Therapeutic potential of phytoconstituents of edible fruits in combating emerging viral infections.

Plant-derived bioactive molecules display potential antiviral activity against various viral targets including mode of viral entry and its replication in host cells. Considering the challenges and search for antiviral agents, this review provides substantiated data on chemical constituents of edible fruits with promising antiviral activity. The bioactive constituents like naringenin, mangiferin, α-mangostin, geraniin, punicalagin, and lectins of edible fruits exhibit antiviral effect by inhibiting viral replication against IFV, DENV, polio, CHIKV, Zika, HIV, HSV, HBV, HCV, and SARS-CoV. The significance of edible fruit phytochemicals to block the virulence of various deadly viruses through their inhibitory action against the entry and replication of viral genetic makeup and proteins are discussed. In view of the antiviral property of active constituents of edible fruits which can strengthen the immune system and reduce oxidative stress, they are suggested to be diet supplements to combat various viral diseases including COVID-19. PRACTICAL APPLICATIONS: Considering the increasing threat of COVID-19, it is suggested to examine the therapeutic efficacy of existing antiviral molecules of edible fruits which may provide prophylactic and adjuvant therapy with their potential antioxidant, anti-inflammatory, and immune-modulatory effects. Several active molecules like geraniin, naringenin, (2R,4R)-1,2,4-trihydroxyheptadec-16-one, betacyanins, mangiferin, punicalagin, isomangiferin, procyanidin B2, quercetin, marmelide, jacalin lectin, banana lectin, and α-mangostin isolated from various edible fruits have showed promising antiviral properties against different pathogenic viruses. Especially flavonoid compounds extracted from edible fruits possess potential antiviral activity against a wide array of viruses like HIV-1, HSV-1 and 2, HCV, INF, dengue, yellow fever, NSV, and Zika virus infection. Hence taking such fruits or edible fruits and their constituents/compounds as dietary supplements could deliver adequate plasma levels in the body to optimize the cell and tissue levels and could lead to possible benefits for the preventive measures for this pandemic COVID-19 situation.

Vasorelaxant property of Plectranthus vettiveroides root essential oil and its possible mechanism.

ETHNOPHARMACOLOGICAL RELEVANCE: Plectranthus vettiveroides (Jacob) N.P. Singh & B.D. Sharma is a traditional medicinal plant used in Siddha System of Medicine and its aromatic root is used to reduce the elevated blood pressure. AIM: The aim of the present study was to study vasorelaxant property of the root essential oil nanoemulsion (EON) of P. vettiveroides. METHODS: The EON was formulated to enhance the solubility and bioavailability and characterized. The preliminary screening was performed by treating the EON with aortic rings pre-contracted with phenylephrine (1 µM) and potassium chloride (80 mM). The role of K⁺ channels in EON induced vasorelaxation was investigated by pre-incubating the aortic rings with different K⁺ channel inhibitors namely, glibenclamide (a non-specific ATP sensitive K⁺ channel blocker, 10 µM), TEA (a Ca2⁺ activated non-selective K⁺ channel blocker, 10-2 M), 4-AP (a voltage-activated K⁺ channel blocker, 10-3 M) and barium chloride (inward rectifier K⁺ channel blocker, 1 mM). The involvement of extracellular Ca2+ was performed by adding cumulative dose of extracellular calcium in the presence and absence of EON and the concentration-response curve (CRC) obtained is compared. Similarly, the role of nitric oxide synthase, muscarinic and prostacyclin receptors on EON induced vasorelaxation were evaluated by pre-incubating the aortic rings with their inhibitors and the CRC obtained in the presence and absence of inhibitor were compared. RESULTS: The GC-MS and GC-FID analyses of the root essential oil revealed the presence of 62 volatile compounds. The EON exhibited significant vasorelaxant effect through nitric oxide-mediated pathway, G-protein coupled muscarinic (M3) receptor pathway, involvement of K+ channels (KATP, KIR, KCa), and blocking of the calcium influx by receptor-operated calcium channel. CONCLUSION: It is concluded that the root essential oil of P. vettiveroides is possessing marked vasorelaxant property. The multiple mechanisms of action of the essential oil of P. vettiveroides make it a potential source of antihypertensive drug.

Root essential oil of Chrysopogon zizanioides relaxes rat isolated thoracic aorta - an ex vivo approach.

Root of Chrysopogon zizanioides (L.) Roberty has been used in Siddha system of medicine to treat hypertension. The present study was therefore to investigate the vasorelaxation effect of root essential oil of C. zizanioides using rat isolated thoracic aortic rings. Chemical characterization of root essential oil was carried out using Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometry (GC-MS). Essential oil nanoemulsion (EONE) was prepared and characterized. Vasorelaxant effect of EONE in endothelium-intact aortic rings precontracted with phenylephrine (PE) (1 µM) or KCl (80 mM) was investigated. Role of Ca2+, nitric oxide and K+ channels in precontracted aortic rings were investigated to elucidate the mechanism of action of the essential oil. Further, the role of muscarinic and prostacyclin receptors in EONE induced relaxation was studied. The EONE significantly induced relaxation (Emax 77.1 ± 4.87%) in PE precontracted aortic rings. The nitric oxide synthase, and cyclooxygenase inhibitors and potassium channel blockers have not significantly inhibited the vasorelaxation induced by EONE. However, EONE induced relaxation in precontracted endothelium-intact aortic rings was significantly inhibited by muscarinic receptor and calcium channel. The root essential oil of C. zizanioides possesses vasorelaxant effect through muscarinic pathway as well as acts as calcium channel blocker.

Chemical characterization, antioxidant, antibacterial and enzyme inhibitory properties of Canthium coromandelicum, a valuable source for bioactive compounds.

The present study aimed at chemical characterization of Canthium coromandelicum leaf extracts (CCLE) and their in vitro pharmacological (antioxidant, enzyme inhibitory, and antibacterial) activities. Chemical characterization includes chemical profile of six extracts of CC by Gas chromatography - Mass spectrometry (GC-MS) analysis and total phenolics and flavonoids by spectrophotometric methods. Antioxidant activity was determined using eight assays. Enzymatic inhibitory property was evaluated by α-amylase and α-glucosidase inhibitory assays and antibacterial activity was studied against 10 pathogenic bacteria by agar disc diffusion method. GC-MS analysis enabled the identification of 65 compounds with palmitic acid, n-pentacosane, cycloartenol, linoleic acid, squalene, γ-sitosterol, nonacosane and α-tocopherol as major constituents of CCLE. Highest amount of total phenolics (58.03 mg GAE/g extract) and flavonoids (44.40 QE/g) was present in hydroalcoholic extract. Hydroalcoholic, methanolic and aqueous extracts showed significant free radical scavenging abilities and positive correlation was detected between antioxidant assays with recorded phenolics and flavonoids. Hydroalcoholic and methanolic extracts exhibited significant α-amylase (IC50 of 44.25 µg/mL) and α-glucosidase inhibitory activities (IC50 of 30.82 µg/mL) respectively.Methanolic and hydroalcoholic extracts at 750 µg/mL showed maximum antibacterial activity against S. typhi and S. flexneri respectively. Also, significant correlation was found between V. cholerae and R. equi as well as V. cholerae and S. epidermis. To conclude, C. coromandelicum could be considered as a natural antioxidant and potential source for therapeutic applications. However, widespread study is necessary to screen the role of recorded phytochemicals through in vivo studies to support its use in traditional medicine.

Evaluation of chemical composition, antioxidant and anti-hyperglycemic activities of the essential oil based nanoemulsions of Cinnamomum litseifolium.

In the present study, antioxidant and anti-hyperglycemic activities of nanoemulsions of the leaf essential oils of Cinnamomum litseifolium Thwaites collected from two different locations in the Western Ghats namely, Kannikatty, Kalakad Mundandurai Tiger Reserve, Tamil Nadu (Cl1) and Karamanayar, Agasthyamalai hills, Kerala (Cl2), India were studied. Essential oils were extracted from the leaves and characterized by GC-FID and GC-MS. Slight variation in the composition of leaf essential oils was observed. Essential oil based nanoemulsions were prepared using a surfactant (Tween-80), co-surfactant (propylene glycol) and an emulsifier (lecithin) by homogenization followed by ultra-sonication. Upon characterization, the nanoemulsion of Cl1 showed better stability than Cl2. Both nanoemulsions inhibited α-amylase and α-glucosidase enzymes with IC50 values of 1.998 and 0.780 mg/mL for Cl1 and 3.587 and 1.455 mg/mL for Cl2 respectively.

Cumin scented leaf essential oil of Cinnamomum chemungianum: compositions and their in vitro antioxidant, α-amylase, α-glucosidase and lipase inhibitory activities.

As part of our work on prospecting of Cinnamomum of the Western Ghats, chemical compositions, antioxidant, α-amylase, α-glucosidase and lipase inhibitory activities of leaf essential oil (EO) of Cinnamomum chemungianum were evaluated. Chemical characterisation of the cumin scented leaf EO from five locations in the southern Western Ghats revealed that they were highly varied. EO from Kannikatti (CC2) exhibited good α-amylase inhibitory activity with IC50 value of 5.97 µg/mL, whereas the EOs from Chemungi (CC1) and Athirumala (CC5) showed better α-glucosidase inhibition with IC50 of 56.65 and 62.12 µg/mL, respectively. The EOs from Chemungi, Kannikatti and Athirumala were found to inhibit lipase with IC50 of 919.75, 923.17 and 838.46 µg/mL, respectively. The EO of C. chemungianum may be used in food products as it has cumin scent and mild inhibitory activities.

Variation in volatile constituents of Cinnamomum keralaense, endemic to the Western Ghats, India.

Leaf essential oils (EOs) of Cinnamomum keralaense, an endemic species to Southern Western Ghats, India, were investigated. Leaves were collected from three distinct populations and hydro-distilled to obtain EOs, which were analysed by GC-FID and GC-MS. A total of 68 constituents was identified from three EOs. Wide variation was found in the composition of EOs. Ten major compounds were identified from three EOs, however, none of the compound was present in all three EOs as major constituent. High content of methyl eugenol (82.5%) in one of the EOs is significant as it could be evaluated for commercial utilization. This is the first report on the chemical compositions of leaf EOs of C. keralaense.

Characterization of the leaf essential oils of an endemic species Cinnamomum perrottetii from Western Ghats, India.

Essential oils from the leaf of Cinnamomum perrottetii Meissn. collected from three distinct populations in the southern Western Ghats, India were analysed by GC-FID and GC-MS. A total of 56 volatile constituents representing 92.2-96.3% of the oils were identified. Variations in the chemical constituents of the oils were found. Only three major components namely, α-pinene (5.1-6.6%), tau-cadinol (8.7-20.5%) and α-cadinol (7.3-13%) out of 10 were found in all three samples. To the best of our knowledge, this is the first report on the chemical compositions of leaf essential oil of C. perrottetii.