ABSTRACT
Garcinia quaesita and Garcinia zeylanica are Sri Lankan endemic plants with significant therapeutic potential and numerous health-care applications. Despite this, there are no adequate literatures reported on the chemical compositions (CCs) and antioxidative potential (AP) of leaves' essential oils (EOs). The purpose of this study was to extract EOs from the leaves and investigate the CCs and AP of the extracted EOs. The hydro-distillation technique was used to extract the EOs, and the CCs of the EOs were identified through gas chromatography-mass spectrometry analysis. Only those compounds that had a matching value of more than 90% were taken into consideration, and the AP of the extracted EOs was determined using the ferric-reducing antioxidant power (FRAP) assay. Hydro-distillation process yielded EOs in the same quantity, 0.12% (v/w) on a fresh weight basis for two varieties. About 33 CCs that were found in the extracted EOs were mainly sesquiterpenes. The most prevalent substances in the EOs were copaene (19.39%), caryophyllene (12.94%), alloaromadendrene (12.12%), α-humulene (11.24%), and α-cubebene (9.38%). It is interesting to note that copaene and alloaromadendrene were only found in G. quaesita, whereas α-cubebene was only found in G. zeylanica. Caryophyllene and α-humulene were identified in both EOs at different concentrations. The EO from G. quaesita showed high AP, presenting FRAP values 274.74 ± 1.32 µL Trolox Eq/L. This study is recognized as being the first to examine the CCs and AP of EOs, and the results may inspire the creation of new uses and high-value leaf products.
ABSTRACT
Despite that Sri Lanka is a biodiversity hotspot with numerous guava varieties (Psidium guajava L.), no adequate scientific research has been reported on leaf essential oil (EO) composition based on varieties and its pharmacological properties, namely antioxidant properties. Therefore, this study focused to evaluate the chemical compositions and antioxidative capacity of EOs isolated from leaves of seven guava varieties grown in Sri Lanka, including apple-guava (P. pomiferum , PGA), common-guava (P. guaja v a , PGCG), two wild-guava; cultivar of P. guajava (PGG) and a cultivar of P. guineense (PGE), two introduced varieties of P. guajava (PGK and PGP), and one introduced variety of P. guineense (PGC). The EOs were isolated using hydro-distillation and the chemical compositions were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) technique, and the compounds that showed greater than 90% matching value were considered for characterization. The yields of EOs ranged from 0.02-0.26% (w/w) where PGE produced the greatest amount. About sixty-eight chemical compounds were identified from seven varieties and Sesquiterpenes were found to be the most abundant in the PGCG, PGG, PGE, and PGA varieties, whereas monoterpenes were found to be the most abundant in PGK, PGP, and PGC varieties. The sesquiterpenes, Nerolidol (70.0-7.9%), (-)-Globulol (21.0-7.0%), and Caryophyllene (20.4-1.4%) and monoterpenes, D-Limonene (30.3-14.1 %) were found as the major compounds of all studied guava varieties. Twenty-eight compounds were identified for the first time in guava EOs, including Cadinadiene-1,4, Benzylacetaldehyde, and Epiglobulol. The antioxidant efficacy of EOs varied from 329.56 ± 2.01 to 85.70 ± 2.01 µL Trolox Eq/L, where PGE showed the highest antioxidative potential. Ultimately, the chemical constituents and antioxidant capacity of isolated EOs varied with the variety, with EO from PGE leaves exerting an amazing antioxidant capacity compared to the others and being rich in Nerolidol. The findings of this study fill the gap in the literature on chemical constituents in the EO of guava leaves, and also it will open the avenue to discover novel potential compounds with outstanding pharmacological activities from guava leaves.
ABSTRACT
Sri Lanka is rich in a wide diversity of fruits, but many are underutilized by the people in Sri Lanka despite their nutritional value. This is mainly due to little awareness of the palatability of many fruits and hence low popularity in the market. The present study aimed at providing comparative data on the main biochemical and nutritional parameters of thirty-seven (37) species of fruits grown in Sri Lanka, including 22 underutilized fruits and 15 commonly consumed fruits. The main parameters of the comparison were the contents of ascorbic acid (AA), total vitamin C (TVC), total phenolic content (TPC), total flavonoid content (TFC), total iron (Fe), and antioxidant capacities (ACs). The mean AA, TVC, TPC, TFC, and Fe contents in 100 g of fresh edible portions of fruits ranged from 2.0 to 185.0 mg, 8.1 to 529.6 mg, 12.9 to 2701.7 mg gallic acid equivalent, 0.2 to 117.5 mg quercetin equivalents, and 0.1 to 1.1 mg, respectively. The IC50 values in a DPPH assay varied between 0.8 to 1856.7 mg/mL and FRAP values in a FRAP assay ranged from 4.2 to 2070 µmol FeSO4/g in the studied fruits. Fruits were ranked based on the levels of the abovementioned biochemical properties. Using this ranking, 12 of the top 15 fruits were underutilized. Phyllanthus emblica (Indian gooseberry) is at the top of these underutilized fruits, and Psidium guajava (guava) is the best among commonly consumed fruits. These results indicate that underutilized fruits in Sri Lanka can be recommended as high quality and low-cost alternatives for securing nutritional requirements. Hence, underutilized fruits can be promoted as healthy additional fruits in Sri Lanka.
