The phytochemistry and medicinal value of Psidium guajava (guava)

Anti-platelet activity and chemical characterization by UPLC-DAD-ESI-QTOF-MS of the main polyphenols in extracts from Psidium leaves and fruits

In Costa Rica, two species of Psidium fruits, P. guajava and P. friedrichsthalianum, are widely consumed as food and used in folk medicine. Although studies have revealed the health effects of these fruits, there has been little research showing the antiplatelet activity of these species. This work evaluated the antiplatelet potential of aqueous extracts made from leaves and fruits of pink guava and Costa Rican guava. Platelet aggregation was induced by the platelet agonists ADP, TRAP-6, collagen and PMA. Platelet activation and secretion were studied using flow cytometry. The chemical profiles of the four extracts were characterized using UPLC-DAD-ESI-QTOF-MS. The studies revealed that the aqueous extracts of leaves and fruits of P. guajava and P. friedrichsthalianum inhibited platelet aggregation induced by ADP (4 µM), TRAP-6 (5 µM), collagen (1 µg mL^-1) and PMA (100 nM), and the effect was dependent on the extract concentration. Extracts of leaves and fruits of pink guava and Costa Rican guava reduced secretion of P-selectin and activation of GP IIb/IIIa. The extracts of leaves and fruits of pink guava and Costa Rican guava proved to be a rich source of phenolic compounds, mainly quercetin aglycones and proanthocyanidins derived from (epi) catechin units. Other compounds such as ellagitannins, and benzophenones were also putatively identified. This research showed that P. guajava and P. friedrichsthalianum could potentially be used for the prevention of thrombotic events.

Psidium guajava Linn leaf ethanolic extract: In vivo giardicidal potential with ultrastructural damage, anti-inflammatory and antioxidant effects

Introduction and aim

Considering the magnitude of giardiasis problem, the side-effects of the used anti-giardia drugs and the resistance posed against them, the current study aimed to evaluate the in-vivo giardicidal effect of Psidium guajava leaf extract (PGLE).

Methods

For fulfilling this aim, five Swiss-albino mice groups were included; GI: non-infected, GII: Giardia-infected and non-treated, GIII: Giardia-infected and metronidazole-treated, GIV: Giardia-infected and PGLE-treated, and GV: Giardia-infected and treated with both metronidazole and PGLE. Treatment efficacy was assessed via; Giardia cyst viability and trophozoite count, trophozoite electron microscopic ultrastructure, duodenal histopathological scoring, immunohistochemistry for TNF-α and duodenal scanning electron microscopy. Moreover, mice serum liver enzymes, total bilirubin, albumin, lipid profile including; total cholesterol, HDL, LDL and triglycerides were assessed. Additionally, hepatic oxidative stress markers including; malondialdehyde (MDA), nitric oxide (NO), reduced glutathione (GSH) and superoxide dismutase (SOD) were measured.

Results

Results showed that PGLE whether alone or combined with metronidazole has induced significant trophozoite count reduction and major architectural changes. Duodenal histological improvement, and local protective anti-inflammatory effect were confirmed. PGLE has also helped in healing of Giardia-induced gut atrophy. Thus, offered a comprehensive therapy for both the pathogen and the resultant pathological sequalae. Serum markers showed favorable hepatoprotective effect. Total cholesterol, LDL and triglycerides levels were less in PGLE-treated group than in metronidazole-treated group. Hepatic oxidative stress markers revealed the promising extract antioxidant effect. This study highlights, the promising in-vivo giardicidal PGLE activity, that was comparable to metronidazole, thus, the extract would be an ideal strongly recommended treatment for giardiasis. When combined with metronidazole, the extract potentiated its therapeutic effect. Besides, having hepatoprotective, anti-inflammatory, and antioxidant properties, the extract can combat the major side effects of metronidazole therapy.

Ethnobotanical study of plants used by the traditional healers to treat malaria in Mogovolas district, northern Mozambique

INTRODUCTION

Malaria is an important parasitic disease that affects mostly the African continent. Traditional medicine is very important in Mozambique and traditional healers play a key role in the primary health care services, particularly in rural areas. We aim to report the results of an ethnobotanical survey undertaken in Mogovolas district, northern region of Mozambique. We recorded and identified the medicinal plants used by traditional healers for treatment of malaria, as well as the mode of preparation and administration.

METHODS

The study was conducted in 14 villages from Mogovolas between June and August 2015. Sixteen traditional healers were interviewed using semi-structured questionnaires. Under their guidance, we collected medicinal plants and prepared herbarium specimens that were sent and kept at Eduardo Mondlane University Herbarium for scientific identification. We searched for information on the in vitro and in vivo studies of the cited plants for antiplasmodial activity.

RESULTS

Traditional healers from Mogovolas district reported the use of 37 plants to treat malaria, belonging to 22 families. The most used species are Ochna kirkii Oliv. (5 citations), Ehretia amoena Klotzsch and Pteleopsis myrtifolia (M.A.Lawson) Engl. & Diels (both with 3 citations). These plants belong to Ochnaceae, Boraginaceae and Combretaceae families, respectively. The herbal remedies are prepared using leaves (22/37), roots (18/37), stem barks (16/37) and stems (3/37). The administration of the herbal remedies was made essentially by oral route and bathing.

CONCLUSION

The ethnobotanical data resulted from this study can be the starting point for further chemical and pharmacological studies aiming to identify medicinal species with antimalarial activity, thus, open the insights for the discovery of new antimalarial substances, as well as better integration of the traditional medicine into the national health systems, particularly in developing countries, as the health system coverage is limited.

In vitro Antifungal Activity of Psidium Guajava Based Silver Nanoparticles

To prepare and characterize silver nanoparticles from Guava leaves (Psidium guajava), extracts (chloroform and ethanol). The fabricated silver nanoparticles were tested on resistant fungal strains, Aspergillus niger and Candida glabrata. Psidium guajava leaf extracts were obtained by cold maceration method, by using Chloroform and Ethanol. To one mL of extract 2mM silver nitrate solution was added. The mixture was kept overnight in a dark chamber at room temperature. The solution was centrifuged at 10,000 rpm for 15 minutes and filtered by wattman filter paper after centrifugation. Psidium guajava leaf extract based silver nanoparticles were prepared and evaluated for anti-fungal activity by microtitre well plate method on resistant strains Aspergillus niger and Candida glabrata. The silver nanoparticles showed significant activity at 120 µL, Nystatin was used as standard.

Network analysis, sequence and structure dynamics of key proteins of coronavirus and human host, and molecular docking of selected phytochemicals of nine medicinal plants

The novel coronavirus of 2019 (nCoV-19) has become a pandemic, affecting over 205 nations with over 7,410,000 confirmed cases which has resulted to over 418,000 deaths worldwide. This study aimed to identify potential therapeutic compounds and phytochemicals of medicinal plants that have potential to modulate the expression network of genes that are involve in SARS-CoV-2 pathology in human host and to understand the dynamics key proteins involved in the virus-host interactions. The method used include gene network analysis, molecular docking, and sequence and structure dynamics simulations. The results identified DNA-dependent protein kinase (DNA-PK) and Protein kinase CK2 as key players in SARS-CoV-2 lifecycle. Among the predicted drugs compounds, clemizole, monorden, spironolactone and tanespimycin showed high binding energies; among the studied repurposing compounds, remdesivir, simeprevir and valinomycin showed high binding energies; among the predicted acidic compounds, acetylursolic acid and hardwickiic acid gave high binding energies; while among the studied anthraquinones and glycosides compounds, ellagitannin and friedelanone showed high binding energies against 3-Chymotrypsin-like protease (3CL^pro), Papain-like protease (PL^pro), helicase (nsp13), RNA-dependent RNA polymerase (nsp12), 2'-O-ribose methyltransferase (nsp16) of SARS-CoV-2 and DNA-PK and CK2alpha in human. The order of affinity for CoV proteins is 5Y3E > 6NUS > 6JYT > 2XYR > 3VB6. Finally, medicinal plants with phytochemicals such as caffeine, ellagic acid, quercetin and their derivatives could possibly remediate COVID-19.Communicated by Ramaswamy H. Sarma.

Characterization of guava (Psidium guajava Linn) seed polysaccharides with an immunomodulatory activity

To clarify the property of a novel guava seed polysaccharide (GSPS), GSPS was subjected to purify using Sepharose 6B gel filtration chromatography and further characterize the property of each individual isolated fraction. GSPS further resolved into three purified fractions, guava seed polysaccharide fraction 1 (GSF1), GSF2 and GSF3. Isolated GSF1, GSF2 and GSF3 were respectively subjected to high performance size exclusion chromatography; molecular weights of three polysaccharide fractions were determined. GSPS, GSF1, GSF2 and GSF3 were suggested to be proteopolysaccharides or glycoproteins. GSPS, GSF1, GSF2 and GSF3, particularly GSF3, were found to have a Th2-inclination property and anti-inflammatory potential. Heated GSF3 did not significantly (P > .05) decreased its immunomodulatory activity, suggesting that GSF3 is a proteopolysaccharide. The deproteinated GSF3 markedly lost its immunomodulatory activity, suggesting that both protein and carbohydrate moiety in GSF3 are essential to its immunomodulatory function. Analyses of monosaccharides composition in GSF3 using a pre-column derivatization high performance liquid chromatography exhibited that GSF3 was composed of glucuronic acid (3.28%), galacturonic acid (28.13%), galactose (14.88%), mannose (3.96%), glucose (22.99%), arabinose (7.31%), ribose (1.55%), xylose (14.81%), fucose (1.68%) and rhamnose (1.43%). Overall, we evidence that GSF3 is a low molecular weight proteopolysaccharide with potent anti-inflammatory and immunomodulatory effects.

Biogenic synthesis of copper oxide nanoparticles using plant extract and its prodigious potential for photocatalytic degradation of dyes

The development of benign and efficient approaches for treating industrial grade toxic organic dyes is an ongoing challenge. To this end, copper oxide nanoparticles (CuO NPs) were prepared by a simple, environment friendly, and economical green synthesis procedure by using Psidium guajava leaf extract as reducing agent (i.e., for the reduction of metal salt) as well as capping agent and copper acetate monohydrate as metal salt. The formation of mono-dispersed and spherical (average size 2-6 nm with BET surface area 52.6 m²/g) CuO NPs was confirmed by various spectroscopic and microscopic techniques. The CuO NPs exhibited excellent degradation efficiency for the industrial dyes, i.e., Nile blue (NB) (93% removal in 120 min) and reactive yellow 160 (RY160) (81% removal in 120 min) with apparent rate constants of 0.023 and 0.014 min^-1, respectively. The CuO catalyst was found to be reusable for photocatalytic dye degradation even after five consecutive cycles. The limit of detection (LOD) values for NB and RY160 were 4 and 9 mg/L, respectively. In light of their high reusability and photocatalytic efficiency along with adaptability to green synthesis, the use of biogenic CuO NPs is a promising option for the purification of water resources contaminated with industrial dye.