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.

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.

Antivirulent Properties of Underexplored Cinnamomum tamala Essential Oil and Its Synergistic Effects with DNase against Pseudomonas aeruginosa Biofilms - An In Vitro Study.

Pseudomonas aeruginosa is a nosocomial pathogen colonizing patients with chronic infectious diseases and has gained resistance to all the known broad spectrum antibiotics available today. The present study showcases the antibiofilm potential of an essential oil (EO) from an underexplored Cinnamomum species namely, C. tamala, against P. aeruginosa biofilms. Furthermore, the synergistic effects of the EO along with a commercially available DNase (DNaseI) and a DNase (MBD) isolated from a marine bacterium were explored for its antibiofilm activity. The results showed that the synergized action has maximum efficacy in inhibiting young and preformed biofilms. The synergized effect of EO and DNaseI showed 70% inhibition against matured biofilms of P. aeruginosa. The EO from C. tamala also showed quorum sensing inhibitory potential as it could inhibit the swarming motility behavior of P. aeruginosa. The synergistic action of EO and DNases offers a novel alternate therapeutic strategy for combating P. aeruginosa biofilm associated infections.

Vasorelaxant and cardiovascular properties of the essential oil of Pogostemon elsholtzioides.

ETHNOBOTANICAL RELEVANCE: Pogostemon elsholtzioides Benth. (Lamiaceae) is an aromatic shrub, endemic to eastern Himalaya region. The leaves are used for treating goiter and high blood pressure (BP) by indigenous people in Arunachal Pradesh, India. Young leaves are used as vegetable and leaf decoction is also used for cough, cold and headache by some indigenous communities in Northeast India. AIM OF THE STUDY: This species is used for treating hypertension and the genus Pogostemon is rich in essential oil. Therefore, the present study was aimed at investigation of the chemical constituents, vasorelaxant and cardiovascular effects of the essential oil of P. elsholtzioides. MATERIALS AND METHODS: P. elsholtzioides was collected from Pasighat, Arunachal Pradesh, India and essential oil was extracted from shade dried leaves. Essential oil was analyzed by GC-FID and GC-MS and the volatile constituents were identified. Vasorelaxant and cardiovascular properties of the essential oil were studied against phenylephrine induced contraction in isolated endothelium intact aortic preparations and by measuring systolic and diastolic BP, mean arterial pressure (MAP) and heart rate (HR) after carotid artery cannulation in Wistar rats. RESULTS: The essential oil was rich in sesquiterpenes and curzerene, benzophenone, α-cadinol and germacrone were major constituents. The essential oil exhibited significant vasodilation effect in phenylephrine induced contracted aortic rings. Vasorelaxant effect of the essential oil was also observed both in the presence and absence of Nitro-L-arginine methyl ester against phenylephrine-contracted aortic rings. It also induced reduction of systolic and diastolic BP, MAP and HR. CONCLUSIONS: Essential oil of P. elsholtzioides exhibited significant vasorelaxant effect against endothelium intact aortic preparation mediated through nitric oxide dependent pathway and also reduced BP. However, further study is needed to screen the role of calcium ions in both intracellular and extracellular pathway.

Pogostemon hirsutus oil, rich in abietane diterpenes.

Volatile oil extracted from the leaves of Pogostemon hirsutus Benth., a rare species from Anamalai hills of the Western Ghats of Tamil Nadu, India was analyzed by GC-FID and GC-MS. Fifty-four compounds amounting to 90.8% of the oil were identified. The oil was rich in monoterpenes and diterpenes. The major components of the oil were alpha-pinene (11.5%), sabinene (8.5%), beta-pinene (5.2%), abietatriene (16.3%), dehydroabietal (3.5%) and dehydroabietol (21.0%). Abietane diterpenes are reported for the first time in the genus Pogostemon of Lamiaceae with six abietanes representing 42.6% of the oil.

Composition of the essential oil of Pogostemon travancoricus var. travancoricus.

The essential oil of Pogostemon travancoricus Bedd. var. travancoricus collected from the Agasthyamalai region of Tamil Nadu, India was analyzed by GC and GC-MS. The major components of the oil were bicyclogermacrene (16.0%), cis-calamenene (6.3%), germacrene B (11.1%), spathulenol (7.6%), viridiflorol (5.8%), alpha-cadinol (4.2%) and pogostone (9.9%).

Volatile oil composition of Pogostemon heyneanus and comparison of its composition with patchouli oil.

The volatile oil of the leaves of Pogostemon heyneanus Benth. (Lamiaceae) was analyzed by GC and GC-MS. Twenty-six components representing 96.0% of the oil were identified. The major components of the oil were acetophenone (51.0%), beta-pinene (5.3%), (E)-nerolidol (5.4%), and patchouli alcohol (14.0%). Comparison of the compositions of the oils of P. heyneanus and P. cablin (Blanco) Benth. (Patchouli oil) showed wide variation between them. Though 13 sesquiterpenes and oxygenated sesquiterpenes were detected in both oils, their concentrations in the oils differed widely. Acetophenone, benzoyl acetone and (E)-nerolidol present in the oil of P. heyneanus were not detected in patchouli oil.