Bioactive compounds, antibacterial and antioxidant activities of methanol extract of Tamarindus indica Linn.

Tamarindus indica is one of the tropical medicinal plants that has been attributed curative potential of numerous diseases by many rural dwellers. This study was designed to evaluate the antioxidant, antibacterial activities and also to determine the various chemical constituents responsible for its pharmacological activities. The methanol extract of Tamarindus indica fruit pulp was analyzed by Gas Chromatography/Mass Spectrometer to determine the volatile compounds present. The antioxidant activities were performed using DPPH and FRAP method and the antibacterial activity was tested against some common pathogens by macro broth dilution method. The GCMS analysis shows the presence of 37 compounds, out of which 14 had their peak area percentages ≥ 1% and only two compounds had no reported pharmacological activities. Most of the bioactive compounds including 5-Hydroxymethylfurfural (31.06%)-3-O-Methyl-d-glucose (16.31%), 1,6-anhydro-ß-D-Glucopyranose (9.95%), 5-methyl-Furancarboxaldehyde (3.2%), Triethylenediamine (1.17%), 1-(2-furanyl)-1-Propcanone (2.18%), Methyl 2-furoate (3.14%), Levoglucosenone (3.21%), methyl ester-Hepta-2,4-dienoic acid, (8.85%), 2,3-dihydro-3,5-dihydrox-4H-Pyran-4-one (3.4%), O-α-D-glucopyranosyl-(1.fwdarw.3)-ß-D-fructofuranosyl-α-D-Glucopyranoside (2.18%), n-Hexadecanoic acid (1.38%), 2-Heptanol, acetate (1.29%), 5-[(5-methyl-2-fur-2-Furancarboxaldehyde (1.08%), 3-Methyl-2-furoic acid (1.05%) and cis-Vaccenic acid (2.85%)have been reported with different activities such as antibacterial, antifungal, antitubercular, anticancer, antioxidant and other prophylactic activities. The extract demonstrated inhibitory potential against all tested pathogen. However, Plesiomonas shigellosis ATCC 15903 and Bacillus pumillus ATCC 14884 are more sensitive with the MIC of 0.22 and 0.44 mg/ml respectively. The antioxidant activity was relatively low due to the low phenolic content of the extract. This shows that there is a strong correlation between antioxidant activities and phenolic content. GC-MS analysis revealed the presence of bioactive phytoconstituents with various biological activities and this justifies the rationale behind its usage as a curative therapy by many local dwellers.

Soxhlet Extraction versus Hydrodistillation Using the Clevenger Apparatus: A Comparative Study on the Extraction of a Volatile Compound from Tamarindus indica Seeds.

The present study aims to compare two traditional extraction techniques. A volatile compound from Tamarindus indica seed was obtained with Soxhlet extraction (SE) and hydrodistillation using the Clevenger apparatus (HDC). The extraction yield and chemical composition of the essential oil samples were compared. Both oils extracted were analyzed with GC-MS, and forty-one chemical compounds were identified in essential oil components from SE while forty chemical compounds were found in the HDC-extracted oil sample. The major essential oil components present in both the SE and HDC method are cis-vaccenic acid, 2-methyltetracosane, beta-sitosterol, 9,12-octadecadienoic acid (Z, Z)-, and n-hexadecanoic acid in varying concentrations. Moreover, the essential oils obtained by both methods look similar quantitatively but differ qualitatively. The HDC method produced more oxygenated compounds that contribute to the fragrance of the oil. The major constituents observed in the essential oil extracted by SE methods include cis-vaccenic acid (17.6%), beta-sitosterol (12.71%), 9,12-octadecadienoic acid (Z, Z)- (11.82%), n-hexadecanoic acid (8.16%), 9,12-octadecadienoic acid, methyl ester (5.84%), oleic acid (4.54%), and 11-octadecenoic acid and methyl ester (3.94%). However, in the hydrodistillation technique, the oil was mostly composed of 9,12-octadecadienoic acid (Z, Z)- (23.72%), cis-vaccenic acid (17.16%), n-hexadecanoic acid (11.53%), beta-sitosterol (4.53%), and octadecanoic acid (3.8%). From the data obtained, HDC seems to be a better method for extraction of Tamarindus indica essential oil compared to the Soxhlet extraction apparatus.

Molecular characterization, gas chromatography mass spectrometry analysis, phytochemical screening and insecticidal activities of ethanol extract of Lentinus squarrosulus against Aedes aegypti (Linnaeus).

Mosquito-transmitted diseases like zika, dengue, chikungunya, and yellow fever are known to affect human health worldwide. Numerous synthetic insecticides have been used as vector control for these diseases, but there is the challenge of environmental toxicity and vector resistance. This study investigated the medicinal and insecticidal potential of Lentinus squarrosulus against Aedes aegypti. The fruiting bodies were identified morphologically as well as using internal transcribed spacer (ITS) sequences for its molecular characterization. Genomic deoxyribonucleic acid (DNA) yield was confirmed with NanoDrop Spectrophotometer ND-1000 and amplified with ITSl and ITS4 primers. The amplicons were sequenced and the National Center for Biotechnology Information (NCBI) database identified the nucleotides. Its ethanol extract was subjected to phytochemical screening and gas chromatography mass spectrometry (GC-MS) analysis and tested against the pupa and fourth instar larva of Aedes aegypti with percentage mortality monitored. The Macrofungus was identified morphologically and confirmed with molecular characterization as Lentinus squarrosulus (LS). The gene sequence was deposited in GenBank (Accession number MK629662.1). GC-MS analysis showed that its ethanol extract has 25 bioactive compounds with 9,12-Octadecadienoic acid, ethyl ester having the highest percentage of 43.32% as well as methyl-2-oxo-1-pyrrolidine acetate and 17-octadecynoic acid having the lowest percentage (0.09%). The macrofungus contained varied concentrations of phytochemicals including phenols (159 mg/g GAE), tannins (1.6 mg/g TAE), and flavonoids (31.4 mg/g QE). The ethanol extract had significant potent effects on Aedes aegypti larva and pupa which could be due to the occurrence and abundance of 9,12-octadecadienoic acid in LS. The LC50 of the extract for larvicidal and pupicidal activities were 2.95 mg/mL and 3.55 mg/mL, respectively, while its LC90 were 6.31 mg/mL and 5.75 mg/mL respectively. Lentinus squarrosulus had insecticidal effects against the Aedes aegypti larva and pupa and possessed great potential as a source of alternative medicine and eco-friendly insecticides.

Antibacterial Activity of Defatted and Nondefatted Methanolic Extracts of Aframomum melegueta K. Schum. against Multidrug-Resistant Bacteria of Clinical Importance.

The antibacterial activity of the extracts of Aframomum melegueta including n-hexane extract (NHE), nondefatted methanol extract (NDME), and defatted methanol extract (DME) was investigated in this study. The NHE exhibited no antibacterial activity. The DME showed higher antibacterial activity than the NDME against the different isolates. At the highest concentration of 10 mg/mL in agar diffusion, NDME produced inhibition zones ranging from 11 to 29 mm against the microorganisms while DME produced inhibition zones ranging from 20 to 40 mm with the concentration of 10 mg/mL against the microorganisms. 0.1 mg/mL of the DME produced inhibition zones ranging between 12 and 14 mm in Aeromonas hydrophila ATCC 35654 and Pseudomonas aeruginosa ATCC 15442, respectively, while none of the isolates were inhibited by the NDME at a concentration of 1 mg/mL or less. In the agar dilution assay, the MICs of the NDME and DME ranged between 0.31 and 10 mg/mL, but more isolates were inhibited at 0.31 mg/mL of DME than those in NDME. In macrobroth assay, the MICs of the NDME ranged between 0.15 and 5.0 mg/mL and the MBCs ranged between 0.63 and 5.0 mg/mL, and the MICs of the DME ranged between 0.08 and 5.0 mg/mL and the MBCs were between 0.31 and 5.0 mg/mL. This study indicated that DME was more active with higher antibacterial activity than the NDME of this plant, and extracting the fatty portion of plant materials prior susceptibility testing would allow plant extracts to be more effective as well as justifying the use of Aframomum melegueta in traditional medicine for the treatment of bacterial infections.

Interaction of Ziziphus mucronata subsp. mucronata Methanol Extract and First-Line Antibiotics is Synergistic In Vitro through Production of Reactive Oxygen Species.

With the increased incidence of antibacterial resistance in microorganisms, combining natural products from plants with antibiotics may be considered interesting alternatives for synergy to attain multitarget effects. In this study, the antioxidant activity of the methanol extract of Ziziphus mucronata and its interactions with antibiotics against bacteria of clinical importance were investigated. While its phytochemicals and antioxidant activities were determined by free radical scavenging assays, the antibacterial activities of the extract and its interactions with the antibiotics were determined by macrobroth dilution and the checkerboard methods. From the results, total phenolic content was 29.67 ± 1.90 mg GAE/100 g, total flavonoid content was 8.72 ± 0.08 mg QE/100 g, and total proanthocyanidin content was 1.94 ± 0.00 mg CE/100 g of dry plant material. The inhibition concentration 50% (IC50) of DPPH, BHT, and ascorbic acid was equal to 0.04 ± 0.02 mg/ml, respectively. Those of the ABTS, BHT, and ascorbic acid were equal to 0.02 ± 0.02, 0.04 ± 0.03, and 0.04 ± 0.02 mg/ml, respectively. The checkerboard assay showed that combining the extract with different antibiotics resulted in synergistic (38.75%), indifferent (30%), additive (28.75%), and antagonistic (2.5%) interactions. The interactions between the extract and antibiotics resulting in enhanced antibacterial activities could have resulted from the antioxidant activities of the extract mopping up the ROS generated by the antibiotics or the ability of both extract and antibiotics simultaneously producing reactive oxygen species with deleterious effects resulting in synergistic antibacterial effects.

Evaluation of combination effects of ethanolic extract of Ziziphus mucronata Willd. subsp. mucronata Willd. and antibiotics against clinically important bacteria.

A pragmatic approach to the treatment of infectious diseases with multicausal agents and prevention of the development of resistant isolates is the combination of herbal remedies with the first-line antimicrobial agents to which most of them have become resistant. This study evaluated the interactions between the ethanolic bark extract of Ziziphus mucronata with known antimicrobial agents in vitro. In this study, the results showed that varied zones of inhibitions (ZME-chloramphenicol (17-42 mm), ZME-amoxicillin (17-35 mm), ZME-tetracycline (17-36 mm), ZME-ciprofloxacin (20-41 mm), ZME-nalidixic acid (17-34 mm), and ZME-kanamycin (17-38 mm)) were produced by the antibacterial combinations. At the highest combined concentrations, 12 isolates (ZME-ciprofloxacin) > 10 isolates (ZME-chloramphenicol) = (ZME-kanamycin) > 6 isolates (ZME-amoxicillin) = (ZME-nalidixic acid) and 5 isolates (ZME-tetracycline) were inhibited with zones of inhibition greater than 20 ± 1.0 mm. Although the agar diffusion assay suggested that the interactions between the ethanolic extract of Z. mucronata and the antibiotics were both synergistic and additive in nature, the fractional inhibitory concentration indices (FICI) showed that the interactions were synergistic (54.17%), additive (27.78%), indifferent (16.67%), and antagonistic (1.39%). While the fractional inhibitory concentration indices (FICIs) for synergism ranged between 0.00391 and 0.5, that of additivity ranged between 0.516 and 1.0, indifferences ranged between 1.062 and 3.0 and antagonistic interaction was 5.0. The synergistic effects implied that the antibacterial combinations would be more effective and useful in the treatment of multicausal and multidrug-resistant bacteria than a single monotherapy of either antibacterial agent.

In vitro antibacterial and time-kill evaluation of the Erythrina caffra Thunb. extract against bacteria associated with diarrhoea.

The antibacterial activities of stem bark ethanolic extract of Erythrina caffra Thunb. against bacteria in diarrhoea was determined in vitro by the agar diffusion and dilution, macrobroth dilution, and time-kill assay methods. The result showed that the extract produced inhibition zones ranging between 15 ± 1.0 mm and 23 ± 1.0 mm, and the bacteria were susceptible at concentrations ranging between ≤100 and ≤1000 µg/mL. While the MICs of the extract ranged between 39.1 and 625 µg/mL, and the MBCs ranged between 78.1 and 625 µg/mL, the MICs of Micrococcus luteus, Proteus vulgaris CSIR 0030, Enterococcus faecalis KZN, and Staphylococcus aureus OK3 were less than 100 µg/mL, and the mechanisms of antibiosis indicated that the crude ethanolic extract was highly bactericidal against the entire test bacteria isolates. In the time-kill assay, the average log reduction of the viable cell count ranged between 0.916 log10 and 1.851 log10 cfu/mL on incubating the bacteria for 4 h at the MICs, while the reduction ranged between 0.183 log10 and 1.105 log10 cfu/mL after 8 h of incubation. Incubating the bacteria for 4 h at 2 × MICs resulted in the reduction of the viable cell count to between -0.264 log10 and 0.961 log10 cfu/mL, while the average log reduction ranged between -3.968 log10 and -0.425 log10 cfu/mL after 8 h of incubation with Micrococcus luteus, Proteus vulgaris CSIR 0030, and Staphylococcus aureus OK3 being the most highly affected bacteria. The result showed that the extract exhibited broader-spectrum antibacterial activity and justifies the use of Erythrina caffra in the folkloric medicine for treating gastrointestinal infections in South Africa.

In vitro antibacterial and time-kill assessment of crude methanolic stem bark extract of Acacia mearnsii de wild against bacteria in shigellosis.

Shigellosis is an important cause of worldwide morbidity and mortality among young children and old people for which treatment with antimicrobial agents is limited. Hence, the need for curative potentials obtainable from medicinal plants becomes inevitable. This study was carried out to assess the antibacterial potentials of crude methanolic extract of the stem bark of Acacia mearnsii against some selected bacteria of clinical importance in shigellosis. The bacteria were inhibited by the extract to produce concentration dependent inhibition zones. The extract exhibited a varied degree of antibacterial activity against all the tested isolates. The MIC values for Gram negative (0.0391-0.3125) mg/mL and those of Gram positive bacteria (0.0781-0.625) mg/mL indicated that the Gram negative bacteria were more inhibited by the extract than the Gram positive bacteria. Average log reduction in viable cell count in time-kill assay ranged between -2.456 Log10 to 2.230 Log10 cfu/mL after 4 h of interaction, and between -2.921 Log10 and 1.447 Log10 cfu/mL after 8 h interaction in 1× MIC and 2× MIC of the extract. The study provided scientific justification for the use of the crude methanolic extract from the stem bark of A. mearnsii in shigellosis. The degree of the antibacterial activity indicated that the crude extract is a potential source of bioactive compounds that could be useful for the development of new antimicrobial agents capable of decreasing the burden of drug resistance and cost of management of diseases of clinical and public health importance in South Africa.