Raman Spectroscopic Study of the Influence of Oxytocin and Uvariodendron anisatum Verdeck (Annonaceae) Freeze-dried Extracts on Diet Induced Obesity in Sprague Dawley Rats

Obesity is a condition affecting many people in the world. Obese people have increased risks of developing chronic metabolic diseases such as type II diabetes, hypertension, cancer among others. Early and rapid diagnosis of the condition together with effective treatment is therefore necessary. This work investigated, first, Raman spectroscopic similarities between oxytocin and a freeze-dried extract of a local herbal plant exhibiting oxytocin-like properties called Uvariodendron anisatum Verdeck (Annonaceae) (UAV). Secondly, whether Raman spectroscopy could be used for comparative studies of the influence of oxytocin and UAV on diet induced obesity in Sprague Dawley (SD) rat models. We also sought for obesity or metabolic syndrome biomarker Raman spectral bands. Both oxytocin and extract samples together with blood extracted from the rats were excited using a 785 nm laser with conductive silver paste smeared glass slides as Raman sample substrates. It was found that Raman spectral profiles of oxytocin solution and UAV freeze dried extract’s powder were identical with a cosine similarity value of 0.95 implying presence of similar Raman active molecules. The prominent peaks were those assigned to disulphide S-S stretching mode at 508 cm−1 and to tyrosine at 645 cm−1, 846 cm−1 and 1617 cm−1. Raman spectra of blood from oxytocin- and UAV-treated rats displayed similar profiles which were different from those of obese and non-obese (normal controls) animals. A prominent peak in spectra of treated rats centred at 401 cm−1 could be used as oxytocin biomarker band in blood. Comparison of average intensity trend of fructose bands at around 638 cm−1 and 812 cm−1 between prepared fructose solution and blood of treated rats, revealed elevated levels of fructose in blood of rats intraperitoneally injected oxytocin and UAV extracts. The result implied upregulation of fructose in oxytocin and UAV treated animals. Principal component analysis (PCA) showed that the Raman spectral profiles from blood of obese rats were different from those of non-obese rats. It also showed that spectra from oxytocin treated and UAV treated rat’s blood were similar indicating identical influence. The study shows the potential of Raman spectroscopy as tool for quick obesity (metabolic syndrome) screening with intensity of Raman bands associated with fructose acting as biomarkers. The same bands can also be used in comparative efficacy studies of anti-obesity drugs. Further studies are needed to validate these Raman spectroscopic results since, to the best of our knowledge, this was the first such investigation regarding comparison of UAV and conventional oxytocin together with their influence on obese SD rats. Weather human subjects exhibits similar results are also not known.

excited using a 785 nm laser with conductive silver paste smeared glass slides as Raman sample 23 substrates. It was found that Raman spectral profiles of oxytocin solution and UAV freeze dried 24 extract's powder were identical with a cosine similarity value of 0.95 implying presence of similar 25 Raman active molecules. The prominent peaks were those assigned to disulphide S-S stretching 26 mode at 508 cm -1 and to tyrosine at 645 cm -1 , 846 cm -1 and 1617 cm -1 . Raman spectra of blood 27 from oxytocin-and UAV-treated rats displayed similar profiles which were different from those 28 of obese and non-obese (normal controls) animals. A prominent peak in spectra of treated rats 29 centred at 401 cm -1 could be used as oxytocin biomarker band in blood. Comparison of average 30 intensity trend of fructose bands at around 638 cm -1 and 812 cm -1 between prepared fructose 31 solution and blood of treated rats, revealed elevated levels of fructose in blood of rats 32 intraperitoneally injected oxytocin and UAV extracts. The result implied upregulation of fructose 33 in oxytocin and UAV treated animals. Principal component analysis (PCA) showed that the Raman 34 spectral profiles from blood of obese rats were different from those of non-obese rats. It also 35 showed that spectra from oxytocin treated and UAV treated rat's blood were similar indicating 36 identical influence. The study shows the potential of Raman spectroscopy as tool for quick obesity 37 (metabolic syndrome) screening with intensity of Raman bands associated with fructose acting as 38 biomarkers. The same bands can also be used in comparative efficacy studies of anti-obesity drugs. 39 Further studies are needed to validate these Raman spectroscopic results since, to the best of our 40 knowledge, this was the first such investigation regarding comparison of UAV and conventional 41 oxytocin together with their influence on obese SD rats. Weather human subjects exhibits similar the best of our knowledge, was the first of its kind. It was found that little Raman spectral 94 differences exist between oxytocin and UAV extracts and no distinguishable differences were 95 observed on their influence on obese SD rats. Administration of these two compounds (i.e.

96
oxytocin and UAV extracts) via intraperitoneal injection to SD rats resulted in elevated levels of 97 fructose in blood as revealed by intensity analysis of assigned Raman bands. Administration of 98 these two compounds (i.e. oxytocin and UAV herbal extract) was done through intraperitoneal 99 routes since this was the most viable option for the SD rats besides being the method with a higher 100 clinical replicability.

227
The trend of the average intensity of peak around 812 cm -1 as a function of fructose concentration 228 (see Figure 2d) was identical to that from blood of SD rats (Figure 2b and 2c). The implication of 229 this was that fructose levels in blood of treated rats (oxytocin-and UAV extract-treated) were 230 higher than in obese and non-obese rats. This trend comparison also indicates that obese rats have The Raman spectral data from blood of obese (red squares) were clearly differentiated from those 257 of non-obese (black squares) rats as seen in the PCA score plot of Figure 3a. The segregation 258 between the rats administered oxytocin and UAV extracts was not clear which meant that their 259 Raman spectral profiles were almost identical due to presence of similar Raman active molecules.

260
Through the loadings plot of Figure 3

289
The study revealed that Raman spectroscopy can be a powerful tool for detecting obesity with 290 bands associated with fructose acting as biomarkers. It also showed that the technique can be used