A bioactive chalcone from the aerial parts of Indigofera conferta Gillet.

Ethnobotanical information indicates that Indigofera conferta is used in northern Nigeria for the management of poisonous snakebites and the methanol extract was previously reported to have antivenin activity. In this study, we report the isolation of an oxyprenylated bioactive secondary metabolite; 2',4'- dihydroxy-4-prenyloxychalcone from the chloroform fraction of the aerial parts of the plant's methanol extract and the in vivo evaluation of the compound against Naja nigricollis venom. The compound has demonstrated significant (p < 0.05) and dose-dependent antivenin activity against LD99 Naja nigricollis venom. At a dose of 10 mg/kg, the compound protected 60% of the animals tested from death. The observed activity lends credence to the traditional use of the plant in the management of snake bites in northern Nigeria. The compound, 2',4'- dihydroxy-4-prenyloxychalcone, could also serve as a lead in the development of novel antisnake venom agents.

Potential Inhibitors of SARS-CoV-2 from Neocarya macrophylla (Sabine) Prance ex F. White: Chemoinformatic and Molecular Modeling Studies for Three Key Targets

Objectives: The novel coronavirus disease-2019 (COVID-19) that emerged in China, is a highly transmittable and pathogenic viral infection caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2); the disease has been declared by the World Health Organization as a Public Health Emergency of International Concern. The unavailability of approved therapeutic agents or vaccines is of great concern. This study performed molecular docking and absorption, distribution, metabolism, excretion and toxicity (ADMET) analysis of some compounds isolated from Neocarya macrophylla (Sabine) Prance ex F. White (Chrysobalanaceae) against three targets of SARS-CoV-2 proteins (3C-like protease, spike protein, and papain-like protease). Materials and Methods: Phytoconstituents isolated from N. macrophylla were screened against key targets of SARS-CoV-2 using Auto Dock Vina, while the ADMET analysis was performed using swiss ADME and pkCSM ADMET descriptors algorithm protocols. Results: The in silico computational studies revealed that the compounds (catechin, catechin-3-rhamnoside, quercetin, and epicatechin) isolated from N. macrophylla can effectively bind with high affinity and lower energy values to the three target proteins of SARS-CoV-2. ADMET analysis was used to predict important pharmacokinetic properties of the compounds, such as aqueous solubility, blood-brain barrier, plasma protein binding, CYP2D6 binding, intestinal absorption, and hepatotoxicity. Conclusion: The findings of this study have shown that N. macrophylla contains potential leads for SARS-CoV-2 inhibition and thus, should be studied further for development as therapeutic agents against COVID-19.

Central nervous system depressant effects of fractions of methanol leaf extract of Cissus cornifolia (Baker) Planch.

Cissus cornifolia is an annual herb used in the treatment of mental derangement in the African Traditional Medicine. As part of a continuous research on this medicinal plant to scientifically validate its use in mental derangement, the fractions of the leaf extract were investigated for central nervous system (CNS) depressant effects. Successive fractionation of the methanol leaf extract of C. cornifolia was utilized to obtain the chloroform fraction (CLF), ethyl acetate fraction (EAF) and the residual aqueous fractions (RAF). These fractions were investigated for CNS-depressant effects in mice using diazepam-induced sleep, head-dip and motor-coordination tests. CLF, EAF and RAF significantly (p<0.01) prolonged the duration of sleep in mice. EAF significantly (p<0.05) reduced the mean head-dips in mice at 75 and 150 mg/kg. Similarly, a significant decrease in the mean head-dips (p<0.05, p<0.01 and p<0.005) was produced by RAF at 150, 300 and 600 mg/kg respectively. In the beam-walking assay test, all the fractions did not produce motor coordination deficit in mice. The data obtained revealed the fractions of methanol leaf extract of Cissus cornifolia possess remarkable central nervous system depressant effects.

Isolation of bergenin from the root bark of Securinega virosa and evaluation of its potential sleep promoting effect.

OBJECTIVES: Securinega virosa Roxb (Ex Willd) Baill (Euphorbaiceae) root bark has been reportedly used in African traditional medicine in the management of mental illnesses. Previously, the sleep-inducing potential of the crude methanol root bark of Securinega virosa extract and its butanol fraction have been reported. The study aimed to isolate and characterize the bioactive constituent that may be responsible for the sleep inducing property of the root of the plant. MATERIALS AND METHODS: The phytochemical investigation of the S. virosa root bark was carried out leading to the isolation of a compound from the butanol-soluble fraction of the methanol extract. The structure of the compound was elucidated on the basis of its spectral data, including IR, 1D and 2D NMR, mass spectrometry as well as X-ray diffraction analysis. The compound was investigated for sleep-inducing potential using diazepam-induced sleeping time test and beam walking assay in mice. RESULTS: This is the first report on the isolation of bergenin from the root of the plant. It significantly decreased the mean onset of sleep [F (2, 15) =7.167; p< 0.01] at the dose of 10 mg/kg, without significantly affecting the total sleep duration [F (2, 15) = 0.090, p=0.914]. Conversely, it did not significantly affect the number of foot slips at the doses of 5 and 10 mg/kg tested. CONCLUSION: Bergenin isolated from the root bark of S. virosa possesses sleep-inducing property and could be partly responsible for the sedative potential of the root of S. virosa.

Chemical composition and antimicrobial activity of hexane leaf extract of Anisopus mannii (Asclepiadaceae).

OBJECTIVE: The aim was to determine the chemical constituents and antimicrobial activity of the hexane leaf extract of Anisopus mannii against a wide range of human pathogenic microorganisms. METHODS: The chemical constituents of the hexane leaf extract was determined using gas chromatography-mass spectrometry (GC-MS) analysis; and the antimicrobial activity was evaluated on "standard strains", clinical susceptible and resistant bacterial and fungal isolates using the disc diffusion and broth microdilution methods. RESULTS: GC-MS analysis of the hexane leaf extract revealed 32 compounds, representing 73.8% of the identified components. The major compounds were hexadecanoic acid, ethyl ester (34%), oxirane, hexadecyl- (11%) and 9, 12, 15-octadecatrienoic acid, ethyl ester, (Z, Z, Z) (9.6%). Results from the antimicrobial activity demonstrated higher inhibition zones against Bacillus cereus (29 mm), followed by Streptococcus pyogenes (28 mm). Other notable inhibitions were observed with Enterococcus faecalis (27 mm), Proteus vulgaris (26 mm) and MRSA (25 mm). The MIC values ranged from 0.625 mg/mL to 1.25 mg/mL while the MBC/MFC values ranged from 2.5 mg/mL to 5.0 mg/mL. CONCLUSION: These results support the traditional use of the plant and demonstrate the huge potential of A. mannii as a source of antimicrobial compounds.

Flavonoids with antimicrobial activity from the stem bark of Commiphora pedunculata (Kotschy & Peyr.) Engl.

The first reported investigation into the phytochemical constituents of Commiphora pedunculata led to the isolation of two flavonoids: kaempferol and dihydrokaempferol from the ethyl acetate-soluble fraction of the methanol extract of the stem bark of the plant. The structures of these compounds were characterised by comparing their spectral data including 1D and 2D NMR with those reported in the literature. The two compounds were active against 6 out of 10 tested microorganisms including two resistant strains [methiciline-resistant Staphylococcus aureus and vancomycin-resistant entrococci (VRE)], Candida albicans and Escherichia coli. The zones of inhibition ranged between 24 and 30 mm for both compounds against the microorganisms. The MIC value was as low as 6.25 µg/mL against VRE and Staphylococcus aureus. This is the first report of the isolation of these compounds from the plant.

Central depressant activity of butanol fraction of Securinega virosa root bark in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Securinega virosa is a commonly used medicinal plant in African traditional medicine in the management of epilepsy and mental illness. Previous studies in our laboratory showed that the crude methanol root bark extract of the plant possesses significant behavioral effect in laboratory animals. In an attempt to isolate and characterize the biological principles responsible for the observed activity, this study is aimed at evaluating the central depressant activity of the butanol fraction of the methanol root bark extract of Securinega virosa. MATERIALS AND METHODS: The medial lethal dose of the butanol fraction was estimated using the method of Lorke. Preliminary phytochemical screening was conducted on the butanol fraction using standard protocol. The behavioral effect of the butanol fraction (75, 150 and 300mg/kg) was evaluated using diazepam induced sleep test, hole-board test, beam walking assay, staircase test, open field test and elevated plus maze assay, all in mice. RESULTS: The median lethal dose of the butanol fraction was estimated to be 1256.9mg/kg. The preliminary phytochemical screening revealed the presence of tannins, saponins, alkaloids, flavonoids, cardiac glycosides, similar to those found in the crude methanol extract. The butanol fraction significantly (P<0.001) reduced the mean onset of sleep in mice and doubled the mean duration of sleep in mice at the dose of 75mg/kg. The butanol fraction and diazepam (0.5mg/kg) significantly (P<0.01-0.001) reduced the number of head dips in the hole-board test suggesting sedative effect. The sedative effect of the butanol fraction was further corroborated by its significant (P<0.01-0.001) reduction of the number of step climbed and rearing in the staircase test. The butanol fraction did not significantly increase the time taken to complete the task and number of foot slips in the beam walking assay, suggesting that it does not induce significant motor coordination deficit. Diazepam (2mg/kg), the standard agent used significantly (P<0.01) increased the number of foot slips. In the open field test, the butanol fraction significantly reduced the number of square crossed as well as the number of rearing. However, the butanol fraction did not significantly alter the behavior of mice in the elevated plus maze assay, while diazepam (0.5mg/kg) significantly (P<0.05) increased the time spent in the open arm and reduced the number of closed arm entry. CONCLUSION: The findings of this study suggest that the butanol fraction of Securinega virosa root bark contains some bioactive principles that are sedative in nature.