Activity-guided isolation of α-amylase, α-glucosidase, and pancreatic lipase inhibitory compounds from Rhus coriaria L

The leaves and fruits of Rhus coriaria are traditionally used in Turkey for the treatment of diabetes. The aim of the present study is to determine α-amylase, α-glucosidase, and pancreatic lipase inhibitory activities of R. coriaria leaf and fruit ethanol extracts (80%), and to isolate active compounds against these enzymes. As a result of the activity-guided isolation, the active compounds were determined as the amentoflavone, agathisflavone, and 1,2,3,4,6-penta-O-galloyl-β-glucopyranose. Agathisflavone, amentoflavone, and penta-O-galloyl-β-glucopyranose inhibited α-glucosidase with 11.4 ± 0.9, 11.3 ± 0.7, and 4.1 ± 0.1 µM IC₅₀ values, respectively. Furthermore, penta-O-galloyl-β-glucopyranose inhibited α-amylase with 6.32 ± 0.18 µM IC₅₀ . These three compounds also significantly inhibited (P < 0.05) pancreatic lipase. The results of high-performance liquid chromatography analysis showed that penta-O-galloyl-β-D-glycopyranose was one of the main compounds in both fruit and leaf extracts. Therefore, it may be considered that R. coriaria fruit and leaf extracts can be standardized on this substance and used in the development of both medicinal products and functional food for diabetes. PRACTICAL APPLICATION: Rhus coriaria (Sumac) is one of the plants that is well known and used around the world as a spice. It is also used against diabetes traditionally. The determination of effective compounds can lead to the standardization and development of both medicinal products and functional foods for diabetes. While the fruits of the plant are used as a spice all around the world, the leaves are generally throw away; therefore, the usage of the leaves to the food and medical industry can lead to beneficial effects on the economy.

The flavonoid agathisflavone modulates the microglial neuroinflammatory response and enhances remyelination

Myelin loss is the hallmark of the demyelinating disease multiple sclerosis (MS) and plays a significant role in multiple neurodegenerative diseases. A common factor in all neuropathologies is the central role of microglia, the intrinsic immune cells of the central nervous system (CNS). Microglia are activated in pathology and can have both pro- and anti-inflammatory functions. Here, we examined the effects of the flavonoid agathisflavone on microglia and remyelination in the cerebellar slice model following lysolecithin induced demyelination. Notably, agathisflavone enhances remyelination and alters microglial activation state, as determined by their morphology and cytokine profile. Furthermore, these effects of agathisflavone on remyelination and microglial activation were inhibited by blockade of estrogen receptor α. Thus, our results identify agathisflavone as a novel compound that may act via ER to regulate microglial activation and enhance remyelination and repair.

Agathisflavone modulates astrocytic responses and increases the population of neurons in an in vitro model of traumatic brain injury

Traumatic brain injury (TBI) is a critical health problem worldwide, with a high incidence rate and potentially severe long-term consequences. Depending on the level of mechanical stress, astrocytes react with complex morphological and functional changes known as reactive astrogliosis. In cases of severe tissue injury, astrocytes proliferate in the area immediately adjacent to the lesion to form the glial scar, which is a major barrier to neuronal regeneration in the central nervous system. The flavonoid agathisflavone has been shown to have neuroprotective, neurogenic, and immunomodulatory effects and could have beneficial effects in situations of TBI. In this study, we investigated the effects of agathisflavone on modulating the responses of astrocytes and neurons to injury, using the in vitro scratch wound model of TBI in primary cultures of rat cerebral cortex. In control conditions, the scratch wound induced an astroglial injury response, characterized by upregulation of glial fibrillary acidic protein (GFAP) and hypertrophy, together with the reduction in proportion of neurons within the lesion site. Treatment with agathisflavone (1 μM) decreased astroglial GFAP expression and hypertrophy and induced an increase in the number of neurons and neurite outgrowth into the lesion site. Agathisflavone also induced increased expression of the neurotrophic factors NGF and GDNF, which are associated with the neuroprotective profile of glial cells. These results demonstrate that in an in vitro model of TBI, the flavonoid agathisflavone modulates the astrocytic injury response and glial scar formation, stimulating neural recomposition.

Agathisflavone, a Biflavonoid from Anacardium occidentale L., Inhibits Influenza Virus Neuraminidase

BACKGROUND

Neuraminidase inhibitors (NAIs) are the only class of antivirals in clinical use against influenza virus approved worldwide. However, approximately 1-3% of circulating strains present resistance mutations to oseltamivir (OST), the most used NAI. Therefore, it is important to catalogue new molecules to inhibit influenza virus, especially OST-resistant strains. Natural products from tropical plants used for human consumption represent a worthy class of substances. Their use could be stimulated in resource-limited setting where the access to expensive antiviral therapies is restricted.

METHODS

We evaluated the anti-influenza virus activity of agathisflavone derived from Anacardium occidentale L.

RESULTS

The neuraminidase (NA) activity of wild-type and OST-resistant influenza virus was inhibited by agathisflavone, with IC50 values ranging from 20 to 2.0 µM, respectively. Agathisflavone inhibited influenza virus replication with EC50 of 1.3 µM. Sequential passages of the virus in the presence of agathisflavone revealed the emergence of mutation R249S, A250S and R253Q in the NA gene. These changes are outside the OST binding region, meaning that agathisflavone targets this viral enzyme at a region different than conventional NAIs.

CONCLUSION

Altogether our data suggest that agathisflavone has a promising chemical structure for the development of anti-influenza drugs.

Agathisflavone isolated from Schinus polygamus (Cav.) Cabrera leaves prevents scopolamine-induced memory impairment and brain oxidative stress in zebrafish (Danio rerio)

BACKGROUND

Agathisflavone, a biflavonoid isolated from Schinus polygamus (Cav.) Cabrera leaves been reported to promote various biological activities such as anti-inflammatory properties, promoting cognition and preventing cancer, antioxidant and antiapoptotic activities.

PURPOSE

Here, we tested the hypothesis whether anxiety, amnesia, and brain oxidative stress induced by scopolamine could be counteracted in zebrafish model by agathisflavone and tried to ascertain the underlying mechanism.

METHODS

Agathisflavone (1, 3 and 5 µg/l) was administered by immersion to zebrafish once daily for 8 days period. Anxiety and memory impairment were induced with scopolamine (100 µM) and measured with the novel tank diving test (NTT) and the Y-maze test. Zebrafish were divided into seven groups (n = 20/group): first group - control, second group - scopolamine (100 μM), the third, fourth and fifth group - agathisflavone treatment groups (FAB, 1 µg/l, 3 µg/l, and 5 µg/l), the sixth group - imipramine (IMP, 20 mg/l, as the positive control in NTT test), and the seventh group - donepezil group (DP, 10 mg/l, as the positive control in Y-maze test). The identification of the agathisflavone was done by spectroscopy, and the structure of the compound was confirmed by (-) Electrospray Ionisation Mass Spectrometry (ESI-MS). The brain oxidative status and acetylcholinesterase (AChE) activity were also investigated.

RESULTS

Agathisflavone from Schinus polygamus (Cav.) Cabrera leaves was identified. Also, we demonstrated that agathisflavone significantly reversed scopolamine-induced behavioral score alteration in the NTT and Y-maze tests. Consequently, agathisflavone promoted inhibition of AChE activity and restored the brain antioxidant status.

CONCLUSION

Our results demonstrate that agathisflavone promotes brain antioxidant action and ameliorates scopolamine-induced anxiety and memory deficits in zebrafish.