Hepatoprotective Potential of Malaysian Medicinal Plants: A Review on Phytochemicals, Oxidative Stress, and Antioxidant Mechanisms

Round 1

Reviewer 1 Report

Authors have reviewed the various hepatoprotective activities of Malaysian medicinal plants in manuscript entitled “Hepatoprotective Potential of Malaysian Medicinal Plants: A Review on Phytochemicals, Oxidative Stress, and Antioxidant Mechanisms”.  However, I didn’t find the manuscript well compiled and hence I am not recommending it for publication in current format. To justify my decision, I have following points for the authors. Moreover, English language also need moderate revisions. Punctuations also need to be checked carefully throughout the manuscript.

Introduction is very weak and not at all informative. Authors have not included the background about the various Malaysian medicinal plants. Mostly introduction is covering the information regarding liver and its role. This not main objective of the review and all the readers are well aware liver’s function and importance.

Novelty statement and scope of previous similar reviews is also missing. I suggest authors to make the review systematic by including information like inclusion and exclusion criteria of article by including PRISMA.

Further, Section 2. Hepatotoxicity and liver diseases, 3. Oxidative stress and ROS, and 3.1 Defense mechanisms against ROS are also not useful. The information mentioned in these sections are well covered in many other reviews and don’t feel this is useful for the current review.

If authors wish to include this information they can discuss while giving the importance of medicinal plants in section 4.

When it comes to the main portion i.e., Malaysian medicinal plants and hepatoprotection there is very little discussion is added by authors. It is desired that authors should discuss all the plants independently by including various successful case studies related to hepatoprotection. Also, I didn’t find all the tables informative. There is no IC₅₀ and other quantitative data in the tables. Even the animal model used in various studies is not mentioned. No concentration of active ingredients is mentioned in table 2 and table 3. Even I don’t feel table 2 and 3 needed independently. The information can be merged in one to make the review more readable and informative.

In current format, I am not recommending the article for the publication but if authors can take serious efforts to improve the manuscript, I will be happy to re-review the manuscript.

 

Author Response

Thank you for your valuable comments and suggestions which are very useful to improve our manuscript.

Authors have reviewed the various hepatoprotective activities of Malaysian medicinal plants in manuscript entitled “Hepatoprotective Potential of Malaysian Medicinal Plants: A Review on Phytochemicals, Oxidative Stress, and Antioxidant Mechanisms”.  However, I didn’t find the manuscript well compiled and hence I am not recommending it for publication in current format. To justify my decision, I have following points for the authors. Moreover, English language also need moderate revisions. Punctuations also need to be checked carefully throughout the manuscript.

Introduction is very weak and not at all informative. Authors have not included the background about the various Malaysian medicinal plants. Mostly introduction is covering the information regarding liver and its role. This not main objective of the review and all the readers are well aware liver’s function and importance.

Res: Thank you very much for your comments and suggestions. We have revised and restructured the manuscript completely and we have improved the introduction.

Novelty statement and scope of previous similar reviews is also missing. I suggest authors to make the review systematic by including information like inclusion and exclusion criteria of article by including PRISMA.

Res: Thank you very much for your comment. We have added search and screening strategy in the main text as ‘The data was obtained from various internet databases, including ScienceDirect, PubMed, ACS publications, Wiley, etc., and proceedings and theses. Records were searched with keywords related to Malaysian medicinal plants, distribution, taxonomy, hepatic protection, hepatic damage, bioactivity, biochemical composition, antioxidant, oxidative stress, etc Around 227 records, approximately from the years 2000 to 2021, were retrieved and screened. Among these, about 80 records were excluded due to being outside the scope of the review. Finally, a total of 147 records were adopted for the present review article. Furthermore, data from organisations such as the World Health Organization was also included”

 

Further, Section 2. Hepatotoxicity and liver diseases, 3. Oxidative stress and ROS, and 3.1 Defense mechanisms against ROS are also not useful. The information mentioned in these sections are well covered in many other reviews and don’t feel this is useful for the current review.

Res: Thank you very much for your comment. General information regarding oxidative stress, ROS, and defence mechanisms against ROS has been improved and kept in the main text as it will be helpful in understanding the mechanisms of recovery indicated by plant extract.

When it comes to the main portion i.e., Malaysian medicinal plants and hepatoprotection there is very little discussion is added by authors. It is desired that authors should discuss all the plants independently by including various successful case studies related to hepatoprotection. Also, I didn’t find all the tables informative. There is no IC₅₀ and other quantitative data in the tables. Even the animal model used in various studies is not mentioned. No concentration of active ingredients is mentioned in table 2 and table 3. Even I don’t feel table 2 and 3 needed independently. The information can be merged in one to make the review more readable and informative.

Thank you very much for your comments and suggestions. We have revised and restructured the manuscript completely. A detailed discussion regarding Malaysian plants has been included. Furthermore, the information regarding animal models, concentrations of active ingredients, duration, and percentage recovery has been mentioned in the main text and Table 1 has been deleted.

Reviewer 2 Report

Kindly improvise language of the text with the native English speaker. There is a lot passive voice misuse. There is a scope of improvement in the following sections. Specific comments are given below.

Page 2:

Line 48-49: Kindly rephrase it.

Line 54-55: Kindly rephrase it.

Line 69: both of them

Line 71-72: Kindly rephrase it.

Page 3:

Line 81-83: Kindly rephrase it

Line 86-92: Not able to understand. Please rewrite in comprehensive manner.

Line 114: Check spelling……Defense

Page 4:

Line 135-136: Kindly rewrite again

Page 5:

Line 146-148: Incorrect phrasing

Line 167-168: Passive voice misuse

Line 175: is used to treat: Wordy sentence. Kindly rewrite again

Line 176: The sap is also used in shampoos. Kindly rewrite again

Line 178-181: Incorrect phrasing

Line 183-185: Passive voice misuse

Page 6:

Line 90: Wordy sentence, Kindly rewrite again

Page 7:

Line 209-211: Passive voice misuse, Kindly rephrase it

Line 211: and are expensive

Line 261-265: Incorrect phrasing

Discussion

 Kindly improvise language of the text with the native English speaker.

1. I suggested authors to discuss in more comprehensive manner with support of recent published reports.

Author Response

Thank you for your valuable comments and suggestions which are very useful to improve our manuscript.

Line 48-49: Kindly rephrase it.

Line 48-49 has been rephrased.

Line 48-49: Kindly rephrase it.

Line 48-49 has been rephrased in the text as “The liver detoxifies and transforms numerous toxic substances so that they can be discharged through the kidneys for urine removal or into bile for colon clearance”

Line 54-55: Kindly rephrase it.

It has been rephrased in the text as ‘The review article aimed to provide an in-depth review of in vivo studies on Malaysian medicinal plants possessing hepatoprotective properties, phytochemical ingredients, and antioxidant mechanisms, with an emphasis on the species proven particularly useful for treating hepatic disorders."

Line 69: both of them

Line 69 has been rephrased as ‘’Acute hepatitis, caused by hepatitis B and C viral infections, also increases the risk of hepatic injuries’’

Line 71-72: Kindly rephrase it.

Line 71-72 has been rephrased as “At present, Malaysia is faced with the heavy burden (both medical and financial) of ongoing liver diseases, which will continue at least for the next 20–30 years [26]”

Line 81-83: Kindly rephrase it

It has been rephrased as ‘’Oxidative stress is a phenomenon caused by the imbalance between free radicals and antioxidants in our bodies. . It has been linked to more than 200 diseases [32].’’

Line 86-92: Not able to understand. Please rewrite in comprehensive manner.

It has been rephrased in the main text as “ROS are highly unstable molecules with only one electron in their outer shell, and they play a key role in tissue damage. Nitric oxide (NO^•), superoxide anion (^•O₂⁻), hydroxyl radical (^•OH), and hypochlorous acid (HOCl) are the most common examples [33]. They damage the cells by interacting with macromolecules such as proteins, lipids, and DNA. The effects of ROS on proteins are largely mediated by the initial modification of cysteine, methionine, histidine, tyrosine, and tryptophan residues, which triggers degradation and conformational changes [34,35].”

Line 114: Check spelling……Defense

The spelling Defense has been corrected

Line 135-136: Kindly rewrite again

it has been rewritten as "Oxidative stress is caused by the inhibition or lack of antioxidant enzymes, which can further damage and lyse cells. Antioxidant defence mechanisms are responsible for the prevention of free radical formation by oxidant scavenging, the transformation of harmful free radicals into less harmful substances, and the inhibition of the development of inflammatory mediators and secondary harmful metabolites. These defence systems work together to protect the body against the damaging effects of oxidative stress [45]."

Line 146-148: Incorrect phrasing

it has been correct as "According to the published data, nearly 25% of modern medicines have been developed from medicinal plants [53]"

Line 167-168: Passive voice misuse

It has been corrected as "Traditional healers have utilised these plants to cure a variety of ailments, including hepatic disorders"

Line 175: is used to treat: Wordy sentence. Kindly rewrite again

One of the medicinal plants used by the local people in Malaysia for treating various diseases is Aloe vera, which is locally known as Dihabuazo. The sticky sap obtained from its leaves is used to treat skin itches, cuts, burns, and stomach aches. This plant contains a variety of bioactive chemicals, including hydroxyanthraquinones, barbaloin, aloe-emodin, hydroxychromones, and aloesone.[68]. 

Line 176: The sap is also used in shampoos. Kindly rewrite again

The sentence has been deleted.

Line 178-181: Incorrect phrasing

Areca catechu L. is known as Lugus locally. This plant's seeds are mashed, and the juice is applied to cuts and scabies. The seeds can also be utilised to fight intestinal parasites and lower blood pressure and heart rate. It is used as a relaxant when eaten with Piper betle leaves. It contains a little amount of nicotine,

Line 183-185: Passive voice misuse

Mallotus miquellianus is used to treat jaundice, diarrhea, fever, and itchy skin [71]. Psidium guajava L. is locally known as Liaba or Siabas. The young leaves are used to cure stomachache, diarrhea, dysentery, and acute gastroenteritis. The fruit of the plant possesses the glucosides, guaijaverin, crataegolic, luteioic, and argamolic acids

Line 90: Wordy sentence, Kindly rewrite again

Line 90  has been corrected in the main text as. “The effects of ROS on proteins are largely mediated by the initial modification of cysteine, methionine, histidine, tyrosine, and tryptophan residues, which triggers degradation and conformational changes [34,35]”

Line 209-211: Passive voice misuse, Kindly rephrase it

Steroids, antiviral drugs, and immunizations are commonly used to treat and prevent liver illnesses; nevertheless, they are not only expensive, but they also have the potential to induce side effects.

Line 211: and are expensive.

The term expensive has been added.

Line 261-265: Incorrect phrasing

The statement has been rephrased. The study also highlighted different phytochemical compounds (tannins, saponins, quinones, terpenoids, steroids, flavonoids, phenols, alkaloids, glycosides, cardiac glycosides, coumarins, anthocyanins, etc.) with hepatoprotective properties found in Malaysian plants. In addition, the review showed various bioactive compounds, including andrographolide, lutein, eugenol, phytol, fucosterol, quercetin, squalene, gamolenic acid, rosmarinic acid, stigmasterol, kojic acid, linalool, kaempferol, ellagic acid, oleanolic acid, etc., with antioxidant, hepatoprotective, and anti-inflammatory properties.

 

 

Reviewer 3 Report

I recommend: 1) to expand the range of chemical compounds, including pharmacological agents that exhibit hepatotoxic properties in the animal body; 2) to characterize the role of chemical compounds, including pharmacological agents, in the regulation of the rate of formation of active oxygen radicals, initiating lipid peroxidation and the formation of oxidative stress; 3) provide data on the hepatoprotective effect of medicinal plants not only when using carbon tetrachloride and PCM, but also other hepatotoxicants; 4) in conclusion, specify the toxic compounds in relation to which medicinal plants have hepatoprotective properties, and explain how they manifest them (with which component the action is most strongly associated).

Author Response

Thank you for your valuable comments and suggestions which are very useful to improve our manuscript

1) to expand the range of chemical compounds, including pharmacological agents that exhibit hepatotoxic properties in the animal body; 2) to characterize the role of chemical compounds, including pharmacological agents, in the regulation of the rate of formation of active oxygen radicals, initiating lipid peroxidation and the formation of oxidative stress; 3) provide data on the hepatoprotective effect of medicinal plants not only when using carbon tetrachloride and PCM, but also other hepatotoxicants; 4) in conclusion, specify the toxic compounds in relation to which medicinal plants have hepatoprotective properties, and explain how they manifest them (with which component the action is most strongly associated).

Thank you very much for your comments. The chemical compound with the hepatoprotection has been highlighted with more details in the main text as  "The above mentioned phytochemical ingredients found in the hepatoprotective plants such as alkaloids, saponins, flavonoids, steroids, anthraquinones, etc., have been reported to have hepatoprotection. [112–117]. Chromatographically analysed active constituents, including andrographolide (diterpenoid), lutein (carotenoid), eugenol (phenol), phytol (diterpene alcohol), fucosterol (steroid), quercetin (flavonoid), squalene (triterpene) etc, have indicated hepatoprotective properties [131–137]."

Pharmacological agents with hepatotoxic properties such as fluconazole, amoxicillin, diclofenac, ciprofloxacin, oral contraceptives, chlorpromazine, and antitubercular drugs have been mentioned in the main text.

Hepatotoxins other than CCl₄ and PCM have been mentioned such as thioacetamide and thermoxidized palm oil.

Reviewer 4 Report

The current review focuses on phytochemical compounds isolated from various Malaysian medicinal plants and their role in hepatoprotection, emphasizing oxidative stress, anti-oxidant and anti-inflammatory markers, which is an interesting area. The review in the current form is not ready for publication but can be considered upon major and significant modifications with an exhaustive literature review and discussion.

 

Figure 2: What is the rationale for adding only four plants figures, the authors need to consider adding figures for plants listed in Table 1

 

Line 219: Due to many variations in the study, the information provided in the table remains incomplete and does not provide a proper and exhaustive overview. Therefore the following changes are suggested:

• Since all the assay types reported in this study are in vivo only, change the title to Table 1. In vivo hepatoprotective activity of Malaysian medicinal plants.
• Remove the word: ‘type of assay’ from the column, including ‘in vivo’ from all the cells under this column. Under the same column, add a concentration of liver damage inducer used, route of administration (PO: oral route, IP: intraperitoneal etc.), and the number of doses (single, two doses, etc.).
• Abbreviate the information under the following columns: Name of the plants (AP: Andrographis paniculate, parts utilized (L: leaves, A: aerial etc.), extract (E: Ethanol, M: Methanol etc.), inducer of liver damage (CCl4:Carbon tetrachloride, PCM: Paracetamol etc.
• Modify the ‘extract’ column title to ‘extract concentration and route of administration’ and add the concentration of extract that was given along (e..g 100 mg/kg..) with the route of administration (PO: oral route, IP: intraperitoneal etc..).
• Add another column with the duration of extract given prior to the induction of hepatotoxicity.
• Two more additional columns have to be added: the source for analyzing parameters (B: blood, T: homogenized tissue), other column reflecting the biochemical and histopathological parameters analyzed (for example, ALT, AST etc..) along with the addition of asterisk (*) sign for the parameters which were reported to be significant (ALT*, AST etc..).
• Under the table legend, expand all the abbreviations used.
• The information collected in this table should encompass the text, comparing and discussing the differences in study methodology, results obtained, etc. Multiple articles might have performed the hepatoprotective studies for similar plants with varied, similar, or contradictory results; a comparison is required to provide a holistic overview.

 

Add another table for in vitro, simulation, and cell line cultures studied for hepatoprotective activities of Malaysian medicinal plants. For example, the hepatoprotective effect of Andrographis paniculata on HepG2 cell line was studied: https://journals.sagepub.com/doi/full/10.1177/0960327112459530#_i2.

 

Table 2: The information provided is not accurate. For example, reference number 81 provided for Andrographis paniculata does not report the phytochemicals as claimed in the current review. Specific references for each phytochemical reported has to be added (e.g., Alkaloids (81), saponins (82) etc. along with the concentration reported total phenolics (65.37 ± 1.20 mg/g) expressed as gallic acid equivalent (GAE, mg/g of extract). Multiple articles may have reported the phytochemical compounds in their study for a similar plant, which needs to be presented, and, as such, probable reasons for differences need to be discussed.

 

Many articles do not seem to have been cited, and a review article should necessarily include such information. The methodology for conducting the review is lacking and should be added. What was the source of seeking information? (google scholar, Pubmed?..)

What were the search criteria used (keywords)?

What were the inclusion and exclusion criteria, and on what scientific rationale?

What was the time period followed for the collection of the information?

Similar plants reported in this study, although not native, may have been reported from other countries. How do they compare in comparison to the Malaysian reported data?

 

A significant percentage of articles are from more than five years ago. More articles from the recent publication also have to be included.

 

The discussion for table 3 is very superficial about the presence of antioxidant, anti-inflammatory, immunomodulatory, and hepatoprotective properties. In addition, which of those isolated compounds have antioxidant, anti-inflammatory, immunomodulatory, and hepatoprotective properties is not identified/highlighted in the table. Divide the active constituents into different columns of antioxidant, anti-inflammatory, immunomodulatory, and hepatoprotective properties. Kindly provide an exhaustive literature discussion on these topics.

 

The article needs to be adequately restructured. For example, the article focuses on oxidative stress and anti-oxidant mechanisms without discussing Malaysian medicinal plants' diverse roles or contributions.

Line 60 reference is required.

Recommend to share supplementary data, if any, used for the preparation of this review.

Author Response

Thank you for your valuable comments and suggestions which are very useful to improve our manuscript.

The current review focuses on phytochemical compounds isolated from various Malaysian medicinal plants and their role in hepatoprotection, emphasizing oxidative stress, anti-oxidant and anti-inflammatory markers, which is an interesting area. The review in the current form is not ready for publication but can be considered upon major and significant modifications with an exhaustive literature review and discussion.

Figure 2: What is the rationale for adding only four plants figures, the authors need to consider adding figures for plants listed in Table 1

Thank you very much for your comments and suggestions. We have added four available figures from our own resources. The rest of the plant figures we could not add due to a lack of copyright approval.

Line 219: Due to many variations in the study, the information provided in the table remains incomplete and does not provide a proper and exhaustive overview. Therefore, the following changes are suggested:

Table 1 has been deleted, and detailed information related to hepatoprotective plants has been added in the main text. The added information includes mode of administration, the concentration of active ingredients, number of doses, duration of extract and hepatotoxin exposure and biochemical and histopathology recovery, etc.

Since all the assay types reported in this study are in vivo only, change the title to Table 1. In vivo hepatoprotective activity of Malaysian medicinal plants.

• Remove the word: ‘type of assay’ from the column, including ‘in vivo’ from all the cells under this column. Under the same column, add a concentration of liver damage inducer used, route of administration (PO: oral route, IP: intraperitoneal etc.), and the number of doses (single, two doses, etc.).
• Abbreviate the information under the following columns: Name of the plants (AP: Andrographis paniculate, parts utilized (L: leaves, A: aerial etc.), extract (E: Ethanol, M: Methanol etc.), inducer of liver damage (CCl4:Carbon tetrachloride, PCM: Paracetamol etc.
• Modify the ‘extract’ column title to ‘extract concentration and route of administration’ and add the concentration of extract that was given along (e..g 100 mg/kg..) with the route of administration (PO: oral route, IP: intraperitoneal etc..).
• Add another column with the duration of extract given prior to the induction of hepatotoxicity.
• Two more additional columns have to be added: the source for analyzing parameters (B: blood, T: homogenized tissue), other column reflecting the biochemical and histopathological parameters analyzed (for example, ALT, AST etc..) along with the addition of asterisk (*) sign for the parameters which were reported to be significant (ALT*, AST etc..).
• Under the table legend, expand all the abbreviations used.
• The information collected in this table should encompass the text, comparing and discussing the differences in study methodology, results obtained, etc. Multiple articles might have performed the hepatoprotective studies for similar plants with varied, similar, or contradictory results; a comparison is required to provide a holistic overview.

Thank you very much for your comments and suggestions. Table 1 has been deleted. We have revised and restructured the manuscript completely. A detailed discussion regarding Malaysian plants has been included. Furthermore, the information regarding animal models, concentrations of active ingredients, duration, and biochemical recovery percentage, as well as histopathological observations, has been mentioned in the main text.

Round 2

Reviewer 1 Report

All manuscript is written good but the font color should be black. Some minor space correction is found in this manuscript.

Comments for author File: Comments.docx

Reviewer 4 Report

Reviewer V1: Q8: Add another table for in vitro, simulation, and cell line cultures studied for
hepatoprotective activities of Malaysian medicinal plants. For example, the
hepatoprotective effect of Andrographis paniculata on HepG2 cell line was studied:
https://journals.sagepub.com/doi/full/10.1177/0960327112459530#_i2.
Author Response: Thank you very much for your comment. In the current review, we have focused on
highlighting the effect of reported hepatoprotective plant extracts only using animal models.

Reviewer V2: Under the methodology of the review include the above author response along with the exclusion criteria 

For example, The current study reported hepatoprotective plant extracts mostly used in Malaysia in in vivo animal models only while excluding in vitro, simulation, and cell line cultures studies.