 11 and 12, respectively. Compounds 8 and 9 were isolated for the first time from the genus Erythrina. Compounds 2 and 4 exhibited the highest degree of activity against Streptococcus strains with an MIC range of 0.78–1.56 μg/ml, whereas compound 7 exhibited the highest degree of activity against Staphylococcus strains, including drug-resistant strains (MRSA and VRSA), with an MIC range of 0.39–1.56 μg/ml. Interestingly, compounds 2, 4, 5 and 7 were more active against several strains of Streptococcus and Staphylococcus than the standard antibiotics vancomycin and oxacillin. Compound 7 showed the highest level of activity against all VRSA strains tested, with an MIC range of 0.39–1.56 μg/ml, which were resistant to both antibiotics. These compounds may prove to be potent phytochemical agents for antibacterial activity, especially against the MRSA and VRSA strains.