Geethaa Sahgal

Bio: Geethaa Sahgal is an academic researcher from Universiti Sains Malaysia. The author has contributed to research in topics: Hymenocallis littoralis & Bulb. The author has an hindex of 6, co-authored 9 publications receiving 221 citations.

In Vitro Antioxidant and Xanthine Oxidase Inhibitory Activities of Methanolic Swietenia mahagoni Seed Extracts

Abstract: This study examines the in vitro antioxidant activities of the methanol extract of Swietenia mahagoni seeds (SMCM seed extract). The extract was screened for possible antioxidant activities by free radical scavenging activity (DPPH), xanthine oxidase inhibition (XOI), hydrogen peroxide scavenging activity (HPSA) and ferric-reducing antioxidant power (FRAP) assays. The total phenolic and flavonoid contents were also determined. The extract exhibits antioxidant activity of 23.29% with an IC50 value of 2.3 mg/mL in the DPPH radical scavenging method, 47.2% in the XOI assay, 49.5% by the HPSA method, and 0.728 mmol/Fe(II)g in the FRAP method at the concentration tested. The amount of total phenolics and flavonoid contents was 70.83 mg gallic acid equivalent (GAE) and 2.5 ± 0.15 mg of catechin equivalent per gram of dry extract, respectively. High Performance Thin Layer Chromatography (HPTLC) screening indicates the presence of phenolic compounds in the SMCM seed extract. The results indicate that the extract has both high free radical scavenging and xanthine oxidase inhibition activity. The antioxidant activity of SMCM seed extract is comparable with that of other Malaysian tropical fruits and herbal plants.

Brine shrimp lethality and acute oral toxicity studies on Swietenia mahagoni (Linn.) Jacq. seed methanolic extract.

Abstract: Background: The seeds of Swietenia mahagoni have been applied in folk medicine for the treatment of hypertension, diabetes, malaria, amoebiasis, cough, chest pain, and intestinal parasitism. Here we are the first to report on the toxicity of the Swietenia mahagoni crude methanolic (SMCM) seed extract. Methods: SMCM seed extract has been studied for its brine shrimp lethality and acute oral toxicity, in mice. Results: The brine shrimp lethality bioassay shows a moderate cytotoxicity at high concentration. The LC50 for the extract is 0.68 mg/ml at 24 hours of exposure. The LD50 of the SMCM seed extract for acute oral toxicity in mice is greater than 5000 mg/kg. Conclusion: This study demonstrates that Swietenia mahagoni crude methanolic seed extract may contain bioactive compounds of potential therapeutic significance which are relatively safe from toxic effects, and can compromise the medicinal use of this plant in folk medicine.

Phytochemical and antimicrobial activity of Swietenia mahagoni crude methanolic seed extract.

Abstract: The present study was designed to evaluate the antibacterial activities of Swietenia mahagoni crude methanolic (SMCM) seed extract. The antimicrobial activity of the oily extract against Gram-positive, Gram-negative, yeast and fungus strains was evaluated based on the inhibition zone using disc diffusion assay, minimal inhibition concentration (MIC) and minimal bactericidal concentration (MBC) values. The crude extract was subjected to various phytochemicals analysis. The demonstrated qualitative phytochemical tests exhibited the presences of common phytocompounds including alkaloids, terpenoids, antraquinones, cardiac glycosides, saponins, and volatile oils as major active constituents. The SMCM seed extract had inhibitory effects on the growth of Candida albicans, Staphylococcus aureus, Pseudomonas aeroginosa, Streptococcus faecalis and Proteus mirabillase and illustrated MIC and MBC values ranging from 25 mg/ml to 50 mg/ml.

Antibacterial Activity of Ag-TiO2 Nanoparticles with Various Silver Contents

Abstract: Bacterial are highly transmitted in our environment and have been identified as a primary contributor to the problem of indoor air quality and consequently lead to the illness of the occupants. Recently, nanotechnology represents an innovative approach to develop new formulations based on metallic nanoparticles with antimicrobial properties. TiO2 has great promise to diminish bacterial activity. Antimicrobial activity of TiO2and Ag-TiO2 nanoparticles against Escherichia coli was examined in this study. TiO2 nanoparticles with various silver contents were synthesized by sol gel method to produce uniform size, unagglomerated state and homogeneous nanoparticles. The nanoparticles were characterized by X-Ray diffraction (XRD) and transmittance electron microscopy (TEM). The effects of different silver concentration were studied using cotton diffusion test under fluorescence light irradiation. 0.06 mol % Ag-TiO2 revealed best antibacterial activity. 0.06 mol % Ag-TiO2 have antibacterial inhibition zone of 38 mm at the concentration of 2.0 M against E. coli. Swab test bacterial counts on left palm, tile, mouse pad and cotton have been tested before and after spraying with 0.06 mol % Ag-TiO2. It showed that the bacterial count decreased for entire samples. The significant enhancement in the antibacterial properties of Ag-TiO2 nanoparticles under visiblelight irradiation is related to the effect of noble metal Ag by acting as electron traps in TiO2 band gap. The phase structure, crystallite size and crystallinity of TiO2 also play an important role inantibacterial activity. The killing mechanism of Ag-TiO2 undervisible light irradiation antibacterial activity over Ag-TiO2nanoparticles was proposed based on our observations.

In vitro and in vivo anticandidal activity of Swietenia mahogani methanolic seed extract.

Abstract: Swietenia mahogani crude methanolic (SMCM) seed extract was investigated for the antifungal activity against Candida albicans which has not been evaluated previously. The antifungal activity was evaluated against C. albicans via disk diffusion, minimum inhibition concentration (MIC), scanning electron microscope (SEM), transmission electron microscope (TEM) and time killing profile. The MIC value of SMCM seed extract is 12.5 mg/ml. The SEM and TEM findings showed there is morphological changes and cytological destruction of C. albicans at the MIC value. Animal model was used to evaluate the in vivo antifungal activity of SMCM seed extract. The colony forming unit (CFU) were calculated per gram of kidney sample and per ml of blood sample respectively for control, curative and ketaconazole treated groups. There was significant reduction for the CFU/ml of blood and CFU/g of kidney. This indicated that the extract was observed to be effective against C. albicans in vitro and in vivo conditions.

Toxicological evaluation of the plant products using Brine Shrimp (Artemia salina L.) model

Abstract: Many natural products could serve as the starting point in the development of modern medicines because of their numerous biological and pharmacological activities. However, some of them are known to carry toxicological properties as well. In order to achieve a safe treatment with plant products, numerous research studies have recently been focused on both pharmacology and toxicity of medicinal plants. Moreover, these studies employed efforts for alternative biological assays. Brine Shrimp Lethality Assay is the most convenient system for monitoring biological activities of various plant species. This method is very useful for preliminary assessment of toxicity of the plant extracts. Rapidness, simplicity and low requirements are several advantages of this assay. However, several conditions need to be completed, especially in the means of standardized experimental conditions (temperature, pH of the medium, salinity, aeration and light). The toxicity of herbal extracts using this assay has been determined in a concentration range of 10, 100 and 1000 μg/ml of the examined herbal extract. Most toxicity studies which use the Brine Shrimp Lethality Assay determine the toxicity after 24 hours of exposure to the tested sample. The median lethal concentration (LC50) of the test samples is obtained by a plot of percentage of the dead shrimps against the logarithm of the sample concentration. LC50 values are estimated using a probit regression analysis and compared with either Meyer’s or Clarkson’s toxicity criteria. Furthermore, the positive correlation between Meyer’s toxicity scale for Artemia salina and Gosselin, Smith and Hodge’s toxicity scale for higher animal models confirmed that the Brine Shrimp Lethality Assay is an excellent predictive tool for the toxic potential of plant extracts in humans.

Antioxidant activity of methanol extracts of different parts of Lantana camara.

Abstract: Objective To investigate the antioxidant activity of methanolic extracts of Lantana camara (L. camara) various parts and the determination of their total phenolics content.

Anti-Candida albicans natural products, sources of new antifungal drugs: A review.

Abstract: Summary Introduction Candida albicans is the most prevalent fungal pathogen in humans. Due to the development of drug resistance, there is today a need for new antifungal agents for the efficient management of C . albicans infections. Therefore, we reviewed antifungal activity, mechanisms of action, possible synergism with antifungal drugs of all natural substances experimented to be efficient against C . albicans for future . Methods An extensive and systematic review of the literature was undertaken and all relevant abstracts and full-text articles analyzed and included in the review. Review A total of 111 documents were published and highlighted 142 anti- C . albicans natural products. These products are mostly are reported in Asia (44.37%) and America (28.17%). According to in vitro model criteria, from the 142 natural substances, antifungal activity can be considered as important for 40 (28.20%) and moderate for 24 (16.90%). Sixteen products have their antifungal activity confirmed by in vivo gold standard experimentation. Microbial natural products, source of antifungals, have their antifungal mechanism well described in the literature: interaction with ergosterol (polyenes), inhibition 1,3-β- d -glucan synthase (Echinocandins), inhibition of the synthesis of cell wall components (chitin and mannoproteins), inhibition of sphingolipid synthesis (serine palmitoyltransferase, ceramide synthase, inositol phosphoceramide synthase) and inhibition of protein synthesis (sordarins). Natural products from plants mostly exert their antifungal effects by membrane-active mechanism. Some substances from arthropods are also explored to act on the fungal membrane. Interestingly, synergistic effects were found between different classes of natural products as well as between natural products and azoles. Conclusion Search for anti- C . albicans new drugs is promising since the list of natural substances, which disclose activity against this yeast is today long. Investigations must be pursued not only to found more new anti- Candida compounds from plants and organisms but also to carried out details on molecules from already known anti- Candida compounds and to more elucidate mechanisms of action.