Endoplasmic reticulum stress in pancreatic ß-cell dysfunction: The potential therapeutic role of dietary flavonoids.

Diabetes mellitus (DM) is a global health burden that is characterized by the loss or dysfunction of pancreatic ß-cells. In pancreatic ß-cells, endoplasmic reticulum (ER) stress is a fact of life that contributes to ß-cell loss or dysfunction. Despite recent advances in research, the existing treatment approaches such as lifestyle modification and use of conventional therapeutics could not prevent the loss or dysfunction of pancreatic ß-cells to abrogate the disease progression. Therefore, targeting ER stress and the consequent unfolded protein response (UPR) in pancreatic ß-cells may be a potential therapeutic strategy for diabetes treatment. Dietary phytochemicals have therapeutic applications in human health owing to their broad spectrum of biochemical and pharmacological activities. Flavonoids, which are commonly obtained from fruits and vegetables worldwide, have shown promising prospects in alleviating ER stress. Dietary flavonoids including quercetin, kaempferol, myricetin, isorhamnetin, fisetin, icariin, apigenin, apigetrin, vitexin, baicalein, baicalin, nobiletin hesperidin, naringenin, epigallocatechin 3-O-gallate hesperidin (EGCG), tectorigenin, liquiritigenin, and acacetin have shown inhibitory effects on ER stress in pancreatic ß-cells. Dietary flavonoids modulate ER stress signaling components, chaperone proteins, transcription factors, oxidative stress, autophagy, apoptosis, and inflammatory responses to exert their pharmacological effects on pancreatic ß-cells ER stress. This review focuses on the role of dietary flavonoids as potential therapeutic adjuvants in preserving pancreatic ß-cells from ER stress. Highlights of the underlying mechanisms of action are also presented as well as possible strategies for clinical translation in the management of DM.

Chemical profiling, bio-guided purification, and cytotoxic effect of two African spices: Hypodaphnis zenkeri Engl. Stapf (Lauraceae) and Staudtia kamerunensis warb (Myristicaceae) on human prostate cancer cell lines.

ETHNOPHARMACOLOGICAL RELEVANCE: Prostate cancer remains a significant burden in low- and middle-income countries and the second leading cause of death around the world. Spices used in daily cuisine contain interesting phytochemical components capable of helping prevent and cure cancer. AIM: This study aims to give sufficient phytochemical information on two understudied species, Staudtia kamerunensis Warb. (Myristicaceae) and Hypodaphnis zenkeri Engl. Stapf. (Lauraceae), and to study their cytotoxicity against prostate cancer cells in its early form and when they have developed metastasis. MATERIALS AND METHODS: To reach this goal, normal procedures for phytochemical analysis were followed; these include collection, drying, crushing and extraction of plant materials using organic solvents. GC-MS (Gas chromatography- Mass Spectrometry) was used to evaluate the volatile phytochemicals contained in the extracts, and open-column chromatography was used to isolate the pure compounds used in this study. A bio-guided exploration of Hypodaphnis zenkeri (Lauraceae) (leaves, seeds, stems) guided us in selecting the extract for further analysis. An established MTT assay was used to measure cell proliferation. Three prostate cancer cell lines were considered in this study, DU145 and PC3, human androgens-independent prostate carcinoma cells and LNCaP, which are cells derived from metastasis of a human prostate and respond to androgens, oestrogens and progestins. The eight compounds isolated were characterized using HREIMS, 1D and 2D NMR. RESULTS: Among the three extracts from Hypodaphnis zenkeri, considered for biological testing, the leaf extract displayed better activities with a CC50 of 180 µg/mL against DU 145 cells, 184 µg/mL against PC3 cells and 194 µg/mL against LNCaP cells. These results were justified when GC-MS analysis of the different extracts was performed. Fifty compounds were identified from the leaves, representing 96.06% of the volatile components, with most displaying anticancer activities or activities against vectors favorizing cancer growth (inflammation, etc.). An attempt to isolate the active principle responsible for the cancer activity led to the isolation of five pure compounds, namely Eicosane [1], Nonacos-1-ene [2], Palmitic acid [3], Glucoside Stigmasterol [4] and Butane-1,2,3,4-tetraol [5]. Eicosane was identified as being responsible in part for the observed activity, even though it exhibited weak cytotoxicity with the lowest CC50 equal to 30 µg/mL against DU 145 cells. Staudtia kamerunensis sap was investigated in our previous studies with the isolation of Oleanan-12-ene-2α,3ß -diol [6] and 2α, 3ß -dihydroxylup-20-ene [7] among the major components, with significant antibacterial properties. Oleanan-12-ene-2α,3ß -diol [7] in this study displayed a CC50 of 20 µg/mL against DU145 cells, 22 µg/mL against PC3 cells, 18 µg/mL against LNCaP cells, and 32 µg/mL in HMEC affording a selectivity index >2. Contrary to what was observed in our previous study, the activity of Oleanan-12-ene-2α,3ß -diol was lost in the presence of 2α, 3ß -dihydroxylup-20-ene. CONCLUSION: the cytotoxic effect of extract from Staudtia and Hypodaphnis genera and pure isolates are here reported for the first time, as well as the pure isolates. These studies exhibit the cytotoxic potential of two traditional African spices and, more specifically, Oleanan-12-ene-2α,3ß -diol and eicosane, isolated from these plant species.

Zeolitic imidazolate framework as humidity-resistant solid state-chemiresistive gas sensors: A review.

With significant technological advances, solid-state gas sensors have been extensively applied to detect toxic gases and volatile organic compounds (VOCs) in confined areas such as indoor environments and industries and to identify gas leakage. Semiconductor metal oxides are the primary sensing materials, although their major drawbacks include a lack of sensitivity, poor performance at high humidity, and operating at high temperatures ranging between 140 and 400 °C. Recently, the use of zeolitic imidazolate frameworks (ZIFs) in gas sensors has received considerable attention as a promising material to overcome the drawbacks possessed by semiconductor metal oxide-based gas sensors. Because of their unique properties, including size tunability, high surface area, and stability in humidity, ZIF becomes a preferred candidate for sensing materials. The use of ZIF materials in gas sensors is limited because of their high-temperature operation and low gas responses. This review outlines the strategies and developments in the utilization of ZIF-based materials in gas sensing. The significant influence of the addition of carbon additives in ZIF materials for temperature operation sensors is discussed. Finally, ZIF-carbon additives and SMO@ZIFs/carbon additives are the proposed materials to be studied for future prospects for the detection of VOCs at low temperatures and exhibiting good selectivity towards the gas of interest.

Carboxymethyl cellulose/poloxamer gels enriched with essential oil and Ag nanoparticles: promising wound dressings.

Aim: Essential oils are promising antibacterial and wound-healing agents that should be explored for the design of wound dressings. Materials & methods: Topical gels prepared from a combination of carboxymethyl cellulose and poloxamer were incorporated with tea tree and lavender oil together with Ag nanoparticles. In vitro release, cytotoxicity, antibacterial, and wound healing studies were performed. Results: The gels displayed good spreadability with viscosity in the range of 210-1200 cP. The gels displayed promising antibacterial activity against selected Gram-positive and Gram-negative bacteria used in the study. The % cell viability of the gels was more than 90.83%. Conclusion: The topical gels displayed excellent wound closure in vitro revealing that they are potential wound dressings for bacteria-infected wounds.

What is this article about? This article reports the efficacy of carboxymethyl cellulose-based topical gels loaded with a combination of essential oils and silver nanoparticles as potential wound dressings for bacterial-infected wounds. What were the results? The topical gels induced a faster rate of closure than the untreated cells in 96 h. The gel formulations did not induce any significant cytotoxic effect. They were effective against Gram-negative and Gram-positive bacteria used in the study. What do the results of the study mean? The topical gels displayed promising healing effects in vitro revealing that they are potential wound dressings for treating bacteria-infected wounds.

From wandering weeds to pharmacy: An insight into traditional uses, phytochemicals and pharmacology of genus Chromolaena (Asteraceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Chromolaena species, of the Asteraceae family, are distributed across the tropical and the temperate regions of Africa, the Americas, southern Asia, and Australia. Despite "falling out of favour" among the people because of their "weedy" nature, Chromolaena species have indisputable long medicinal history in the treatment of malaria, nasal congestion, inflammation, eye disorders, asthma, cough, flu, headache, and cold. AIM OF THE REVIEW: The aim of this review is to systematically summarize the current knowledge on ethnopharmacology, phytochemistry, pharmacology, toxicology, and real-time scientific applications of the genus Chromolaena after its re-classification from genus Eupatorium, as well as to proffer integrated approaches in maximizing their therapeutic values despite their "weedy" nature. MATERIALS AND METHODS: First, the current species in the genus were verified by "The Plant List" (http://www.theplantlist.org) and "Royal Botanic Gardens, Kew/Missouri Botanical Garden" (http://mpns.kew.org/mpns-portal/). Second, the relevant information on each of the identified species was gathered from following databases: Google Scholar, Online Wiley library, ScienceDirect, SciFinder, Scopus, PubMed. Scientific literature was searched from inception till August 2021. RESULTS: More than 190 phytochemicals have been isolated and identified from 27 species of the genus, including flavonoids, alkaloids, triterpenoids, diterpenoids, sesquiterpenoids, steroids, fatty acids, and coumarins among others. Pharmacological investigations, both in vitro and in vivo, have shown that the extracts and the compounds have antimicrobial, anticancer, antioxidant, insecticidal, anti-inflammatory, and anti-diabetic activities among others. CONCLUSIONS: Many species of genus have potential therapeutic values, and hence they are more than "wandering" weeds. In addition, there is growing interest in the real-time scientific applications of the genus in the production of pharmacological polyherbal products, and this should serve as a stimulus to strategically develop integrated control approaches for preserving these species, with a view of maximizing their therapeutic values and reducing their cost of eradication.

Hybrid Compounds Containing Carvacrol Scaffold: In Vitro Antibacterial and Cytotoxicity Evaluation.

BACKGROUND: The design of hybrid compounds is a distinct approach for developing potent bioactive agents. Carvacrol, an essential oil, exhibits antimicrobial, antifungal, antioxidant, and anticancer activity, making it a good precursor for the development of compounds with potent biological activities. Some patents have reported carvacrol derivatives with promising biological activities. OBJECTIVE: This study aimed to prepare hybrid compounds containing a carvacrol scaffold with significant antibacterial and anticancer activity. METHODS: Esterification reactions between carvacrol and known pharmacophores were performed at room temperature and characterized using 1H-NMR, 13CNMR, and UHPLC-HRMS. In vitro antibacterial study was determined using the microdilution assay and cytotoxicity evaluation using sulforhodamine B staining assay. RESULTS: The FTIR spectra of the carvacrol hybrids revealed prominent bands in the range of 1612-1764 cm-1 and 1014-1280 cm-1 due to (C=O) and (C-O) stretching vibrations, respectively. The structures of the carvacrol hybrids were confirmed by 1H-NMR, 13C-NMR, and UHPLC-HRMS analysis, and compound 5 exhibited superior activity when compared to the hybrid compounds against the strains of bacteria used in the study. The in vitro cytotoxicity evaluation showed that compound 3 induced cytotoxicity in all the cancer cell lines; MDA (16.57 ± 1.14 µM), MCF-7 (0.47 ± 1.14 µM), and DU145 (16.25 ± 1.08 µM), as well as the normal breast cells, MCF-12A (0.75± 1.30 µM). Compound 7 did not induce cytotoxicity in the cell lines tested (IC50 > 200 µM). CONCLUSION: The modification of carvacrol through hybridization is a promising approach to develop compounds with significant antibacterial and anticancer activity.

Ecdysteroids from the Stem Bark of Vitex doniana Sweet (Lamiaceae; ex. Verbenaceae): A Geographically Variable African Medicinal Species.

Vitex doniana Sweet is an African medicinal species that is prescribed as an aqueous bark extract to be applied topically or orally to achieve anti-infective outcomes. In select regions it is also taken orally as an antimalarial agent. The aim of the current study was to explore the biological properties of V. doniana and isolated compounds in the context of pathogenic bacteria and the protozoan parasite Plasmodium falciparum. Three compounds were isolated and assigned by nuclear magnetic resonance spectroscopy as ecdysteroids: (1) 20-hydroxyecdysone, (2) turkesterone, and (3) ajugasterone C. Interestingly, two of these compounds had not previously been identified in V. doniana, providing evidence of chemical variability between regions. The bark extract and three ecdysteroids were screened for activity against a panel of pathogenic bacteria associated with skin, stomach and urinary tract infections, and the protozoan parasite P. falciparum. The crude extract of the bark inhibited all bacterial strains with MIC values of 125-250 µg.mL-1. The three isolated compounds demonstrated less activity with MIC values of 500-1000 µg.mL-1. Furthermore, no activity was observed against P. falciparum at the screening concentration of 4.8 µg.mL-1. Nevertheless, we present a hypothesis for the possible mechanism for symptomatic relief of malarial fever, which may involve reduction of prostaglandin E(1) & E(2) activity in the hypothalamus via modulation of the monoaminergic system. While further studies are required to identify all antimicrobial agents within this plant species and to determine the cytotoxicity of each of these compounds, these data suggest that the traditional application of this species as an antiseptic is valid.

Synthesis, Antibacterial, and Cytotoxicity Evaluation of Oleanolic Acid-4-aminoquinoline Based Hybrid Compounds.

AIM: The study aims to prepare a class of oleanolic-based compounds. BACKGROUND: Conventional drugs used to treat infectious diseases suffer from limitations such as drug toxicity and drug resistance. The resistance of microbes to antimicrobial agents is a significant challenge in treating microbial infections. Combining two or more drugs with different modes of action to treat microbial infections results in a delay in developing drug resistance by the microbes. However, it is challenging to select the appropriate drugs for combination therapy due to the differences in stability and pharmacokinetic profile of the drugs. Therefore, developing hybrid compounds using the existing drugs is a promising approach to design effective antimicrobial agents. OBJECTIVES: To prepare oleanolic-based hybrid compounds followed by characterization, in vitro antibacterial and cytotoxicity evaluation. METHODS: Oleanolic acid-4-aminoquinoline-based hybrid compounds were synthesized via esterification and amidation. The compounds were characterized using FTIR, NMR, and UHPLC-HRMS. Oleanolic acid (OA) was isolated from the flower buds of Syzygium aromaticum (L.) Merr. & L.M.Perry, a species from Kingdom Plantae, order Mytales in the Myrtaceae family. Antibacterial activity was determined against selected strains of bacteria using the microdilution assay and cytotoxicity activity was assessed using the sulforhodamine B assay against selected cancer cell lines. RESULTS: The synthesized hybrid compounds exhibited antibacterial activity against the Gram-positive bacteria Enterococcus faecalis (ATCC13047), Bacillus subtilis (ATCC19659), Staphylococcus aureus as well as Gram-negative bacteria, Klebsiella oxytoca (ATCC8724), Escherischia coli (ATCC25922), and Proteus vulgaris (ATCC6380) with minimum inhibitory concentrations of 1.25 mg/mL compared to oleanolic acid (2.5 mg/mL). Compounds 13 and 14 displayed cytotoxicity in vitro against the cancer cell lines (MCF-7 and DU 145) compared to the oleanolic acid (IC50 ˃ 200 µM). CONCLUSION: Modification of C28 of OA enhanced its biological activity.

Synthesis of substituted N-(2'-nitrophenyl)pyrrolidine-2-carboxamides towards the design of proline-rich antimicrobial peptide mimics to eliminate bacterial resistance to antibiotics.

The treatment of diseases is under threat due to the increasing resistance of disease-causing bacteria to antibiotics. Likewise, free radical-induced oxidative stress has been implicated in several human disease conditions, such as cancer, stroke and diabetes. In the search for amino acid analogues with antibacterial and antioxidant properties as possible mimics of antimicrobial peptides, substituted N-(2'-nitrophenyl)pyrrolidine-2-carboxamides 4a-4k and N-(2'-nitrophenyl)piperidine-2-carboxamides 4l-4n have been synthesized via a two-step, one-pot amidation of the corresponding acids, using thionyl chloride with different amines in dichloromethane. The carboxamides were characterized by infrared and nuclear magnetic resonance spectroscopy, mass spectrometry and elemental analysis. Carboxamides 4a-4n were assayed against five Gram-positive and five Gram-negative bacterial strains using the broth micro-dilution procedure and compared to standard antibiotic drugs (streptomycin and nalidixic acid). 4b showed the highest antibacterial activity with a minimum inhibitory concentration (MIC) value of 15.6 µg/mL against Staphylococcus aureus. Pertinently, 4b and 4k are promising candidates for narrow-spectrum (Gram-positive) and broad-spectrum antibiotics, respectively. The antioxidant properties of the carboxamides were also evaluated using the 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical cation. 4a and 4k recorded the lowest IC50 values of 1.22 × 10-3 mg/mL (with DPPH) and 1.45 × 10-4 mg/mL (with ABTS), respectively. Notably, 4k recorded about 2.5 times better antioxidant capacity than the positive controls - ascorbic acid and butylated hydroxyanisole. These results bode well for N-aryl carboxamides as good mimics and substitutes for antimicrobial peptides towards mitigating bacterial resistance to antibiotics as well as ameliorating oxidative stress-related diseases.

Ethanol-extracted Cameroonian propolis: Antiproliferative effects and potential mechanism of action in prostate cancer.

The present study was conducted to evaluate in vitro and in vivo antiproliferative potential of the Cameroonian propolis and to elucidate its underlying mechanism. In vitro, ethanol-extracted propolis (EEP) was tested on cell growth, cell proliferation, cell cycle, cell death mechanism and cell migration. The cell cycle- and apoptosis-regulating proteins were assessed by Western blotting. In vivo the testosterone-induced benign prostatic hyperplasia (BPH) in Wistar rat was used to evaluate the antiproliferative potential of EEP. EEP reduced DU145 and PC3 cell survival with an IC50 of 70 and 22 µg/ml respectively. It increased the number of late apoptotic cells, the amount of cells in G0/G1 phase in DU145 and PC3 cells at 50 µg/ml. Cell cycle proteins (cdk1, pcdk1 and their related cyclins A and B) were down-regulated in both DU145 and PC3 cells, while cdk2 and pcdk2 were down-regulated only in PC3 cells. The pro-apoptotic Bax protein was up-regulated, while the anti-apoptotic Akt and pAKT, and Bcl-2 proteins were down-regulated. It increased prostate cell adhesion and chemotaxis. EEP reduced prostate weight, volume and epithelial thickness in rats. We demonstrated for the first time that Cameroonian propolis is endowed with in vitro and in vivo antiproliferative properties in the prostate.

Anti-HIV-1 integrase potency of methylgallate from Alchornea cordifolia using in vitro and in silico approaches.

According to the 2018 report of the United Nations Programme on HIV/AIDS (UNAIDS), acquired immune deficiency syndrome (AIDS), a disease caused by the human immunodeficiency virus (HIV), remains a significant public health problem. The non-existence of a cure or effective vaccine for the disease and the associated emergence of resistant viral strains imply an urgent need for the discovery of novel anti-HIV drug candidates. The current study aimed to identify potential anti-retroviral compounds from Alchornea cordifolia. Bioactive compounds were identified using several chromatographic and spectroscopic techniques and subsequently evaluated for cytotoxicity and anti-HIV properties. Molecular modelling studies against HIV-1 integrase (HIV-1 IN) were performed to decipher the mode of action of methylgallate, the most potent compound (IC50 = 3.7 nM) and its analogues from ZINC database. Cytotoxicity assays showed that neither the isolated compounds nor the crude methanolic extract displayed cytotoxicity effects on the HeLa cell line. A strong correlation between the in vitro and in silico results was observed and important HIV-1 IN residues interacting with the different compounds were identified. These current results indicate that methylgallate is the main anti-HIV-1 compound in A. cordifolia stem bark, and could be a potential platform for the development of new HIV-1 IN inhibitors.

Antioxidant and prooxidant effects of Piptadeniastrum africanum as the possible rationale behind its broad scale application in African ethnomedicine.

ETHNOPHARMACOLOGICAL RELEVANCE: Piptadeniastrum africanum is widely used in treating oxidative stress related diseases. Oxidative stress, defined as the disturbance in the balance between the production of free radicals and antioxidant defenses, is the root cause of many pathophysiological conditions. Based on the dual properties of prooxidants as toxic and beneficial compounds, both prooxidants and antioxidants may be effective in the treatment of these conditions when the right dose is given to the right subject at the right time for the right duration. AIM OF THE STUDY: This study was aimed at investigating the in vitro and ex vivo anti- and pro-oxidative effects of P. africanum. MATERIALS AND METHODS: Total phenolic and flavonoid contents of methanol and aqueous extracts of P. africanum stem back were quantified spectrophotometrically. The methanol extract, ascorbate radicals and reactive oxygen species in brain and liver homogenates of mice treated with the methanol stem bark extract were analyzed by electron paramagnetic resonance (EPR) spectroscopy. Free radical scavenging of DPPH was determined by spectrophotometric and EPR assays. RESULTS: The methanol extract was richer in both phenolic and flavonoid contents compared to the aqueous extracts and also showed better DPPH radical scavenging capacity. The EPR spectroscopy in vitro analysis exhibited high DPPH scavenging capacity before and after UV irradiation (99.5% and 98.76%) at 40 µg/ml extract. The ex vivo EPR spectroscopy studies demonstrated increased levels of ascorbate radicals (•Asc) in liver and brain homogenates of healthy mice treated with P. africanum in comparison with those of the non treated controls (0.6141 ±â€¯0.026 vs 0.1800 ±â€¯0.0073 arb. units for liver homogenates and 0.9605 ±â€¯0.0492 vs 0.3375 ±â€¯0.0062 arb. units for brain homogenates, correspondingly). Considerably, higher levels of reactive oxygen species (ROS) were measured in mice liver and brain homogenates after treatment with P. africanum extract compared to the control group, as well (1.9402 ±â€¯0.1200 vs 0.6699 ±â€¯0.062 arb. units for liver homogenates and 1.7325 ±â€¯01503 vs 0.3167 ±â€¯0.0403 arb.units, respectively). CONCLUSION: Therefore, P. africanum exhibited antioxidant and pro-oxidant properties which may explain its broad spectrum use in a wide variety of ailments.

Profiling of volatile flavor compounds in nkui (a Cameroonian food) by solid phase extraction and 2D gas chromatography time of flight mass spectrometry (SPME-GC×GC-TOF-MS).

The objective of this study was to investigate the volatile flavor compounds of nkui, a Cameroonian food, using solid phase microextraction (SPME) and a two-dimensional gas chromatography time of flight mass spectrometry GC×GC-TOF-MS system. Using SPME, volatile compounds were extracted from nkui and analyzed by GC×GC-TOF-MS. The data retrieved revealed the presence of flavor volatiles including acids (20%), alcohols (4%), aldehydes (10%), aromatic compounds (4%), esters (7%), furans (4%), ketones (11%), terpenes and terpernoids (27%). Although the terpene compounds were the most predominant, an ester (linalyl acetate) had the highest percentage of 19%, conferring a sweet, green and citrus flavor. Results obtained from this study suggest that the characteristic flavor of nkui was due to the combination of different volatile flavor compounds, which contributed to its aroma. Considering the medicinal importance of these compounds, their presence positions nkui as a vital food source with health benefits and medicinal properties.

2,4-Ditellurouracil and its 5-fluoro derivative: Theoretical investigations of structural, energetics and ADME parameters.

2,4-Ditellurouracil exhibits keto-enol tautomerism via different pathways resulting in seven tautomers. These pathways were studied in the gas phase using density functional theory method. The functionals used were BLYP, B3LYP and BHLYP and the basis sets were 6-311++G(d,p) for all atoms except that LanL2DZ ECP was used for tellurium atom only. The results indicate that the diketo form is more stable as observed for uracil and its sulfur and selenium analogues. The effect of introducing fluorine at position 5 was also investigated and the energy difference between the diketo and dienol forms is reduced. 2,4-Ditellurouracil and its 5-fluoro analogue are expected to exist exclusively as the diketo form due to the high interconversion energy barrier. We extended the investigation to predict ADME parameters of the most stable diketo and dienol tautomers in view of understanding their biological properties. This research enlightens keto-enol tautomerism of 2,4-ditellurouracil and its 5-fluoro derivative with additional insights to biological functions.

Charge-assisted hydrogen bonding in salts of 2-amino-1H-benzimidazole with 3-phenylpropynoic acid and oct-2-ynoic acid.

The 100 K structures of two salts, namely 2-amino-1H-benzimidazolium 3-phenylpropynoate, C7H8N3(+)·C9H5O2(-), (I), and 2-amino-1H-benzimidazolium oct-2-ynoate, C7H8N3(+)·C8H11O2(-), (II), both have monoclinic symmetry (space group P21/c) and display N-H...O hydrogen bonding. Both structures show packing with corrugated sheets of hydrogen-bonded molecules lying parallel to the [001] direction. Two hydrogen-bonded ring motifs can be identified and described with graph sets R(2)(2)(8) and R(4)(4)(16), respectively, in both (I) and (II). Computational chemistry calculations performed on both compounds show that the hydrogen-bonded ion pairs are more energetically favourable in the crystal structure than their hydrogen-bonded neutral molecule counterparts.

Determination of catechins from Elephantorrhiza elephantina and Pentanisia prunelloides using voltammetry and UV spectroscopy.

In this work, we report the identification and quantification of catechins by electrochemistry and UV-Vis spectroscopy in Elephantorrhiza elephantina (Fabaceae) and Pentanisia prunelloides (Rubiaceae), both of which are medicinal plants that are widely used in Southern Africa to remedy various ailments. A comparative study of the catechin content as (-)-epicatechin equivalent is reported for the first time, with E. elephantina exhibiting a higher concentration relative to P. prunelloides in both aqueous and methanol extracts.