Biological effects of essential oils - A review

To identify the potential of green leafy vegetables (GLV) as antioxidants, methanolic extracts of Amaranthus sp., Centella asiatica, Murraya koenigii and Trigonella foenum graecum were studied for their antioxidant activity in different systems at multiple concentrations. Total antioxidant activity assessed by phosphomolybdenum method, free radical scavenging activity by 1,1-diphenly-2-picryl hydrazyl (DPPH), reducing power and ferrous ion chelating activity were determined. The GLV were analyzed for ascorbic acid, total and β-carotene and total polyphenol contents. The ascorbic acid, total carotene, β-carotene and total phenolic content (tannic acid equivalents) of the GLV ranged between 15.18–101.36, 34.78–64.51, 4.23–8.84 and 150.0–387.50 mg/100 g GLV, respectively. The extracts were found to have significantly different levels of antioxidant activities in the systems tested. The total antioxidant activity was highest in Murraya koenigii (2,691.78 μmol of ascorbic acid/g sample) and least in Centella asiatica (623.78 μmol of ascorbic acid/g sample). The extract concentration causing 50% inhibition of DPPH (IC50) was determined (M. koenigii < C.asiatica < Amaranthus sp. < T. graecum). The maximum DPPH scavenging activity and reducing power was exhibited by Murraya koenigii. Multiple regression analysis showed that the relationship of total antioxidant activity, free radical scavenging activity, and reducing power with polyphenol and total and β-carotene was highly significant.

Studies on Indian green leafy vegetables for their antioxidant activity.

Of the total carotenoids in respective algal samples, β-carotene in Spirulina platensis was 69.5%, astaxanthin and its esters in Haematococcus pluvialis was 81.38%, and lutein in Botryococcus braunii was 74.6%. The carotenoids were characterized by mass spectrometry. A time−course study of carotenoids in rats after administration of microalgal biomass showed peak levels in plasma, liver, and eyes at 2, 4, and 6 h, respectively. β-Carotene accumulation in Spirulina-fed rats was maximum in eye tissues at 6 h. Similarly, levels of astaxanthin and lutein in Haematococcus- and Botryococcus-fed rats were also maximal in eye tissues. Astaxanthin from H. pluvialis showed better bioavailability than β-carotene and lutein. The antioxidant enzymes, catalase, superoxide dismutase, peroxidase, and TBARS were significantly high in plasma at 2 h and in liver at 4 h, evidently offering protection from free radicals. This study implies that microalgae can be a good source of carotenoids of high bioavailability and nutrace...

Characterization of microalgal carotenoids by mass spectrometry and their bioavailability and antioxidant properties elucidated in rat model.

The antioxidative effect of Iranian Mentha pulegium extracts and essential oil in sunflower oil

Commercially available oils (olive oil, sunflower oil, palm oil, and a vegetable shortening) were enriched in polyphenols, by adding olive leaf extract. Addition of the extract was performed in suc...

Oxidative Stability of Edible Vegetable Oils Enriched in Polyphenols with Olive Leaf Extract

The investigation was undertaken with an objective of analyzing the antioxidant capacity of leafy vegetables (LV) and testing their efficacy on storage of heated oils. Four leafy vegetables viz., cabbage ( Brassica oleracea var. capitata), coriander leaves ( Coriandrum sativum ), hongone ( Alternanthera sessilis ), and spinach ( Spinacia oleracea ) were analyzed for antioxidant activity by standard methods. The ethanol extracts of LV were added to refined sunflower and groundnut oils heated to frying temperature and stored for 4 weeks, analyzed for peroxide value that indicates the oxidative state of oils. The polyphenol content ranged from 5 mg in cabbage to 69.5 mg in spinach. Reducing power of the leafy vegetables indicative of electron donating property for termination of free radical chain reactions followed the order—spinach Industrial relevance This paper presents an interesting approach using leafy vegetable extract with antioxidative properties to prevent oxidative damage during storage of heated oils. The temperature stability of antioxidants from leavy vegetables would allow to produce highly useful antioxidantive extracts from vegetable processing wastes.

Leafy vegetable extracts—antioxidant activity and effect on storage stability of heated oils

A considerable amount of bio-waste is generated while processing foods in the form of peel, seeds and inedible pulp material, which can be re-used for edible purposes after appropriate processing Ridge gourd peel is an edible bio-waste which is not used due to high dietary fiber content and a rough texture Hence, the present study was planned to explore the possibility of utilizing ridge gourd peel in a snack product to increase its fiber content Dried ridge gourd peel was incorporated to a traditional deep fried product, namely diamond cuts at 3, 6 and 9 per cent levels and the products were evaluated for nutritional composition, sensory quality and storage stability in different packaging materials Results showed that value addition of diamond cuts with ridge gourd peel increased the dietary fiber content of products significantly Lower level of incorporation were organoleptically acceptable, while higher level obtained a lesser sensory score The products were shelf stable as judged by lipid peroxidation upto 30 days of storage Metalized foil was superior for storage Hence, it can be concluded that ridge gourd peel could be used for food use and can be utilized for value addition in formulation of different products

B. N. Shyamala

Papers

Leafy vegetable extracts—antioxidant activity and effect on storage stability of heated oils

Utilizing Dehydrated Peels of Ridge Gourd ( Luffa Acutangula ) for Development of a High Fiber Snack Product

Quality Parameters of Fruit Cheese Developed Using Pineapple Pomace