Long-term application of organic manures and chemical fertilizers improve the organic carbon and microbiological properties of soil under pearl millet-wheat cropping system in North-Western India.

An on-going long term field experiment started in Rabi 1995 at the Research Farm of the Department of Soil Science, Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana (India) under the pearl millet-wheat cropping system was selected to study the effect of long-term application of organic manures and fertilizers on soil organic carbon and microbiological properties. Highest soil organic carbon (SOC: 1.18 %), dissolved OC (DOC: 64.74 mg kg-1) content, microbial biomass C (MBC: 618.40 mg kg-1), dehydrogenase (DHA: 72.83 µg TPF g-1 24 hr-1), alkaline phosphatase (APA: 685.44 µg PNP g-1 soil hr-1) and aryl sulfatase (ASA: 12.56 µg PNP g-1 soil hr-1) activities were observed with the application of 15 Mg FYM+150 kg N+30 kg P2O5 ha-1. Integrated application of chemical fertilizers with pressmud showed superiority in the improvement of microbial biomass nitrogen (MBN: 73.73 mg kg-1) and urease activity (69.54 µg NH4+ g-1 hr-1) than FYM or poultry manure plus NP. Beneficial impacts of the sole application of organic manures on SOC, DOC, MBC content, DHA, APA, and ASA were found in order as: FYM > pressmud > poultry manure. Impacts of nutrient management practices on soil carbon fractions decreased with depth. Poultry manure application, either alone or in combination with NP fertilizers was inferior to FYM and pressmud. The SOC had a positive relationship with MBC (R2 = 0.95) and MBN (R2 = 0.75) and, also showed a highly positive and significant correlation with microbiological properties of soil. This dynamic equilibrium among soil properties indicated that the nutrient management practices that improve SOC could lead to improve soil fertility and accrued microbiological properties in these soils. This study revealed that conjuctive use of organic manures and chemical fertilizers have positive impact on soil fertility and microbiological properties as compared to sole application of organic manures or fertilizers; and among organic manures, FYM was superior to pressmud followed by poultry manure.

Metabolic differentiation and quantification of gymnemic acid in Gymnema sylvestre (Retz.) R.Br. ex Sm. leaf extract and its fermented products.

INTRODUCTION: Gymnemagenin is the bioactive metabolite found in Gymnema sylvestre leaves and possesses different therapeutic potential. Due to its lower abundance and higher market potential, gymnemagenin was obtained from chemical conversion and bacterial biotransformation. OBJECTIVE: To obtain the probiotic-based fermentative conversion of gymnemic acid-enriched G. sylvestre leaf extract to gymnemagenin-containing nutraceuticals and its metabolites based chromatographic comparison. MATERIAL AND METHODS: Gymnema sylvestre leaves were extracted through soxhalation, and the extract was prepared and characterised. Gymnemic acid was fermented, separately, by Lactobacillus casei, Lactobacillus rhamnosus, Bifidobacterium bifidum, and by their mix co-culture. The fermented materials were analysed for their gymnemagenin content, antioxidant potential, antidiabetic potential, and metabolomics analysis. RESULTS: Extraction yielded about 35% w/w of raw plant material, and 8.5% was found to be as total saponin content. Extract at higher concentration (≥ 5%, w/v) significantly altered the growth behaviour of probiotics. High-performance thin-layer chromatography (HPTLC) based quantification of gymnemagenin revealed that a maximum increase of 95.5% gymnemagenin was found in extract incubated with B. bifidum followed by mix co-culture containing (B. bifidum, L. casei, and L. rhamnosus), L. casei, and L. rhamnosus. However, liquid chromatography mass spectrometry (LC-MS) analysis resulted in the identification of a total of 56 metabolites. CONCLUSION: Chromatographically profiled, and probiotic-based fermented G. sylvestre leaves can be used as a potent nutraceutical for diabetes and other metabolic disorders.

Ultrasound-assisted extraction of gymnemic acids from Gymnema sylvestre leaves and its effect on insulin-producing RINm-5 F ß cell lines.

INTRODUCTION: Gymnema sylvestre is an important anti-diabetic medicinal plant, hence it is necessary to study the effective extraction of its active medicinal components. OBJECTIVE: To develop an efficient ultrasound-assisted extraction method for anti-diabetic gymnemic acids from Gymnema sylvestre leaves and measure their effect on insulin-producing RINm-5 F ß cells. METHODS: Box-Behnken's design and response surface methodology was applied to the ultrasound-assisted extraction of gymnemic acids from Gymnema sylvestre leaves. Analysis of gymnemic acids was carried out by high-performance thin-layer chromatography by converting total gymnemic acids into gymnemagenin by alkali hydrolysis. Effects of extracts on insulin production were tested on cultured, insulin-producing RINm-5 F ß cell lines. RESULTS: The point prediction tool of the design expert software predicted 397.9 mg gymnemic acids per gram of the defatted G. sylvestre leaves using ultrasound-assisted extraction, with ethanol at 60 °C for 30 min. The predicted condition shows 93.34% validity under experimental conditions. The ultrasound-assisted extract caused up to about four times more insulin production from RINm-5 F ß cells than extracts obtained from Soxhlet extraction. CONCLUSIONS: Response surface methodology was successfully used to improve the extraction of gymnemic acids from G. sylvestre leaves. The ultrasound-assisted extraction process may be a better alternative to prepare such herbal extracts because it saves time and may prevent excess degradation of the target analytes.