Investigation on hypoglycemic effects of ethanol extract of Alpinia nigra (Gaertn.) in animal model.[Pubmed: 27104033]

Our study aims at exploring the hypoglycemic effect, efficacy, and possible mode of action of ethanol extract of Alpinia nigra (EEAN) as an antidiabetic agent in an animal model.

Phytochemical, analgesic, antibacterial, and cytotoxic effects of Alpinia nigra (Gaertn.) Burtt leaf extract.[Pubmed: 26587396]

This research evaluated the phytochemical contents as well as the analgesic, cytotoxic, and antimicrobial effects of the methanolic extract of Alpinia nigra leaf. Phytochemical analysis was carried out using established methods. The analgesic effects of the extract were measured with the formalin test and tail immersion test. The antibacterial activity of the extract was evaluated using the disc diffusion technique. Cytotoxicity was assessed with the brine shrimp lethality bioassay. Data were analyzed with one-way analysis of variance using statistical software (SPSS, Version 19.0). The qualitative phytochemical screening of A. nigra leaf extract showed the presence of medicinally active secondary metabolites such as alkaloids, glycosides, cardiac glycosides, flavonoids, steroids, tannins, anthraquinone glycosides, and saponins. The extract at a dose of 200 mg/kg revealed a prevailed central nociception increasing the reaction time in response to thermal stimulation. The extract also showed a response to chemical nociceptors, causing pain inhibition in the late phase. The leaf extract (2 mg/disc) showed mild antibacterial activity compared to tetracycline (50 μg/disc). In the brine shrimp lethality bioassay, the LC50 (lethal concentration 50) value of the extract was found to be 57.12 μg/mL, implying a promising cytotoxic effect. The results evidenced the moderate analgesic and antibacterial effects with pronounced cytotoxic capability.

Molecular docking and inhibition kinetics of α-glucosidase activity by labdane diterpenes isolated from tora seeds (Alpinia nigra B.L. Burtt.).[Pubmed: 25410799]

Current approach against type 2 diabetes involves α-glucosidase inhibitors like acarbose associated with many side effects. Therefore, as an alternative to the existing drug, many natural products mainly from plant sources have been investigated which inhibit α-glucosidase. Here, we have selected medicinally important Alpinia nigra to explore its α-glucosidase inhibitory activity. Organic extracts of seeds and two purified natural diterpenes I: (E)-labda-8(17), 12-diene-15, 16-dial and II: (E)-8β, 17-epoxylabd-12-ene-15, 16-dial from A. nigra were investigated towards inhibition of α-glucosidase activity. Dose-dependent inhibition pattern were observed for seed extracts and both the compounds. Further, inhibition kinetics studies of the diterpenes indicated a non-competitive type of inhibition against α-glucosidase. Docking studies were carried out which revealed that both the diterpenes interacted within the active site of N-terminal and C-terminal domain of human maltase-glucoamylase enzyme, respectively. This is the first report of α-glucosidase inhibitory activity of these isolated diterpenes and their higher inhibitory potential than any terpenoids studied till date against α-glucosidase.

Investigation of in vivo neuropharmacological effect of Alpinia nigra leaf extract.[Pubmed: 25182285]

To analyze in vivo neuro-pharmacological effects of Alpinia nigra as anxiety is a particular form of behavioral inhibition that occurs in response to novel environmental events.

Unveiling the mode of action of antibacterial labdane diterpenes from Alpinia nigra (Gaertn.) B. L. Burtt seeds.[Pubmed: 23792320]

The labdane diterpene, (E)-labda-8(17), 12-diene-15, 16-dial (compound A) and its epoxide analogue, (E)-8β, 17-Epoxylabd-12-ene-15, 16-dial (compound B) were isolated from the seeds of Alpinia nigra for the first time. The antibacterial activities of both compounds were evaluated against three Gram-positive and four Gram-negative bacteria, and flow cytometric analysis revealed that these compounds caused significant damage to the bacterial cell membranes. Further, field emission scanning electron microscope imaging and cell leakage analysis confirmed that the labdane diterpenes were responsible for bacterial cell membrane damage and disintegration. Our findings provide new insight into the broad-spectrum effects of two natural labdane diterpenes that may be useful in the future development of herbal antibiotic products.

Evidence of apoptosis in Raillietina echinobothrida induced by methanolic extracts of three traditional medicinal plants of Northeast India.[Pubmed: 23680183]

The therapeutic benefits of medicinal plants in terms of anthelmintic properties are known since time immemorial in India, particularly among natives of the Northeast India. However, only sporadic and scarce reports on scientific validation of these plants are available. The present study was conducted on the cestode Raillietina echinobothrida, to establish whether the anthelmintic activity of Potentilla fulgens, Alpinia nigra and Millettia pachycarpa was mediated by apoptosis or not. Light microscopic observation following MTT assay revealed the highest percentage of inhibition of viability among the worms by methanol extract of M. pachycarpa (89.33%), followed by A. nigra (65%) and P. fulgens (37%). Ultrastructural observations revealed swelling of mitochondria, disruption of mitochondrial membrane, vacuolization of mitochondria, appearance of apoptotic bodies in the cytoplasm, disintegration of nuclear membrane and nucleolus were very common throughout the tegument. DAPI stained specimens showed typical morphology of apoptosis, like nuclear condensation and fragmentation in the extracts treated parasites. A decrease in mitochondrial membrane potential was also recorded in the treated groups. Confirmatory TUNEL assay and DNA fragmentation assay of the extracts treated parasites also confirmed the apoptotic nature of cell death and is concluded to be responsible for paralysis and death of the parasite.

Anthelmintic efficacy of ethanolic shoot extract of Alpinia nigra on tegumental enzymes of Fasciolopsis buski, a giant intestinal parasite.[Pubmed: 23129888]

Ethanolic shoot extract of Alpinia nigra, a traditionally used anthelmintic medicinal plant among the Tripuri tribes of north-east India, was tested in vitro to determine its anthelmintic efficacy in gastrointestinal trematode Fasciolopsis buski, using alterations in the activity of vital tegumental enzymes viz. acid phosphatase (AcPase), alkaline phosphatase (AlkPase) and adenosine triphosphatase (ATPase). Live adult F. buski treated in vitro with different concentrations of the plant extract showed significant decline in the visible stain histochemically and enzyme activities. Quantitatively, the total enzyme activity of AcPase, AlkPase and ATPase was found to be reduced by 45, 41 and 43%, respectively compared to the control. The reference drug, praziquantel also showed more or less similar effect like that of the plant extract. The results suggest that the tegumental enzymes of the parasite may be an important target of action for active component(s) of A. nigra, which appears to act transtegumentally.

Ultrastructural observations on Fasciolopsis buski and its alterations caused by shoot extract of Alpinia nigra.[Pubmed: 18924137]

The ultrastructural alterations in the tegument of Fasciolopsis buski in response to incubation in the alcoholic extract of Alpinia nigra were evaluated using transmission electron microscopy. The body tegument of the trematode is composed of an external syncytial layer, musculature, and an inner layer containing tegumental cells. The syncytium comprises various organelles like mitochondria, lysosomes, and tegumentary bodies of the type 2 kind with rare sighting of the type 1. Severe distortion and disorganization of the tegument was revealed in the parasite exposed to the A. nigra extract in the current study. The extent of vacuolization was such that vacuoles proceeded down to the basal lamina causing the syncytium to separate from the tegument at different places. There was depletion of parenchyma material and loss of connecting tubules running down from the syncytium to the tegumental cells causing the cells to be deprived of any proper boundaries.

[Pharmacognostical studies on the rhizome and root of Alpinia nigra].[Pubmed: 11668738]

Morphological and histological characters of the rhizome and root of Alpinia nigra (Gaertn.) Burtt, used as the origin of a traditional Chinese medicine, were described and illustrated with line drawing. These studies provide referential information for the identification and quality control.